Guy Holt

Two diva lights and two 2ft kino flos won’t be enough to fill talent against the windows and get the kind of detail outside the windows seen in the first picture unless Jose gels the windows with a combination 85/ND gel. When shooting interiors with windows you have two basic problems: color temperature and contrast. Without either gelling the windows or substantially boosting the light levels inside, when you expose for your talent, your exterior will blow out. If you expose for the exterior to hold detail, your talent will be underexposed and become a near silhouette. If there are not many windows you can cover the windows with a combination of 85/ND9 gel. The gel both converts the exterior daylight from 5500K to 3200K and knocks down the level outside by three stops, so that the Kino Flos with 3200K tubes will be effective as fill lights. But, where a roll of 85/ND9 gel will set you back $140.00, it will be expensive and time consuming to gel the windows if there are a lot of them and it will have the effect of warming up the 5k coming through the window. Without gelling the windows to 3200K, using 3200K balanced lights doesn’t make a lot of sense. Balancing tungsten to 5500K is not very efficient because full color temperature blue correction gel (Full CTB) cuts the output of the light by 70% in converting it to 5500K. Jose’s 5000W 3200K light becomes a 1500W 5500K light when you put Full CTB on it. The output he would get after correction is not enough to key through the windows and not even enough to fill the wide shot with the windows uncorrected. In my experience, if you can’t gel the windows you probably need at least a 4k HMI par to pick up the interior levels in wide shots. For example, my company, ScreenLight & Grip, lit a segment of a special two-hour program for British Television’s Channel 5 that presented the same problem that you are facing. Host June Sarpong interviewing a marine archaeologists The show told the story of the Whydah - a pirate ship that sank off Cape Cod nearly 300 years ago. In a unique TV experiment, marine archaeologists on Cape Cod dove to the wreck to salvage pirate booty live on air. In addition to the dive on the wreck, the program also included specially shot dramatic recreations of the story of the Whydah’s notorious pirate captain Black Sam Bellamy. To link between the modern-day adventures of the marine archaeologists and those of Black Sam Bellamy, co-presenter June Sarpong hosted marine archaeologists and pirate historians from a makeshift studio under a tent situated on a bluff overlooking the dive site. Host June Sarpong interviewing a marine archaeologists Where they wanted the dive site to serve as a backdrop to the makeshift studio, the show's producers wanted the Salvage Ship to be seen clearly on the water in the shots of June and her guests. This requirement created a similar interior/exterior contrast problem to the one you are facing. The task of balancing interior levels to exterior levels was further complicated by the fact that it was a clear sunny day. We rigged a couple of 4kw and 2.5kw HMI Pars into the frame of the tent in order to get them as close as possible to our subjects, but even then we didn’t have quite enough output to compete against the sun outside. A 4k HMI Par was rigged overhead as a key for each subject The final ingredient for success was a double net strung across the open backside of the tent. The net further reduced the contrast by bringing the exterior levels down and in line with the pumped-up interior. The trick in situations like this is to strike a delicate balance between the interior and exterior light levels so that the net disappears to the camera without the exterior becoming overexposed and losing important detail – the Salvage Ship out on the water in this case.

Another advantage to netting the background is that it takes the hard edge off of HD. It creates the illusion of a shallower depth of field or the selective focus we associate with film. A double net was stretched across the open side of the tent facing out onto the water. Where it took a 4k Par on each of the talent, plus a double net across the back, you can see that you need a lot of light to balance interiors to exteriors. The problem with using 4k par HMIs is usually powering them. If you know how, you can plug them into wall outlets that are available on most locations – but, I should leave that to a latter post. Guy Holt, Gaffer, ScreenLight & Grip , Boston

Like every other DP & Gaffer, I have put together my favorite lighting package based upon my more than 20 years operating a lighting rental and production service company. For my package, I have picked lights that I feel offer both the highest output (lumens/watt) and the best production capability and have combined them with distribution technology I've developed that enhances the production capability of the new Honda Inverter Generators. As yet, I have not found a LED lighting fixture that warrants inclusion in my package. Trust me, I have looked at all of them and some still to come. Here are a few of my reasons why I prefer the Parabeam 400 fixtures over LED Panels and it has to do with more than just their spectral distribution. In HD Digital Cinema, the quality of light is more critical than ever. In High Def every detail of “on-camera” talent is rendered clearly on the screen – even the imperfections. Where LED and traditional hard light sources can exaggerate textural details, it is my opinion that fluorescent soft light is better for lighting talent in High Def productions because it can subdue those same textures and render a more cosmetic appearance. Primarily for this reason, I prefer the Kino Flo Parabeam fixtures, over LED Panels and other light sources, to serve as a Key source. Here are a few other reasons as well. What distinguishes the Parabeam fixtures from LED Panels and other fluorescent lights is their throw, power efficiency, and the innovative accessories Kino Flo makes available for the fixtures. Accessories include barndoors, a gel frame, a diffusion panel, and Honeycomb Louvers. These features enhance the production capabilities of the Parabeam fixtures and make them suitable to serve as a key, or even backlight, source where conventional fluorescent movie lights and LED light panels are not. Both conventional fluorescent movie lights (Kino Flo’s included) and LED light panels have a very broad light output that is hard to control. These lights also tend to drop off rapidly which means that to serve as a Key source, the units need to be positioned close to the subject they are lighting. These characteristics make them best suited to serve as Key sources in documentary interview set ups where the Keys are typically positioned close to the interview subject. In that capacity conventional fluorescent lights and LED light panels (with heavy diffusion) can generate a wonderful soft light that wraps around the interview subject without wilting them. But, given these characteristics, conventional fluorescent movie lights and LED light panels have only limited applications as fill sources in dramatic set lighting. The ParaBeam fixtures, on the other hand, have computer aided designed (CAD) parabolic reflectors that focus their light output where it is needed most for lighting dramatic scenes - at a medium distance – making them better suited as a Key source for HD Digital Cinema. If you compare the photometric tables of the Parabeam 400 and the Diva 400 (which uses the same four lamps), you will notice that at 16’ the Parabeam 400 puts out almost three times the light level (28FC) than the Diva 400 (10FC) even though they both use the same tubes. You can always diffuse a Parabeam to create a soft source, but nothing you do will make a Diva 400 or LED light panel punchier. In fact, a Parabeam 400 generates as much light at 16’ as the 4’ 8-Tube Kino Flathead 80 fixture, yet uses less than a quarter of the power (2 Amps verses 9.2 Amps.) While the seven amp difference is not a major consideration when using house power, it can make a difference when your power is limited (coming from a portable generator) because you can use four Parabeam 400s for the same power as a 4’ – 8 Bank Kino Flathead 80. And unlike the ballasts of Kino Flo’s fixture that use the T12 tubes, the Parabeam ballasts also include filters to reduce the return of harmonic currents into the power stream and improve their power efficiency. This makes them an especially efficient fluorescent light source that is comparable to the power efficiency of LED light panels and suitable for battery operation. For instance a Parabeam 400 puts out more light than even Zylight’s new high output LED light panel yet draws just .2 Amps more power. While the newest LED light panels (that use the higher output LEDs) approach the Parabeams in output, the Parabeam fixtures are more easily controlled – an essential requirement in a Key source. Parabeam fixtures are controlled by interchanging Kino Flos’ innovative Honeycomb Louvers. Louvers are available in 90, 60 and 45 degrees. Swapping louvers provides beam control similar to that of swapping lenses on an HMI Par. These features enhance the production capabilities of the Parabeam fixtures and make them suitable to serve as a Key or Backlight source where conventional fluorescent movie lights and LED light panels will spill all over the set. Kino Flo Parabeam fixtures are ideal for filming with the Red One. Since the Red’s native color balance is 5000K, it looks best when the lighting package consists of 5500K sources. Kino Flo Parabeam fixtures are a cost effective alternative to HMIs because they can use 5500K tubes. They provide beam control similar to that of swapping lenses on an HMI by interchanging their honeycomb louvers. And, they are even more efficient sources than HMIs. When using 5500K tubes to light for the Red’s 5000K native color balance, you can warm the lights without losing output to CTO gels by simply mixing in 3200K tubes with the 5500k tubes. Given the light sensitivity of the Red Camera, the more focused light of the Parabeam 400s is all that is needed for a key light even at a distance. The power that I save by using Parabeam 400s for key sources in my package, enables me to power more lights on the enhanced 7500W output of my modified Honda EU6500is generator. Using a 60A Full Power Transformer/Distro on my modified Honda EU6500is I am able to power a lighting package that consists of a 2.5kw, 1200, & 800 HMI Pars, a couple of Parabeam 400s and Parabeam 200s, and a Flat Head 80. Given the light sensitivity of the Red Camera this is all the light I need to light a large night exterior. (Use this link - http://www.screenlightandgrip.com/html/ema...generators.html - for a detailed description of the benefits to using Kino Parabeam 400s on portable generators (the section on the Parabeams is about three quarters of the way through the article.) Compared to LED fixtures, Kino Flo Parabeam fixtures are just as efficient but offer greater versatility. Able to interchange different color temperature tubes, and vary beam spread with their interchangeable honeycomb louvers, the Parabeam fixture can do what it takes four different LED Litepanel fixtures to accomplish – Spot and Flood in both 5500K and 3200K. Offering better light quality, output, beam control, and versatility, the Kino Flo ParaBeams make for a better key or back light for HD cinema production than just about any other light source. Not to mention that you can buy two Parabeam 400s for the asking price of a single LED light panel. Guy Holt, Gaffer, ScreenLight & Grip , Boston

The intent of my original post was not to ferment a rebellion against the established order of Alternating Current. While older HMIs with magnetic ballasts are less expensive to purchase or rent, Power Factor Correction (PFC) makes the newest electronic ballasts worth the extra money when it comes to lighting with portable generators. For example, the substantial reduction in line noise that results from using power factor corrected ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the load you can put on a generator. In the past we had to de-rate portable gas generators because of the inherent short comings of conventional generators with AVR and Frequency governing systems when dealing with non-PFC electronic ballasts. The harmonic distortion created by non-PFC ballasts reacting poorly with the distorted power waveform of conventional AVR generators limited the number of HMIs you could power on a portable generator to 75% of their rated capacity (4000Watts on a 6500W Generator). But now, where inverter generators have virtually no inherent harmonic distortion or sub-transient impedance and power factor correction (PFC) is available in small HMI ballasts, this conventional wisdom regarding portable gas generators no longer holds true. Where before you could not operate more than a couple 1200W HMIs with non-PFC ballasts on a conventional generator because of the consequent harmonic distortion, now according to the new math of low line noise, you can load an inverter generator to capacity. And if the generator is one of our modified Honda EU6500is inverter generators, you will be able to run a continuous load of up to 7500W as long as your HMI and Kino ballasts are Power Factor Corrected. According to this new math, when you add up the incremental savings in power to be gained by using only PFC HMI ballasts, add to it energy efficient sources like the Kino Flo Parabeam fixtures, and combine it with the pure waveform of inverter generators, you can run more lights on a portable gas generator than has been possible before. For example, as I mentioned in a previous post, on a Red shoot I operated a lighting package that consisted of a PFC 2.5kw HMI Par, PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80 on our modified Honda EU6500is Generator. Given the light sensitivity of the Red Camera, this was all the light we needed to light a large night exterior. For more details on how this is accomplished I suggest you read my newsletter article on the use of portable generators in motion picture production which I mention above. The article is available at www.screenlightandgrip.com/html/emailnewsletter_generators.html. Guy Holt, Gaffer, ScreenLight & Grip, Boston

Since power factor correction circuitry can add 20-25% to the cost of a ballast, rental houses will not buy them unless they are forced to by customer demand or regulatory agencies. In permanent installations, many jurisdictions are beginning to legally require power factor correction for all power supplies above a certain power level. Regulatory agencies such as the EU have also set harmonic limits as a method of improving power factor. The current EU standard EN61000-3-2 requires that all power supplies over 80w have a power factor of 0.9 or more. I detect in JD’s comment a whiff of nostalgia for the solidly reliable magnetic ballasts of yesteryear. I agree with him. There is a popular misconception that you should only use electronic ballasts with portable generators. Where that is true with conventional generators without crystal governors, it is not true of inverter generators like the Honda EU series. In the interest of full disclosure, I should say at this point that in addition to being a gaffer, I own and operate ScreenLight & Grip – a lighting and grip equipment rental and sales company. If what I am about to say sounds like I’m hyping magnetic ballasts it is not because we rent and sell them exclusively. We are dealers and rental agents for just about all the major brands and I don’t stand to profit from the sale or rental of magnetic HMI ballasts since we have made the transition to PFC electronic ballasts. As a professional Gaffer of a lot of tight budgeted historical documentaries for PBS’ American Experience and The History Channel (see my “credit-entials” on Imbd), I think it is worth noting that magnetic ballasts are still a viable production tool when used with the new inverter generators because they offer low budget independent filmmakers a cheaper alternative to high priced rental house equipment. Magnetic ballasts will operate reliably on the Honda EU series generators because Honda's sine-wave inverter technology provides much higher quality power than conventional (non-inverter) generators. With a waveform distortion factor of less than 2.5%, the power generated by Honda’s EU series of generators is quite often better than what you get out of the wall outlet. The power these machines generate is rock solid with a frequency variance of only hundredths of a cycle - which eliminates the need for costly crystal governors. The Honda EU series generators provide true sine wave power with low enough distortion, and frequency stability, to power HMI's with magnetic ballasts without problems. As long as you shoot at one of the many safe frame rates, magnetic ballasts are also “flicker free” (where the topic of safe frame rates for magnetic ballasts is discussed extensively elsewhere in this forum I won’t get into it here.) Besides the extra bulk and weight of magnetic ballasts, the smaller magnetic ballasts (575-2500W) offer the distinct advantage of being less expensive and drawing less power (once they have come up to speed) than the commonly available non-PFC electronic equivalents. If you don’t have access to the newest PFC electronic ballasts, you are better served by using the older magnetic ballasts on an inverter generator like the Honda EU 6500is over non-PFC electronic ballasts. I know this is contrary to the conventional wisdom, so I will quickly summarize why. When electronic square wave HMI ballasts came on the market, they were at first thought to be the solution to all the problems inherent in running HMI lights on small portable generators. By eliminating the flicker problem associated with magnetic ballasts, they also eliminated the need for the expensive and ultimately unreliable AC governors required for flicker free filming with magnetic HMI ballasts and portable gas generators. Electronic square wave ballasts eliminate the potential for flicker by squaring off the curves of the AC sine wave supplying the globe. Squared off, the changeover period between cycles is so brief that the light no longer pulsates but is virtually continuous. Even if the AC Frequency of the power were to vary, a frame of film or video scan, would receive the same exposure because the light intensity is now not pulsating but nearly constant. Electronic square wave HMI ballasts allow you to film at any frame rate and even at a changing frame rate. Since they are not frequency dependent, it was thought at first that electronic square wave ballasts would operate HMI more reliably on small portable generators – even those without frequency governors. For this reason, as soon as electronic square wave ballasts appeared on the market, many lighting rental houses replaced the more expensive crystal governed portable generators with less expensive non-synchronous portable generators. The theory was that an electronic square wave ballast would operate reliably on a non governed generator and allow filming at any frame rate, where as a magnetic HMI ballast operating on an unreliably AC governed generator allowed filming only at permitted frame rates. In practice, electronic square wave ballasts turned out to be a mixed blessing. Part of the problem with operating electronic HMI ballasts on portable gas generators in the past has to do with the purity of the power waveform they generate. With an applied voltage waveform distortion of upwards of 19.5%, conventional generators do not interact well with the leading power factor (current leads voltage) of the capacitive reactance created by electronic square wave HMI ballasts. The net result is harmonic currents are thrown back into the power stream, which results in a further degradation of the voltage waveform and ultimately to equipment failure or damage (for the reasons discussed in my previous post.) The oscilloscope shots of the power waveforms below is from my article mentioned above and is typical of what results from the operation of a 1200W HMI with non-power factor corrected ballast on grid power (left), on a conventional generator (middle), and inverter generator (right.) The adverse effects of the harmonic noise generated by non-PFC electronic ballasts and exhibited here in the middle shot, can take the form of overheating and failing equipment, circuit breaker trips, excessive current on the neutral wire, and instability of the generator’s voltage and frequency. Harmonic noise of this magnitude can also damage HD digital cinema production equipment, create ground loops, and possibly create radio frequency (RF) interference. Left: Grid Power w/ 1.2Kw Arri non-PFC Elec. Ballast. Center: Conventional AVR Power w/ 1.2Kw Arri non-PFC Elec. Ballast. Right: Inverter Power w/ 1.2Kw Arri non-PFC Elec. Ballast. As is evident in the oscilloscope shots below of a 1200W magnetic HMI ballasts on grid power, on power generated by a conventional Generator (Honda EX5500), and power generated by an inverter generator (Honda EU6500is), the lagging power factor caused by the inductive reactance of magnetic ballasts has by comparison only a moderately adverse effect on the power waveform. Outside of causing a voltage spike in the inverter power, magnetic ballasts actually show a positive effect on the already distorted power waveform of the Honda EX5500 conventional generator. For this reason magnetic ballasts work better on conventional generators with frequency governors than do non-PFC electronic square wave HMI ballasts. Left: Grid Power w/ 1.2Kw Arri Magnetic Ballast. Center: Conventional AVR Power w/ 1.2Kw Arri Magnetic Ballast. Right: Inverter Power w/ 1.2Kw Arri Magnetic Ballast. These oscilloscope shots show that if you don’t have access to the newest PFC electronic ballasts, the older magnetic ballasts are in fact cleaner running on portable gas generators than non-PFC electronic ballasts. And, where inverter generators like the Honda EU6500is do not require crystal governors to run at precisely 60Hz, you can operate magnetic HMI ballasts reliably on them. In addition, the smaller magnetic ballasts (575-2500W) offer the distinct advantage of being less expensive and draw less power (once they have come up to speed) than the commonly available non-PFC electronic equivalents (13.5A versus 19A for a 1.2kw.) Of course there are downsides to using magnetic ballasts. One down side is that you are restricted to using only the safe frame rates and shutter angles. But when you consider that every film made before the early 1990s was made this way, you realize it is not such a limitation. Another downside to magnetic ballasts is that you can’t load the generator to full capacity because you must leave “head room” for their higher front end striking load. When choosing HMIs to run off portable generators, bear in mind that a magnetic ballasts draws more current during the striking phase and then they “settle down” and require less power to maintain the HMI Arc. By contrast, an electronic ballasts “ramps up”. That is, its’ current draw gradually builds until it “tops off.” For example, even though a 2.5kw magnetic ballast draws approximately 26 amps you will not be able to run it reliably on the 30A/120V twist-lock receptacle on a 6500W generator’s power panel. As mentioned above, magnetic ballasts have a high front end striking load. For this reason, you must always leave “head room” on the generator for the strike. But, even though the twist-lock receptacle is rated for 30 Amps conventional 6500W generators are only capable of sustaining a peak load of 27.5 Amps per leg for a short period of time. Their continuous load capacity (more than 30 minutes) is 23 Amps per leg. And if there is any line loss from a long cable run the draw of a 2.5kw magnetic ballast will climb to upward of 30 Amps. To make matters worse, the lagging power factor caused by the inductive reactance of the magnetic ballast kicking harmonic currents back into the power stream causes spikes in the supply voltage that can cause erratic tripping of the breakers on the generator or ballast. For a more detailed explanation of why that is I, again, suggest you read my newsletter article. The article is available at www.screenlightandgrip.com/html/emailnewsletter_generators.html. In my experience the load of a 2.5kw magnetic ballast is too near the operating threshold of a 6500W generator for it to operate reliably. The only sure way to power a 120V 2.5kw (or even a 4kw) HMI magnetic ballast on a portable gas generator is from its 240V circuit through a 240v-to-120v step down transformer like the one we manufacture for our modified Honda EU6500is. Our 60A Full Power Transformer/Distro steps down the 240V output of the generator to a single 60A 120V circuit that is capable of accommodating the high front end striking load, and even the voltage spikes, of either a 2.5kw or 4kw magnetic ballast at 120V. And, by splitting the large front end striking load of 2.5/4kw HMIs evenly over the two legs of the 240V circuit of the generator, the transformer reduces the impact on the generator when you first switch on the light. The same holds true when you switch on large tungsten lights like 6000W Molepar Six Lights or 5ks. And since, magnetic HMI ballasts will operate flicker free at all standard frame rates on an inverter generator (without the need for a crystal governor), our 60A Full Power Transformer/Distro gives new production life to older 2.5kw & 4kw HMIs with 120V magnetic ballasts. It provides an affordable way of powering more affordable HMIs. Guy Holt, Gaffer, ScreenLight & Grip, Boston

Since, this is getting way off the topic of this thread, I have started a new thread ( What is Power Factor Correction in HMIs) to give a detailed answer this question. If you haven't already, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind harmonic distortion and how it can adversely effect generators. The article is available on our website. Guy Holt, Gaffer, ScreenLight & Grip , Boston

John’s guess is correct. It is when the voltage waveform induced by the load deviates from a sine wave that power factor correction gets expensive. For instance, in the strictest sense magnetic HMI ballasts are “Power Factor Corrected.” In order to understand what I mean, it would help to understand some basic electrical engineering principles. If you haven't already, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind harmonic distortion and how it can adversely effect generators. The article is available on our website. Here is a much simplified explanation of power factor and why it is necessary in HMI & Kino ballasts. With a purely resistive AC load (Incandescent Lamps, Heaters, etc.) voltage and current waveforms are in step (or in phase), changing polarity at the same instant in each cycle ( a high power factor or unity.) With “non-linear loads” (magnetic and electronic HMI & Fluorescent ballasts) energy storage in the loads, impedes the flow of current and results in a time difference between the current and voltage waveforms – they are out of phase (a low power factor.) In other words, during each cycle of the AC voltage, extra energy, in addition to any energy consumed in the load, is temporarily stored in the load in electric or magnetic fields, and then returned to the power distribution a fraction of a second later in the cycle. The "ebb and flow" of this nonproductive power increases the current in the line. Thus, a load with a low power factor will use higher currents to transfer a given quantity of real power than a load with a high power factor As John correctly surmises, basic power factor correction brings the voltage and current waveforms back in phase (closer to unity power factor) by supplying reactive power of opposite sign, adding capacitors or inductors which act to cancel the inductive or capacitive effects of the load, respectively. For example, the inductive effect of motor loads may be offset by locally connected capacitors. If a load had a capacitive value, inductors are connected to correct the power factor. In the electricity industry, inductors are said to consume reactive power and capacitors are said to supply it, even though the reactive power is actually just moving back and forth on each AC cycle. The make up of a magnetic HMI ballast is very similar to an electric motor and hence, like an electric motor, has an inductive effect on the power supply. Between the power input and the HMI lamp is a transformer that acts as a choke coil. The transformer provides the start-up charge for the igniter circuit, rapidly increasing the potential between the electrodes of the head’s arc gap until an electrical arc jumps the gap and ignites an electrical arc between the lamp electrodes. The transformer then acts as a choke, regulating current to the lamp to maintain the pulsating arc once the light is burning. Essentially a large coil of wire that is tapped at several places to provide for various input voltages and a high start-up voltage, the transformers of magnetic HMI ballasts exhibit high self-inductance. Self-inductance is a particular form of electromagnetic induction characteristic of coils (like those in magnetic HMI ballasts and electric motors) that inhibits the flow of current in the windings of the coil. This opposition to the flow of current is called inductive reactance. In the case of a magnetic HMI ballast, the multiple fine windings of the ballast transformer induces appreciable voltage and considerable current that is in opposition to the primary current, causing the primary current to lag behind voltage, a reduction of current flow, and an inefficiency in the use of power supplied by the generator. Put simply, the ballast draws more power than it uses to create light. As John Sprung' suggests, the addition of capacitors will compensate for the high inductance of the transformer and bring the current partially back in phase with the voltage. For this reason a bank of capacitor is typically included in the design of magnetic HMI ballasts as a power factor correction circuit. In this sense magnetic ballasts are power factor corrected. If, in the case of a magnetic ballast, you were to measure the current (using a true RMS Amp Meter) and voltage (using a Volt Meter) traveling through the cable supplying the magnetic HMI ballast and multiply them according to Ohm’s Law (W=VA) you would get the “apparent power” of the ballast. But, if you were to instead, use a wattmeter to measure the actual amount of energy being converted into real work (light) by the ballast, after the applied voltage overcomes the induced voltage, you would get the “true power” of the ballast. The ratio of “true power” to “apparent power” is a measure of the “power factor” of the ballast and is expressed by a number somewhere between 0 and 1. Where a typical 1200W magnetic HMI ballast takes 13.5 Amps at 120 Volts to generate 1200 Watts of light the power factor is .74 (13.5A x 120V= 1620W, 1200W/1620W= .74). The favorite analogy electricians like to use to explain power factor is that if apparent power is a glass of beer, power factor is the foam that prevents you from filling it up all the way. When lights with a low power factor are used, a generator must be sized to supply the apparent power (beer plus foam), even though only the beer (true power) counts as far as how much actual drinking is possible. By comparison to magnetic HMI ballasts, electronic HMI ballasts are quite a bit more complicated. In an electronic HMI ballast, AC power is first converted into DC. Then, a high-speed switching device (micro processor controlled IGBTs) turns the flat current into an alternating square wave. Hence, they are commonly referred to as square wave ballasts. Electronic square wave ballasts utilize solid state electronic components (rectifiers, capacitors, and IGBTS) which use only portions of the input power sine wave. Put simply, they place all their load on the peak values of the power waveform. These devices then return the unused portions to the power stream as harmonic currents. These harmonic currents stack on top of one another creating harmonic distortion that likewise creates an opposition to the flow of current, pulls the voltage and current out of phase, and when the power is supplied by a generator can lead to severe distortion of the voltage waveform in the power distribution system. For example, the power waveform below left (from my article) is typical of what results from the operation of a 2500W non-Power Factor Corrected load (electronic HMI & Kino ballasts) on a conventional portable generator (a Honda EX5500 with a Barber Coleman Governor.) The severe harmonic noise exhibited here can cause overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral return, and instability of the generator's voltage and frequency Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400. The opposition to the flow of current caused by harmonic distortion is called capacitive reactance. Capacitive reactance acts on the waveform in a way opposite to inductive reactance. It causes current to lead voltage. Since an electronic ballast also puts current and voltage out of phase with one another, it also has a power factor. An electronic square wave HMI ballast typically has a power factor less than .6, meaning the ballast has to draw 40 percent or more power than it uses. Where a typical 1200W non-power factor corrected electronic HMI ballast takes 18.5 Amps at 120 Volts to generate 1200 Watts of light the power factor is .54 (18.5A x 120V= 2220W, 1200W/2220W= .54). When using a lighting package with low power factor (like the pkg. of non-PFC electronic HMI & Kino ballasts depicted above), the conventional wisdom in the past has been to not load the generator beyond 75% for more than a short period. Where the maximum recommend continuous load on a 6500W generator is 5500W, the de-rated continuous load rating would be roughly 4000 watts. By de-rating the load capacity in this fashion, the Gaffer minimizes the adverse effects of high THD so that both the generator and the loads placed upon it operate more reliably. However, this conventional wisdom no longer holds true if the HMI & Kino ballasts are power factor corrected and powered by an inverter generator. For example, the power waveform above on the right, is the same 2500W load but with power factor correction operating on our modified Honda EU6500is Inverter Generator. As you can see, the difference between the resulting waveforms is startling. Even though the load is the same, the fact that it is power factor corrected, and the power is being generated by an inverter generator, results in virtually no power waveform distortion. What this means is that an inverter generator can be loaded to capacity with PFC HMI and Kino Flo ballasts. The substantial reduction in line noise that results from using PFC ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the continuous load you can put on a portable gas generator (in the case of our modified Honda EU6500is generator a capacity of 7500 Watts.) Since power factor correction can be of tremendous benefit when operating HMIs and Kinos on portable gas generators, it is worth understanding in more detail. Since, as exhibited in the waveform above, capacitive reactance distorts the shape of the voltage waveform from a sine wave to some other form, the addition of linear components such as inductors cannot counteract the harmonic currents as the addition of capacitors counteracted the inductive reactance of magnetic HMI ballasts. In the case of electronic ballasts, other more complicated (translate expensive) means of power factor correction is required to smooth out the power waveform they induce. To understand how power factor correction circuits work in electronic HMI ballast it helps to understand the source of the harmonic currrents. The harmonic currents produced by electronic HMI ballasts are primarily generated by the diode-capacitor section of the ballast. As you may recall from our discussion above, the diode-capacitor section rectifies the AC input power into DC, which is then used by the power module to create the square wave. The diode-capacitor section accomplishes this by first feeding the AC input current through a full wave bridge rectifier, which inverts the negative half of the AC sine wave and makes it positive. The rectified current then passes into a bank of capacitors which removes the 60 Hz rise and fall and flattens out the voltage-making it essentially DC. The required DC is then fed from these capacitors to the power module where the IGBTs switch it into an alternating square wave. (ILLUSTRATION COURTESY OF HARRY BOX) Step 1: Rectifier Bridge converts AC power to rectified sine wave. Step 2: capacitors flatten the rectified sine wave to DC. Step 3: micro processor switching alternates polarity of DC creating an AC square wave. The source of harmonics currents lies in the rectifying circuit of the diode-capacitor section of the ballast. The rectifying circuit only draws current from the AC line during the peaks of the supply voltage waveform, charging the capacitors to the peak of the line voltage. Since the capacitors only charge when input voltage is greater than its stored voltage, a non-PFC circuit only charges the capacitors for a brief period of the overall cycle time. After 90 degrees, the half cycle from the bridge drops below the capacitor voltage; which back biases the bridge, inhibiting further current flow into the capacitor. During this brief charging period, the capacitors must be fully charged, requiring large pulses of current to be drawn for a short duration. As can be seen in the illustration below, electronic ballasts draw current in high amplitude short pulses. The remaining unused current feeds back into the power stream as harmonic currents. (ILLUSTRATION COURTESY OF FAIRCHILD SEMICONDUCTOR) Thin Black Trace: Rectifier Bridge converts AC power to rectified sine wave. Thick Black Trace: Stored Capacitor Voltage. Red Trace: Current drawn by capacitors once input voltage is greater than voltage stored in the capacitor (thick black trace.) Notice how big the input current spike (red trace) of the rectifier circuit is. All the circuitry in the ballast as well as the supply chain (the generator plant, distribution wiring, circuit breakers, etc) must be capable of carrying this high peak current. In order not to have these high amplitude current pulses, the capacitors in the diode-capacitor section of the ballast must charge over the entire cycle rather than just a small portion of it. The power factor correction circuitry of electronic HMI ballasts use a multi-stage boost converter topology to accumulate energy in the capacitors over the entire cycle, which averages out the peak load, and greatly reduces the huge peak current. In the “Active Power Factor Correction” circuits used in electronic square wave ballasts, a boost converter is inserted between the bridge rectifier and the main input capacitors. The boost converter maintains a constant DC bus voltage on its output while drawing a current that is always in phase with and at the same frequency as the line voltage. Another switch mode converter produces the desired output voltage from the DC bus. Where the input to the converter is the full-rectified AC line voltage, the output voltage of the boost converter is set higher than the peak value (hence the word boost) of the line voltage (a commonly used value is 385VDC to allow for a high line of 270VACrms.) Now that the capacitors charge throughout the AC cycle rather than just a brief portion of it, harmonic currents are not generated. And, with the boost pre-converter voltage higher than the input voltage, the load is forced to draw current in phase with the AC main line voltage. In this fashion, the PFC circuit realigns voltage and current and induces a smoother power waveform at the distribution bus. PFC circuits successfully increase the power factor to as much as .9, making ballasts with it near linear loads. As a result, the ballast uses power more efficiently with minimized return current and line noise and also reduces heat, thereby increasing their reliability. If you still don’t entirely understand how power factor correction works in electronic HMI ballasts, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it, is a more detailed explanation of the basic electrical engineering principles behind harmonic distortion and how it can adversely effect generators. The article is available on our website. Guy Holt, Gaffer, ScreenLight & Grip, Boston

So that we could rent a 1200W ballast that our customers could plug equally into a 20A as well as 15A circuit, I asked our Arri rep several years ago why they did not offer power factor correction in their 1200 electronic ballasts. His response was that no body would pay what PFC circuitry would add to the cost of the ballast. While it is true that all major manufacturers include PFC circuitry in HMI ballasts in the 6-18kw range - they do so by necessity. The early line of Lightmaker electronic ballasts (some of which are still kicking around ebay) proved that PFC circuitry was absolutely necessary in large ballasts to reduce heat and returns on the neutral, and to increase ballast reliability. Because of the added cost, weight, and complexity of PFC circuitry, ballast manufacturers in the US have offered PFC circuitry only as an option in medium-sized 2.5-4kw ballasts. And, until very recently manufacturers did not offer PFC circuitry in HMI ballasts smaller than 2.5kw in the US (in the EU PFC circuitry in mandatory in all HMI ballasts sold.) Part of the problem was that PFC circuitry did not offer a huge advantage when plugging into house power. A typical 1200W Power Factor Corrected electronic HMI ballast will draw 11 Amps at 120 Volts verses the 19 Amp draw of a non-PFC electronic ballast. While not a huge advantage when plugging into house power, the added efficiency of a PFC 1200 ballast can make a huge difference when powering a lighting package off of a portable generator. For example, when you consider that a Kino Flo Parabeam 400 draws only 2 amps, the 8 Amp difference between using a PFC 1200W electronic ballast and standard non-PFC 1200W electronic ballast, can mean the difference between running four additional Parabeam 400s on a portable generator or not – I think you would have to agree that is a major boost in production capability and pertinent to any one using a portable generator as their principle source of set power. But that is not the only benefit to using PFC electronic ballasts. The substantial reduction in line noise that results from using power factor corrected ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the load you can put on a generator. In the past we had to de-rate portable gas generators because of the inherent short comings of conventional generators with AVR and Frequency governing systems when dealing with non-PFC electronic ballasts. The harmonic distortion created by non-PFC ballasts reacting poorly with the distorted power waveform of conventional AVR generators limited the number of HMIs you could power on a portable generator to 75% of their rated capacity (4200Watts on a 6500W Generator). But now, where inverter generators have virtually no inherent harmonic distortion or sub-transient impedance and power factor correction (PFC) is available in small HMI ballasts, this conventional wisdom regarding portable gas generators no longer holds true. Where before you could not operate more than a couple 1200W HMIs with non-PFC ballasts on a conventional generator because of the consequent harmonic distortion, now according to the new math of low line noise, you can load an inverter generator to capacity. And if the generator is one of our modified Honda EU6500is inverter generators, you will be able to run a continuous load of up to 7500W as long as your HMI and Kino ballasts are Power Factor Corrected. Except for one notable exception, when manufacturers do offer PFC circuitry in smaller ballasts it is at a premium, adding as much as a $1000 to the cost of a 1200W ballast for instance. The new ballast manufacturer Power-2-Light, on the other hand, is including PFC circuitry in their ballasts at the same price point as other manufacturer’s non-PFC ballasts. But where Power-2- Light is still very new to the market, it is still the case that almost every 575 - 1200 W ballast that you will find in a rental house in North America will be a non-PFC electronic ballast. Don’t blame the rental houses, until recently they never were offered the choice. Guy Holt, Gaffer, ScreenLight & Grip , Boston

Marc, I appreciate your feed-back. I know I can have a tendency to go on too long, but when it comes to handling electricity, as I said at the beginning of my post, a little knowledge can be a dangerous thing. I think that an emphasis on brevity can create misunderstanding. For example John’s post below. John’s post is correct, but only as it pertains to purely non-linear resistive loads. After reading that post, the Colleen Marshalls of the world might think he/she knows enough to accept the next offer to serve as generator operator and end up melting the neutral as happens, or worse creating a hazardous situation where someone takes a lethal shock. It is not always a bad thing to lose readers when discussing the complexity of handling electricity – it creates what I think is a healthy respect for the electrical department. After reading my post and not understanding it 100%, the next time Colleen Marshall is asked by a cost cutting producer to operate a generator so that they can save a few bucks, Colleen Marshall will say no. Or, if it is a producer/cameramen reading the post, they won’t ask a film student to operate a generator because my post left them with the impression that there is a lot more to operating a generator than simply balancing the loads. Having instilled in them a respect for the craft, they will come up with the money to hire a qualified genny operator. Because the opposite is naturally assumed given their small size, I went to great lengths in my post to make the point that operating small portable gas generators (Hondas & such) is actually more difficult, than operating Crawford Studio Plants, because of much higher levels of Total Harmonic Distortion (THD). I also went on at length because if you know the “whys” of harmonic distortion, you can design a production lighting and power generation package that will reliably operate a continuous load of up to 7500W on a portable gas generator. Because of the brevity of posts, I find again and again that online forums like this are filled with blanket assertions based upon erroneous assumptions or conventional wisdom. Another example, of this is the assumption prevalent in this forum that fluorescent lights are better than quartz lights when using a small gas generator because they use a quarter of the power of a comparable tungsten soft light. However, how many readers of this forum know that the ballasts of the older style Kino Flo fixtures, like the 4’ – 4 bank Kinos, that use the T-12 tubes (the Single, Double, and 4 Bank Fixtures, the Wall-o-Lite, Flathead 80, and the Image 20, 40, & 80 fixtures) are not power factor corrected and return harmonic currents into the power stream. And, when used in quantity, as in studio chroma key productions, they can constitute a source of considerable harmonic noise in the power stream. So much noise in fact, that Kino Flo cautions users on their website: “Kino Flo ballasts are generally not power factor corrected. They will draw double the current on the neutral from what is being drawn on the two hot legs. On large installations it may be necessary to double your neutral run so as not to exceed your cable capacity.”( FAQ “Why is the neutral drawing more than the hot leg” at http://www.kinoflo.com/FYI/FAQs.htm#2) Left: Grid Power w/ no load and a THD of less then 3%. Center: Conventional Generator w/ no load and a THD of 17-19%. Right: Inverter Generator w/ no load and a THD of 2.5%. Or, how many readers appreciate that it is an all together different situation when plugging Kino Flo T-12 fixtures into conventional portable generators than plugging them into a wall outlet. As a comparison of the oscilloscope shots above and below indicate, the return of harmonic currents by conventional Kino Flo T-12 ballasts can contribute to severe voltage distortion of the power stream generated by conventional portable gas generators. Left: Grid Power w/ Kino Flo Wall-o-Lite. Center: Conventional AVR Power w/ Kino Flo Wall-o-Lite. Right: Inverter Power w/ Kino Flo Wall-o-Lite. And it is also assumed that operating a couple of 1200W HMIs along with a couple of 4’-4 Bank kinos on a small portable gas generator doesn’t require an experienced electrician, when the exact opposite is the case. Because of the higher levels of Total Harmonic Distortion for the reason given above, it is actually harder to get production equipment to operate reliably on small gas generators than it is to operate on large diesel generators. For example the harmonic currents generated by a package consisting of two Arri 1200 HMI Par Pluses (with standard Arri non-PFC electronic ballasts) and the equivalent of 3 – 4’ – 4 Bank Kinos operating on a Honda EX5500 (a conventional generator) creates the severe voltage waveform distortion below left. And how many readers of this forum appreciate that the severe voltage waveform distortion exhibited below left can cause overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral return, and instability of the generator’s voltage and frequency. Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400. Or, how many readers of this forum know that when your lighting package consists predominantly of non-linear light sources, like HMI and Fluorescent lights, you can operate substantially more fixtures on portable gas generators if the HMI & Kino ballasts are Power Factor Corrected (PFC) and the power is supplied by an inverter generator through transformers. For example, the power waveform above on the right, is the same 2500W load but with power factor correction operating on our modified Honda EU6500is Inverter Generator. As you can see, the difference between the resulting waveforms is startling. Even though the load is the same, the fact that it is power factor corrected and the power is being generated by an inverter generator, results in virtually no power waveform distortion. For this reason, sensitive electronic production equipment will operate reliably and without damage. And, the generator is capable of operating larger, or more smaller, lights than has ever been possible before on a portable gas generator. For instance, we can operate a continuous load of 7500W on our modified Honda EU6500is because we include only the Power Factor Corrected Kino Flo Parabeam fluorescent fixtures and Power-2-Light HMI ballasts in our HD Plug and Play Pkg. When you add up the incremental savings in power to be gained by using only PFC HMI ballasts, add to it energy efficient sources like the Kino Flo Parabeam fixtures, and combine it with the pure waveform of inverter generators, you can run more HMI lights on a portable gas generator than has been possible before. For example, the 7500W capacity of our modified Honda EU6500is Inverter Generator can power a lighting package that consists of a PFC 2.5kw HMI Par, PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80. Given the light sensitivity of HD cameras, this is pretty much all the light you will need to light even night exteriors. If at this point I have lost a few readers, it is not necessarily a bad thing. Especially, if one of those readers is a cameramen. Perhaps, the next time their gaffer insists on more money to rent Kino Flo Parabeam 400s, HMIs with PFC ballasts, a modified Honda EU6500is inverter generator, and a transformer/distro to operate them, when the producer wants to know why the cheaper T12 4’-4 Bank Kino fixtures and a conventional Honda ES6500 generator won’t do, the cameramen will go to bat for the Gaffer. Even though he doesn’t fully comprehend the Gaffers’ reasons he will know from this post that there is more to operating lights on portable gas generators than meets the eye. Where It is beyond the scope of this post to go into more details about harmonic distortion and why it has an adverse effect on power from generators when it does not on power from the grid, I am going to take Marc’s advise and refer those interested to an article I wrote for our company newsletter (mentioned above) on the use of portable generators in motion picture production. The article is available at www.screenlightandgrip.com/html/emailnewsletter_generators.html.) I would hope that those who don’t follow this link, will at least have a new respect for film electricians. So that if an electrician says there is not enough power to run that additional light, when the generator is operating at only 50% capacity, the cameramen will accept that recommendation even if they don’t completely understand why. Guy Holt, Gaffer, ScreenLight & Grip , Boston

David McLean’s experience demonstrates, there is a lot more to operating a generator than just balancing its’ load. While there is good information in this thread on how to balance a generator, there has been very little discussion of why generators need to be balanced in the first place. Without an understanding of why generators should be balanced and the difference between lighting loads there is the possibility of creating a hazardous situation like David’s. A little knowledge can be a dangerous thing – especially when it comes to handling electricity – so I would like to take this opportunity to explain in some detail why the neutral burned on David’s shoot. As Marc Roessler correctly observed in his post the reason for David’s problem has to do with the vagaries associated with the load he put on the generator. If you haven't already, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind harmonic distortion and how it can adversely effect generators. The article is available on our website. As John Sprung correctly states one of the primary reasons to balance a generator is to minimize current on the neutral return. Where there are two (single phase) or three (three phase) hot wires to only one neutral wire, you must balance the load on the hot legs so that there is minimal return on the neutral after phase cancellation. If you don’t balance the load there is the possibility of overloading the neutral wire – a potentially hazardous situation. If we draw equal current from each leg of a single phase generator with incandescent lights (a resistive or linear load), there will be no return current on the neutral. That is because with a linear load current & voltage remain in sync, and where the legs are 180 degrees out of phase, the current cancels out when combined on the neutral return. If we draw 100A on one leg and 140A on the other leg, we will have 40A on the neutral. With a linear load, the more balanced the load the less current on the neutral return. Things get a bit more complicated with inductive (magnetic HMI ballasts) and capacitive (electronic HMI & Kino ballasts) non-linear lighting loads, or the “special” consumers Marc refers to. Since non-linear loads cause current and voltage to be out of sync, the phase currents no longer entirely cancel when they return on the neutral. When using magnetic HMI ballasts, it is normal to have as much as 20-25% of the total amperage return on the neutral when the legs are evenly loaded. Electronic square wave ballasts (both HMI & Kino), in addition to pulling the voltage and current out of phase, also create harmonic currents that can stack on top of one another, creating very high currents returning to the power source on the neutral wire. As David found out the hard way, if the neutral return path has not been oversized to accommodate additional current, these high currents can cause excessive heat on the neutral wire, and the neutral bus of the generator. Where the neutral of a distribution system is not fused, this excessive heat can lead to a possibly hazardous situation. Where high currents on the neutral can be hazardous, it is important to understand the root cause of these currents. Electronic square wave HMI ballasts are a major source of harmonic currents. These currents are produced by the diode-capacitor section of the ballast. This is the part of the ballast that rectifies the AC input power into the DC power that is then used by the power module to create the square wave. The diode-capacitor section accomplishes this by first feeding the AC input current through a full wave bridge rectifier, which inverts the negative half of the AC sine wave and makes it positive. The rectified current then passes into a bank of capacitors which removes the 60 Hz rise and fall and flattens out the voltage-making it essentially DC. The DC is then fed from these capacitors to the power module. Since the rectifying circuit of the power supply only draws current from the AC line during the peaks of the supply voltage waveform, charging the capacitors to the peak of the line voltage, these power supplies draw current in high amplitude short pulses. The remaining unused current feeds back into the power stream as harmonic noise that distorts the voltage waveform at the distribution bus. Of the harmonic currents that electronic ballasts generate, the odd harmonics (i.e. 3rd, 5th, 7th, 9th, etc.) are more of a concern because the even harmonics have a tendency to cancel out. Of these the 3rd harmonic, and odd multiples of the 3rd (9th, 15th, etc) are particularly troublesome. These harmonics are called the “triplens.” What makes them troublesome is that the triplen harmonics dumped back onto each phase of the distribution system are all in phase with each other. For this reason, rather than cancel each other out on the neutral conductor, as the out of phase fundamentals do, they instead add up. If the lighting package consists entirely of electronic HMI & Kino ballasts without power factor correction, about 80 percent of the current does not cancel out between legs, resulting in very high current on the neutral return. The Triplin Harmonics (shaded) add rather than cancel on the neutral return For example, even if we draw a perfectly balanced load of 125A per leg on 2Awg banded feeder cable (rated for 190A) from a three phase generator (375A total), if our load consists predominantly of electronic HMI & Kino ballasts, we could potentially have upwards of 300A on the neutral wire. Since the neutral wire in banded feeder is also 2 Awg rated for 190A, return currents of this magnitude can cause sufficient heat to overload the neutral wire, and the neutral bus of the generator, leading to a possibly hazardous situation since the neutral return has no fused protection. Unfortunately, much of today's lighting technology is of a non-linear type because it relies on electronics such as DC rectifiers (electronic HMI ballasts), silicone-controlled rectifiers (SCRs), capacitors (magnetic & electronic HMI ballasts), and high-frequency switching power supplies (the IGBTs of electronic ballasts). And since this kind of load (non-linear) generates harmonic currents that can have undesirable effects like stacking on the neutral, it is no longer sufficient to just balance the load on a generator. One must also closely watch the current on the neutral return and take preventive measures when there is the possibility that it will be high. On large film sets it is a standard practice when powering large numbers of electronic ballasts without Power Factor Correction to size the neutral feeder of the distribution system to carry the sum of the currents of the phase legs times 80 percent (.8). Likewise, the generator is typically oversized to handle the higher return current. On small film sets using small portable gas generators other measures must be taken. Other measures must be taken because the means by which the motion picture industry has more or less successfully dealt with harmonics - namely the over-sizing of generators, the over-sizing of neutrals, the incorporation of power factor correction circuitry in large HMI ballasts, and finally the use of generators, like the Crawford Studio Generators, with 2/3 pitch windings are generally not available to users of small portable generators as their primary source of power. The reason being, productions using portable gas generators are using them by necessity. For budgetary or logistical reasons, it is simply not an option to upscale their generator and customize their distribution package to accommodate a dirty load; and until very recently, power factor correction has not been available in HMI ballasts smaller than 4kw. Not only do users of small portable gas generators have to find other means of remediating the adverse effects of harmonic distortion, but they also have to deal with much higher levels of Total Harmonic Distortion (THD.) It is a basic principle in electrical engineering that the magnitude of voltage waveform distortion is a function of the inherent harmonic distortion of the applied power waveform, the size of the source impedance, and the relative size of nonlinear loads with respect to the capacity of the power generating system. That is, the amount of voltage distortion increases as distortion of the applied waveform increases and the percentage of nonlinear loads taking up the total capacity of the power generating system increases. As previously discussed, voltage waveform distortion as a result of harmonic currents is not a practical problem on large film sets because of remedial steps taken in the design of form specific generating and power distribution systems engineered to remediate the adverse effects of harmonic currents. With 2/3 pitch windings, MQ Power studio (Crawford) generators are specifically designed to remediate the most troublesome of the harmonics generated by non-linear loads and as such have specifications for total harmonic distortion (THD) values of less than 7% under full linear load, and of not more than 3% of any given harmonic current. For this reason, and the fact that they offer a comparatively low sub-transient impedance value and are typically oversized for the load, harmonic currents do not cause substantial voltage waveform distortion. However, it is an all together different situation when plugging a couple of 1200W HMIs into a small portable generator that is not specifically designed to remediate the effects of harmonics. Given the comparatively large sub-transient impedance of conventional small gas generators, and the high THD value of their inherent power waveform (19.5% under full linear load), you have a situation where even a small amount of harmonics being fed back into the power stream will result in a large amount of harmonic distortion in its’ voltage. Making the matter worse is that, given the increasing prevalence of non-linear light sources in production, it is likely that the percentage of the generator’s capacity taken up by non-linear loads will be very high given its small size relative to the size of HMIs typically used on these generators (575-2500 Watts.) Conventional small gas generators present a perfect (electrical) storm where the return of any harmonic currents results in a very high degree of voltage waveform distortion. For example, the power waveform below left (from my article) is typical of what results from the operation of a 2500W non-Power Factor Corrected load (electronic HMI & Kino ballasts) on a conventional portable generator (a Honda EX5500 with a Barber Coleman Governor.) Where the severe voltage waveform distortion exhibited here can cause overheating and failing equipment in addition to excessive current on the neutral return, it is even more imperative that users of small gas generators take preventive measures to minimize the voltage waveform distortion that can result from harmonic currents being dumped back into the power stream. Besides meticulously balancing the load (keeping legs within 20% simply won’t do it) users of small gas generators have two alternatives. The first is to de-rate the continuous load capacity of the generator so that the maximum load is small enough that the generator is able to accommodate the harmonic currents generated by the smaller load; or, alternatively eliminate harmonic currents being dumped back into the power stream by only using power factor corrected HMI and Kino electronic ballasts on inverter generators. For those of you not familiar with Power Factor Correction (PFC), a PFC circuit utilizes a RF Mains Filter to restrict the flow of harmonic currents back onto the supply service. In this fashion, the PFC circuit realigns voltage and current and induces a smoother power waveform at the distribution bus. Formerly only available in large HMI ballasts, this advanced electronics reduces voltage waveform distortion and contributes to a more economical use of power than typical HMI and fluorescent electronic ballasts. Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400. By de-rating the load capacity of a generator, you can minimize the adverse effects of harmonic noise so that the generator and the load operate more reliably. The conventional wisdom in the past has been to not load a generator beyond 75% of its continuous load capacity for more than a short period (the maximum recommend continuous load on a 6500W generator, with a continuous load rating of 5500W, would be roughly 4000 watts.) However, this conventional wisdom no longer holds true of inverter generators when used with Power Factor Corrected (PFC) HMI & Kino ballasts. For example, the power waveform above on the right, is the same 2500W load but with power factor correction operating on our modified Honda EU6500is Inverter Generator. As you can see, the difference between the resulting waveforms is startling. Even though the load is the same, the fact that it is power factor corrected and the power is being generated by an inverter generator, results in virtually no power waveform distortion. What this means is that an inverter generator can be loaded to capacity with PFC HMI and Kino Flo ballasts without any adverse effects. The substantial reduction in line noise that results from using PFC ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the continuous load you can put on a portable gas generator. And if the inverter generator is one of our modified Honda EU6500is generators, you will be able to power a continuous load of 7500 Watts as long as your HMI and Kino ballasts are Power Factor Corrected. Wide Shot of Night exterior scene lit with a pkg. consisting of PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 powered by a modified Honda EU6500is. We maximize the continuous load that can run off the enhanced output of our modified Honda EU6500is inverter generator, by operating HMI and Kino Flo lights with Power Factor Corrected ballasts through a 240V-to-120V step down transformer/distro that perfectly balances the load on the two legs of the generator. The PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 of our HD P&P Pkg. powered by our modified Honda EU6500is through our 60A Full Power Transformer/Distro Where, in the past we had to de-rate portable generators because of the inherent short comings of conventional generators when dealing with the harmonic noise generated by non-PFC electronic ballasts; now you can load an inverter generator to capacity. And, the generator is able to handle the load more easily because the transformer/distro perfectly balances the load. According to this new math, when you add up the incremental savings in power to be gained by using only PFC HMI ballasts, add to it energy efficient sources like the Kino Flo Parabeam fixtures, and combine it with the pure waveform of inverter generators, you can run more HMI lights on a portable gas generator than has been possible before. For example, the 7500W capacity of our modified Honda EU6500is Inverter Generator can power a lighting package that consists of a PFC 2.5kw HMI Par, PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80. Given the light sensitivity of HD cameras, this is pretty much all the light you will need to light even night exteriors. A Distro System consisting of a 60A Full Power Transformer/Distro, 2-60A GPC (Bates) Splitters, 2-60A Woodhead Box distributes power from a modified Honda EU6500is. Even though the generator is 100' away to reduce noise, plug-in points remain conveniently close to set. It is beyond the scope of this post to go into more details about harmonic distortion and why it has an adverse effect on power from generators when it does not on power from the grid . Those interested should read the article I wrote for our company newsletter (mentioned above) on the use of portable generators in motion picture production. The article is available at www.screenlightandgrip.com/html/emailnewsletter_generators.html.) Guy Holt, Gaffer, ScreenLight & Grip , Boston

Since, this is getting off the topic of this thread I will start a new thread ( More Power from Small Generators) to answer this question. Guy Holt, Gaffer, ScreenLight & Grip , Boston

Continued from above: The third and final reason we can run a continuous 7500W load on our modified EU6500is is the most difficult to understand because it has to do with the vagaries associated with the load put on generators. If you haven't already, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind harmonic distortion and how it can adversely effect generators. The article is available on our website. The reason that the same engine and generator components (the engine/generator set) marketed to the construction trades carries a higher continuous load rating than that marketed for RV power or Home standby power is that the load that the construction trades put on generators is typically a "resistive load" - motors, heaters, etc - that does not create harmonic distortion of the power waveform. Where as, the same engine/generator set marketed for RV power or home standby power will carry a lower continuous load rating because the typical load put on it is a "reactive load" - computers, fluorescent lights, microwaves, etc. - that creates harmonic distortion of the power waveform. In our discussion above, the heat generated by electrical components operating on highly distorted power (the square wave above) is just one of many vagaries associated with load that manufacturers take into account in determining the continuous load rating of a generator for a specific market. Another consideration related to load, and the one that JD alludes to above, is overheating of the generator windings caused by high Total Harmonic Distortion (THD) levels. Harmonic currents produce high frequency flux change in the generator's stator cores which can lead to them overheating. Higher magnetic core temperatures result in higher winding temperatures. Winding heating is, in fact, proportional to effective or RMS current squared. Rotor loss can also occur because harmonic currents in the stator will induce currents in the pole faces and windings. And, of course, harmonic currents cause increased resistive losses everywhere in the generator's electrical distribution, resulting in increased temperatures everywhere, not only in the generator windings. For this reason, if an engine/generator set is intended for a market whose typical load is reactive (either reductive or capacitive), the manufacturer will de-rate the inherent generating capacity - i.e. lower the continuous load rating - for that engine/generator set for that market in order to reduce flux change in the generator's stator cores that could lead to the windings burning out under "normal load." In other words, the lower Continuous Load rating builds in a margin of safety that allows for the harmonic distortion generated by reactive loads (both inductive and reactive.) Overheating of electrical components and overheating of the generator windings are just two of many vagaries of load related to high THD values that generator manufacturers take into account when rating generators. Other vagaries of load related to high THD values are generator voltage regulation problems, generator speed governor problems, and excessively hight returns on the nuetral. An analogous situation is when a genny operator over sizes the plant and the size of the neutral return (a Super Neutral) when they know they are going to be dealing with a lot of non-PFC HMI or Kino Ballasts. Electronic square wave ballasts, in addition to pulling the voltage and current out of phase, also create harmonic currents that can stack on top of one another, creating very high currents returning to the power source on the neutral wire. If the nuetral return path has not been oversized to accomodate additinal current, these high currents can cause excessive heat on the neutral wire, and the neutral bus of the generator. Where the neutral of a distribution system is not fused, this excessive heat can lead to a possibly hazardous situation. For this reason it is a standard practice when powering large numbers of electronic ballasts on large film sets to size the neutral feeder of the distribution system to carry the sum of the currents of the phase legs times 80 percent (.8). Likewise, the generator is typically oversized to handle the higher return current. The means by which the motion picture industry has more or less successfully dealt with harmonics - namely the over-sizing of generators, the over-sizing of neutrals, the incorporation of power factor correction circuitry in large HMI ballasts, and finally the use of generators with 2/3 pitch windings (Crawford Studio Generators) are generally not available to users of small portable generators as their primary source of power. That is because, productions using portable gas generators are using them by necessity. For budgetary or logistical reasons, it is simply not an option to upscale their generator and customize their distribution package to accommodate a dirty load. The only alternative is to de-rate the continuous load capacity of the generator and distribution equipment. Unfortunately, much of today's lighting technology relies on electronics such as DC rectifiers (electronic HMI ballasts), silicone-controlled rectifiers (SCRs), capacitors (magnetic & electronic HMI ballasts), and high-frequency switching power supplies (the IGBTs of electronic ballasts). And since these kinds of load can have undesirable effects on the current waveform, many Gaffers will further de-rate the continuous load capacity over and above what the generator manufacturer has already de-rated the generator set. For example, the power waveform below left (from my article) is typical of what results from the operation of a 2500W non-Power Factor Corrected load (electronic HMI & Kino ballasts) on a conventional portable generator (a Honda EX5500 with a Barber Coleman Governor.) Where the severe harmonic noise exhibited here can cause overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral return, and instability of the generator's voltage and frequency, the conventional wisdom in the past has been to not load a generator beyond 75% for more than a short period (the maximum recommend continuous load on a 6500W generator, with a continuous load rating of 5500W, would be roughly 4000 watts.) Like the generator manufacturer, by de-rating the load capacity, the Gaffer minimizes the adverse effects of high THD so that the generator will operate more reliably. Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400. However, this conventional wisdom no longer holds true of inverter generators when used with Power Factor Corrected (PFC) HMI & Kino ballasts. For example, the power waveform above on the right, is the same 2500W load but with power factor correction operating on our modified Honda EU6500is Inverter Generator. As you can see, the difference between the resulting waveforms is startling. Even though the load is the same, the fact that it is power factor corrected and the power is being generated by an inverter generator, results in virtually no power waveform distortion. What this means is that an inverter generator can be loaded to capacity with PFC HMI and Kino Flo ballasts without its' stator core overheating from high frequency flux change, its electrical wiring overheating from excessive resistance, and its distribution panel overheating from a high neutral return. The substantial reduction in line noise that results from using PFC ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the continuous load you can put on a portable gas generator. Wide Shot of Night exterior scene lit with a pkg. consisting of PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 powered by a modified Honda EU6500is. We maximize the continuous load that can run off our modified Honda EU6500is inveter generator, by offering HMI and Kino Flo lights with Power Factor Corrected ballasts. For those of you not familiar with Power Factor Correction (PFC), a PFC circuit utilizes a RF Mains Filter to restrict the flow of harmonic currents back onto the supply service. In this fashion, the PFC circuit realigns voltage and current and induces a smoother power waveform at the distribution bus. Formerly only available in large HMI ballasts, this advanced electronics reduces voltage waveform distortion and contributes to a more economical use of power than typical HMI and fluorescent electronic ballasts. The PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 of our HD P&P Pkg. powered by our modified Honda EU6500is through our 60A Full Power Transformer/Distro Where, in the past we had to de-rate portable generators because of the inherent short comings of conventional generators when dealing with the harmonic noise generated by non-PFC electronic ballasts; now you can load an inverter generator to capacity. And if the generator is one of our modified Honda EU6500is inverter generators, you will be able to run a continuous load of up to 7500W as long as your HMI and Kino ballasts are Power Factor Corrected. According to this new math, when you add up the incremental savings in power to be gained by using only PFC HMI ballasts, add to it energy efficient sources like the Kino Flo Parabeam fixtures, and combine it with the pure waveform of inverter generators, you can run more HMI lights on a portable gas generator than has been possible before. For example, the 7500W capacity of our modified Honda EU6500is Inverter Generator can power a lighting package that consists of a PFC 2.5kw HMI Par, PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80. Given the light sensitivity of HD cameras, this is pretty much all the light you will need to light both the foreground and deep background of night exteriors. A Distro System consisting of a 60A Full Power Transformer/Distro, 2-60A GPC (Bates) Splitters, 2-60A Woodhead Box distributes power from a modified Honda EU6500is. Even though the generator is 100' away to reduce noise, plug-in points remain conveniently close to set. It is beyond the scope of this post to go into more details. Those interested should read the article I wrote for our company newsletter (mentioned above) on the use of portable generators in motion picture production. The article is available at www.screenlightandgrip.com/html/emailnewsletter_generators.html.) Guy Holt, Gaffer, ScreenLight & Grip , Boston

Continued from above: Even though our test demonstrates that the inverter module of the EU6500is can support continuous loads of 7650W does not necessarily mean that the generator's engine can. Quite often, when you find yourself in the situation with a conventional AVR generator, where lights that have been running fine, suddenly fail when another light is turned on, it is because the generator engine bogs down because it is over loaded. As the engine RPMs drop, frequency and voltage drop as well, causing the HMI lights to cut out from low voltage. For this reason it is important to factor engine capacity whenever sizing a generator for a predominantly HMI load. The power behind the EU6500is is Hondaís workhorse GX390 engine. According to Honda literature, the GX390 is a 13HP Twin Cylinder, Overhead Cam (OHV), Liquid Cooled gas engine with a Displacement ( Bore X Stroke ) of 389cc / 23.7 cu. inches and a Gross Torque of 20 ft-lb at 2,500 rpm. This same engine is used worldwide by manufacturers of all kinds of power tools, from pumps to roto-tillers, and is rated with a maximum output of 9600 Watts (13ps, 13bhp) at 3,600 RPM. Surveying the continuous load capacity ratings of 5000W-7000W of generators by manufacturers other than Honda that use the GX390, one quickly realizes that the factors generator manufacturers use to derive these ratings include not only the mechanical components (engine & alternator), or the electrical components (circuitry & wiring), but also the market for which it is intended (how it will be used) and the brand image of the manufacturer (life expectancy of the product.) For these reasons we can only speculate as to the true power generating capacity of the GX390 engine. To get an idea of the true power generating capacity of this engine we need look no further than the Coleman Model PM0497000 Generator. Coleman uses the Honda GX390 engine in this conventional AVR generator it manufactures for the construction market. Colman rates the Model PM0497000 Generator at 7000W continuous and 8750W peak load capacity. Where the Model PM0497000 Generator is manufactured by Coleman for the construction trades to run power equipment with high front end loads (3X) it is probably safe to bet that Coleman is under-rating the PM0497000 generator at 7000W continuous and 8750W peak load capacity. Using Coleman's rating of the Model PM0497000 Generator as a conservative bench mark of the engine's true capacity, and taking into account that an inverter generator puts out 20% more power from each revolution of the generator core (thanks to its multiple coils and multiple magnets generating several hundred overlapping sine waves per revolution), it is probably safe to assume that the GX390 engine in an inverter generator is capable of generating at least 8400W of continuous and 10500W of peak power. Where Honda does not make this information public, there is no way of knowing for certain what the actual generating capacity of the GX390 engine is in an inverter generator like the EU6500is. We can, however, safely conclude that the GX390 provides a quiet and efficient power plant that more than compliments the 7650W continuous power output of the EU6500isí inverter power module. Guy Holt, Gaffer, ScreenLight & Grip , Boston

We are not just providing an additional 1000W, but 2000 more watts because the 7500 Watt load we put on our modified Honda EU6500is is a continuous load. How we modify the generator is proprietary information. What I can say is that our Transformer/Distro is able to provide 7500 Watts in a single 60A circuit because the capacity is already built into the machine by Honda. In order to understand how it is possible to get 7500W of continuous power in a single 120V circuit out of a Honda EU6500is generator, one must first appreciate three things about the continuous load ratings given for generators. First, the factors generator manufacturers use to derive load ratings include not only the mechanical components (engine & alternator), and the electrical components (circuitry & wiring), but also the market for which it is intended (how it will be used) and the brand image of the manufacturer (life expectancy of the product.) A quick survey of the wide range of continuous load ratings (5000W-7000W) of generators, by manufacturers other than Honda, using the same Honda GX390 engine as the EU6500is supports this fact. Second, when Honda engineered the EU6500is it was not only for the North American market. Like a car, Honda engineered a base model for the world market that they then customize for the different national markets. The difference between the various national models is primarily in the power output panel, which is configured according to the electrical system and prevailing standards used in the national market in which the generator will be used. The 120V power output panel on the North American EU6500is is under-rated for the actual generating capacity of the machine. Finally, the continuous load rating of generators is what you can reasonably expect to get at the business end of the power panel allowing for all the vagaries associated with the load put on the generator. That is, the same engine and generator components will carry different continuous load ratings depending on its' intended use or the type of load (resistive, inductive, capacitive) that will be put on it. I would like to explain each of these in more detail. When you compare how Honda outfits the base model of the EU6500is generator for the European and UK markets, where the standard circuit for domestic power is 230/240 Volts and 13 and 16 Amps, to how Honda outfits the same generator for the North American Market, where the standard circuit is 120 Volts and 15 or 20 Amps, one realizes that the continuous power rating of 5500w for the North American Model of the generator is under-rated. Where England and Ireland have not entirely conformed to the European Union Standard of 230 Volts, but still generate 240V power, Honda has engineered the base model to support a version of this generator for the UK market (the EU65i) with two 240V/16A circuits (3840 Watts/circuit). To support the UK market, the base model must be designed to generate at least 7680 Watts (2x3840W/circuit = 7680W). It is beyond the scope of this post to go into more details (those interested should contact me off list for a detailed side by side analysis of the wiring schematics of the two generators) but simple math (16A x 240V = 3840 W/circuit x 2 circuits = 7680 Watts) clearly demonstrates that it the base model must be designed to generate at least 7680 Watts. To empirically test how much generating capacity the base model is capable of, we tapped an EU6500is in a similar fashion to the UK model, the EU65is, and used a step-down transformer to convert the 240 Volt output to a single 120 Volt circuit. We then used the generator's overload sensor to empirically test its' capacity with a load bank following the parameters as set forth in the manual: "If the generator is overloaded, or if the inverter is overheated, the red overload indicator will go ON. When an electric motor is started, the red overload indicator may come on. This is normal if the red overload indicator goes off after about five seconds. When the generator is operating overloaded, the red overload indicator will stay ON and, after about five seconds, current . will shut offî What we discovered about our modified EU6500is was startling. We found that we could power a continuous load (more than 30 minutes) of up to 7650 Watts without the overload indicator coming on. When we exceeded 7650 Watts, the red indicator blinked intermittently. When we exceeded 7800 Watts the red indicator came on continuously and power was cut off to the receptacles. Since, according to the Honda Manuel it is normal for the overload indicator to come on for short front-end loads, like electric motors starting, our results suggest that the continuous load capacity of the base model, or the EU6500is after our modification, is actually 7650 watts. And, when you consider that electric motors require up to three times more power to start than is required to keep them running, it suggests that the peak rating is actually well above 7650W. Suspecting that it was not just coincidental that the actual continuous load capacity of 7650 Watts is the equivalent of two standard household circuits in the UK, we confirmed with Honda Motors USA that in fact the base model of the EU6500is generator is engineered to generate the equivalent of two UK circuits and has a continuous load capacity of 7650Watts. And, that when Honda configures the base model for the North American market with 120V circuits, it is not fully utilizing the power generating capacity they have built into the machine for the worldwide market. Since I am out of space, I will have to explain the second reason it is possible to run a continuous 7500W load on our modified EU6500is in my next post. Guy Holt, Gaffer, ScreenLight & Grip , Boston

Unfortunately for me, there is no relation. And you are right that every tool has an application. The added expense of a Honda EU6500is is not necessary if you are not recording sound and using predominantly tungsten light instruements. In my experience, when you do need to power HMI & Kino ballasts and record clean audio tracks a Honda EU6500is can do the job. It comes down to how you use the generator. If you know how to use it, it is possible to record location audio without picking up generator noise - especially if you use them with a transformer. The Honda EU6500is inverter generator to begin with is much quieter than the older movie blimped Honda EX5500. Part of what makes the new Honda EU6500is so quiet is it's "Eco-Throttle." The Eco-Throttle's microprocessor automatically adjusts the generator's engine speed to produce only the power needed for the applied load. It can do this because the inverter technology of the Honda EU6500is enables it to run at different RPMs and maintain a constant frequency and voltage. Where conventional generators like the Honda EX5500 and ES6500 have to run full speed at a constant 3600 RPM to produce stable 60 hertz (cycle) electricity, a Honda EU6500is only needs to run as fast as required to meet the load demand. Since their engines do not have to run at full speed, and given the fact that an inverter generator generates 20% more power per revolution of the engine, makes the Honda EU series of inverter generators substantially quieter than conventional models. The net result is that the EU6500is operates between 34 to 44 dBA at 50 ft. - half as loud (ten decibels) as the comparable EM7000is and ES6500 generators and comparable to our Crawford 1400A. But you can't park a Crawford right on set and record sound without picking up the generator either. With sound specs this good all you need to record sound without picking up generator noise is a real distro system that will allow you to move the EU6500is off set (like you would a Crawford), minimize line loss over a long cable run, and provide plug-in pockets conveniently close to set. That is where the transformer comes in. My company, ScreenLight & Grip (SL&G), has developed a Gen-set that is designed to provide clean quiet set power from a modified Honda EU6500is. What we do is tap the Honda EU6500is inverter generator as it is designed for 230/240V markets like the UK, EU, Australia, & India (to name just a few.) By doing so, we gain access to the full 7650 Watt power capacity designed into the generator for these 230/240V markets, but not available in generators manufactured for 120V Markets like the US. We then use a proprietary step-down transformer/distro we have developed to convert the full 240V power into a single 60A/120V circuit (7500Watts) capable of powering large lights. And, where PWM inverter generators, like the Honda EU6500is, generate a nearly pure power waveform, our modified Honda EU6500is is capable of reliably powering more lights than has been possible before. Finally, to record sync sound without picking up any generator noise, all you need to do is add 100' - 150' of heavy duty 250V twist-lock extension cable between the generator and our Full Power Transformer/Distro. This is usually enough cable to place the generator around the corner of a building, or to run it out of a van or truck - which is usually all the additional blimping you need with these generators. The heavy-duty 250V twist-lock cable eliminates multiple long cable runs to the generator and minimizes line-loss; as well as, eliminates the voltage drop you would have using standard electrical cords. A Distro System consisting of a 60A Full Power Transformer/Distro, 2-60A GPC (Bates) Splitters, 2-60A Woodhead Box distributes power from a modified Honda EU6500is. Even though the generator is 100' away to reduce noise, plug-in points remain conveniently close to set. To assure full line level (120V) on set, our 60A Full Power Transformer/Distro is designed to compensate for the slight line loss you will have over an extended cable run. That is, it is designed to slightly boost the voltage on the load side (secondary) so that if you were to feed the supply side (primary) of the transformer 240 volts from the generator, 127 volts would come out on the secondary side where you plug in the lights. This slight boost enables you to place the generator further from set where you won't hear it, yet assure that the supply voltage on set does not drop too low. Our 60A Full Power Transformer/Distro is equipped with a 60A Bates and three 20 A Edison circuits so that you have plug-in pockets conveniently on set. 60A GPC (Bates) Splitters and Woodhead Box. Our new 60A Full Power Transformer/Distro offers a number of other benefits as well. Without our Transformer/Distro you can never fully utilize the full power of the generator because the load of a light has to go on one circuit/leg of the generator or the other. For example, when plugging lights into the factory installed power outlet panel of a Honda EU6500is, you quickly reach a point where you can't power an additional 1200W HMI because there is not 11.5 amps (w/ a PFC ballast) available on either one of the factory installed 20A outlets/leg of the generator. With our Full Power Transformer/Distro you can still add that 1200W HMI because the Transformer/Distro not only accesses more power (7500 Watts) through a higher rated circuit (60 Amps), but it also splits the load evenly over the two legs (5.75A/leg) of the generator. The end result is that the generator is capable of handling a larger load more easily because it is a perfectly balanced load. 60A Woodhead Box running Power-to-Light PFC 800W ballast (left) and PFC 1200W ballast (right.) Another benefit to using our Transformer/Distro is that it greatly simplifies set electrics by splitting the load of what ever you plug into it automatically. This means you no longer have to carefully balance the load over the generator's two 20A/120 circuits/legs as you plug in lights because the Transfomer/Distro does it for you. With our modified Honda EU6500is you simply plug in lights until the load wattage displayed on the generator's iMonitor reaches 7500 Watts. Now that you are able to fully utilize the generator's available power, you are able to power larger lights, or more smaller lights, than you could without a transformer/distro. For more details on the use of transformers for set power, I suggest you read the article I wrote for our company newsletter (mentioned above) on the use of portable generators in motion picture production. Use this link - www.screenlightandgrip.com/html/emailnewsletter_generators.html for more information about using inverter generators with transformers for motion picture lighting. Guy Holt, Gaffer, ScreenLight & Grip , Boston

Hey Thomas, Like Shadowstone, we also routinely rotate inventory so that it is the most up to date. Look for our auctions on ebay or send a detailed list of what you are looking for to rentals@screenlightandgrip.com and we will respond with a quote. We look to get 60-70 cents on the dollar for what the gear would cost new. If you are prepared to spend that send me your list. - Guy Holt, ScreenLight & Grip

It has been suggested in this thread that the motives for my posts are suspect because "a rental company posted this...so it might be somewhat biased..." I would like to make clear that I post as a professional gaffer and can offer the following credentials: IATSE Local 481 Certified Generator Operator Certificate Holder of the MQ Power "MQP Special Generator (Crawford) Technical Service Seminar" Gaffer, Set Electrician, and Generator Operator on numerous features and television productions (for a partial list of credits see my imdb listing at http://www.pro.imdb.com/name/nm1471247) Owner of ScreenLight & Grip, a lighting and grip rental company renting Honda, MQ, and Crawford generators for motion picture production for 18 years. But, don't take just my word that harmonic currents can cause problems for switch-mode power supplies: according to the Caterpillar Application and Installation Guide for "Electric Power Applications, Engine and Generator Sizing" *: "Most loads will continue to operate with THD at 15 to 20%. However, loads with sensitive electronic equipment can develop problems with THD greater than 5%." The THD value of the severe voltage waveform distortion, generated by two 1200 Pars (with non-PFC ballasts) operating on a conventional AVR gas generator, that can been seen in the oscilloscope shots in my article (available at www.screenlightandgrip.com/html/emailnewsletter_generators.html) is well over 100%. There is no question that THD values of this magnitude in a power waveform will cause erratic behavior in other equipment running on the same distribution system. But don't just take my word for it. Here is a bit of anecdotal evidence relayed to me by Dave Talamas, the owner and chief engineer, of Talamas Broadcast Systems, in Newton Ma.: they sent several non-linear editing systems to the Iron Man Triathlon for field editing. The laptops kept inexplicably locking up. They put a scope meter on the power supply which was coming from a generator that was also supplying a large number of HMIs and found the voltage waveform was severely distorted. They moved the lap tops to the onboard generator of a satellite truck. Once they were moved from the highly distorted power supply of the lighting generator to the highly refined power supply of the satellite truck the laptops operated flawlessly. This incident clearly demonstrates that the switch-mode power supplies of production equipment are not as extremely good at avoiding problems with dirty mains, as Phil suggests. If you like I can present plenty more anecdotal evidence that harmonic currents kicked back into the power stream by HMI & Kino ballasts can cause problems on set. There is simply no question that THD values of this magnitude seen in the power waveforms in my article will cause such adverse effects such as overheating, circuit breaker trips, high currents on the neutral wire, and instability of the generator voltage and frequency. There is also no question that the severe harmonic noise exhibited in my oscilloscope shots can damage HD digital cinema production equipment, create ground loops, and create radio frequency (RF) interference. It is a well established fact that ground looping can be caused by total harmonic distortion of the magnitude we see in my oscilloscope shots. As Tomi Engdahl establishes in "Ground loop problems and how to get rid of them" ** current on neutral conductors with a high THD value will induce voltage in ground wires greater than the 2 volt maximum stipulated by IEEE Standard 1100-1992 (Recommended Practice for Powering and Grounding Sensitive Electronic Equipment.) To paraphrase Tomi Engdahl: neutral-to-ground voltages cause current to flow on the ground wires and under the right circumstances can lead to the creation of ground loops betweeen the tethered components of a production package. The circumstances under which a ground loop will occur is when there is more than one ground connection path between two pieces of equipment. The duplicate ground paths form the equivalent of a loop antenna that very efficiently picks up interference currents. Lead resistance transforms these currents into voltage fluctuations. As a consequence of ground loop induced voltages, the ground reference in the system is no longer a stable potential (a floating ground), so the signals ride on the noise. The noise becomes part of te program signal. The result is that the unwanted signal will be amplified until it is audible and clearly undesirable. Small voltage differences just cause noise to be added to the signals. This can cause an audio hum, interference bars to video signals, and transmission errors in computer networks. Higher currents can cause more serious problems that can damage equipment like sparking in connections and burned wiring. As more and more electronic components, like lap top computers, hard drives, and HD monitors, are integrated into the typical location HD production package, ground loops become more of a hazard. I'm not scare-mongering when I warn that harmonic currents can cause problems for electronic production equipment. But again, don't just take my word for it: apparently, harmonics when using a generator for lighting is enough of a problem to warrant several sections in the third edition of the "Set Lighting Technicianís Handbook." *** To quote Harry Box (Page 337 under "Power Problems from Electronic Loads"): "Much of today's lighting technology relies on electronics such as DC rectifiers (electronic HMI ballasts), silicone-controlled rectifiers (SCRs), capacitors (magnetic & electronic HMI ballasts), and high-frequency switching power supplies (the IGBTs of electronic ballasts). These kinds of load can have undesirable effects on the current waveform, revealing themselves in the form of overheating or failing equipment , efficiency losses, circuit breaker trips, excessive current on the neutral wire, interference and instability with generators, noisy or overheating transformers and service equipment, and even loosened electrical connections. In the following sections, we discuss the power factor and current harmonics and look at their effects. Your awareness of these effects will help you to build systems that avoid or mitigate problems and show how to test for problems.(the parenthesis are mine)" Now does this sound like harmonics is not a problem when using a generator for lighting and I am just "scaremongering"? Or, does Phil want to also accuse Harry Box of trying to scare the ignorant public into buying a solution to a problem that doesn't exist. The problem exists. Now you can either deny it and be worse off for it; or as Harry Box suggests, you can accept it and "your awareness of these effects will help you to build systems that avoid or mitigate problems (on set.)" Which, incidentally, is all that I have tried to do in my posts. Harmonic distortion has just recently become a problem because small conventional generators like the Honda ES6500 and EX6500 were not designed to deal with the abundance of non-linear loads like electronic HMI and Kino Flo ballasts in use today. Running incandescent lights on these generators was never a problem because as purely resistive loads they didnít create harmonic currents. While the inductive reactance of magnetic ballasts running on these generators created voltage spikes, they operated pretty reliably if the generator was equipped with an AC frequency governor. The problem began with the increasing use of non-linear lighting loads, like electronic HMI and Kino Flo ballasts, that generate harmonic currents. The problem is being further compounded by the increasing prevalence on set of sophisticated electronic production equipment like computers, hard drives, and HD monitors which require clean stable power to operate, but are themselves sources of harmonic distortion. Where in the past, much attention was given to portable generator features such as automatic voltage regulation, speed regulation and AC Frequency. Given the increasing prevalence of harmonic currents and the problems they cause, an increasingly more important feature today is the quality of the generated waveform. I have put many hours into researching generators, the harmonic noise generated by electronic ballasts, and the adverse effect it has on set power because I have run into them repeatedly in my professional life as a Gaffer and Generator Operator. I have spent many more hours trying to put what I have learned down in writing so that others can benfit by it as well. I have made this information available for free in this forum rather than selling it to a trade magazine or publisher that would make you pay for it. Finally, I have gone to great length to explain the electrical engineering principles behind our new gen-set system to show that the claims I make are not " somewhat biased...." And, as I think I have demonstrated without a doubt in this post, it is not so much "pigswill." To return to the topic of this thread: Thomas, so that you don't have to take my word alone on this issue, it has been heavily discussed on RedUser.net ( see http://reduser.net/forum/showthread.php?t=24768 - Guy Holt, Gaffer, ScreenLight & Grip, Boston * Caterpillar. "Application and Installation Guide for Electric Power Applications, Engine and Generator Sizing (CAT publication LEBE5294." (Online) Availabe at the Caterpillar Electronic Media Center. **Engdahl, Tomi. "Ground loop problems and how to get rid of them." (Online) Available www.blueguitar.org/new/articles/other/ground_loop.pdf,1997-2000 *** Box, Harry. Set Lighting Technician's Handbook, Third Edition. London: Elsevier Press, 2008

Cont. from above The Honda EU6500is inverter generator is much quieter than the movie blimped Honda EX5500. Part of what makes the new Honda EU6500is so quiet is it's "Eco-Throttle." "Eco-Throttle" is Honda's trade name for a feature of inverter generators already discussed. It is the name Honda give to the fact that the generator's microprocessor automatically adjusts the generator's engine speed to produce only the power needed for the applied load. It can do this because the PWM inverter of the Honda EU6500is enables it to run at different RPMs and maintain a constant frequency and voltage. Where conventional generators like the Honda EX5500 and ES6500 have to run full speed at a constant 3600 RPM to produce stable 60 hertz (cycle) electricity, a Honda EU6500is only needs to run as fast as required to meet the load demand. Since their engines do not have to run at full speed, and the fact that an inverter generator generates 20% more power per revolution of the engine, makes the Honda EU6500is inverter generator substantially quieter than conventional models. To make them even quieter, Honda has designed a new separate triple chamber construction and a new centralized intake/exhaust system. The net result is that the EU6500is is half as loud (ten decibels) as the comparable EM7000is and ES6500 generators typically found at lighting rental houses. Honda's EU Series generators operate at 34 to 44 dBA at 50 ft. - well below what is required for trouble free location recording and quieter than your typical Crawford 1400 Amp "Movie Blimped" Generator. With sound specs this good all you need to record sound without picking up generator noise is a real distro system that will allow you to move the generator off set but yet keep your plug-in pockets conveniently on set. My company, ScreenLight & Grip (SL&G), has developed a Gen-set that is designed to take advantage of the benefits of "True Sine Wave" Inverter genertors and recent technological advances in HMI ballast design to create clean stable set power that is capable of operating larger lights (HMIs up to 6kw or Quartz lights up to 6kw), or more smaller lights, off of portable gas generators than has ever been possible before. What we do is tap the Honda EU6500is inverter generator as it is designed for 230/240V markets like the UK, EU, Australia, & India (to name just a few.) By doing so, we gain access to the full 7650 Watt power capacity designed into the generator for these 230/240V markets, but not available in generators manufactured for 120V Markets like North America. We then use a proprietary step-down transformer/distro to convert the full 240V power into a single 60A/120V circuit (7500Watts) capable of power large lights. Finally, where PWM inverter generators, like the Honda EU6500is, generate a nearly pure power waveform, our modified Honda EU6500is is capable of reliably powering more lights than has been possible before. To maximize the number of HMI & fluorescent lights that can run off our modified Honda EU6500is inveter generator, we offer HMIs and Kino Flo lights with Power Factor Corrected ballasts. For those of you not familiar with Power Factor Correction (PFC), a PFC circuit utilizes a RF Mains Filter to restrict the flow of harmonic currents back onto the supply service. In this fashion, the PFC circuit realigns voltage and current and induces a smoother power waveform at the distribution bus. Formerly only available in large HMI ballasts this advanced electronics reduces voltage waveform distortion and contributes to a more economical use of power than typical HMI and fluorescent electronic ballasts. The substantial reduction in line noise that results from using PFC ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the load you can put on a portable gas generator. In the past we had to de-rate portable generators because of the inherent short comings of conventional generators when dealing with non-PFC electronic ballasts. The voltage waveform distortion created by non-PFC ballasts reacting poorly with the distorted power waveform of conventional generators limited the number of HMIs you could power on a portable generator to 60% of their rated capacity (4200Watts on a 6500W Generator). The power waveform below left (from my article) is typical of what results from the operation of a 2500W non-Power Factor Corrected load (electronic HMI & Kino ballasts) on a conventional portable generator (a Honda EX5500 with a Barber Coleman Governor.) The adverse effects of the severe harmonic noise exhibited here - overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral return, and instability of the generator's voltage and frequency - limits the number of non-PFC HMIs and Fluorescent lights you can reliably operate on the generator. Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400. For this reason, when your lighting package consists predominantly of HMI and Fluorescent lights, it is important to have power factor correction (PFC) circuitry in the ballasts and operate them on inverter generators. The combination of improved power factor and the nearly pure power waveform of inverter generators makes it possible to power larger lights, or more smaller lights, than has been possible before on a small portable gas generator. For example, the power waveform above on the right, is the same 2500W load but with power factor correction operating on our modified Honda EU6500is Inverter Generator. As you can see, the difference between the resulting waveforms is startling. Even though the load is the same, the fact that it is power factor corrected and the power is being generated by an inverter generator, results in virtually no power waveform distortion. For this reason, sensitive electronic production equipment will operate reliably and without damage on the same power. And, the generator is capable of operating larger, or more smaller, lights than has ever been possible before on a portable gas generator. Wide Shot of Night exterior scene lit with a pkg. consisting of PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 powered by a modified Honda EU6500is. The extremely low low line noise exhibited in the inverter generator power waveform above (right) creates a new math when it comes to calculating the lighting load you can put on a portable generator. Where before you could not operate more than a couple 1200W HMIs with non-PFC ballasts on a conventional generator because of the consequent harmonic distortion, now you can load an inverter generator to capacity. And if the generator is one of our modified Honda EU6500is inverter generators, you will be able to run a continuous load of up to 7500W as long as your HMI and Kino ballasts are Power Factor Corrected. The PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 of our HD P&P Pkg. powered by our modified Honda EU6500is through our 60A Full Power Transformer/Distro According to this new math, when you add up the incremental savings in power to be gained by using only PFC HMI ballasts, add to it energy efficient sources like the Kino Flo Parabeam fixtures, and combine it with the pure waveform of inverter generators, you can run more HMI lights on a portable gas generator than has been possible before. For example, the 7500W capacity of our modified Honda EU6500is Inverter Generator can power a lighting package that consists of a PFC 2.5kw HMI Par, PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80. Given the light sensitivity of HD cameras, this is pretty much all the light you will need to light both the foreground and deep background of night exteriors. For more details on how this is accomplished I suggest you read the article I wrote for our company newsletter (mentioned above) on the use of portable generators in motion picture production. Since, the power issues it discusses have been vexing set electricians for years, I highly recommend that anyone responsible for generating power on a set, whether large or small, read this article. The article is available at www.screenlightandgrip.com/html/emailnewsletter_generators.html.) A Distro System consisting of a 60A Full Power Transformer/Distro, 2-60A GPC (Bates) Splitters, 2-60A Woodhead Box distributes power from a modified Honda EU6500is. Even though the generator is 100' away to reduce noise, plug-in points remain conveniently close to set. If tie-ing marine cells into the alternator of a car doesn't give you sufficient power, I would highly recommend our new Gen-set system. The generator is super quiet. The transformer/distro gives you access to more power (7500 Watts continuous)in a larger 60A/120V circuit that is capable of power larger lights or more smaller lights than has ever been possible on a portable gas generator. Use this link for more information about using inverter generators with transformers for motion picture lighting. Guy Holt, Gaffer, ScreenLight & Grip , Boston

Cont. from above Pulse Width Modulation (PWM) inverters provide a more sinusoidal current and for that reason are commonly called True Sine Wave inverters. PWM inverters use extremely fast micro-processor control modules to switch Insulated Gate Bipolar Transistors (IGBTs) at extremely high speeds to produce AC power with a "true" sine wave (with full width and amplitude) from DC power (whether from batteries or the rectifier bridge of an inverter generator.) Pulse Width Modulated (PWM) Voltage Steps(ILLUSTRATION COURTESY OF SIEMENS CORP) In the case of "True Sine Wave" inverter generators, the PWM inverter module consists of a converter, DC link, control logic, and an inverter. The converter section consists of a fixed diode bridge rectifier which converts the more than 300 three phase AC sine waves generated by the multi-pole core of the generator's alternator to high voltage DC power. AC Output is then generated from the high voltage DC by the inverter section with voltage and frequency set by a PWM control logic. A highspeed microprocessor switches IGBTs on and off several thousand times a second according to the PWM control logic to create a variable voltage and frequency. Waveform of power output of PWM inverter generator. Note there no discernable distortion or frequency error. (ILLUSTRATION COURTESY OF KIRK KLEINSCHMIDT] The "true" sine wave that PWM inverters deliver is more suitable for computers, solid-state equipment with built-in computer functions or microcomputer-controlled functions. Not as cheap as MSW inverters, generator manufacturers only put PWM inverter modules in their deluxe or Super Quiet product lines. For instance, the Honda super quiet EU series of generators employ Pulse Width Modulation (PWM) inverter modules with a waveform distortion factor of less than 2.5% - which is considerably better than conventional generators and quite often better than what you get out of the wall outlet. Even though "True Sine Wave battery" inverters generate clean stable power, they have limited application in motion picture lighting because they are only capable of limited power output (1800W max.) The amount of power they can generate from a car battery through the lighter socket is further limited by the wiring of the 12V car lighter socket. That is because when voltage goes down, amperage goes up. Wire that carries 12V DC has to be sized considerably larger then wire that carries 120V AC for the same load (wattage.) For instance to supply 12 volts to a 1800W inverter requires 2 ought feeder cable to the car's battery. Also the car's alternator has to be large enough to take the load without burning out (most are not.) The wiring of a car cigarette lighter circuit is typically only sufficient to power a 300W inverter. This is enough power to operate a few fluorescent fixtures, but for the reasons cited above you would want to make sure to use a "True Sine Wave" Inverter. Exo-skeletal pipe rig on shuttle to rig lights and mount 750W batt-verter on front (covered for rain protection) A better alternative to using a car's lighter socket is a Battery/Inverter set up that is commonly called a "Batt-verter." A "Batt-verter" system consists of one or more deep cycle 12V batteries (usually Marine Cells), a 12V DC-to-120V AC "True Sine Wave" Power Inverter, and a 12V Battery Charger. Batt-verters can work great for traveling car shots but offer limited capacity and run time. Your run time will depend on your load and how many batteries you wire in paralell. Here are some production stills that show you two Batt-verter systems we built to run Kinos to light the inside of an airport shuttle bus for the feature "Shuttle." The first is a 750W "Batt-Verter" rig wired into in a Calzone case and mounted on an Exo-skeletal pipe rig that also held the Kino Flos. 750W "Batt-Verter" Rig wired into in Calzone case and tied into the Shuttle's alternator To maximize the running time on however many batteries you use, I suggest you use a "jumper cable" to attach the marine cells to the leads of the car's alternator. That way you can use the car alternator as a generator to run the lights during set up and rehearsals. When it comes time to shoot, shut off the engine and continue to run the lights on the silent Batt-verter alone. Running the vehicle engine between takes charges the batteries so that they will run longer. 1800W "Batt-Verter" Rig wired into the back of Shuttle The production stills above and below show you a more elaborate 1800W Batt-verter system that we built to run 16 - 4' Kino T-12 tubes inside the airport shuttle bus. Use this link - - for details on how we wired it. To supply 12 volts to the 1800W inverter we ran 2 ought feeder to the buses' alternator. And since the shuttle bus was equipped with a wheel chair lift and extensive inside lighting of it's own, it was equipped with an oversized alternator that could bear the 1800W DC load. Even then we were able to run only four 4' - 4 Bank Kinos on our 1800W rig. SL&G's custom 1800W Batt-Verter powers 16 - 4' Kino Flo single tubes rigged in the interior and on the exterior of an Airport Shuttle If you need more than 1800 Watts you have no alternative but to use a generator. I would suggest the Honda EU6500is inverter generator. The Honda is so quiet that all you have to do to record clean sound is move the generator around the corner of a building or operate it out of a van or truck. Since I am out of space, I will have to explain in my next post what makes the Honda EU6500is inverter generator much quieter than any other portable generator available - including the "Crystal Synced" Honda EX5500. Guy Holt, Gaffer, ScreenLight & Grip [/ur], Boston

Cont. from above When you plug a single 4' - 4 Bank Kino into a wall outlet you need not be concerned about harmonic currents causing voltage waveform distortion. It is, however, an all together different situation when plugging fluorescent fixtures into the inherently distorted voltage waveform of MSW inverters (as seen above) or conventional portable generators (as we will see below.) If we compare the oscilloscope shots below of the voltage waveform induced at the power bus by a Kino Flo Wall-0-Lite (with 10 - 4' T-12 Tubes) operating on grid power (left), power generated by a conventional generator (middle), and power generated by a Pulse Width Modulated (PWM) Inverter generator to the same power sources without a load, we see clearly that the degree of voltage waveform distortion caused by the return of harmonic currents by the Kino Flo T-12 ballasts is directly proportional to the degree of distortion of the inherent power waveform. Left: Grid Power w/ no load and a THD of less then 3%. Center: Conventional Generator w/ no load and a THD of 17-19%. Right: Inverter Generator w/ no load and a THD of 2.5%. The fact that the original supply voltage waveform of conventional generators is appreciably distorted (a THD of 17-19%) to begin with (see middle frame above) causes harmonic currents returned by an electronic Kino ballasts to induce significant waveform distortion of the voltage in the distribution system. The magnitude of current and voltage waveform distortion depends upon the quality of the original applied power waveform and the relative size of the electronic load with respect to the source impedance and capacity of the power system. That is, the amount of voltage distortion increases as distortion of the applied waveform increases and the percentage of electronic ballasts taking up the total capacity of the power system increases. Left: Grid Power w/ Kino Flo Wall-o-Lite. Center: Conventional AVR Power w/ Kino Flo Wall-o-Lite. Right: Inverter Power w/ Kino Flo Wall-o-Lite. This is evident in the oscilloscope shots below of an Arri 1200 HMI Par Plus with standard Arri electronic ballasts. The adverse effects of the severe voltage waveform distortion exhibited in the power of the conventional generator below, can take the form of overheating and failing equipment, efficiency losses, and circuit breaker trips. This is because, as we saw above, circuits that depend on the peak value of the voltage waveform to operate effectively (the diode-capacitor power supplies in computers, hard drives, and electronic ballasts), will work sporadically, if at all, on a squared off wave form whether it is created by harmonic currents distorting the voltage waveform (above) or created by the switching of a MSW battery inverter. Common symptoms are computers locking up and other operational malfunctions that are unexplainable. Left: Grid Power w/ 1.2Kw Arri non-PFC Elec. Ballast. Center: Conventional AVR Power w/ 1.2Kw Arri non-PFC Elec. Ballast. Right: Inverter Power w/ 1.2Kw Arri non-PFC Elec. Ballast. On top of that, the excess part of the wave (the shaded area in the diagram below) must be dissipated somehow. This comes in the form of heat. The bigger the current draw from the unit, the more it produces excess heat within the unit that was not factored for in its' original design. Extended exposure to square wave power supplies, and the heat it generates, may eventually cause premature component level failures within the unit. Harmonic distortion of the magnitude above can also create ground loops and radio frequency (RF) interference. For a detailed explanation for why this is, see my article on the use of portable generators in motion picture production available on our website. Unuseable portion of distorted waveform (shaded) dissipated in heat. For these reasons, audio/video production equipment, computers, electronic ballasts, and battery chargers require a nearly pure (low distortion) true sine wave input. If these devices are to be run from a battery inverter or an inverter generator, then the inverter must supply a sine wave or something pretty close to it. As discussed at the outset, inverters of this sophistication are appreciatively more expensive - from 2 to 3 times - because of the number of and prohibitive cost of high power electronic switch devices and components required. However, recent rapid developments in the field of IGBT (Insulated Gate Bipolar Transistors) electronics and miniaturization/mass production of microprocessor based digital control systems have reached the stage that Pulse Width Modulation inverter modules are now economically viable and affordable. Since I am out of space, I will have to explain the benefits of Pulse Width Modulation in my next post. Guy Holt, Gaffer, ScreenLight & Grip [/ur], Boston

Cont. from above MSW Battery Inverters and Inverter Generators are not suitable for HD digital cinema productions because a modified square wave will cause sensitive electronic equipment (computers, hard drives, video cameras) to overheat, and will cause electronic HMI and Fluorescent light ballasts to kick harmonic noise back into the power stream. Furthermore, electrical components that depend on the peak value of the voltage waveform to operate effectively (the diode-capacitor power supplies in computers, hard drives, and electronic HMI ballasts, as well as the bridge rectifiers of battery chargers) will not operate effectively on a modified square wave. In his article "The “Hows” and “Whys” of Inverters and Inverter Generators," John De Armond explians why using the example of a battery charger powered by a rudimentary MSW inverter generator - a Honda EX350. Output waveform of a Honda EX350 square wave inverter generator ( ILLUSTRATION COURTESY OF JOHN DE ARMOND) The illustration above is of an oscilloscope shot of the modified square wave of a Honda EX350 inverter generator. The output of a MSW battery inverter would be almost identical. Notice the Root Mean Square (RMS) voltage indication (on the right side) is 120 volts even though the peak voltage is only 142 volts. A true sine wave with a RMS voltage of 120 would have a peak voltage of 169 volts (120 x 1.414 = 169 volts.) This difference in peak voltages is what makes MSW inverters unsuitable for motion picture production applications. This becomes apparent when we compare the operation of a battery charger on the true sine wave of grid power to its operation on a modified square wave of an MSW inverter. A battery charger typically consists of a step down transformer, a rectifier and support electronics like charge control circuitry. On each half-cycle of the 60 hz line voltage, the voltage first increases and then decreases in the shape of a sine. The transformer secondary of the battery charger follows this voltage. Connected to the secondary is the rectifier that converts the AC to DC for battery charging. Only when the instantaneous AC voltage exceeds the battery voltage plus the 0.7 voltage drop of the rectifier does current flow to charge the batteries. Photo 5 illustrates this effect. The two lines at “1” and “2” mark on the voltage sine wave where the rectifier starts conducting and causing current to flow. ( ILLUSTRATION COURTESY OF JOHN DE ARMOND) Problems arise when a charger of this type is powered by a modified square wave regardless if it is generated by a battery inverter or inverter generator. Recall from the first photo above that the peak voltage of a modified square wave does not rise as high as a sine wave (142 volts verses the 169 volts of a true sine wave.) The horizontal line in the photo above shows about where the modified square wave would reach. In this particular case, the modified square wave would never reach a voltage sufficient to make the rectifier conduct and so the battery would never charge even though power is connected, the LED indicators light up, and a true RMS voltmeter would indicate about 120 volts. Problems also arise when a modified square wave is used to power the electronic ballasts of HMI and fluorescent lights. This becomes apparent when we compare the power waveform induced by the operation of a Quartz Incandescent Light (an Arri 300) to that of a fluorescent fixture that uses Compact Fluorescent Lamps (CFL) operating on MSW inverter (the same Honda EX350.). Voltage and the current output waveforms of a Honda EX350 square wave inverter generator powering 300W incandescent light ( ILLUSTRATION COURTESY OF JOHN DE ARMOND) The illustration above is of a scope shot of both the voltage and the current output of the Honda EX350 generator driving a 300 watt Quartz Incandescent light (a resistive load.) As you see, a modified square wave works well for a resistive load like an incandescent light. The current waveform rises and falls with the voltage waveform (they are in phase) and the inherent distortion of the modified square wave does not induce distortion of the current. Things get a whole lot more interesting when we connect a Compact Fluorescent Lamp (CFL) to the modified square wave. As you can see in illustration below the fluorescent lamp creates all kinds of current oscillation that slightly distorts the voltage waveform (creates a spike). Voltage and the current output waveforms of a Honda EX350 square wave inverter generator powering fluorescent light ( ILLUSTRATION COURTESY OF JOHN DE ARMOND) Electronic ballasts (both fluorescent & HMI) utilize solid state electronic components (rectifiers, capacitors, and IGBTS) that use only portions of the power waveform - they place all their load on the peak values of the voltage waveform. These devices then return the unused portions to the distribution system as a harmonic current. These harmonic currents stack on top of one another in the distribution system creating harmonic distortion that pulls the voltage and current out of phase. Under certain conditions, these harmonic currents that are kicked back into the power stream by the electronics of the ballast can cause a distortion of the voltage waveform (the spike in the waveform above) that manifests itself as a noticeable audio buzz or equipment to malfunction. For a detailed explanation for why harmonic currents cause voltage waveform distortion see my article on the use of portable generators in motion picture production available on our website. Fluorescent lights are a good choice for operation on battery inverters in the limited sense that they use a quarter of the power of a comparable tungsten light. However, the ballasts of the many fluorescent fixtures, like the Kino Flo fixtures that use the T-12 tubes (the Single, Double, and 4 Bank Fixtures, the Wall-o-Lite, Flathead 80, and the Image 20, 40, & 80 fixtures) and fluorescent fixtures that use Compact Fluorescent Lamps (CFLs) return harmonic currents into the power stream. For this reason, Kino Flo cautions users, on their website: "Kino Flo ballasts ... will draw double the current on the neutral from what is being drawn on the two hot legs. On large installations it may be necessary to double your neutral run so as not to exceed your cable capacity."( FAQ "Why is the neutral drawing more than the hot leg" at http://www.kinoflo.com/FYI/FAQs.htm#2) For a detailed explanation for why harmonic currents cause unusually high neutral returns see my article on the use of portable generators in motion picture production available on our website. When you plug a single 4' - 4 Bank Kino into a wall outlet you need not be concerned about harmonic currents causing voltage waveform distortion. The impedance of the electrical path from the power plant is so low, the distortion of the original voltage waveform so small (1-3%), and the plant capacity so large in comparison to the load of the one light, that the inherently noisy load of the 4'- 4 Bank Kino will not affect the voltage at the distribution bus. Since I am out of space, I will have to explain in my next post how it is a different situation when plugging fluorescent fixtures into the inherently distorted voltage waveform of MSW inverters or conventional portable generators. Guy Holt, Gaffer, ScreenLight & Grip , Boston

You have to be really careful when choosing a DC-to-AC inverter for film production because there are three basic types of inverters and not all of them are suitable for production applications. The recommendations I will make are based upon extensive research I have done on the use of portable gas generators in motion picture production. For this research, I ran a series of tests in order to analyze the interaction of the different type of portable generators with the prevalent light sources available today. Since inverter generators use the same three types of inverters, the findings of my research are applicable to stand alone DC-to-AC inverters designed for use with batteries as well. The results of my tests are going to be cited in the upcoming 4th edition of the "Set Lighting Technicianís Handbook." I have also compiled the results in an article for my company newsletter and it is available on our website. Waveform of power output by conventional generator. Note the frequency error and noticeable distortion (ILLUSTRATION COURTESY OF KIRK KLEINSCHMIDT] To understand how the application is the same it may help to review why inverters are used in generators in the first place. Even though a conventional generator makes a pretty decent AC power sine wave, it is considered “dirty” power. Measured on an oscilloscope (pictured above), its’ sine wave appears jagged. Those small spikes in the sine wave indicate harmonic distortion that can cause problems for sophisticated electronics, like video cameras, monitors, computers, and hard drives that need a clean sine wave to operate. With the increasing use of personal computers and microprocessor-controlled recording equipment in motion picture production, there is a greater demand for clean, reliable power on sets. Step 1: Rectifier Bridge converts multi-phase AC power to rectified sine wave. Step 2: rectified sine wave is flattened to DC. Step 3: micro processor switching alternates wave polarity creating a modified square wave. (ILLUSTRATION COURTESY OF HARRY BOX] Inverter generators meet this demand for cleaner power by adding an additional step that completely processes the “dirty” AC power from the generator’s alternator. An inverter module takes the raw power produced by the generator's alternator and passes it through a microprocessor controlled multi-step process to condition it. But, rather than using the simple two pole cores of conventional genertors, inverter generators use multi-pole cores and small stators to produce a raw AC power that is multiphase (more than 300 overlapping sine waves), high frequency (up to 20’000 Hz), and upwards of 200 Volts. This high voltage AC power is then converted to DC. Finally the DC power is converted back to low voltage single phase AC power by an inverter. In the process the inverter cleans and stabilizes the power. There is a popular misconception that you should only use electronic ballasts with portable generators. Where that is true with conventional generators without crystal governors, it is not true of inverter generators. By using a microprocessor to convert AC power to DC, and then an inverter module to convert the DC back to AC, inverter generators generate power that is independent of engine speed and rock solid with a frequency variance of only hundredths of a cycle - which eliminates the need for costly crystal governors. In this limited sense, it can be said that inverters, whether for batteries or built into a generator, are "actually better for use with the HMI electronics." In fact, only one of the three types of inverters are suitable to power HMI lights. The three types of inverters are, "true sine wave", "modified square wave" (also known as "modified sine wave"), and "square wave." One might wonder why there are so many types of inverters. As John De Armond, explains in his informative article "The “Hows” and “Whys” of Inverters and Inverter Generators" the primary reason is cost. To paraphrase John's article, to make a nice sine wave from DC power (whether generator power or battery power) is expensive. There is a trade-off between cost and waveform purity. An approximation of a sine wave may be created by outputting one or more stepped square waves with the amplitudes chosen to approximate a sine (a "modified square wave" inverter). The more steps, the more like a sine wave the output (a "true sine wave" inverter). However, each of the voltage steps requires its own voltage supply, its own transistor switch, plus the necessary control circuitry. The bottom line is that the more steps, the more expensive the inverter. The two go hand in hand. Ideal Sine Wave (black), Single Step Square Wave (blue), Three Step Square Wave (red)( ILLUSTRATION COURTESY OF JOHN DE ARMOND) Take a look at the figure above. The black trace is a pure AC sine wave. The blue wave is a single step approximation or square wave. The red wave is a three step wave or simple modified square wave. As is intuitive, the three step wave produces a closer approximation of a sine wave and thus will satisfactorily operate more devices than the single step one. The trade-off is cost and complexity Switch sequence of three step output stage of a modified square wave inverter. ( ILLUSTRATION COURTESY OF JOHN DE ARMOND) The figure above is a line drawing of a typical three step output stage of a simple modified square wave inverter. The voltages V1 through V3 are increasingly higher DC voltages. A microprocessor generates this pseudo sine wave by sequentially switching S1 through S3 on, S3 through S1 off, S4 through S6 on, S6 through S4 off. It repeats this 60 times a second. Where each of the voltage steps requires its own voltage supply, its own transistor switch, plus the necessary control circuitry, one can intuit that the more steps in the modified square wave, the more complicated and thus more expensive the inverter. Where it is less expensive to make a modified square wave that will satisfactorily operate most construction equipment and RV appliances, than it is to make a true sine wave there is not the cost/benefit return to warrant the incorporation of more switches in inverters manufactured for these markets. This is why there are still three types of inverters available on the market to this day for use with batteries and built into generators. Square wave (SW) inverters will run simple things like tools with universal motors with no problem, but not much else. For this reason, SW inverters are now found only in the construction trades, where they offer the benefit of being cheaper. For the reasons detailed below, SW inverters have no application in motion picture production. “Modified Sine Wave”, “Psuedo Sine Wave”, and “Cycloconverter” are all sales terms used for a modified square wave type of AC power generated by inverters with more switching capacity. Modified square wave (MSW) inverters are low in cost and will satisfactorily operate almost all common household appliances and power tools. For this reason, MSW inverters are the most prevalent and the ones typically used in the economy RV/Residential Standby and Industrial lines of inverter generators. Unfortunately, they also are not suitable for use in motion picture production except for the powering of quartz lights. Since I am out of space, I will have to explain in my next post why MSW Battery Inverters and Inverter Generators are not suitable for HD digital cinema productions. -Guy Holt, Gaffer, ScreenLight & Grip , Boston

Unless done by a licensed electrician, it is illegal to tie into a breaker box. You probably don't even need to tie-in a special circuit to power your 5k. There are a number of 240 volt wall outlets in a typical house, office, or industrial plant that you can safely and legally use to power a 5k and even HMIs as large as a 6k. The most common are air conditioner outlets, dryer outlets, range outlets, outlets for large copy machines in offices, and the outlets for motorized equipment and compressors in industrial plants. If you look at the breaker of these circuits on the building service panel you will notice that they use two pole breakers - either 30A or 50A. Each pole of the breaker is in a sense an independent 30A or 50A 120 volt circuit. That is, if you measure the voltage from each pole of the breaker to ground it will be 120 volts, and if you measure the voltage between the two poles of the breaker you will notice that it is 240 volts. The 120 volts of the two poles adds up to 240V because the 120V circuits are on opposing legs (and are therefore additive) of either a single phase electrical service of a house, or a single phase secondary step down transformer of a office or industrial plant. In residential settings, this is how higher voltages are supplied to household appliances like Dryers, Electric Ranges, Air Conditioners, Motors, etc. that require more power than can be reasonably supplied by a single 120V circuit. Many of these household and industrial 240V receptacles use a three wire system (no neutral) because they are designed to power single phase motors or heating elements that draw a perfectly balanced load and return no current because the single phase service legs are 180 degrees out of phase and cancel each other out. Where a state of the art Power Factor Corrected (PFC) Electronic HMI ballast, like the Power -2- Light 6kw ballast, draws only 25 Amps on each leg of a single phase 240V circuit, its' load is well within the capacity of these common 240V circuits. In our rental inventory we keep an assortment of adapters because all of these 240V wall receptacles use a different pin configuration. You can also power 5ks from these 240V circuits by using a 240v-to-120v step down transformer like the 60A Full Power Transformer/Distro we make for our modified Honda EU6500is generators. Like it does with the 240V output of the Honda EU6500is Generator, our 60A Transformer/Distro will convert the 240 volts supplied by these industrial and household receptacles back to 120 volts in a single circuit, that is the sum of the two single phase legs of 30/50 amps each, and is capable of powering bigger lights, like a 5k or a 6000W Six Light Mole Par. It can also be used to power multiple 120V luminaries off of 240 Volt circuits because our Transformer/Distro automatically splits the load of whatever you plug into it evenly over the two legs of the 240V circuit so there is no neutral return. 4k & 1.2ks HMI Pars powered from 30A/240V dryer outlet through step-down transformer/distro for Bose still shoot. I would be negligent if I did not caution you that some people will advocate the use of a "Splitter Box" on 240V outlets. A "Splitter Box" is a special distro panel that a rental house will make up that is wired to split out the two 120V circuits that make up the 240V outlet. If the 240V outlet is a 4-wire 50A/240V Range plug (the receptacle has four slots: one for ground, one for neutral, and two for hot), you could use a splitter box to power a 5k. But, you have to be really careful when splitting 240 volt circuits. If the 240 volt circuit is a four wire system, one can use a distro box as long as it is wired so that each circuit has a ground and neutral. Where you run into trouble is when the 240V circuit uses a three wire system (the receptacle has three slots: one for ground, and two for hot, and no neutral.) Many household and industrial 240V receptacles use a three wire system (no neutral) because they were wired for the sole purpose of powering single phase motors or heating elements that draw a perfectly balanced load and return no current. A perfectly balanced load doesn’t require a neutral because the single phase service legs are 180 degrees out of phase and cancel each other out – hence there is no return that would require a separate neutral. You run into trouble with this kind of circuit when you start to pull an unbalanced load on your "Splitter Box." And, where under most production situations you can never perfectly balance your lighting load, the two 120V circuits that make up this 240V circuit will not have 100% phase cancellation and the extra current of the high leg will not have a safe return path because by necessity with a three wire system you have had to bond the ground and the neutral in the splitter box (after all what else can you do with the ground and neutral of your splitter box but to bond them when plugging into a three wire 240V circuit.) There are some people that will argue that it is not such a big deal to carry current on the ground wire. I would argue that it is both unsafe and unwise to carry current on the ground wire. It is unsafe because the ground wire is intended only as a default conduit in the event of equipment failure (which is why it is permissible according to the National Electrical Code (NEC) to use a smaller conductor for the ground wire.) It is unwise because bonding ground and neutral after the service side of a main service head (which is what you have to do with the ground and neutral of a splitter box when plugging into a three wire 240V circuit.) is a violation of the NEC. To quote Mike Holt, of Mike Holt Enterprises, Inc. again: “The National Electrical Code (NEC) requires a neutral-to-ground connection to be made at service equipment only and there shall not be any neutral-to-ground connection on the load side of service equipment [250-23(a), 250-24(a)(5)]” (full excerpt is available online at his website) If some one were to fall off a ladder because they took a non-lethal shock because the cable they were handling was carrying current on the ground wire your liability insurance would be null and void because you were using equipment that need not meet code. It is also unwise to carry current on the ground wire because it can induce ground loops. It is a given that whenever you carry current on the ground wire there will be a slight difference in the voltage between receptacles in the power distribution system. A ground loop occurs when there is more than one ground connection path between two pieces of equipment and there exists a voltage differential. Under these circumstances, the duplicate ground paths form the equivalent of a loop antenna that very efficiently picks up interference currents. Lead resistance transforms these currents into voltage fluctuations. As a consequence of ground loop induced voltages, the ground reference in the system is no longer a stable potential (a floating ground), so signals ride on the noise. The noise becomes part of the program signal. The result is that the unwanted signal will be amplified until it is audible and clearly undesirable. Whenever you have current on the grounding system as well as the multiple connections between electronic components that is typical of HD production packages, there is the potential for a "ground loop." Interference bars caused by current induced on a ground loop by high THD. Small voltage differences just cause noise to be added to the signals. This can cause an audio hum, interference bars to video signals (above), and transmission errors in computer networks. Higher currents can cause more serious problems that can damage equipment like sparking in connections and burned wiring. As more and more electronic components, like lap top computers, hard drives, and HD monitors, are integrated into the typical location HD production package, ground loops become more of a hazard. Left: Conventional generator power w/ THD over 100 percent caused by pkg. of non-PFC Elec. HMI & Kino Ballasts. Right: Same lighting Pkg. but with PFC HMI & Kino Ballasts powered by our modified Honda EU6500is inverter generator. Note the THD is now under 7 percent. It is also worth noting that “ground loops” can result from the harmonic currents that non-power factor corrected electronic ballasts (HMI & Kino) throw back into the distribution system. Current on neutral conductors with a high Total Harmonic Distortion (THD) value will induce voltage in ground wires greater than the 2 volt maximum stipulated by IEEE Standard 1100-1992 "Recommended Practice for Powering and Grounding Sensitive Electronic Equipment." For instance, there was an episode, recently reported on CML, of a pilot shooting in HD that found they had 50 volts between the shield of the SDI line and ground. In that case the problem was fixed by running a "Drain" wire from the SDI Shield back to the Genny via the electrical lunchbox at the DIT station. For more details on why this is I suggest you read my newsletter article on the use of portable generators in motion picture production. The article is available on our website. The only safe way to pull power from a three wire 240V wall outlet that meets the requirements of the National Electrical Code, and won't create ground loops, is to run your lighting load through a 240v-to-120v step down transformer. A transformer converts the 240 volts supplied by these industrial and household 240V receptacles back to 120 volts in a single circuit that is the sum of the two legs of the circuit. For instance, a transformer can make a 60A/120v circuit out of a 30A/240v dryer circuit that is capable of powering bigger lights, like a 5k or 4k HMI. What makes it safe to plug a step town transformer into three wire 240V outlets is that the transformer automatically splits the load of whatever you plug into it evenly over the two legs of the 240V circuit so that you have 100 percent phase cancellation. In other words, where there is no high leg, the loads on each leg of the 240V circuit completely cancel out and there is no return that would require a separate neutral and there is no return current on the ground wire to create ground loops. A PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 powered by a modified Honda EU6500is through a 60A Full Power Transformer/Distro You can maximize the power you can pull from 240 Volt wall receptacles if, rather then plugging a 4k HMI directly into the 240 receptacle, you plug it in through a combination Transformer/Distro (like the one we make for our modified Honda EU6500is generators pictured above) and operate it at 120 Volts. Where the Power-2-Light (P2L) 4/2.5 LVI ballast operating a 4k HMI luminary at 120V draws only 36 amps, you will still be able to power additional lights, like a 1200 Watt HMI luminary powered by a P2L 575/1200 ballast (11 Amps) and a 800 Watt HMI luminary powered by a P2L 800/1200 ballast (8 Amps), off of the same circuit. The PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 of our HD P&P Pkg. powered by our modified Honda EU6500is through our 60A Full Power Transformer/Distro Unlike a 240V "Splitter Box," where you have to meticulously balance your load, a transformer greatly simplifies your set electrics by automatically splitting the load evenly. As long as you plug lights in through the transformer, you no longer have to carefully balance the load over the two 120V circuit/legs because the transformer does it for you automatically. If you outfit the transformer, like our Full Power 60A Transformer/Distro, with a 60 Bates receptacle, you can use 60A GPC extension cables, 60-to-60 Splitters, and fused 60A GPC-to-Edison Breakouts (snack boxes) to run power around set - breaking out to 20A Edison outlets at convenient points (rather than one central point.) The best part about using a transformer with a 240V receptacle in this fashion is that no matter where in the distribution system you plug in, the transformer automatically balances the additional load, so that you don't have to. Wide Shot of Night exterior scene lit with our HD P&P Pkg. I use transformers to power bigger HMIs (2.5-4Kw) in situations where a tie-in is not an option and the budget doesn’t permit for a tow generator. Where the production budget is particularly tight, I use a package consisting of two transformers and a portable generator. I use one transformer to access more power through a 240V circuit on location to run lights inside; while the other I use to bring larger HMIs in the windows from outside. This approach eliminates the need for a dangerous tie-in or expensive tow generators, it also greatly reduces the amount of cable that has to be run. In my 20 plus years as a Gaffer I have found the three wire 240V circuits (hot, hot, ground, no neutral) to be much more prevalent and accessible than the four wire circuits (usually just range plugs with a hot, hot, ground, neutral.) Over the years, I have used a combination of 3 wire/240V wall outlets, step-down transformer/distros, and Honda EU6500is generators without problem on many historical documentaries I have gaffed. For example, I have used this approach repeatedly at a historical mansion in Easton MA called the Ames Estate. Scene from "Unsolved History" powered from 50A/240V range outlet through step-down transformer/distro at the Ames Estate. A popular state fee free location, the Ames Estate, like many historical house/museums, does not permit tie-ins and the electrical wiring in the house is so antiquated that it is unusable. Fortunately, they have a 50A/240 volt circuit in the carriage house for a welder they use to repair the mowers they use at the park. Our standard mode of operation when shooting there is to run 250V extension cable from the welding receptacle to our 60A Full Power Transformer/Distro placed in the entry hall of the house. Using a 60A Siamese at the Transformer/Distro, we then run 60A 6/3 Bates extensions, down to the library, to the second floor, and back to the maid’s pantry. At the end of each run we put another 60A Siamese. A 60A snackbox on one side of the Siamese gives us 20A branch circuits. The other side we leave open for a large HMI or Quartz Light. Now we can safely plug 1200 & 2500W HMIs, or even a 5k Quartz, into our own distribution anywhere in the house. Typhoid Mary in quarantine on an island in New York's East River. Note the view out the window of the East River shoreline at the turn of the century. To maintain continuity between shots on these dramatic historical recreations, we usually bring a 4kw HMI Par in a window on one side of the room as a sun source and a 1200 par through a window on the other side as a northern light source. We power both heads off of our modified Honda EU6500is through a Transformer/Distro. We are able to power both lights off our modified EU6500is because the Transformer/Distro provides access to the enhanced 7500W capacity of the generator in a single 60A/120V circuit (for more details on how this is accomplished I suggest you read my newsletter article on the use of portable generators in motion picture production available on our website. And, since the Honda EU6500is can be placed right on the lawn, we are saved from running hundreds of feet of feeder back to a tow generator in the drive. (The exterior of the actual location used for the quarantine island. A 30' blowup of a picture of the East River at the turn of the century was rigged outside the windows of a house in Arlington MA.) We have been able to use this same basic distribution package (two Transformer Distros, 1- modified EU6500is) at numerous museums and historical houses throughout New England including Sturbridge Village. Fortunately for us, to make ends meet, many historical houses rent themselves out for events and weddings. For that reason, they usually have at least one updated service with 30 or 50 Amp 240 volt circuit for the warming ovens of caterers. I have included in this post several production stills from these shows. For those who would like to see samples of what can be accomplished with this basic package, I have attached these links to production stills of the PBS and History Channel historical documentaries shot entirely, or in part, with just a couple of transformers and a Honda generator. The History Channel’s “Unsolved History” episode “Presidential Assassins” American Experienes Typhoid Mary Biography "The Most Dangerous Women in America" WGBH’s Ben Franklin Biography “Franklin” Or, use this link for more details about using step-down transformers on set: . By giving you safe and legal plug-in access to more house power through common 240V house outlets, a transformer can quite often eliminate the need for tie-ins or generators. - Guy Holt, Gaffer, ScreenLight & Grip, www.screenlightandgrip.com

Personally, I would choose the following #1 Parabeam 400 #2 Parabeam 400 #3 4'- 4 Bank. As a rental house owner operator I would choose the same. You can always diffuse a Parabeam 400 to get the equivalent of a Diva 400 and BarFly 400. But you will never get the punch or control out a Diva 400 or BarFly 400 that you get out of a Parabeam 400. The 4'- 4 Bank is still a very popular light because of it's flexibility. Good Luck - Guy Holt, ScreenLight & Grip

Since you do spot work and large corporate projects, you would probably be better served by a Kino Flo Parabeam 400 rather than either the Diva, BarFly, Vistabeam, or 4' 4 Bank T12 Kino fixture which are more suited to documentary production. Before I give you my reasons, in the interest of full disclosure, I should first say that in addition to being a gaffer, I own and operate a rental house that rents and sells the equipment I am abour to recommend. If what I am about to say sounds like I’m hyping the Kino Flo product line it is not because we rent and sell them exclusively. We are dealers and rental agents for just about all the major brands. As a professional Gaffer of a lot of tight budgeted historical documentaries for PBS’ American Experience and The History Channel (see my “credit-entials” on Imbd), I think it is worth noting that the Kino Flo Parabeam fixtures are a viable alternative to HMIs when used with the new inverter generators because they offer low budget independent filmmakers a more affordable alternative to HMI lighting. My recommendations are also based upon extensive research I have done on the use of portable gas generators in motion picture production. For this research, I ran a series of tests in order to analyze the interaction of conventional AVR generators (a Honda EX5500 with Crystal Governor), as well as inverter generators (a Honda EU6500is), with the prevalent light sources available today. I have compiled the results of my tests in an article for my company newsletter and it is available on our website. What distinguishes the Parabeam fixtures from the Diva fixtures (and all other fluorescent lights for that matter) is their throw, power efficiency, and the innovative accessories Kino Flo makes available for the fixtures that enhance their production capabilities. Accessories include barndoors, a gel frame, a diffusion panel, and Honeycomb Louvers. Honeycomb Louvers are available in 90, 60 and 45 degrees. Swapping louvers provides beam control similar to that of swapping lenses on an HMI Par. The Diffusion Panel, on the other hand, slightly softens the beam structure in the open face mode. In the end, which fluorescent light will serve you best, depends on how you plan to use it. By the description of what you shoot, it sounds like you would be best served by the ParaBeam 400 fixtures because they have computer aided designed (CAD) parabolic reflectors that focus the light output where it is needed most for lighting dramatic scenes - at a medium distance – making it a better key source for spot work than the Diva 400, Bar Fly 400, or 4’ 4 Bank Kinos. If you compare the photometric tables of the Parabeam 400 and the Diva 400 (which uses the same four lamps), you will notice that at 16’ the Parabeam 400 puts out almost three times the light level (28FC) than the Diva 400 (10FC) even though they both use the same tubes. In fact a Parabeam 400 generates as much light at 16’ as the 4’ 8-Tube Kino Flathead 80 fixture, yet uses less than a quarter of the power – making it an ideal light to operate on a portable generator. The flip side, is that the Parabeam 400 will be harder and less flattering to your talent as a key source in an interview set up. Given its large size, a 4’ – 4 Bank Kino makes for a more flattering key source in interview set ups than the Parabeam 400. But, where a 4’ – 4 Bank Kino generates a very broad soft light that tends to drop off rapidly they generally do not have the “throw” to serve as a key source in dramatic sets ups. Another advantage to the Parabeam 400 is that you can use the accessory diffusion panel or put diffusion on it to make it softer, where you can not make a 4’ – 4 Bank Kino Flathead harder or make it throw further. Not only do the Parabeam fixtures have more throw, but they are also easily controlled – an essential requirement in a Key source. Parabeam fixtures are controlled by interchanging Kino Flos’ innovative Honeycomb Louvers. Louvers are available in 90, 60 and 45 degrees. Swapping louvers provides beam control similar to that of swapping lenses on an HMI Par. These features enhance the production capabilities of the Parabeam fixtures and make them suitable to serve as a key or backlight source where conventional fluorescent movie light fixtures will spill all over the set. These features make the Parabeam fixtures the best candidate of all fluorescent lights to replace incandescent soft lights in their roll as dramatic key sources. And, the power you save by not using tungsten instruments for keys and backlights, enables you to power more lights on the generator than you could otherwise. Another, advantage to the Parabeam 400 is that it draws less than half of the power (2 Amps) than a 4’ – 4 Bank Kino (4.6 Amps). While this nearly 3 amp difference is not a major consideration when using house power, it can make a difference when your power is coming from a portable generator because you can use two Parabeam 400s for the same power as a 4’ – 4 Bank Kino. Kino Flo is able to obtain such efficiency in their Parabeam fixtures by incorporating Power Factor Correction circuitry into their ballasts. As it does in HMI ballasts, this advanced electronics contributes to a more economical use of power than Kino Flo’s conventional electronic ballasts and reduces the return of harmonic currents into the power stream. With a Power Factor Rating of over .9, the Parabeam 400 fixtures are especially well suited for use on small portable generators which is an important consideration for spot work. All Kino Flo fixtures are a good choice for operation on small portable generators in the limited sense that they use a quarter of the power of a comparable tungsten soft light. However, the ballasts of the older style Kino Flo fixtures, like the 4’ – 4 bank Kinos, that use the T-12 tubes (the Single, Double, and 4 Bank Fixtures, the Wall-o-Lite, Flathead 80, and the Image 20, 40, & 80 fixtures) are not power factor corrected and return harmonic currents into the power stream. When used in quantity, as in studio chroma key productions, they can constitute a source of considerable harmonic noise in the power stream. For this reason, Kino Flo cautions users, on their website: “Kino Flo ballasts are generally not power factor corrected. They will draw double the current on the neutral from what is being drawn on the two hot legs. On large installations it may be necessary to double your neutral run so as not to exceed your cable capacity.”( FAQ “Why is the neutral drawing more than the hot leg” at http://www.kinoflo.com/FYI/FAQs.htm#2) For a detailed explanation for why harmonic currents cause unusually high neutral returns see my article on the use of portable generators in motion picture production available on our website. When you plug a single 4’ - 4 Bank Kino into a wall outlet you need not be concerned about harmonic currents. As is the case with non-PFC HMI ballasts discussed elsewhere in this forum, the impedance of the electrical path from the power plant is so low, the distortion of the original voltage waveform so small (1-3%), and the plant capacity so large in comparison to the load of the one light, that the inherently noisy load of the 4’- 4 Bank Kino will not affect the voltage at the distribution bus. Left: Grid Power w/ no load and a THD of less then 3%. Center: Conventional Generator w/ no load and a THD of 17-19%. Right: Inverter Generator w/ no load and a THD of 2.5%. It is, however, an all together different situation when plugging Kino Flo T-12 fixtures into conventional portable generators. As a comparison of the oscilloscope shots above and below indicate, the return of harmonic currents by conventional Kino Flo T-12 ballasts can generate voltage distortion in the power stream. Given the large sub-transient impedance of conventional portable generators, and the fact that the original supply voltage waveform of conventional generators is appreciably distorted (a THD of 17-19%) to begin with , you have a situation where the return of any harmonic currents by a non-PFC electronic ballast (HMI or Kino) will result in significant waveform distortion of the voltage in the distribution system. Left: Grid Power w/ Kino Flo Wall-o-Lite. Center: Conventional AVR Power w/ Kino Flo Wall-o-Lite. Right: Inverter Power w/ Kino Flo Wall-o-Lite. Given the effect of just one 10–tube Kino Flo Wall-o-Lite with non-pfc electronic ballasts on a 5500W conventional generators, what would be the accumulative effect of a typical lighting load on a generator? To see, I ran a package consisting of two Arri 1200 HMI Par Pluses with standard Arri non-PFC electronic ballasts in addition to the Kino Flo Wall-o-Lite on the Honda EX5500 (a conventional generator). And, for the sake of comparison, I ran the same package but with power factor corrected electronic ballasts on our modified EU6500is (an inverter generator.) The difference between the resulting waveforms below is startling. The adverse effects of the severe harmonic noise exhibited below left, can take the form of overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral return, and instability of the generator’s voltage and frequency. For these reasons it has never been possible to reliably operate more than a couple of 1200W HMIs on a conventional 6500W portable gas generator. Harmonic noise of this magnitude can also damage HD digital cinema production equipment, create ground loops, and possibly create radio frequency (RF) interference. For a detailed explanation for why this is, see my article on the use of portable generators in motion picture production available on our website. Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Center: Scope time base adjusted to bring elongated waveform back on screen. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400. Why are harmonics suddenly an issue in motion picture electrical distribution systems? First, one must appreciate that the power generation and electrical distribution systems developed for motion picture production were never designed to deal with an abundance of non-linear loads like electronic HMI and Kino Flo ballasts. It’s a problem that has only recently begun because of the increasing use of these types of non-linear lighting loads. The problem is being further compounded by the increasing prevalence on set of sophisticated electronic production equipment like computers, hard drives and HD monitors which are themselves sources of harmonic distortion. The increasing use of these microprocessor-based equipment in production has created an unprecedented demand for clean, reliable power on set at a time when the prevailing light sources are dumping more and more noise into the power stream.? It is worth noting in the oscilloscope shots above that the distortion of the voltage waveform is considerably less in the case of the inverter Honda EU6500is generator (far right) than that of the conventional Honda EX5500 generator (left.) The reason for this is that, as discussed at length in my article, the original waveform of the power generated by the EU6500is (an inverter generator) has less harmonic distortion at the outset than that originally generated by a EX5500 (conventional generator.) For this reason, when your lighting package consists predominantly of non-linear light sources, like HMI and Fluorescent lights, it is important to have power factor correction (PFC) circuitry in the ballasts (HMI & Kino) and operate them on inverter generators like our modified Honda EU6500is. The combination of improved power factor and the nearly pure power waveform of inverter generators makes it possible to power larger lights, or more smaller lights, than has been possible before on a small portable gas generator. Wide Shot of Night exterior scene lit with our HD P&P Pkg. For example, the substantial reduction in line noise that results from using power factor corrected Kino and HMI ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the load you can put on a generator. In the past we had to de-rate portable gas generators because of the inherent short comings of conventional generators with AVR and Frequency governing systems when dealing with the harmonic noise of non-PFC electronic ballasts. The harmonic distortion created by non-PFC ballasts reacting poorly with the distorted power waveform of conventional AVR generators (as evident in the oscilloscope shots above) limited the number HMIs and Kinos you could power on a portable generator to 60% of their rated capacity (4200Watts on a 6500W Generator). Two Shot reverse keyed by a pair of Parabeam 400s But now, that inverter generators have virtually no inherent harmonic distortion or sub-transient impedance and power factor correction (PFC) is available in both small HMI and Kino Flo Parabeam ballasts, this conventional wisdom regarding portable gas generators no longer holds true. Where before you could not operate more than a couple 1200W HMIs with non-PFC ballasts on a conventional generator because of the consequent harmonic distortion, now according to the new math of low line noise, you can load an inverter generator to capacity. And if the generator is our modified EU6500is inverter generator, you will be able to run a continuous load of up to 7500W as long as your HMI and Kino ballasts are Power Factor Corrected. The PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 of our HD P&P Pkg. powered by our modified Honda EU6500is through our 60A Full Power Transformer/Distro According to this new math, when you add up the incremental savings in power to be gained by using only PFC ballasts, and combine it with the pure waveform of inverter generators, you can run more lights on a portable gas generator than has been possible before. For example, the 7500W capacity of our modified Honda EU6500is Inverter Generator powered a lighting package for a recent Red shoot (see production stills above and below) that consisted of a PFC 2.5kw HMI Par, PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80. Given the light sensitivity of HD cameras, this is all the light needed to light even a large night exterior. (For more details on how this is accomplished I suggest you read my newsletter article on the use of portable generators in motion picture production. The article is available on our website. A Distro System consisting of a 60A Full Power Transformer/Distro, 2-60A GPC (Bates) Splitters, 2-60A Woodhead Box distributes power from a modified Honda EU6500is. Even though the generator is 100' away to reduce noise, plug-in points remain conveniently close to set. Given how well Kino Flo Parabeam ballasts interact with inverter generators, not to mention their versatility (they can operate both 5500K & 3200K lamps) and their efficiency (they consume 1/10 the power of comparable incandescent soft lights), Kino Flo Parabeam lights would appear to be the better source for the type of filming you do. Guy Holt, Gaffer, ScreenLight & Grip, Boston

Continued from above. If you have some large scenes, with a number of extras, and a preponderance of warm light sources like house lights or street lamps, I would suggest that in addition to using the HMI pkg. described above to light your deep background, you bounce a large tungsten light into a 8x8 Ultra bounce as your key source. The most powerful tungsten light that you will be able to run off a portable generator or power off a wall outlet is Mole’s new 5KW Tungsten Par. Unlike traditional 5KW luminaries, the Tungsten Par uses a specifically designed General Electric 5KW Tungsten Halogen lamp intended for Axial Operation. Like an HMI par, the new Mole 5KW Tungsten Par places the lamp on its side and uses a highly polished parabolic reflector and converter lenses to adjust the field of light. Mole has computer engineered the interaction of lamp, reflector and converter lens to obtain unmatched light performance. This fixture is able to achieve output comparable to a standard 14 inch 10K Fresnel, but it draws only 42 Amps (compared to a 10k’s 84 Amps). To power the new Mole 5KW Tungsten Par without a large diesel generator or tie in, you can use a Transformer/Distro to step down the 240V output from our modified Honda EU6500is to a single 60A/120V circuit capable of running the 42 Amp load of the 5k. A Transformer/Distro will also enable you to safely access more “house power” on your location. It is likely that, unless the bungalow uses propane gas, it will have a 240V Range Plug and/or Dryer Plug. A Transformer/Distro can also step down these common 240V power outlets to a single 120V circuit capable of powering bigger lights (like the 5k Tungsten Par or 4k HMI Par) , or more smaller lights, than is possible on the house 120V circuits alone. By giving you access to more “house power” through common 240V household outlets, a Transformer/Distro can eliminate the need for dangerous tie-ins or expensive tow generators. Use this link - www.screenlightandgrip.com/html/HDPP_Transformer.html - for more details on the use of Transformer/Distros to access more “house power”. You might consider renting two transformer/Distros and two Honda EU6500is inverter generators. I have found this to be an ideal set up for many of the situations you face in indie film production. For night exteriors, you could use one generator with a transformer distro to power the 4k Par to light the deep background. The second generator with a transformer distro would power smaller HMIs or Kino Flos that would light your talent action area. Two generators would allow you to light both foreground & background (the sign of good production values) without having to run tons of cable. You might also consider renting a 18 Gallon Extended Run Fuel Tank for the EU6500is supplying power to the 4K Par lighting the deep background. An extendend Run Fuel Tank will run the generator for a continuous 18 hours, so that you can set it and forget it, without worrying about it running out of fuel in the middle of a shot (use this link for more details http://www.screenlightandgrip.com/html/HDP..._Fuel_Tank.html.) You can use one of the transformers on a 240V range or dryer receptacle to power the 5k Tungsten Par; while using the other transformer to run a 4k Par along with a 1200 Par on the Honda 6500is to light the deep background and back edge your extras. I have used this same combination of wall outlets, 60A step-down transformer distros, and Honda EU6500is generators to eliminate the need for tie-ins or a tow genny on many of the historical documentaries I have gaffed. For example, I have used this same package repeatedly at a historical mansion in Easton MA called the Ames Estate. (Scene from "Unsolved History" powered from 50A/240V range outlet through step-down transformer/distro) A popular state fee free location, the Ames Estate, like many historical house/museums, does not permit tie-ins and the electrical wiring in the house is so antiquated that it is unusable. Fortunately, they have a 50A/240 volt circuit in the carriage house for a welder they use to repair the mowers they use at the park. Our standard mode of operation when shooting there is to run 250V extension cable from the welding receptacle to a 60A Full Power Transformer/Distro placed in the entry hall of the house. Using a 60A Siamese at the Transformer/Distro, we then run 60A 6/3 Bates extensions, down to the library, to the second floor, and back to the maid’s pantry. At the end of each run we put another 60A Siamese. A 60A snackbox on one side of the Siamese gives us 20A branch circuits. The other side we leave open for a large HMI or Tungsten Light. Now we can safely plug 1200 & 2500W HMIs, or even a 5k Quartz, into our own distribution anywhere in the house. (Typhoid Mary in quarantine on an island in New York's East River. Note the view out the window of the East River shoreline at the turn of the century.) To maintain continuity between shots on these dramatic historical recreations, we usually bring a 4kw HMI Par in a window on one side of the room as a sun source and a 1200 par through a window on the other side as a northern light source. We usually power both heads off of a Honda EU6500is through a second 60A Full Power Transformer/Distro. Since the Honda EU6500is can be placed right on the lawn, we are saved from running hundreds of feet of feeder back to a tow generator in the drive. (The exterior of the actual location used for the quarantine island. A 30' blowup of a picture of the East River at the turn of the century was rigged outside the windows of a house in Arlington MA.) We have been able to use this same basic distribution package at numerous museums and historical houses throughout New England including Sturbridge Village. Fortunately for us, to make ends meet, many historical houses rent themselves out for events and weddings. For that reason, they usually have at least one updated service with 30 or 50 Amp 240 volt circuit for the warming ovens of caterers. I have included several production stills from these shows. Use this link - http://www.screenlightandgrip.com/html/HDPP_Transformer.html - for more production stills of PBS and History Channel historical documentaries shot entirely, or in part, with our 60A Full Power Transformer/Distro at the Ames Estate. Guy Holt, Gaffer, ScreenLight & Grip, Boston