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Guy Holt

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Everything posted by Guy Holt

  1. Not true. As I said above, when you use lights sources like HMIs, Fluorescents, & CLF lamp banks, on generators it matters not only what type of generator you use but also what type of HMI & fluorescent ballasts you use. To make matters worse, the information provided by generator manufacturers and dealers is woefully lacking - so much so, that I think it is by design. For this reason I have written an article for our company newsletter on the use of portable generators in motion picture production that answers your questions completely and then some you didn’t even know to ask. The article is available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html An electrician I sometimes work with has summarized the part of my article that deals with just this question in a post on DVX User (http://www.dvxuser.com/V6/showthread.php?p=1789268#post1789268.) You have several options when it comes to operating a 2.5kw HMI off of a 6500W generator depending on the type of ballast and generator you use. Where electronic HMI ballasts are typically auto-sensing multi-volt ballasts (with an operating range of 90–125 & 180-250 Volts), you can plug it directly into the 240V 4 pin twist-lock receptacle on the generator and it will operate at 240 Volts (where 2.5 kw ballasts are typically wired with a 120V 60Amp Bates Plug (Stage Pin) you will need a 120V 60A Female Bates to 240V 4pin twist-lock adapter to plug a 2.5 kw ballast directly into the generator. Or, if the electronic ballast is power factor corrected (draws 23 Amps) you can plug it into the 30A/120V twist-lock receptacle on the generator’s power panel. If the electronic ballast is not power factor corrected (draws 35 Amps) you will not be able to run it off of the 30A/120V twist-lock receptacle without tripping it’s fuse. 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 the generator’s power panel. That is because, as John Sprung correctly points out, 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 magnetic ballasts have a high front end striking load. That is, a magnetic ballast 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 ballast “ramps up”. That is, its’ current draw gradually builds until it “tops off.” For this reason, you must always leave “head room” on the generator for the high front end striking load of magnetic ballasts. And to complicate matters even more, 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.) As others have already pointed out in this thread, the load of a 2.5kw 120V 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 Ross Neugeboren mentioned in a post above. A Transformer can step 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. Use this link - http://www.screenlightandgrip.com/html/emailnewsletter_generators.html - for more information on the use of transformers with portable generators to operate larger HMIs. Guy Holt, Gaffer, ScreenLight & Grip, Boston
  2. I completely disagree. You have to over think situations like this or you get burned on location. When you use lights sources like HMIs, Fluorescents, & CLF lamp banks, on generators it matters not only what type of generator you use but also what type of HMI & fluorescent ballasts you use. The poor Power Factor and Harmonic Noise that magnetic and non-Power Factor Corrected electronic ballasts (both HMI & Kino) kick back into the power stream can have a severe adverse effect on the power waveform of some generators, but not others. Under the best of circumstances a 1.2kw HMI & a Kino will only draw 16 Amps and you will have no problem operating them on a 20A circuit of a generator. Under the worst of circumstances a 1.2kw HMI & a Kino will draw 23.6 Amps and you will have nothing but trouble operating them on the generator. Why the difference? Because it depends on whether the HMI & Kino ballasts are Power Factor Corrected and whether the generator is an inverter generator or a conventional AVR generator. The Leading Power Factor of lights that use Switch Mode Power Supplies (Electronic HMI, Fluorescent, & CFL ballasts) can cause them to use excessive amounts of power for the wattage of light they generate and to kick harmonics back into the power stream that can have a severe adverse effect on not only the generator, but also other electronic equipment operating on the same power. There is a video on You-Tube by a Lighting Designer by the name of Kevan Shaw that illustrates just this. In his You-Tube Video, “Compact Fluorescent verses the generator,” (available at ) Kevan Shaw compares the effect of equal wattages of CFLs and Incandescent lights on a small portable generator. In his test, he first operates a 575W ETC Source Four Leko with Quartz Halogen bulb on an 850W two stroke conventional gas generator without problem. However, when he tries to operate an equivalent wattage of CFLs (30-18W bulbs) the generator goes berserk. Only after turning off half the CFL Bulbs does the generator operate normally with a remaining load of 15 - 18W CFLs (270 W.) What accounts for the erratic behavior of the generator in this video under a smaller load of CFLs? It is a combination of the poor Power Factor of the CFL bulbs and the harmonic currents they generate. Even though the 15 CFL bulbs have a True Power of 270W (15 x 18W = 270W ), the Watt indicator on Kevan's generator indicates that they draw twice that in Apparent Power (535W), or have a Power Factor of .5 (270W/535W =.504.) The fact that CFL bulbs consume double the energy (Apparent Power) for the 18 Watts of light (True Power) they generate, is only half the story here. Kevan Shaw’s video also clearly demonstrates the severe effect that leading power factor loads - like CFLs, HMIs, & Fluorescents - can have on the governing systems of conventional AVR generators. When Kevan turns off the 18W CFL bulbs one at a time until the generator stabilizes, he is not only demonstrating that 15 – 18W CFL bulbs has roughly the same Apparent Power (535W), according to the generator’s Watt meter, as a 575W incandescent light; but, also that the maximum Leading Power Factor load a 850W conventional generator can operate satisfactorily is 270 Watts (15 – 18W CFL bulbs). Looked at from another angle, 576 Watts of Apparent Power with a Leading Power Factor (16 - 18W CFL bulbs) overloaded the generator, while 575 Watts of Apparent Power with a Unity Power Factor (the 575W Quartz Leko) did not. What accounts for this difference? Since the load is almost the same (576 & 575 Watts of Apparent Power respectively), the only factor that can account for the generator going berserk with the equivalent load of CFL lights is the harmonic currents that they generate, that the Quartz Leko does not. Without a doubt, Kevan Shaw’s video is a clear demonstration of the adverse effect that harmonic currents have on the governing systems of conventional AVR generators. For the same reason that Kevan Shaw was not able to operate more than 270 Watts of CFL bulbs (15–18W bulbs) on his little 850W generator, you may not be able to operate a couple of 1200W HMIs and Kinos on a conventional 6500W AVR generator if the ballasts are not Power Factor Corrected. The adverse effects of the harmonic currents that non PFC ballasts generate, so graphically demonstrated in Kevan’s video, limits the total amount of Leading Power Factor loads, as compared to Unity Power Factor loads, that can be reliably operated on conventional AVR generators. For more details on what type of generator to use with HMIs and fluorescent lights see the following thread: http://www.dvxuser.com/V6/showthread.php?t=58422&page=4 For more information on the Power Factor of HMIs & Fluorescent ballasts see the following thread - http://www.dvxuser.com/V6/showthread.php?t=205548 . Guy Holt, Gaffer, ScreenLight & Grip, Boston
  3. A generator like this has limited applications in low budget filmmaking. You can use it if you are using only incandescent lights (not the most efficient source), you are not recording sound, and you are not using the generator as your primary supply for tech equipment like monitors, lap tops, hard drives, and battery chargers. If you want to use other lights sources like HMIs, Fluorescents, & CLF lamp banks , it matters not only what type of generator you use but also what type of HMI & fluorescent ballasts you use. The harmonic noise that magnetic and non-Power Factor Corrected electronic ballasts (both HMI & Kino) kick back into the power stream can have a severe adverse effect on the power waveform of conventional AVR generators like this one. The harmonic noise these light sources generate will not nearly have as bad an effect on the power supplied by an inverter generator like the Honda EU6500is you mentioned above. For more details on what type of generator to use with HMIs and fluorescent lights see the following thread: http://www.dvxuser.com/V6/showthread.php?t=58422&page=4 Or, this link - www.screenlightandgrip.com/html/emailnewsletter_generators.html. Guy Holt, Gaffer, ScreenLight & Grip, Boston
  4. What kind of problems did you have with the Lightmaker ballasts? Sharing your grief will lessen the pain and perhaps save someone from wasting a lot of money on the number of used HMI systems being sold with Lightmaker ballasts. Guy Holt, Gaffer, ScreenLight & Grip, Boston
  5. We don't use a multi-tap transformer because it would make the transformer larger and heavier. Instead we have them made specifically 240/127 because we know that the applications in which they will be used will have some line loss. Guy Holt, Gaffer, ScreenLight & Grip, Boston
  6. As John mentioned, I have covered this in other posts in this forum, so I won’t go into details here. For details read my posts: “How to Plug 5k Quartz & 6k HMIs into wall sockets” “More Power from Small Generators” While transformers can offer many benefits, certain features are required in a transformer to make it suitable for motion picture production. The Simran 7500W Power Converter (transformer) you linked in your post has none of those features. It is ill suited for production work. Simron 7500W Transformer In developing our HD Plug & Play Pkg. product line, we had considered this very same transformer and ruled it out for a number of reasons. If you look at the pictures I have attached below of the Simran transformer with it’s cover off you will see, that it is a traditional air cooled Open-Core Design in a Nema 1 enclosure that it is only suited for indoor use. Like all transformers it consists of two coils called windings wrapped around a core. A transformer works when a source of AC voltage is connected to one of the windings and a load device is connected to the other. The winding connected to the source is called the Primary. The other winding, which is connected to the load, is called the Secondary. 

The Primary is wound in layers directly on a rectangular form. The wire is coated with varnish so that each turn of the winding is insulated from every other turn. When the primary winding is completely wound, it is wrapped with insulating paper. The secondary winding is then wound on top of the primary winding. After the secondary winding is done, it too is covered with insulating paper. Open-Core Transformer Design If you look at the transformer in our HD Plug & Play package (pictured below) you will notice it looks quite different. For our HD Plug & Play package we decided instead to use an Epoxy Encapsulated-Core Design Transformer. Epoxy encapsulated transformers use a mixture of silica sand resin and epoxy to completely encapsulate the transformer in a heavy gauge steel casing. Their steel cases are welded and treated with conversion coating before priming and painting to withstand the harshest elements. Encapsulated-Core Transformer Encapsulated Transformers offer a number of advantages over open-core designs. The most obvious benefit arises from the physical protection that the encapsulate and outer steel casing provide to the windings, core, and lead connections. With these fragile components sealed in epoxy inside a tough, waterproof casing, encapsulated transformers will withstand the harshest indoor and outdoor applications - making them the clear choice for exterior location production. However, physical toughness and environmental ruggedness are not the only advantages. Constructed of a welded heavy gauge steel casing filled with epoxy, an Encapsulated Transformer forms a single solid mass with no moving or loose parts that can vibrate. Encapsulating the transformer significantly reduces its’ audible noise – another important feature in motion picture production. 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 The most important benefit to encapsulation, however, is the improvement to the thermal and electrical performance of the transformer that results. Encapsulation greatly improves the transformer’s K-Rating. What is a K-Rating? 
It is a value used to determine how much harmonics a transformer can handle without exceeding its’ maximum temperature rise level. Encapsulation is a design element K-rated transformers use to deal with the heat that harmonic generating loads create – an increasing problem in motion picture production today. Over the past several years there has been dramatic growth in the use of production equipment that generates harmonic distortion. Examples are the AC power supplies of video cameras, lap top computers, video display terminals, battery chargers, and electronic lighting ballasts (HMI & Kino.) These electronic devices contribute to the distortion of the current waveform and the generation of harmonics because they use switching power supplies called SMPSs (an abbreviation for Switch-mode Power Supplies.) SMPSs generate harmonics when they rectify AC line current to DC, and back again in supplying current to the load. In the process, a capacitor is charged then discharged in each half-cycle of the AC line current. This process is repeated 120 times a second. This action of recharging capacitors 120 times per second causes AC current to flow only during the peak portion of the AC voltage wave, in abrupt pulses. These abrupt pulses distort the fundamental wave shape and create harmonic currents, which in turn generate heat in distribution equipment and neutral conductors. 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 affect power generation and distribution equipment. The article is available on our website at http://www.screenlightandgrip.com/html/ema...generators.html. Harmonic currents cause transformers to heat up more than other types of distribution equipment because the currents cycle in their Primary windings. The heat harmonics generate can cause non-K-rated transformers to overheat - possibly causing electrical insulation failure and electrical arcing. K-rated transformers are designed to handle this additional heat and are tested to rigid UL standards. Design features K-rated transformers use to handle the adverse effects of harmonics is double sized neutral conductors, multiple conductors for the coils, more core and coil material, different designs, and different construction techniques like epoxy encapsulation. Encapsulation is used in K-rated transformers because it greatly improves thermal and electrical performance and consequently the transformer’s K-rating. The mixture of silica sand resin and epoxy compound used for potting has a high coefficient-of-thermal conductivity and is very effective at dissipating heat away from the windings and core; while the heavy gauge steel casing serves as a heat sink. This thermal management reduces winding temperature differentials and allows for the generation of more heat without exceeding allowable temperatures for the insulation class. Besides causing equipment to overheat, Harmonics can cause device malfunctions, breaker tripping, and excessive vibration. Harmonic currents cycling inside the primary of the transformer can cause Open-Core transformers to vibrate and hum loudly. Epoxy encapsulation dampens the vibration and significantly reduces the hum created by cycling harmonic currents. Encapsulation also increases electrical insulation reliability when compared to tape or paper insulation. Potting is done under vacuum to eliminate air gaps around the windings. With no air around the windings, there is reduced potential for corona and electrical arcing under surge conditions. Even though, K-rating is a heat survival rating, not a treatment of associated power quality issues like voltage distortion, encapsulation can reduce harmonic losses to a slight degree as well. Finally, in motion picture production it is beneficial to have the transformer compensate for line loss by slightly boosting the voltage output on the secondary side. 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. This boost enables you to add up to 200' of heavy duty 250V twist-lock cable between the generator and the transformer/distro. This way the generator can be further away, while your plug-in points remain conveniently close to set. You also eliminate multiple cable runs to the generator and the subsequent drop in voltage from line-loss from using standard electrical cords. The Simran 7500 you link to steps down/up voltage in a fixed 2:1 ratio. As specified on their website, if you feed the supply side 240 volts you get exactly 120V on the load side. If you feed the supply side 220 volts you get exactly 110V on the load side. If you were to put a fixed 2:1 ratio transformer, like this Simran 7500, at the end of a 200’ cable run, the line loss over the long cable run, may result in a line level on set that is too low. For this reason alone the Simran 7500W Power Converter (transformer) is ill suited for production work with generators. Encapsulated-core boost transformers like the one we use in our HD P&P Pkg, are ideal for use with generators and for motion picture production applications in general. Use this link - http://www.screenlightandgrip.com/html/hd_...n-play_pkg.html - for more details about using step-down transformers to power larger lights on interior sets. Guy Holt, Gaffer, ScreenLight & Grip , Boston
  7. That is only an option with 5k Fresnels and not an option with other popular luminaries in that range. For instance, a step down transformer will enable you to also operate 2.5 & 4k HMIs with magnetic ballasts, Par 64 Six Lights (6000W), Par 36 Nine Lights (5850W), as well as the new Mole Richardson 5kw Quartz Par off of dryer receptacles and 6500W generators. The ability to operate the new Mole 5k Quartz Par off of dryer outlets and portable generators is a huge improvement in location lighting. For those not familiar with it, the new Mole Richardson Quartz Par places the lamp on its side and, like an HMI Par, 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 maximize the light output from a 5k globe. This fixture is able to achieve output comparable to a standard 14 inch 10K Fresnel, but is similar in size, weight, and design to a 2.5/4k Single Ended HMI Par. The new Mole 5KW Quartz Par puts out as much light as heads twice its size, yet draws only 42 Amps (compared to a 10k’s 84 Amps). However, since it places the lamp on its side it uses a 120V General Electric 5KW Tungsten Halogen lamp specifically designed for Axial Operation. 240 Volt 5k globes can not be used in the new Mole 5KW Tungsten Par. Since it uses a special 120V lamp, you will need a step down transformer to power it from a dryer outlet or 6500W generator. Guy Holt, Gaffer, ScreenLight & Grip , Boston
  8. Buying a used 1200W HMI light has got to one of the hardest lights to buy. Because of the constant improvement in HMI technology there are many options available. If you are not careful you can get stuck with a lemon so I will go into more details on ballasts. In ballast design you have a choice between magnetic and electronic ballasts; and to complicate matters even more, you have a choice between Power Factor Corrected electronic ballasts and non-Power Factor Corrected electronic ballasts. Given the type of filming you do, you may in fact be better served by an older magnetic ballast over a non-Power Factor Corrected electronic ballast. A 1.2kw non-PFC electronic ballast draws 18-19 amps ( verses the 13.5 amps of a magnetic ballast) so it will always trip the common 15 amp house circuit and will trip a 20 Amp circuit if there is something else, like a computer or light, on the same circuit. Where you can't always know what else is on the same circuit, or even if it is a 20 or 15 Amp circuit, a 1.2kw magnetic ballast drawing only 13.5 Amps is the safer bet since it can operate on a 15 amp circuit even with other things on the circuit. Non-Power Factor Corrected electronic ballasts are meant to be used on film sets where every circuit is 20 Amps and you know what is on the circuit because you are distributing the power yourself from a tie in or generator. Since your style of shooting requires that you plug into wall outlets, you will be better served by a magnetic ballast. But that is not the only benefit to using a magnetic ballast over a non-PFC electronic ballasts. 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. As mentioned above 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. The primary factors limiting the use of HMIs on portable generators has been the inefficient use of power by non-PFC electronic ballasts and the harmonic noise they throw back into the power stream. The adverse effects of this harmonic noise, can take the form of overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral wire, and instability of the generator’s voltage and frequency. For these reasons it has never been possible to operate more than a couple of 1200W HMIs on a conventional 6500W portable gas generator. The increasing use of personal computers, hard drives, and microprocessor-controlled recording equipment in production has created an unprecedented demand for clean, reliable power on set. However, now that inverter generators, like the Honda EU6500is, do not require crystal governors to run at precisely 60Hz, magnetic ballasts offer a cost effective alternative to dirty non-PFC electronic ballasts because you can operate magnetic HMI ballasts “flicker free” on inverter generators. And as mentioned above, 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 up to the early 1990s were made with magnetic HMI ballasts you can see that being limited to the safe frame rates is not all that restrictive. 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 magnetic ballasts draw 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.” 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. 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 electronic 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. Power Factor Correction (PFC) is very new in 1200W HMIs and so it is highly unlikely you will find it in a used ballast – even a Power Gems or Arri ballast. Since Power Factor Correction (PFC) is not mandated in this country, as it is in Europe for any electrical device that draws more than 75W, we are pretty much ignorant of Power Factor and effect that poor Power Factor can have on a distribution system. However, any film technician familiar with large HMI heads will be quite familiar with Power Factor and Power Factor Correction (PFC.) That is because after a false start back in the 90s, all major manufacturers now include PFC circuitry in HMI ballasts in the 6-18kw range. They do so by necessity. The early line of Lightmaker electronic ballasts were nick named by film electricians “Troublemaker” ballasts because they were not Power Factor Corrected and proved that PFC circuitry was absolutely necessary in large ballasts to reduce heat and returns on the neutral, and to increase ballast reliability (beware, some are still kicking around ebay). But, because of the added cost, weight, and complexity of PFC circuitry, ballast manufacturers in the US still only offer PFC circuitry 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 reason 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. 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. But where PFC is still very new to smaller heads, it is still the case that almost every 575 - 1200 W electronic ballast that you will find in a rental house or for sale used in North America will be a non-PFC electronic ballast. For a detailed explanation of PFC see my post "What is Power Factor Correction in HMIs" at http://www.cinematography.com/index.php?showtopic=43872 I would suggest you read the article I wrote for our company newsletter (especially the section titled “New Life to Old Ballasts”) on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind poor Power Factor, the harmonic distortion it can generate, and how it can adversely affect generators. The article is available at http://www.screenlightandgrip.com/html/ema...generators.html. As far as used HMIs that are available for sale I would caution you against buying a system with Lightmaker ballast. As mentioned above Lightmaker ballasts were the first generation of non-PFC electronic ballasts made and were nicknamed the “Troublemaker” ballasts because of the problems they caused. While the Power Gem & Arri ballasts are of a later generation, the used ones out there will likely be also non-Power Factor Corrected. Which is why you may be better served by a magnetic ballast for your type of filming. Guy Holt, Gaffer, ScreenLight & Grip , Boston
  9. I thought it inappropriate to answer the questions because they were specific to a particular product we sell and the information requested somewhat proprietary. And what is "technical " about the price. I never mentioned that we sell or rent transformers customized for motion picture production until John asked about our product specifically. Even then, my responses were in regard to the use of transformers in motion picture production in general and not about our product specifically. According to your logic I could never post as a gaffer on a question regarding lighting craft because I sell and rent lights - it makes no sense. - Guy Holt, Gaffer, ScreenLight & Grip, Boston
  10. Where it would be inappropriate for me to use this forum for marketing a product, I will only answer those questions by email. What I can say is that the use of a small transformer (whether one of ours or one you pick up locally) on a stove/dryer outlet or 240V output of portable gas generator offers benefits that far outweigh it. Besides isolating harmonic currents from the power supply, a step down transformer plugged into a 240V receptacle (house or generator) will give you access to the full capacity of that circuit in a single 120V circuit. For instance, for the tests I describe in my article I tapped a 240V circuit designed into the Honda EU6500is generator for the UK market and used a step down transformer to convert it into a 7500W/120V circuit capable of powering larger lights. A transformer makes it possible for a generator to operate larger lights than it could otherwise because it automatically splits the load of whatever you plug into it evenly over the two legs of the generator’s 240V circuit. In effect, it reduces the impact of switching on a large Tungsten light (like a 5k) or striking a large HMI (like a 4k) with 120V magnetic ballast. By automatically splitting the high front end striking load of these lights into two smaller perfectly balanced loads, a transformer makes the load more manageable for the generator. Besides creating a 120V circuit capable of powering larger lights, I have found that step down transformers also enable you to run more smaller lights on a generator than you could without it. You can run more lights with a transformer because it enables you load the generator more fully. With out a transformer you can never fully utilize the available power of a portable 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 power outlet panel of a Honda EU6500is Generator, you reach a point where you can't power an additional 1kw light because there is not 8.4 amps available on either one of the factory installed 20A outlets/leg of the generator. With a transformer you can still add that 1kw light because the transformer will split the load evenly over the two legs (4.2A/leg) of the generator. If the lighting package consists predominantly of HMIs and Kinos with Power Factor Corrected (PFC) ballasts, a transformer on an inverter generator will enable you to operate more of these lights on a portable generator than has ever been possible before. Where 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 use to a third of the generators capacity. With the aid of a transformer, an inverter generator can be loaded to capacity with PFC HMI and Kino Flo ballasts because the near-linear nature of these loads and the extremely low harmonic distortion (less than 2.5%) of the original AC power waveform of inverter generators results in virtually no distortion of the power waveform. 

With a transformer and PFC ballasts, you can safely power bigger HMI lights, or more smaller HMI lights, on an inverter generator than has ever been possible on a conventional portable gas generator. Whether plugged into a range/dryer receptacle or the 240V outlet of a portable generator, a transformer will also greatly simplify your set electrics. As long as you plug lights in through the transformer, you no longer have to carefully balance the load over the circuit's two 120V legs because the transformer does it for you automatically. If you outfit the transformer 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. The best part about using a transformer in this fashion is that no matter where in the distribution system you plug in, the transformer automatically balances the additional load on the generator, so that you don't have to. Another advantage to using a transformer with a portable generator is that it enables you to place the generator further away while your plug-in points remain conveniently close to set. The Honda EU6500is Inverter generator is so quiet, that to record sync sound without picking up any generator noise, all you need to do is add 200' of heavy duty 250V twist-lock cable between the generator and the transformer (which is usually enough cable to place the generator around the corner of a building.) Using a heavy duty 250V twist-lock cable in this fashion also eliminates multiple cable runs to the generator. And if you use a boost transformer like the one we customize for our modified Honda EU6500is generator, the transformer will assure that you have full line level (120V) on set by compensating for the slight line loss you will have over an extended cable run. That is, because a boost transformer 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 even further from set where you are sure not to hear it, yet assure that the supply voltage on set does not drop too low. Some may argue that transformers are not only bulky and noisy, but also totally unnecessary in this age of power efficient Fluorescent and LED light sources. I use transformers to power bigger HMIs (2.5-4Kw) in situations where smaller lights simply don’t cut it – for balancing the sun on day exteriors or for bringing a large “sun” source in a window on a day interior. 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. 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. American Experienes Typhoid Mary Biography "The Most Dangerous Women in America": www.screenlightandgrip.com/html/tmintro.html WGBH’s Ben Franklin Biography “Franklin”: www.screenlightandgrip.com/html/franklinintro.html The History Channel’s “Unsolved History” episode “Presidential Assassins” : www.screenlightandgrip.com/html/unhisintro.html - Guy Holt, Gaffer, ScreenLight & Grip
  11. If the plug has three pins instead of four, don’t “fuggedaboudit.” Wire your three pin stove plug to a step down transformer. The safe and legal way to pull power from a three wire 240V stove outlet that meets the requirements of the National Electrical Code is to run your lighting load through a 240v-to-120v step down transformer. A transformer converts the 240 volts supplied by 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 (the missing fourth wire in a three wire system.) A step down transformer can also be used on 4-wire 240V circuits as well as 3-wire circuits. You can use this link for more details about using step-down transformers on set: . By giving you 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
  12. What are you trying to accomplish with the contraption that you want to build. If you will tell us, we can tell you if there is a safer way to do it. Guy Holt, Gaffer, ScreenLight & Grip, Boston, Ma
  13. For some reason the image of the Current and Voltage Waveforms of a CFL Bulb in the comparison to an incandescent bulb in my explanation of power factor above did not load. Here is that passage again with the image. Sorry for the screw up. Guy Holt, Gaffer, ScreenLight & Grip, Boston
  14. If you observed the flicker on both mains and Genny power than it probably does not have to do with erratic voltage supplied by a generator. To get technical, what you probably experienced is a type of flicker problem called an “eratz ripple.” Even though the bulbs of CFLs operate at high-frequency, the cycles can stack to create a lower frequency waveform which causes the light to pulsate. In a number of incidents, 24p video cameras and film cameras operating within a flicker-free window have picked up flicker from the “eratz ripple” effect. When using CFLs in fluorescent soft banks or using solid-state high frequency fluorescent ballasts for built-in set practical light fixtures, it is necessary to shoot tests with the CFL or ballast you plan to use to make sure you will not get an “eratz ripple.” Guy Holt, Gaffer, ScreenLight & Grip, Boston
  15. Since the voltage waveform distortion exhibited in my post above can adversely effect other equipment operating on the same power, the generation of harmonic currents by electronic HMI & Fluorescent ballasts should be eliminated whenever possible. Otherwise they can build to a point where they will have a disastrous effect upon other equipment. As more and more electronic components, like lap top computers, hard drives, and HD monitors, which are themselves sources of harmonic distortion (but of a lower amplitude than solid state lighting ballasts) are integrated into the typical location production package, harmonic currents begin to combine with unpredictable consequences. In fact, a viscous cycle can get started. The more harmonic orders that are generated, the more distorted the power supplied by the generator becomes. The more distorted the power waveform becomes, the more harmonic currents are thrown back into the electrical distribution system, which in turn, creates additional voltage distortion. In this fashion, something akin to a feedback loop can get started. Very often, the operation of electrical equipment may seem normal, but under a certain combination of conditions, the impact of harmonics is enhanced with unpredictable results. Sprectrum analysis of the high frequency Harmonic Currents that induce a flat-topped a voltage waveform at the load bus. The severe voltage waveform distortion exhibited above can cause overheating and failing equipment, efficiency losses, circuit breaker trips, and instability of the generator's voltage and frequency. In addition to creating the radio frequency interference (RFI) mentioned on the Lowell Light website, Harmonic noise of this magnitude can also cause component level damage to HD digital cinema production equipment and create ground loops. Harmonics can also cause excessive current on the distribution system neutral (see below.) And, since the neutral conductor of a distribution system is not fused, it can cause the neutral to overheat and possibly catch fire. Substituting incandescent lamps with the equivalent wattage of CFLs in a small single phase distribution system substantially increases the current on the system neutral. For this reason, on their website Kino Flo cautions users of their older style fixtures, that the 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”.) 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. The first step in mitigating the problems caused by harmonic currents is to eliminate the currents. Where customarily the largest source of harmonic currents in a typical lighting package are HMI and Fluorescent lights with electronic ballasts, using only ballasts with power factor correction (PFC) circuitry will go a long way in reducing the number of harmonic currents in the power stream. By simply eliminatng the generation of harmonic currents, a PFC circuit realigns voltage and current and induces a smoother power waveform at the distribution bus. As a result, the ballast uses power more efficiently with minimized return current and line noise and also reduces heat, thereby increasing their reliability (see my post on “How Power Factor Correction Works” for more details.) The second step in mitigating the problems caused by harmonic currents is to use inverter generators. The combination of the improved power factor of the ballasts and the nearly pure power waveform of inverter generators makes it possible to reliably power larger lights, or more smaller lights, than has been possible before on a small portable gas generator. For example, the power waveform below, 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. The nearly pure voltage waveform of Power Factor Corrected ballasts operating on an inverter generator. Note: No Flat Topping The extremely low line noise exhibited in the inverter generator power waveform above 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. 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 (which are also PFC), and combine it with the pure waveform of inverter generators, you can run more HMI and Flo 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 for a low budget HDV production. Use this link for more information about the benefits of low line noise. Unfortunately for Isabelle, according the table at top, power factor correction is only available in the high voltage versions of these 200watt 8u CFL bulbs. So her best bet is to use an inverter generator when she needs to power her lantern on locations without grid power. 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
  16. Why would they flicker on a generator? The high-frequencies at which CFLs operate, 20,000 - 50,000 Hz, make them essentially flicker-free. At those frequencies the period of time between the off and on pulse of each cycle is so short that the illuminating phosphors do not decay in light output. Like the glowing tungsten coil of an incandescent lamp, the fluorescent phosphors become essentially continuous and so are flicker free at any normal frame rate or shutter angle. To address the original poster’s question. The bulb pictured won’t fit in the Softbank fixture pictured. The softbank fixture has closely-spaced medium-base (E27) sockets, but the 200W CFLs are mogul base (E39) and about 5 inches in diameter. Even if they did fit, it wouldn’t work. Nine 200watt 8u CFL bulbs will not draw 15 amps but close to 30 Amps. You will not be able to use it on a household circuit, you will likely overheat the neutral in the light, and if you were to power it on a portable gas generator you can expect power problems (not flicker) because this set up will generate severe harmonic distortion in the power supplied by the generator. I know I can have a tendency to go on too long in my posts. But, I find again and again that because of the brevity of the posts, online forums like this are filled with blanket assertions based upon erroneous assumptions or conventional wisdom. Since a little knowledge can be a dangerous thing when it comes to handling electricity, I feel it necessary to explain briefly why Isabelle’s set up will not work. For a more detailed explanation, 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 power factor and how it can adversely effect generators. The article is available on our website. What Isabelle is failing to take into account is that the 120V versions of the 8u CFL bulbs have a power factor of .5. Since power factor is commonly overlooked in the design and implementation of lighting systems in motion picture production applications, I would like to take this opportunity to explain it in detail and show how it effects Isabelle’s ballon set up. If we look at the technical specifications for a representative 200 watt 8u CFL bulb below (available at http://www.maxlite.com/PDFs/FocusSheets/HighMax.pdf), we find that with a power factor of .5 the bulb in fact draws 3.3 Amps. The difference between the actual current drawn by the bulb (3.3A) and the 1.66A Elrosten calculated a 200W bulb should draw using Ohm’s Law (W=VxA), is the difference between what is called “Apparent Power” and “True Power.” Specifications for Maxlite 200W 8u CFL Bulbs If, in this case, you were to measure the current (using a Amp Meter) and voltage (using a Volt Meter) traveling through the cable supplying the CFL bulb and multiply them according to Ohm’s Law (VxA= W) you would get the “apparent power” of the bulb (120V x 3.3A = 396W). 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 of the CFL bulb you would get the “true power” of the bulb which in this case is specified by the manufacturer as 200W. The ratio of “true power” to “apparent power” is called the “power factor” of the bulb. A 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 the glass all the way up with beer. When lights with a low power factor are used, the distribution system must be sized to supply the apparent power (beer plus foam), even though only the true power (beer) counts. What accounts for this discrepancy between Apparent Power and True Power? To understand the power factor of a CFL bulb, and its’ effect on the power supply, it is helpful to compare it to an incandescent bulb. An incandescent light is a simple resistive load. The high resistance of its tungsten filament creates heat until the filament glows - creating light. As we see in the oscilloscope shot below, of a 25W incandescent bulb operating on grid power, the current is always proportional to the voltage (current is represented on the scope as the voltage drop on a 1 Ohm resistor.) Current and Voltage Waveform of a ACEC 25W Incandescent bulb If the applied voltage is sinusoidal, the current generated is also sinusoidal. That is, the current increases proportionately as the voltage increases and decreases proportionately as the voltage decreases. Since the peak of the voltage corresponds to the peak in current, the voltage and current are also in phase and so have a unity power factor (Power Factor of 1.) The voltage and current waveforms below of a CFL bulb operating on grid power is very different from that of the incandescent light above. The most noticeable difference is that the current, generated by the CFL bulb, no longer proportionately follows the nice smooth sinusoidal voltage waveform supplied to it by the power grid. Rather, it has been distorted by electrical components in the ballast of the CFL bulb so that it instead consists of sharp spikes in power that quickly drop off over a short duration. A second distinguishing characteristic is that the peak of the voltage no longer corresponds to the peak in current. The current now “leads” the voltage by 1.7 micro seconds. The voltage and current are no longer in phase as in the case of an incandescent bulb, but instead exhibits what we call a leading power factor. The distorted current waveform and leading power factor exhibited here is caused by components in the electronic ballast which use only portions of the voltage waveform, draw current in quick bursts, and then return the unused portions as harmonic currents that stack on top of one another, creating harmonic distortion that pulls the voltage and current out of phase. This creates an opposition to the flow of current that is called capacitive reactance. Where capacitive reactance leads to an inefficient use of power (lots of foam), and the harmonic currents generated can have severe adverse effects on other equipment operating on the same power, it is worth exploring the cause of capacitive reactance and the source of the harmonic currents in more detail. Typical schematic of CFL electronic ballast: L-to-R consists of half-bridge rectifier, conditioning capacitor, DC/AC Inverter The electronic ballasts of self ballasted CFLs, are very similar in design to the high frequency ballasts used in fluorescent movie lights in general (Kino Flo, Lowell, etc.) All electronic fluorescent ballasts are essentially AC-to-AC power converters in that they convert line-frequency power from the utility line (60Hz) to a high-frequency AC power (20’000-50’000 Hz) to excite the gases in the fluorescent lamp so that they glow continuously. The diagram above illustrates the typical components that make up the high-frequency electronic ballasts found in most all high frequency fluorescent movie lights and CFL bulbs. Step 1: Rectifier Bridge converts AC power to rectified sine wave. Step 2: rectified sine wave is flattened to DC by conditioning capacitor. They consist, first, of a diode-capacitor section that converts the AC input power to DC power, and then an inverter section that converts the DC power back to a high frequency AC power that ignites the lamp gases. The diode-capacitor section converts the AC power to DC power by first feeding the AC input current through a bridge rectifier, which inverts the negative half of the AC sine wave and makes it positive. The rectified current then passes into a conditioning capacitor which removes the 60 Hz rise and fall and flattens out the voltage - making it essentially DC. The DC is then fed from the conditioning capacitor to the inverter section which typically consists of a pair of MOSFETs (metal–oxide–semiconductor field-effect transistors) which generate the high frequency (20-50kHZ) AC waveform. Where, the harmonic currents produced by electronic fluorescent ballasts are primarily generated by the diode-capacitor section of the ballast, lets look at how this circuit works in more detail. Yellow Trace: Rectifier Bridge converts AC power to rectified sine wave. Blue Trace: Stored Capacitor Voltage. Red Trace: Current drawn by capacitors once input voltage is greater than voltage stored in the capacitor (Blue trace.) As shown in the illustration above, the diode-capacitor circuit only draws current during the peaks of the supply voltage waveform and charges the conditioning capacitor to the peak of the line voltage. Since the conditioning capacitor can only charge when input voltage is greater than its stored voltage, the capacitor charges for only a very 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. Since, during this very brief charging period, the capacitor must be fully charged, large pulses of current are drawn for short durations. Consequently, electronic ballasts, draw current in high amplitude short pulses. The remaining unused current feeds back into the power stream as harmonic currents. These simple diode-capacitor circuits are used in CFL bulbs and in many fluorescent movie lights because they are compact and inexpensive. However, they have a number of drawbacks. For instance, notice how big the input current spike (red trace above) of the diode-capacitor circuit is. Without power factor correction, the in-put bridge rectifier requires a large conditioning capacitor at its output. This capacitor results in line current pulses (as seen in our oscilloscope shot above) that are very high in amplitude. All the circuitry in the ballast as well as the supply chain (the generator, distribution wiring, circuit breakers, etc) must be sized to carrying this high peak current (the foam in our analogy). Also notice that the line current pulses are narrow, with fast rise and fall times. Since the rectifying circuit uses only the peaks of the voltage waveform, they generate high harmonic content as the unused portions of the voltage waveform are returned as harmonic currents (see graph below.) Distribution of Harmonic Currents generated by CFL bulb These harmonic currents stack on top of one another creating harmonic distortion that creates an opposition to the flow of current; and, as we see in the oscilloscope shot above, pulls the voltage and current out of phase. When the power is supplied by a conventional generator, these harmonic currents can also lead to severe distortion of the voltage waveform in the power distribution system (see below for more details.) Finally, the fast rise time of these harmonic currents can cause Radio Frequency Interference (RFI) problems. For this reason, on their website Lowell warns about their compact fluorescent (CFL) fixture, the Lowel Ego, that: “The lamps may cause interference with radios, cordless phones, televisions, and remote controls. If interference occurs, move this product away from the device or move to a different outlet” (http://www.lowel.com/ego/lamp_info.html.) While self ballasted CFLs generate the most severe harmonics, all electronic ballasts (both fluorescent and HMI) generate harmonic currents (see table below.) Besides possible RFI problems, you need not be concerned about current harmonic distortion producing voltage distortion when you plug an electronic ballast (fluorescent or HMI) into a wall outlet. The impedance of the electrical path from the power plant to the outlet is so low, the distortion of the original applied power waveform so small (less than 3%), and the power plant generating capacity so large by comparison to the load, that harmonic currents fed back to it will not effect the voltage at the load bus (electrical outlet.) However, it is an all together different situation when plugging an electronic ballast (fluorescent or HMI) into a portable generator. In this case, the impedance of the power generating system (generator and distribution cable) is sufficient enough that a harmonic current will induce a voltage at the same frequency. For example, a 5th harmonic current will produce a 5th harmonic voltage, a 7th harmonic current will produce a 7th harmonic voltage, etc. Since, as we saw above, a distorted current waveform is made up of the fundamental plus one or more harmonics currents, each of these currents flowing through an impedance will, result in voltage harmonics appearing at the load bus, a voltage drop, and distortion of the voltage waveform. Each harmonic current in the electrical distribution system will cause a voltage at the same harmonic to exist when the harmonic current flows into an impedance. [/img] Since electronic ballasts consume current only at the peak of the voltage waveform (to charge the smoothing capacitor), voltage drop due to system impedance occurs only at the peak of the voltage waveform. In this fashion, the pulsed current consumed by electronic ballasts produces voltage distortion in the form of flat-topping of the voltage waveform. The pulsed current consumed by electronic ballasts produce voltage distortion in the form of flat- topping. For example, the power waveform above (from my article) is typical of what results from the operation of a 2500W load consisting of non-Power Factor Corrected electronic Kino & HMI ballasts on a conventional portable generator (a Honda EX5500 with a Barber Coleman Governor.) Since the voltage waveform distortion exhibited here can adversely effect other equipment operating on the same power, the generation of harmonic currents by electronic HMI & Fluorescent ballasts should be eliminated whenever possible. Where I am just about out of space, I will pick up with how Isabelle could mitigate the problems caused by harmonic currents and make her CFL balloon light work in my next post. Guy Holt, Gaffer, ScreenLight & Grip, Boston
  17. Is your question just hypothetical or does it pertain to an actual production. If it pertains to an actual production you should take a different tack. That is find out what you need and then figure out how to get it - tie-in, pole drop, generator, etc. Do you know yet what you will be using for a lighting package on that location? - Guy Holt, Gaffer, ScreenLight & Grip
  18. There is a parking garage under one end of Boston Commons that inhibits the driving of ground rods more than a couple of feet. So what we do is to dig a shallow 10ft long trench and bury the ground rod in it. It must meet code because it satisfies the Electrical Inspectors in Boston. - Guy Holt, Gaffer, ScreenLight & Grip, Boston
  19. Do you have any visual references you can post to give us an idea of the look you are going for. If it is what I think it is, there are easier ways to accomplish it. - Guy Holt, Gaffer, ScreenLight & Grip, Boston
  20. I resent the implication of this post. Eileen Ryan is not one of my employees. She is an area freelancer, occasional spark on my crews, and a rental customer. If she has experienced the benefit of working with low line noise on my jobs and benefited from my article, the worst that I am guilty of is not discouraging her from sharing her enthusiasm. This post impugns my motives for posting by suggesting they amount to advertizing. 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. Yes, I have posted extensively on the harmonic noise generated by HMIs, and lately I am posting on the harmonic noise generated by fluorescent fixtures because it is a problem that is becoming more prevalent. This post seems to imply that I am trying to sell an ignorant public a product they don’t need by scaremongering, when in fact I am only trying to raise an awareness of the adverse effect that an increase in harmonic noise as a result of a change in lighting technology, the introduction of Switch Mode Power Supplies (SMPS), is having on set power. But, don't just take my word for it: apparently, harmonics generated by SMPSs 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 an increasing problem when using a generator for lighting and I am just "scaremongering"? If at times it sounds like I am hyping the Honda Inverter generators ("guy/honda") and power factor corrected lights, it is not because we sell and rent the technology. Rather, it is because, as a professional gaffer of numerous low budget historical documentaries for PBS, Discovery, TLC, and the History Channel, I feel other low budget productions can benefit as well from the low line noise they offer. Guy Holt, Gaffer, ScreenLight & Grip , Boston
  21. I have to agree with John. LED lights are only a special purpose tool. If you looked at how LED lights were used in the list of productions provided by Jay, I would bet it was as Obie lights or to light car interiors at night. 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 Kinos, especially the Parabeam 400 fixtures, over LED Panels for many of the applications that LEDs are being marketed for and it has to do with more than just their deficient 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 nearly 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. 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
  22. If you are not recording sound but playing it back for the video, you can use "mechanical dimmers." Large rental houses should have mechanical shutters that will slide into the barndoor ears. If not you can use a piece of sheet metal that is large enough to cover the face of light at about a foot away. Set it up on a c-stand (without the arm) so that it is perpendicular to the light (acting as a blade), now to dim the light, simply rotate the sheet metal by rotating the top riser of the stand until it completely covers the face of the light. That close to the light the sheet metal will not throw a noticeable shadow when perpendicular to the light. If you are doing fairly quick fades up and down, no one will notice that the light doesn't actually dim, but blacks out from the center to the sides instead. You should spray paint the sheet metal with high heat black paint so that the polished metal doesn't bounce light. Incidentally, how had you planned to power the 2.5 HMI. - Guy Holt, Gaffer, ScreenLight & Grip, Boston
  23. This reminds me of a story that the former tech at LTM once told me. Consider yourself lucky, he told me about a night shoot on a large feature when the bulbs of six 18k exploded - taking the lenses with them. As he explained it, the problem was that when the 18ks first came out, everyone bought them (and lamped them) at roughly the same time. So when just about all the 18ks in town were out on this one features (they had 18 on the set I think) most of the bulbs reached maturity at roughly the same time. It was a night not soon forgotten. Truth or lore? You be the judge. Guy Holt, Gaffer, ScreenLight & Grip, Boston
  24. In order to create consistent light for a long scene you usually have to do more than just fill the interior - you should also bring in your own sun source. If the sun is shining directly on the window you should silk it for two reasons. First, it will be hard to balance direct sunlight. Second, the sun moves. If it is a big scene that takes a while to shoot, as Isabelle found out, you will notice the movement of the sun when you edit it all together. The best approach is to silk the real sun so that you take any directionality out of it, and then bring in your own sun source for consistency. If you are shooting on a low budget, your best bet is to use 4ks because you can operate them on common 240V wall outlets or our modified Honda EU6500is inverter generator. A set-up that would give you the most natural look would be to silk the sun, use a 4k Fresnel outside for a consistent sun feel, and then use a heavily diffused 4k Par inside to fill. Diffusing the 4K inside will take the “source-i-ness” out of it and using a 4k Fresnel outside will give you the crisp direct sunlight feel. To operate both 4ks without having to tie-in or rent an expensive diesel tow generator (with all its hidden costs), I would suggest you use a step-down transformer/distro on a 240v receptacle to power the inside 4k. To power the outside 4k, I would suggest a second step-down transformer/distro powered by one of our modified Honda EU6500is inverter generators. When shooting interiors (like the one discussed here), you use one of the transformers on a 240V range or dryer receptacle to power a larger light inside; while using the other transformer to run a 4k Fresnel along with a 1200 Par on the Honda EU6500is outside. 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 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 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 - 4000W HMIs (or even a 5k Quartz) into our own distribution anywhere in the house to balance the interior levels to the exterior. A good example of this approach is an American Experience program titled “The Most Dangerous Women in America” about Typhoid Mary that I lit for PBS. For part of her life Typhoid Mary was quarantined on an island in New York's East River. (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.) Because New York’s East River today looks nothing like it did when she was in quarantine, we used a 30' blowup of a picture of the East River at the turn of the century rigged outside the windows of a house in Arlington MA. As you can see by the production stills I have attached, the requirements of this production were very similar to the “Pirate Ship Live” production I described earlier. We had to strike a delicate balance between the interior and exterior levels. We wanted to overexpose the exterior by one stop so that it would look realistic and hide the fact that the exterior was a blow-up. As you can see in the production still of the exterior of the actual location used for the quarantine island, we rigged a solid over the porch windows and the blow-up to keep the sun off both. That way we could light the blow-up and interior so that it remained consistent even though the sun moved on and off the porch in the course of the day. To take the edge off the blow-up, we used a single scrim outside the window to help throw it out of focus. (The actual exterior of Mary’s cottage was the backyard of a house in Arlington Ma with a 30’ blow up of a picture of New York’s East River shoreline at the turn of the century.) To maintain continuity between shots, we brought 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 powered both heads off a dryer plug in the laundry room of the house using one of our transformer/distros. The two 2.5k Par lights used outside to light the blow-up were powered by a Honda EU6500is through a second 60A Full Power Transformer/Distro. Since the Honda EU6500is could be placed right on the lawn, we were saved from running hundreds of feet of feeder back to a tow generator. (A child dying of Typhoid Mary filmed in a bedroom of the Ames Estate) We have been able to use this same basic 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. (The New York City Health Inspector filmed in the library of the Ames Estate) 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/Distros and modified Honda EU6500is inverter generators at the Ames Estate. Guy Holt, Gaffer, SreenLight & Grip, Boston
  25. A lot of gaffers may rule out using a 4k HMI par as we did on the Bose still shoot pictured below because they think it requires either a tie-in or renting a generator - both of which can be an expensive proposition. They don’t realize that common 240V wall receptacles, like the dryer outlet in this loft, can power HMIs as large as 4kw. How it is done depends on whether the 4k has a magnetic or electronic ballast, and whether the electronic ballast has Power Factor Correction (PFC) or not (Arri calls it ALF for Active Line Filter.) Samples from still shoot for Bose where a 4k HMI par was used to fill talent against windows (Bob Packert Photography) A multi-volt 4k electronic ballast with Power Factor Correction (PFC) will give you the most options. If you are not familiar with Power Factor Correction, a PFC circuit realigns voltage and current and induces a smoother power waveform at the distribution. As a result, the ballast uses power more efficiently with minimized return current and line noise. 4kw electronic ballasts with PFC (like the Power Gems (PG) 425CDP, the Power-to-Light (P2L) 425LVI, and Arri 2.5/4 EB w/ALF) typically have an operating range of 90–125 & 180-250 Volts. At 120V they will draw approximately 37 Amps. At 240V they will draw 18.5 Amps on each leg of a 240V single phase power supply. These ballasts draw too much at 120V for a 20A wall outlet. But, fortunately there are a number of 240 volt outlets in a typical house, office, or industrial plant in this country that you can also use to power a 4k with PFC electronic ballast. The most common are air conditioner outlets, dryer outlets, range outlets, outlets for large copy machines in offices, and the outlets for motorized equipment in industrial plants. 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 4kw HMI with PFC electronic ballast, operating at 240 Volts draws roughly 18.5 Amps on each leg of a single phase 240V circuit, its’ load is well within the capacity of these circuits. You will also be able to operate a non-PFC 4k electronic ballast off of most 240V receptacles like range plugs and dryer plugs because they draw 26 Amps per leg and these circuits are fused at minimally 30 Amps. Where most magnetic 4k ballasts operate at only 120V and draw 40 Amps this method is not an option with magnetic ballasts. Where 4kw ballasts are typically wired with a 120V 60Amp Bates Plug (Stage Pin), you will need a 120V Female Bates to 240V adapter. I keep an assortment of adapters because all these 240V receptacles use a different pin configuration. 4k & 1.2ks HMI Pars powered from 30A/240V dryer outlet through step-down transformer/distro for Bose still shoot. The only way to power 120V 4kw HMI magnetic ballasts on wall receptacles is from 240V circuits through a 240v-to-120v step down transformer like the one my company, ScreenLight & Grip (SL&G), manufactures for the Honda EU6500is generators that we modify. Like it does with the enhanced 240V output of our Honda EU6500is Generator, a step down transformer can be used to convert the 240 volts supplied by these industrial and household 240V receptacles to 120 volts in a single circuit that is the sum of the two single phase legs of 30/50 amps each. In other words, out of a “30A/240v” or a “50A/240v” circuit our transformer makes a 60A/120v circuit that is capable of powering bigger 120V lights, like 4kw HMIs with magnetic ballasts (even Quartz 5ks, mini brutes (5850W) or Six Light Mole Par (6000W)). There are benefits to be gained by powering even 4kw electronic ballasts (PFC or not) on 240V circuits through a 240v-to-120v step down transformer. For instance, you will be able to run additional large lights (like 1.2kws) on the same circuit if, rather than plugging the 4kw electronic ballast directly into the 240 receptacle (operating it at 240V) and monopolizing it, you plug it in through a transformer (operating it at 120 Volts), you will be left with 25 - 37 Amps to power additional lights on the same circuit. That’s a lot of additional power to waste by plugging the 4k directly into the 240V receptacle. And, since an electronic ballast “ramps up” gradually during the striking phase, you don’t have to leave head room as you would with a magnetic ballast. By operating the light through a transformer you can more fully utilize the capacity of the 240V circuit. For example, since the P2L 4/2.5 LVI ballast at 120V operates a 4k HMI luminary at 37 amps, you will still be able to power an additional 1.2kw HMIs (if operated by P2L 575/1200 ballast (11 Amps)), as well as a 800 Joker HMI (if operated by a P2L 800/1200 ballast (8 Amps)), off of the same circuit. That’s a lot of additional light to be gained by not plugging the 4k directly into the 240V receptacle. A transformer will also greatly simplify your set electrics by automatically splitting the load of whatever you power through it. 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, like our 60a Full Power Transformer/Distro, the transformer is outfitted 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. It is so simple that you don’t have to be an experienced electrician to distribute power on set. Use this link for more details about using step-down transformers to power larger lights on interior sets. 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 Everything I have said thus far is also true when it comes to operating HMIs off of portable gas generators with 240V outputs. Where before you could not operate more than a couple 1200W HMIs on portable generators because of their limited 120V power outlets, with a step-down tranformer you can operate bigger lights, or more small lights, on portable gas generaotors than has been possible before. 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. But, where I have covered this in another post in this forum I won’t go into more details here. For more details read my posts at http://www.cinematography.com/index.php?sh...honda+generator Guy Holt, Gaffer, ScreenLight & Grip , Boston
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