Generator to Lunch Pail or Snack Box

[Steve McBride]

I've been on set with generators before, but being an AC I've never set up the distribution myself. I'm just wondering if I get a Honda 6500 to run a 2.5k PAR and 1.2 fresnel as well as misc. other units what would I need to run those as well as how to do this?

[Michael Collier]

Possibly. I've seen 2.5K run fine on a Honda 6500 modified with a xstal sync and 60 amp bates (it also would work off the 30A twist lock. Not sure if that twist lock was standard or an after market thrown on with the bates. That was with a magnetic ballast. For reasons discussed in great detail in other threads by some very smart individuals (search for PFC or power factor correction) you may not be able to get a 2.5k on a 30A circuit if your ballast is Electronic. At 2.5Kw/120v theoretically 20.83A, but of course that is not the whole story. You need to find the actual draw of the units you plan to run, and be sure plan a 70% payload for safety with electronic ballasts (30% safety overhead).

 

Do you have a bates coming from the engine that can carry the full capacity of the generator? (50ish amps theoretically, so a 60A bates would be enough) again check the actual sustained sourcing potential the generator has. sometime 6500w means 6500w peak, or during over-voltage situations.

 

If you have electronic ballasts, plan your overhead accordingly (4550w/38ish amps). Now check out the actual power draw of the units you plan to run. 2.5K could easily be up to 30A draw. 1.2 could be bordering on 17A. You might have a spare 3 amps or so (enough for a tweenie? or crafty's coffee pot). But your close to the safety threshold, so if you plan to do this you must verify the draws are what they are labeled.

 

If you feel comfortable running a multimeter and have a VERY solid understanding of Ohms law and set power distribution, you would probably only need a 60A bates runner to a lunchbox that breaks into bates (for the 2.5k) and hubbels for the 1.2 and other lights.

 

electronic ballasts + 30A twist locks are a no go for 2.5 (even if you have two 30A circuits). They would be enough for the 1.2. You will need a single 60A circuit at least to run all of this. 100A and a stronger generator would be better.

[Steve McBride]

Thanks for the reply. What I'm basically reading is that it wouldn't be safe to run a 2.5k, 1.2k and maybe a few more sources from a single 6500w generator.

 

If I were to get the following, would it all work together? (sorry for the vague question, new to electrics and such)

 

- 6500w generator

- 60 Amp Edison Snack Box (3 20 Amp duplexes)

- 50' Bates extension

 

To power...

 

- 2x 1.2k Fresnels

- 2x 4x4 Kinos

 

Thanks!

[Ross Neugeboren]

Thanks for the reply. What I'm basically reading is that it wouldn't be safe to run a 2.5k, 1.2k and maybe a few more sources from a single 6500w generator.

 

If I were to get the following, would it all work together? (sorry for the vague question, new to electrics and such)

 

- 6500w generator

- 60 Amp Edison Snack Box (3 20 Amp duplexes)

- 50' Bates extension

 

To power...

 

- 2x 1.2k Fresnels

- 2x 4x4 Kinos

 

Thanks!

 

Working on the 120v/30A twist-lock off the 6500, you would still only have access to 30A, so you couldn't do a single 60A run. You could split the HMIs, putting one on a run of stingers from the 20a, and put the other on 60a distro with a woodhead and only book up 30a worth of load. For a single 60a run, you'd need a step down transformer on the 240v/30A output as the even split across the legs would give you full access to the 60A. Screenlight, Guy Holt's rental house, rents a transformer that does this.

[Joshua EarlesBennett]

Do you have a picture of the panel for the 6500 Honda? We have two at the G&E house I work at. Ones got camlock coming out, while the others got 240V twistlock coming out. So they can definitely handle a couple of 1200 and Kinos. We use them to run a 4k and 1200 at the same time.

 

The biggest issues we ever run into is the fact that the electronic ballast are really sensitive to how much voltage is coming down the pipe, so if something isn't striking be sure to check the voltage is pretty close to 120. Then we just tweak the barber colemans to get it where we need it to be.

[JD Hartman]

A "standard" Honda 6500, be it the EU, ES, EM, EB is rated at 5500w continuous. From the 30A receptacle you can only draw 22.9A before you start to overload the generator winding (theoretically). If you use the 30A 125/250 twistloc, you could build an adapter whip to split the output into 2, 60A bates females. You are still limited to the maximum output of each leg. Personally never seen a Honda which had the ability to vary the out voltage. I'm sure the AVR circuit inside has an adjustment, but it's not meant to be user adjustable.

[Rob Vogt]

I think everyone's overthinking this a little two much. Steve, on that genny I've seen 2 20 amp circuits and one 30A twistlock... If you just wanna run 2 kinos and 2 1.2s just run a kino and a 1.2 into each 20A circuit.

[Guy Holt]

I think everyone's overthinking this a little two much. Steve, on that genny I've seen 2 20 amp circuits and one 30A twistlock... If you just wanna run 2 kinos and 2 1.2s just run a kino and a 1.2 into each 20A circuit.

 

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

[Guy Holt]

What I'm basically reading is that it wouldn't be safe to run a 2.5k, 1.2k and maybe a few more sources from a single 6500w generator.

 

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

Edited May 18, 2010 by Guy Holt