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First time working with large HMI

HMI generators generator power distro night exteriors 6K HMI par

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#1 Arman Cole

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Posted 30 July 2013 - 04:17 PM

Hi all,

 

I'm currently prepping to DP a short film that has some night exteriors in the woods.  We're shooting on Red One MX and have it in our budget for a 6K HMI par, but I've never worked with such large lights.  Given that we won't have a professional gaffer or electrician on set, is this realistic or even safe?  What kind of genny would you recommend for this type of light?  A condor is out of the question so we would be placing the light on a tall stand.  My main goal is to provide enough background and rim light such that the scene doesn't suffer from a low-budget student film look.

Best,

Arman


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#2 Christoph Helms

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Posted 30 July 2013 - 06:56 PM

Hey Arman,

just a question for my understanding: Are you trying to turn a night scene into a day scene with the 6K?

You'll need to get a 7000W generator which is quite a heavy beast. It can be rented from places like HomeDepot...


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#3 Adrian Sierkowski

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Posted 30 July 2013 - 07:08 PM

You'd need a lot more than a 7000W genny from Home Depot because it sure as hell isn't going to give you anywhere near enough power once you factor in the power factor of the HMI, let alone the bates connection you'd need to plug it in. . .

 

It's just a light; granted a very large and heavy and power hungry light. There is a first time for everything but if you've never run distro off of a tow genny, which you'll need, you should probably reconsider going in without a qualified electric. Or you know, you can just run the risk and liability of hurting yourself and everyone around you.


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#4 Oliver Hadlow Martin

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Posted 03 August 2013 - 09:24 AM

240v 32amp 10k gen with distro box. 

 

 

Use a qualified electrician. 


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#5 Phil Rhodes

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Posted 03 August 2013 - 09:43 AM

Doing that wouldn't worry me. Hard to hurt oneself unless you throw it in a pond, no?


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#6 Adrian Sierkowski

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Posted 03 August 2013 - 10:14 AM

Depends on the genny you're running. Gotta make sure you wire it all up right, ground it properly, all that fun stuff. If he's getting a tow-behind with cam-locks, running distro isn't hugely difficult; but you have to know what you're doing to protect the equipment and people around you.

Depends too if he's on 120 or 240. 240 makes this substantially easier; but isn't as likely in the state where you'd want to get a 120 genny and run 120 power anyway just so you can plug in more than 1 6K HMI.


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#7 Phil Rhodes

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Posted 03 August 2013 - 11:04 AM

Ah, that's the rub. Here, that'd just be a 32 amp connector. Plug in and go. Depending on the specific circumstances you might have to run some form of distribution, but I'd expect to be able to do it without recourse to camlocks.

 

P


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#8 Adrian Sierkowski

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Posted 03 August 2013 - 11:29 AM

I am often quite envious of the power options available in 240 countries. 


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#9 Guy Holt

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Posted 21 August 2013 - 10:09 PM

It's just a light; granted a very large and heavy and power hungry light. There is a first time for everything but if you've never run distro off of a tow genny, which you'll need, you should probably reconsider going in without a qualified electric. 

 

The problem with diesel tow plants is that, not only do you need a qualified electric to distribute and balance your load, but they are expensive and come with a lot of hidden costs.  The hidden costs of blimped studio generators is one of the biggest hurdles to lighting night exteriors. It starts with the fact that rental trucks like those from Ryder or Penske are not equipped to tow, so you have to hire the rental house’s grip truck to tow them. And, since most rental houses require that one of their employees drive their trucks for insurance reasons, you have to hire a driver at roughly $575/10hrs – which is probably more than anyone else on a typical indie crew is getting paid.

 

A solution to this dilemma that has worked for me is to use a portable generator like the new 10’000W Honda EB10000 with a boost transformer. While 10’000W is enough to power to run a 6k HMI Par, I would recommend that you use the new ARRI M40 with ARRIMAX reflector instead. Since it is a “lens-less par” it has an output comparable to a 6k Par and will draw a lot less power.  It will be more than enough to light the deep background and there will be enough power left over on the EB10000 to power not only talent keys but also backlights, rim lights, and kickers to edge light your talent. A lot of productions hesitate to use non-blimped industrial generators like the new 10kw Honda EB100000 because of the noise they make – don’t. Whether you pick up generator noise on your audio tracks comes down to how you use it. 

 

A common problem with open-frame industrial generators like the EB10000 is that by the time you move them far enough off set that you don't hear them you have significant "Line Loss" (often referred to as "Voltage Drop") from the long cable run back to set. To the problem of line loss, you have the added problem that as you add load, the voltage drops on portable generators (it is not uncommon for a generator to drop 5-10 volts under full load.) The combination of voltage drop on the generator and line loss on a long cable run can cause voltage to drop to the point where HMI and Kino ballasts cut out unexpectedly or won't strike at all. Low voltage can also cause problems such as reduced efficiency and excessive heat in equipment, unnecessary additional load on the generator, and a dramatic shift in the color temperature and in the output of lights. For these reasons, portable gas generators are typically operated too close to set where they are picked up on audio tracks.

 

The trick to recording clean audio with the EB10000 is to use the generator with a boost transformer that will enable you to operate the generator at a distance where it won’t be heard, yet maintain full line level on set.

 

EB10000_w-Trans_&_Caddy_Sm.jpg

Honda EB10000 with Voltage Select 84A Transformer/Distro and  14 Gallon Fuel Caddy

 

A boost transformer will enable you to add 300'- 400' of larger gauge 250V twist-lock extension cable between the generator and the Transformer/Distro. This is usually enough cable to place the generator around the corner of a building, or to run it out of a van or truck - which is usually all the additional blimping you need with these generators. The heavy-duty 250V twist-lock cable eliminates multiple long cable runs to the generator and minimizes line-loss (eliminating the severe voltage drop you would have using standard electrical cords.) And, by compensating for the unavoidable voltage drop you will have on a fully loaded generator, a boost transformer will assure full line level (120V) on set.

 

EB10_Paralarva_Comp_1Sm.jpg

 

Left: Honda EB10000 operating out of grip truck (note set at distance (bright spot on right side.)) Center: 84A Full Power Transformer/Distro compensates for Voltage Drop over 400ft cable run. 

Right: Beach Set with 120v full line level 500ft from power source.

 

A good example of how the voltage boost capacity of Transformer/Distro makes it possible to record clean audio tracks with the EB10000, even under the worst of conditions, is the indie short "Paralarva" (pictured above and below.) The film takes place around a campfire on a beach on Cape Cod. To record sync sound without picking up the noise of a generator, the crew ran our modified 10kw Honda EB10000 out of their grip truck 500 ft from their beach set. To assure full line level on set, the production used the boost capacity of our 84A Select Transformer/Distro to compensate for the line loss over the long cable run.   

 

EB10_Paralarva_Comp_2Sm.jpg

 

Left: Beach Set lit by two 1800W Arrimaxes. Center: Secondary side power distributed with standard 100 Bates Gang Boxes. Right: Set viewed from generator (note: distance and extent of set power distribution.)

 

From the Transformer/Distro they then ran 100' of 4/3 Bates Extension to set where they broke out to 20A Edison receptacles using 100A gang boxes. While running the generator near full capacity with a lighting package that consisted of two 1800W Arri M18 Baby Max HMIs, several Tegra 400s,  and assorted Litepanels and Quartz Fresnels, they experienced no appreciable voltage drop on set even after a 500' cable run because our Select Transformer/Distro was able to compensate for both the line loss of the cable and voltage drop of the generator under near full load.

 

EB_Gasp_Composite.jpg

 

Left: Ready for rain on the set of "Gasp." Center: Two 4kw Pars operate on a 10kw Honda EB10000 Generator through our 84A Full Power Transformer/Distro. Right: 100A Shock Block GFCI downstream of Full Power Transformer/Distro offers Ground Fault Protection for entire 100A distro system

 

By comparison, had the crew of "Paralarva" run 500' of standard 14 Awg electrical cord they would have experienced a line loss alone of 24.5V. To avoid having their 1800W Baby Maxs cut out from low voltage, they would have had to move the generator closer to set where it would be picked up on the audio tracks. This example clearly demonstrates how the boost capacity of transformers can enable you to not only place the generator further from set where it won't be heard, but also assures that the supply voltage on set does not drop too low (use this link  for information about Line-Loss and how to combat it.)

 

Another benefit to using a Transformer/Distro is that it splits the load of what ever you plug into it automatically. The iMonitor display on the Honda generators makes it especially easy to load them to the max. Simply plug in lights. When the load wattage displayed on the iMonitor reaches 10'000 Watts (EB10000) you are fully utilizing the power capacity of the generator. An overload alarm on the iMonitor display will tell you if you inadvertently overload the Transformer/Distro. You no longer have to carefully balance the load over the generator's legs as you plug in lights because the Transfomer/Distro does it for you automatically. Now that you are able to fully utilize the EB10000's 10’000 Watts, you are able to power not a large HMI light, like the new ARRI M40, but also smaller HMI, Kino, & Quartz lights.

 

If you have trouble finding the EB10000 because it is so new, look for a 7500W Honda EU6500is.  A modified 7500W Honda EU6500is Inverter Generator with a 60A Full Power Transformer/Distro is capable of powering a 4k HMI along with  800, & 400 Pars with PFC ballasts, plus a couple of Parabeam 400s and Parabeam 200s. Given the light sensitivity of HD Camcorders, this can constitute a complete location lighting package for a low budget HD Digital Cinema production.

 

portableGenBook.jpg

 

 

 

For more detailed information on successfully using Honda portable generators in digital cinema productions, I would suggest you read a white paper I wrote on the use of portable generators in motion picture production that will be available soon as an e-book from the Academy of Production Technology Press (APT.)

 

BoxBookLinkGenSetSm.jpg

 

Harry Box, author of The Set Lighting Technician’s Handbook has cited

my article in the just released 4th Edition of Harry Box's “Set Lighting Technician's Handbook”  and featured on the companion website “Box Book Extras."   Of the article Harry Box exclaims:

 

“Great work!... this is the kind of thing I think very few technician's ever get to see, and as a result many people have absolutely no idea why things stop working.”

 

“Following the prescriptions contained in this article enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before."

 

The original white paper is still available online for free at

http://www.screenlig...generators.html.

 

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston


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