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Author Topic: Paralleling Two Generators  (Read 1163 times)

Stephen Swaffer

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Re: Paralleling Two Generators
« Reply #20 on: July 01, 2014, 12:53:52 am »

Their brochure shows a wiring diagram.  The paralleled gennys provide 240 volt 4 wire out-like is typically seen.  Their distro includes a transformer that does not use a neutral-just connects to the 240 volt hots and steps it down to the 120 volt "heavy duty" circuit.  I would think for general use you would want breakers to protect equipment/cords.  Not sure if the lighting gear they are selling for is designed for an unusually heavy supply circuit or not.

To get the full "benefit" of their design you have to buy both pieces-it seems to me.
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Steve Swaffer

Tim McCulloch

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Re: Paralleling Two Generators
« Reply #21 on: July 01, 2014, 09:47:59 am »

Their brochure shows a wiring diagram.  The paralleled gennys provide 240 volt 4 wire out-like is typically seen.  Their distro includes a transformer that does not use a neutral-just connects to the 240 volt hots and steps it down to the 120 volt "heavy duty" circuit.  I would think for general use you would want breakers to protect equipment/cords.  Not sure if the lighting gear they are selling for is designed for an unusually heavy supply circuit or not.

To get the full "benefit" of their design you have to buy both pieces-it seems to me.

Well, this is a purpose-built system and I think it prudent to engage the designers if we're going to publically question their work.  Los Angeles has some of the strictest Code and enforcement for entertainment and visual media production in the USA.  If this system passes muster in LA County, I tend to believe that it is safe when used according to the manual,  but it would be nice to hear from the designer.

Mike, grip equipment is OT here but the genset use is not.  Can you see if they want to comment or explain their system?
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Mike Sokol

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Re: Paralleling Two Generators
« Reply #22 on: July 01, 2014, 01:17:56 pm »

Well, this is a purpose-built system and I think it prudent to engage the designers if we're going to publically question their work.  Los Angeles has some of the strictest Code and enforcement for entertainment and visual media production in the USA.  If this system passes muster in LA County, I tend to believe that it is safe when used according to the manual,  but it would be nice to hear from the designer.

Mike, grip equipment is OT here but the genset use is not.  Can you see if they want to comment or explain their system?

That's a good idea. Even though I'm mostly a sound guy, I do interface with film and lighting guys a good bit, especially for political events around Wash DC. I'll shoot them an email today and ask if they'll explain their system and answer a few questions from you guys. I think it would be a great learning experience for all of us.

Everyone promise to play nice with the lighting guys, OK?

Frank DeWitt

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Re: Paralleling Two Generators
« Reply #23 on: July 01, 2014, 02:30:40 pm »

Everyone promise to play nice with the lighting guys, OK?

No problem,  we are all in this together.


A lighting guy and a sound guy died in a van wreck coming home from a show.
As they stand at the gates of heaven, St. Peter checks over the list;
"I see you were loved by many fans, you did a lot of charity work too."
St. Peter reads on in the records; "and I see you were even good to
your roadies, very commendable, well it looks like you can come into heaven,...
go around to the back, past the dumpsters and load in through the kitchen!"
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frank kayser

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Re: Paralleling Two Generators
« Reply #24 on: July 01, 2014, 02:34:15 pm »

No problem,  we are all in this together.


A lighting guy and a sound guy died in a van wreck coming home from a show.
As they stand at the gates of heaven, St. Peter checks over the list;
"I see you were loved by many fans, you did a lot of charity work too."
St. Peter reads on in the records; "and I see you were even good to
your roadies, very commendable, well it looks like you can come into heaven,...
go around to the back, past the dumpsters and load in through the kitchen!"


Thanks, Frank.  I needed a good belly laugh.


We'll play nice... we're learning, right?  We learn little if we kill the teacher.


frank
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Stephen Swaffer

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Re: Paralleling Two Generators
« Reply #25 on: July 01, 2014, 02:45:14 pm »

Yep-always more to learn.  The step down doesn't make sense to me-but I have seen 150 HP 230/460 volt motors run off 460 through a step down transformer wired as a 230 volt motor because of the environment they were running in-so there may well be valid reason for doing it.
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Steve Swaffer

Jonathan Johnson

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Re: Paralleling Two Generators
« Reply #26 on: July 01, 2014, 05:30:11 pm »

The step down doesn't make sense to me- ... -so there may well be valid reason for doing it.

My guess is that for a generator with 120/240V 100A output (24kVA), you are limited to 100A per leg. If you have a lighting rig that requires a single 120V connection in excess of 100A, that output won't work for you. However, if you have a step-down transformer with an input of 240V 100A, you can have an output of 120V 200A. (Well, a little less, to account for transformer losses.) You would be able to connect your 120V 150A singel-connection lighting rig to the output of that step-down transformer.

Such a setup would allow you to avoid renting or buying a 50kVA generator (25kVA per 120V leg). Not sure there would really be a cost savings, but perhaps there are applications where the physical size of a 50kVA makes it impractical, such as a remote video shoot in an area inaccessible to vehicles.
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Cailen Waddell

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Re: Paralleling Two Generators
« Reply #27 on: July 01, 2014, 05:51:00 pm »

I'm actually wondering to get the 100a output if they are stepping both hot legs down to +60/-60...

The triplen harmonics stuff though....


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Mike Sokol

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Re: Paralleling Two Generators
« Reply #28 on: July 01, 2014, 07:14:07 pm »

I'm actually wondering to get the 100a output if they are stepping both hot legs down to +60/-60...

The triplen harmonics stuff though....


Don't know about the 60/60 stuff, but I do know a lot about triplen harmonics, having blown up the power for an entire million square foot warehouse and packaging plant back in the 70's. Ouch...  ::)

I've sent an email to the OP's genny designer offering them a guest spot on the forum to discuss their technology. This is going to be really interesting.

Hey, I don't see any other forums doing this kind of stuff. YOU GUYS ROCK!!!!! ;D ;D ;D ;D ;D

Mike Sokol

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Re: Paralleling Two Generators
« Reply #29 on: July 01, 2014, 09:03:14 pm »


Mike, grip equipment is OT here but the genset use is not.  Can you see if they want to comment or explain their system?

Just got this answer back from the double 6500 watt genny designer. Let table the discussion until Guy gets back from vacation and read over his white paper in the meantime.

Hello Mike Sokol,

I appreciate the opportunity to defend/inform the readers of your forum about our product line. Unfortunately though you have caught me at a bad time as I am trying to finish up several projects before going on vacation on Friday for a week. What I might suggest is that in the mean time  your members read a white paper I wrote on this subject that is available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html.  It will put the system in context and explain where we are coming from and where  the systems is meant to go.  It meets very specific needs in the motion picture lighting market, which is not to say that in the final analysis it may offer no real benefit to your readers even though it offers tremendous benefit to producers of regional commercial spots, documentaries, and independent features. When I get back in town, I will be happy to answer any questions that the white paper has not answered.

Thanks again and extend my thanks to your readers - not many forums would be so fair minded as to reach out to the manufacturer before piling on.

Guy Holt
ScreenLight & Grip
rentals@screenlightandgrip.com
(617)224-8534 
« Last Edit: July 01, 2014, 09:32:44 pm by Mike Sokol »
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