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Author Topic: Paralleling Two Generators  (Read 13805 times)

Jonathan Johnson

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Re: Paralleling Two Generators
« Reply #10 on: June 29, 2014, 07:26:43 pm »

Aspects of safety, warranty, and liability aside, I can see a few reasons to go for parallel/synchronized generators:
  • Size: you may need to transport the generators in a vehicle where two small gennys can fit but a larger one won't.
  • Price: you may be just starting your business and only need one generator, and eventually need to expand to larger capacity and don't want to dish out for a generator of the proper size.
  • Flexibility: sometimes you only need 2000VA; sometimes you need more. Maybe you and another provider want to be able to team up for those big jobs.

By the time you need over 5000VA, you're probably better off buying or renting a single unit with sufficient capacity. I suppose the argument for teaming two 7000VA generators is that you get the benefit of the inverter, but I suspect that a 15kVA non-inverter generator will have superior voltage and frequency control when compared to a <5kVA unit, so the inverter doesn't matter as much. Don't underestimate the regulating ability of the rotating mass of a flywheel on a large diesel engine.

Just because you can (teaming) doesn't mean you should (get a bigger one instead). Beware of the solution in search of a problem: where no problems exist, an unsolicited solution will happily provide one. If nothing else, it will raise your costs.
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Mike Sokol

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Re: Paralleling Two Generators
« Reply #11 on: June 29, 2014, 09:07:34 pm »

Aspects of safety, warranty, and liability aside, I can see a few reasons to go for parallel/synchronized generators:

So here's a hypothetical question. If you have two of these generators running in parallel and need to refuel them, can't you just shut one down during a low-power draw part of your show (band change), let it cool down for a few minutes, then fill it up with gas (or petrol if you're in the UK, I think). You could start it back up, then repeat the shutdown/refueling process on the second generator.

I've never used a pair of these in parallel, but I think logically it would work. Can anyone confirm? 
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Mike Sokol
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Re: Paralleling Two Generators
« Reply #12 on: June 29, 2014, 09:11:51 pm »

So here's a hypothetical question. If you have two of these generators running in parallel and need to refuel them, can't you just shut one down during a low-power draw part of your show (band change), let it cool down for a few minutes, then fill it up with gas (or petrol if you're in the UK, I think). You could start it back up, then repeat the shutdown/refueling process on the second generator.

I've never used a pair of these in parallel, but I think logically it would work. Can anyone confirm?

Unfortunately, no.  It has to do with the master/slave relationship of the two generators.  The slave unit revs up to meet current draw as needed and as such the master unit will require fueling first.  That's the one that cannot be shut down.
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Frank DeWitt

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Re: Paralleling Two Generators
« Reply #13 on: June 29, 2014, 10:39:53 pm »

So here's a hypothetical question. If you have two of these generators running in parallel and need to refuel them, can't you just shut one down during a low-power draw part of your show (band change), let it cool down for a few minutes, then fill it up with gas (or petrol if you're in the UK, I think). You could start it back up, then repeat the shutdown/refueling process on the second generator.

I've never used a pair of these in parallel, but I think logically it would work. Can anyone confirm?

Many users do this.  You are not supposed to connect or disconnect them while one or more are running, but you can turn either one off and restart it at will.  RVs will do this to conserve fuel during times they don't need a lot of power.  Many of them alternate what generator is shut off to keep the hours near equal.

 
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Stephen Swaffer

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Re: Paralleling Two Generators
« Reply #14 on: June 29, 2014, 11:18:18 pm »

That's the one that cannot be shut down.

So what actually happens-real world-when the master runs out of fuel?  (Maybe I am the only one that would let that happen?)  I am guessing nothing self destructs?
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Steve Swaffer

Steve M Smith

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Re: Paralleling Two Generators
« Reply #15 on: June 30, 2014, 01:45:19 am »

So here's a hypothetical question. If you have two of these generators running in parallel and need to refuel them, can't you just shut one down during a low-power draw part of your show (band change), let it cool down for a few minutes, then fill it up with gas (or petrol if you're in the UK, I think).

You think correctly.  Petrol it is (or diesel).

I'm sure every time I have seen someone refuel a generator, it has been left running (you can now all scream in horror and explain why that's a bad idea!).


Steve.
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frank kayser

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Re: Paralleling Two Generators
« Reply #16 on: June 30, 2014, 01:56:59 am »

You think correctly.  Petrol it is (or diesel).

I'm sure every time I have seen someone refuel a generator, it has been left running (you can now all scream in horror and explain why that's a bad idea!).


Steve.


That is one thing I like about the remote extended run tanks.  If you're using a kit with the bulb-type fuel lines and marine quick connects, one could completely swap tanks simply with nary a drop spilled.


frank
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Rob Spence

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Re: Paralleling Two Generators
« Reply #17 on: June 30, 2014, 12:09:30 pm »

In reading the original linked advert, it seemed to me that this was targeted at large lighting loads for remote movie production. I concluded this based on the discussion on connectors.

Also, they talk about stepping down the 240v to 120. I am not sure how the CA (Hollywood ) connector works in to that. My distros that have a CA connector expect center tapped 240v which will keep the neutral current within the wire capacity.

Or, did I missread it?


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Cailen Waddell

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Re: Paralleling Two Generators
« Reply #18 on: June 30, 2014, 12:15:06 pm »

Rob I think you read it correctly.  That is but one of the reasons my bullshit-o-meter was reading high.


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Tim McCulloch

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Re: Paralleling Two Generators
« Reply #19 on: June 30, 2014, 07:11:38 pm »

Rob I think you read it correctly.  That is but one of the reasons my bullshit-o-meter was reading high.


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Contact the manufacturer.  This is a piece of "grip" equipment used in film/TV/video industries.  I'm making an educated (and Union-based) guess that the Honda gensets are for high current lighting (the ARRI/HMI lights) in locations where it's impractical to get a towed, diesel generator or where even the super-hushed gensets would be too loud.  Things like this get built to meet a particular need, not to sell bullshit to the unsuspecting.

Also note that grips are lighting guys.... and in the movie/video industry there is a huge amount of tradition regarding nomenclature and some of the word choices are not accurate technical descriptors.

Does it "step down"?  I don't know what they mean exactly, but I gather that I can power devices that use either 240v or 120v.  Do they have a downloadable manual?
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Re: Paralleling Two Generators
« Reply #19 on: June 30, 2014, 07:11:38 pm »


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