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Title: Paralleling Two Generators
Post by: Cailen Waddell on June 29, 2014, 10:31:07 am
I have been looking at Honda's newer EU7000i, and their parallel capability, as together, two could handle a couple of our larger outdoor gigs... 

As I was doing some googling, I came across this site, and wanted to ask everyone's thoughts,

The theory makes sense to me - but I wonder about applicability, we have about 15A of LED units, 4 Crown xti 6002, and then the console, various other miscellaneous stuff.... 

Thoughts?  Is it a way for people to waste money or a legit device?

http://www.screenlightandgrip.com/html/slg_home.html

Thanks
Title: Re: Paralleling Two Generators
Post by: g'bye, Dick Rees on June 29, 2014, 12:38:06 pm
I have been looking at Honda's newer EU7000i, and their parallel capability, as together, two could handle a couple of our larger outdoor gigs... 

As I was doing some googling, I came across this site, and wanted to ask everyone's thoughts,

The theory makes sense to me - but I wonder about applicability, we have about 15A of LED units, 4 Crown xti 6002, and then the console, various other miscellaneous stuff.... 

Thoughts?  Is it a way for people to waste money or a legit device?

http://www.screenlightandgrip.com/html/slg_home.html

Thanks

It'll be less expensive (and give you more power for your money) to just buy a single diesel unit.  In addition you'll get:

1.  Warranty.  Modding the Hondas voids the warranty.

2.  Insurable.  Modded units may not be coverable in liability claims.

3.  More power, no phase issues and longer run time.

4.  No after-market kludges, no (well, fewer...) hassles with inspectors.
Title: Re: Paralleling Two Generators
Post by: Cailen Waddell on June 29, 2014, 01:33:34 pm
Dick. Thanks for this...

I wasn't thinking of modding the Hondas, I was thinking of the honda bridge kit.  My question was more to - are these guys solving a legit problem or is this a solution with only a theoretical problem. 

Diesel is certainly an option, whatever we get goes through fleet, and gets a pm program.  We are local gov.

Correct about run time, etc

We are our own inspectors or at least the AHJ (which is us) leaves us alone.  We currently follow best practices with genny grounding, operation etc.


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Title: Re: Paralleling Two Generators
Post by: Frank DeWitt on June 29, 2014, 02:29:11 pm
I have been studying the whole line of Honda Inverter generators after seeing a set of them in action and being impressed.  I can't find any owner anywhere that isn't pleased with them. They run quiet.  They give good clean power.  Honda EU series AC power with a voltage stability within 1%, and frequency stability within 0.1 HZ. The end result is a nearly pure sine wave with a wave distortion of only 2.5%

They are easy to parallel with Honda equipment.  No mods, no kluge.  Extend run tanks are available that can be mounted in a safe place and connected to the generator without mods or kluge.

What I like is that each individual unit is lighter in weight and easier to manage, load, unload, then one big generator.

Frank
Title: Re: Paralleling Two Generators
Post by: frank kayser on June 29, 2014, 04:31:13 pm
the only argument I have is with your statement about a extended-run tank.


The gas cap on the 1000-2000 series requires modification (kludge) to make it work.


That same mod will not work with the 3000 series. 


Like an outboard motor, the 1000-2000 series employ a vaccuum-pulse fuel pump, where the 3000 is strictly gravity fed.  The 3000 can be retrofit with the fuel pump from the 2000 which will enable a safe extended-run tank. http://www.youtube.com/watch?v=cqJ41vhfR9w


The other option is to siphon feed the 3000 or gravity feed the existing tank on the 3000, but I'm not thrilled with that idea.


Hold the phone!  A new system I have not seen before...
http://www.youtube.com/watch?v=Ok2moAAttgM


frank
Title: Re: Paralleling Two Generators
Post by: Frank DeWitt on June 29, 2014, 04:49:17 pm

Hold the phone!  A new system I have not seen before...
http://www.youtube.com/watch?v=Ok2moAAttgM

frank

Here is another.  No mods, and for God's sake, no Kludge
http://www.generator-line.com/fuel-systems.html
Title: Re: Paralleling Two Generators
Post by: g'bye, Dick Rees on June 29, 2014, 05:09:34 pm
Here is another.  No mods, and for God's sake, no Kludge
http://www.generator-line.com/fuel-systems.html

I've got a request for info in to Honda regarding this.  Waiting for an answer.
Title: Re: Paralleling Two Generators
Post by: Mike Sokol on June 29, 2014, 05:23:56 pm
Here is another.  No mods, and for God's sake, no Kludge
http://www.generator-line.com/fuel-systems.html

Something like this appears to be safe at first blush. One would think that the marine guys would have figured this out since small boats often have these remote fuel tanks, and fire on a boat is truly terrifying.

As far as the OP, the beauty of a pair of smaller inverter generators that can be paralleled is that they can be split up for smaller shows, they sip fuel compared to big constant RPM motors, and the redundancy factor could be important. Plus these small Honda gennys  are really quiet compared to many mid-sized diesel units. Of course, the really large diesel generators can be super quiet as well, are delivered on a trailer, and will run all day without thinking about refilling. However, not every gig can afford the rental price or the room.

As long as they can be made electrically safe, pass all inspections for fuel and grounding using manufacturer approved hardware, and generate clean power, I don't see any reason to avoid using paralleled inverter generators for smaller stages.   
Title: Re: Paralleling Two Generators
Post by: Cailen Waddell on June 29, 2014, 05:42:18 pm
Mike can you look at the info in the link I posted.  I'm specifically interested in their claims about non power factor corrected loads, neutral currents and inverter damage.

The theory makes sense to me but they don't discuss the ampacity of the loads created by their indicated conditions, and I question whether it is enough to matter....


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Title: Re: Paralleling Two Generators
Post by: Mike Sokol on June 29, 2014, 06:33:10 pm
Mike can you look at the info in the link I posted.  I'm specifically interested in their claims about non power factor corrected loads, neutral currents and inverter damage.

The theory makes sense to me but they don't discuss the ampacity of the loads created by their indicated conditions, and I question whether it is enough to matter....


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A quick read of their website gets my spidey sense tingling. They're using the fear of 3-phase triplen harmonic currents in the neutral to promote their special modified Honda generators running in parallel mode. Of course generators in parallel mode are at 0 degree phase angle (so no triplen harmonics), and even if they were running at 180 degrees for a true 240/120 volt output, there's still no triplen currents.

So while I think that running Honda generators in parallel using the factory kit is safe and legal, I think these specially modified units to eliminate non-existent triplen harmonics is a sales pitch full of boloney.

Now, in the interest of full disclosure I just finished a big crab and shrimp birthday party (yes, Maryland Blue Crabs and jumbo shrimp) with my twin brother who flew in from California and my own twin boys who just turned 21, I've had quite a few toasts this afternoon and not in full IQ mode. However, I'll read it over once again tomorrow and see if it still tracks the same way. Seems fishy to me, and not the good kind of fishy... ::)
Title: Re: Paralleling Two Generators
Post by: Jonathan Johnson 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:

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.
Title: Re: Paralleling Two Generators
Post by: Mike Sokol 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? 
Title: Re: Paralleling Two Generators
Post by: g'bye, Dick Rees 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.
Title: Re: Paralleling Two Generators
Post by: Frank DeWitt 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.

 
Title: Re: Paralleling Two Generators
Post by: Stephen Swaffer 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?
Title: Re: Paralleling Two Generators
Post by: Steve M Smith 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.
Title: Re: Paralleling Two Generators
Post by: frank kayser 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
Title: Re: Paralleling Two Generators
Post by: Rob Spence 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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Title: Re: Paralleling Two Generators
Post by: Cailen Waddell 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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Title: Re: Paralleling Two Generators
Post by: Tim McCulloch 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?
Title: Re: Paralleling Two Generators
Post by: Stephen Swaffer 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.
Title: Re: Paralleling Two Generators
Post by: Tim McCulloch 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?
Title: Re: Paralleling Two Generators
Post by: Mike Sokol 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?
Title: Re: Paralleling Two Generators
Post by: Frank DeWitt 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!"
Title: Re: Paralleling Two Generators
Post by: frank kayser 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
Title: Re: Paralleling Two Generators
Post by: Stephen Swaffer 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.
Title: Re: Paralleling Two Generators
Post by: Jonathan Johnson 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.
Title: Re: Paralleling Two Generators
Post by: Cailen Waddell 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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Title: Re: Paralleling Two Generators
Post by: Mike Sokol 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
Title: Re: Paralleling Two Generators
Post by: Mike Sokol 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 (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 
Title: Re: Paralleling Two Generators
Post by: Cailen Waddell on July 01, 2014, 09:55:29 pm
Mike - thanks for this.  I will read the white paper in detail tomorrow...

I think my initial impetus for this was the web site specifically calls out switching power supplies causing harmonic distortion that can lead to increased neutral currents on paralleled generators.  Our rig that would be on generators like this is all switching power supply amplifiers, switching power supply console, powered wedges, and LEDs.   Essentially everything is powered by a switching supply.

I remember a discussion at one point on this board, possibly including JR about harmonic distortion and non power factor corrected supplies on many switching power supply amps....


I suppose the fun thing to do would be to setup our rig, rent some genny's and measure neutral current and look at waveform distortion.    Anyway I am sure I will have more comments, questions after reading the white paper.


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Title: Re: Paralleling Two Generators
Post by: Mike Sokol on July 15, 2014, 09:37:06 am
Everyone,

I've split this thread into the first "Led Talks" so please continue your questions and comments about running generators in parallel on the new thread so we keep it all in one place.