# Have you ever seen one of these?



## Apostle (Aug 31, 2020)

Has anyone seen a small THREE PHASE portable power generator?  I remember waaaay back, while in the USAF, seeing those HUGE generators on wheels, but I'm talking about a smaller one, 120V, 240V and/or 480V, 3PH, 60 Hz, that could be used to power up small 3 phase machines?


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## larryg (Aug 31, 2020)

What do you intend to use as a prime mover, gas, diesel, natural gas, or electricity?  It sounds to me like you need a rotary phase converter or a couple of VFD's. How many and what horsepower are these machines?

lg
no neat sig line


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## Apostle (Aug 31, 2020)

Hi Larry,
Thanks for your reply.  I have several VFD's driving machines in my shop.  However, I have often thought how nice it would be to have a three phase gas-driven generatior that could used to check the machine out in advance of receiving the VFD.  I've never seen one, though.  I'll bet there are many folks out there that would love to have one too!
Mike


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## Cogsy (Aug 31, 2020)

How small is 'small'? 6kVA units are pretty common and they are described as portable, weighing in around 60kg (~130lbs). Some also output single phase but down here it's only 240V as we don't use 120V.


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## Apostle (Aug 31, 2020)

Cogsy said:


> How small is 'small'? 6kVA units are pretty common and they are described as portable, weighing in around 60kg (~130lbs). Some also output single phase but down here it's only 240V as we don't use 120V.


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## Apostle (Aug 31, 2020)

Cogsy said:


> How small is 'small'? 6kVA units are pretty common and they are described as portable, weighing in around 60kg (~130lbs). Some also output single phase but down here it's only 240V as we don't use 120V.



  In my case, 6 KW would be fine.  From another group, I've been referred to this URL:  Gillette Portable 3-Phase Generator - GPE-75EH-3-3 | Absolute Generators 

  I've filed it for the future.  Thanks for your reply.
Best, 
Mike


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## Ghosty (Aug 31, 2020)

This is my 3ph 9kva genset I use to power the house when no power, just need to search that bay site, picked this up on special.


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## Apostle (Sep 1, 2020)

Ghosty said:


> This is my 3ph 9kva genset I use to power the house when no power, just need to search that bay site, picked this up on special.
> View attachment 119011


Wow, that's great!  Currently there are no real deals on "the bay place" here in the USA.  BUT, I'll keep an eye out.  Wish I knew how to PM you as I'd like to ask you a rather personal question regarding your "bay site" experience.  Best, Mike


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## ajoeiam (Sep 2, 2020)

Apostle said:


> Wow, that's great!  Currently there are no real deals on "the bay place" here in the USA.  BUT, I'll keep an eye out.  Wish I knew how to PM you as I'd like to ask you a rather personal question regarding your "bay site" experience.  Best, Mike


I haven't tried it but what I'm seeing is that if you click on their 'handle' you are given the option to 'start a conversation'. 
Dunno how private it is (I'm quite new to the site) but there is one option.     Regards


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## kvom (Sep 2, 2020)

I have a rotary phase converter in my shop.  Uses a 7HP GE 3Ph motor.  The phase converter box mainly serves to start the motor via its large capacitors.  Input is 240V single phase.  One of the output legs is 190V, but neither of my machines that it powers complains.  

Advantage here is that's it's pretty quiet; a low hum that is drowned out when the machine being powered starts up.  Also cheaper to buy and run than the Honda generator Ghosty has.

Disadvantage is that it's not portable.

2HP or less VFD is the way to go IMO.


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## Apostle (Sep 2, 2020)

kvom said:


> I have a rotary phase converter in my shop.  Uses a 7HP GE 3Ph motor.  The phase converter box mainly serves to start the motor via its large capacitors.  Input is 240V single phase.  One of the output legs is 190V, but neither of my machines that it powers complains.
> 
> Advantage here is that's it's pretty quiet; a low hum that is drowned out when the machine being powered starts up.  Also cheaper to buy and run than the Honda generator Ghosty has.
> 
> ...



My interest in a portable three phase generator is for testing and a temporary supply of power for newly acquired machines.  Then I set them up with VFD's.  I use a VFD to power my Hardinge lathe and another one to power my Rockwell horizontal mill.  The portability is helpful when going to a site that's selling but has no power to demonstrate if a machine is working.  Best, Mike


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## mu38&Bg# (Sep 2, 2020)

In the US, it will be virtually impossible to find a small three phase generator. There is simply no market or application for such a thing. Any facility that runs three phase needs a substantial amount, so backup generators are sized accordingly. A quick look on ebay found nothing small used, and only one brand of 22kW 250V 3PH unit new.

The cheapest and typical solution is a rotary phase converter.


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## Apostle (Sep 2, 2020)

Prior to initially posting this thread, I also could not find anything.  However, after some responses, I have discovered they are available in the USA.  Check this site, Gillette Portable 3-Phase Generator - GPE-75EH-3-3 | Absolute Generators 
Mike



dieselpilot said:


> In the US, it will be virtually impossible to find a small three phase generator. There is simply no market or application for such a thing. Any facility that runs three phase needs a substantial amount, so backup generators are sized accordingly. A quick look on ebay found nothing small used, and only one brand of 22kW 250V 3PH unit new.
> 
> The cheapest and typical solution is a rotary phase converter.


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## ddmckee54 (Sep 2, 2020)

Mike:

That generator is rated at 6000 Watts surge.  If I'm doing my math right that translates to about 7.25Hp and that's the absolute max.  However before you start thinking that will run anything you've got, remember that when starting, a motor will pull about 6 times its' full load amps.  So effectively you'd be able to start about a 1.25Hp motor, anything larger and I think you might run the risk of damaging something.  You could probably run several motors of that size, just start them individually and watch the meters on the generator to keep it in the green.

I remember that many years ago when we lived on the farm we had a 20KW alternator powered by the tractor's PTO.  We could run three 5Hp motors at the same time, as long as we didn't push them too hard..  But they had to be started separately and let come up to speed before we tried starting the next one.  At least it let us run the vacuum pump for the milkers, the auger on the feed bunk, and the silo unloader at the same time so we could get the milking done and feed the cows.

Don


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## Apostle (Sep 3, 2020)

Hi Don,

  Thanks for your input.  All the motors running equipment in my hobby shop are 2 HP or less.  Your input is greatly appreciated.

Best,
Mike



ddmckee54 said:


> Mike:
> 
> That generator is rated at 6000 Watts surge.  If I'm doing my math right that translates to about 7.25Hp and that's the absolute max.  However before you start thinking that will run anything you've got, remember that when starting, a motor will pull about 6 times its' full load amps.  So effectively you'd be able to start about a 1.25Hp motor, anything larger and I think you might run the risk of damaging something.  You could probably run several motors of that size, just start them individually and watch the meters on the generator to keep it in the green.
> 
> ...


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## SmithDoor (Sep 3, 2020)

I have seen few about 35 years ago.
I think they where made for electronics.
You can find 3 phase generators on most cars today. 
If I need 3 phase I just use a single phase generator and build a 3 phase converter.

Dave



Apostle said:


> Has anyone seen a small THREE PHASE portable power generator?  I remember waaaay back, while in the USAF, seeing those HUGE generators on wheels, but I'm talking about a smaller one, 120V, 240V and/or 480V, 3PH, 60 Hz, that could be used to power up small 3 phase machines?


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## Richard Hed (Sep 3, 2020)

dieselpilot said:


> In the US, it will be virtually impossible to find a small three phase generator. There is simply no market or application for such a thing. Any facility that runs three phase needs a substantial amount, so backup generators are sized accordingly. A quick look on ebay found nothing small used, and only one brand of 22kW 250V 3PH unit new.
> 
> The cheapest and typical solution is a rotary phase converter.


I will be wanting one of those RPCs.  How does one go about getting  a quality one but cheap as possible?  What is the expected price range?


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## kvom (Sep 4, 2020)

For the cheapest possible rotary, do manual start.  The "box" that you find on eBay is just for starting the 3PH motor that serves as the generator.  So if you have a pulley on the motor shaft with a rope wrap that can spin it up, you can start it that way.

Otherwise you size the box according to motor HP.


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