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Author Topic: Rotary Phase Converter  (Read 1322 times)

Mike Sokol

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Rotary Phase Converter
« on: October 23, 2017, 08:51:05 am »

I'm in the middle of doing a bunch of demo gigs where we need to provide 3-phase 208 for up to four 1/2 motor for temporary lighting truss. The problem is, many of these churches don't have 3-phase power so I'm renting in a generator for a week at a time, just to turn it on long enough for the crew to run the truss motors. It's a pain and a waste of money when we just need 3-phase power for a few hours at load-in, and a few hours at load-out a week later. Has anyone used something like an American Rotary phase converter like this one to power maybe four 1/2 ton motors? I can buy one for the cost of a single week-long generator rental.

https://www.americanrotary.com/products/view/ar-pro-series

Jeff Baumgartner

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Re: Rotary Phase Converter
« Reply #1 on: October 23, 2017, 08:53:45 am »

Why not just rent/buy single phase motors?
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Steve M Smith

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Re: Rotary Phase Converter
« Reply #2 on: October 23, 2017, 09:00:29 am »

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Mike Sokol

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Re: Rotary Phase Converter
« Reply #3 on: October 23, 2017, 09:21:21 am »

Can you do it like this?

https://www.electricneutron.com/electric-motor/use-three-phase-motor-single-phase-power-supply/


Steve.

No, this has to run through a standard 4-pack motor controller, so I'm pretty sure it won't work.

Mike Sokol

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Re: Rotary Phase Converter
« Reply #4 on: October 23, 2017, 09:25:05 am »

Why not just rent/buy single phase motors?

Buying four single-phase lift motors costs WAY more than a phase converter, plus I'll need a central controller box to run them. In addition we would have to do yearly inspections, etc. I would much rather have the A-V crew who are already supplying the truss and lights just bring their own 3-phase motors and controller, and I'll drop them 3-phase 208 on cams.

Mac Kerr

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Re: Rotary Phase Converter
« Reply #5 on: October 23, 2017, 10:07:31 am »

I'm in the middle of doing a bunch of demo gigs where we need to provide 3-phase 208 for up to four 1/2 motor for temporary lighting truss. The problem is, many of these churches don't have 3-phase power so I'm renting in a generator for a week at a time, just to turn it on long enough for the crew to run the truss motors. It's a pain and a waste of money when we just need 3-phase power for a few hours at load-in, and a few hours at load-out a week later. Has anyone used something like an American Rotary phase converter like this one to power maybe four 1/2 ton motors? I can buy one for the cost of a single week-long generator rental.

https://www.americanrotary.com/products/view/ar-pro-series

Those phase converters are intended for running 3 motors so I would expect it to work. They are used all the time in home shops that have 3 machinery. It is intended for permanent installation, so may need some packaging.

I still can't get my head around how they work, but they do seem to work.

Mac
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Mike Sokol

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Re: Rotary Phase Converter
« Reply #6 on: October 23, 2017, 10:21:36 am »

Those phase converters are intended for running 3 motors so I would expect it to work. They are used all the time in home shops that have 3 machinery. It is intended for permanent installation, so may need some packaging.

I still can't get my head around how they work, but they do seem to work.

Mac

I just talked to their application engineer and he says they're 3P Delta output with 240V between the legs, not 208V. I might need to get a buck-boost transformer on the input to drop the voltage a bit since I'm not sure the lift motors are rated for 3P/240V. Still, it's a possibility. 

Mike Sokol

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Re: Rotary Phase Converter
« Reply #7 on: October 23, 2017, 10:45:45 am »

I just talked to their application engineer and he says they're 3P Delta output with 240V between the legs, not 208V. I might need to get a buck-boost transformer on the input to drop the voltage a bit since I'm not sure the lift motors are rated for 3P/240V. Still, it's a possibility.

I just looked, and it appears that most 3P chain hoist motors are rated at 230 volts, so I won't need a buck-boost transformer to drop the voltage. I'm guessing 230/240 volts would work just fine.

Mike Sokol

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Re: Rotary Phase Converter
« Reply #8 on: October 23, 2017, 11:08:36 am »

I just talked to the marketing/applications department at Phase-A-Matic and they're telling me I need a 20 horsepower rotary converter to run four 1-ton lifts. And it needs a 125-amp/120-volt breaker on the input of the converter. They're just looking at their marketing literature and won't let me talk to an engineer about the application. I need to measure actual current draw when I'm there next week.

Frank Koenig

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Re: Rotary Phase Converter
« Reply #9 on: October 23, 2017, 11:12:35 am »

If you want a project I think you can make your own funky phase convertor from a three-phase motor running on a single phase using one of its windings and a small single-phase motor with a belt clutch that you use to start the three-phase motor. The other two phases are taken from the non-driven windings of the the three-phase motor. I'm sure you can find plans with motor sizing guidance on the Internet. While not for industrial use, such a rig might have educational value in and of itself. -F
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