Best options to get 3-phase power from single phase source?

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sw_ross

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I have a customer that moved from one location where he had 3-phase to another location that only has single phase.
He owns some 3-phase machines that are 240v. I think maybe 4 machines. Milling type machinery.
He wants to be able to run these machines and only anticipates running one at a time.
Somebody sold him a "home-made" rotary converter. It'll run a couple of the smaller machines, but not the larger machines.
I don't know what the rating of the converter is.

Since he's only planning to operate one machine at a time I'm looking for some feedback on what the best option might be?

Thanks!
 
Without knowing more, a properly sized rotary phase converter is still a good option. These days, though, VFD's (Variable Frequency Drives) have come down in price and are worth looking into. They have the added benefit of speed control for many machines as well.

I've installed a few, but I've not done the engineering on the systems to know what to get, nor do I know what the latest and greatest are these days.
 
This situation is kinda interesting. This guy originally built the main part of his shop a few years ago. It has a 200 amp single phase service.

Then he built additional space (bump-out) for this milling machinery. In this area he hired an electrician to set it up for 3-phase. The electrician installed a 3-phase panel,there's no 3-phase available near this guys place. The owner doesn't really know what that electrician had planned out for 3-phase. The guy skipped town, never to be seen again!

The owner kinda thinks the electrician had ideas of some sort of rotary converter that was going to feed the three phase panel.

I have seen another location where this was done for a concrete batch plant. They had a converter sized to feed a 200 amp 240v 3-phase panel.

Maybe that's what the electrician had in mind?

I'm not sure that the cost of this type of setup is justifiable just to operate one machine at a time, as this owner plans to operate!?

I'm wondering if you could have one smaller/medium sized converter with a receptacle that he could plug in whatever machine he needed at the time?
 
Best options to get 3-phase power from single phase source?

I agree with every answer so far. Sizing and Rating of Home Made type Rotary Phase Converters are the Horsepower and FLA of the Motor being used for the Converter. That's a real simple rule of thumb and there are other considerations but it would give you an idea of the size and capabilities of the one the Customer has now and an idea of what they would need for the larger Machines.

There are basically three styles. A Pony Motor to spin up the Converter Motor. A Capacitor Start and Run System Motor that doesn't use a Pony Motor. The third is a Solid State Phase Converter. Each have their good and bad points but Machine Drive Motors are very forgiving on Voltage variations and will operate very well.

YouTube has a mountain of examples and how to Videos and many will scare you how folks are building and using these things. Look past that and you will start seeing Manufactured Systems that are quite good.
JimO
 
Based on my limited experience, Roto-Phase and similar are good if the load is a motor, but not very good if there are electronics that need a true sine wave three phase source, such as those with phase monitoring of loss of phase protection. But the last ones I connected were built in the '90's, so times change.
 
sw_ross said:
I have a customer that moved from one location where he had 3-phase to another location that only has single phase.
He owns some 3-phase machines that are 240v. I think maybe 4 machines. Milling type machinery.
He wants to be able to run these machines and only anticipates running one at a time.
Somebody sold him a "home-made" rotary converter. It'll run a couple of the smaller machines, but not the larger machines.
I don't know what the rating of the converter is.

Since he's only planning to operate one machine at a time I'm looking for some feedback on what the best option might be?

Thanks!
Click to expand...
I don't know what size your machines are but probably not very large. A VFD might be the way to go but you would need to make sure you can your 240V 3-ph. May need a transformer.
 
POCO

POCO

This is in a rural farm area. He said that he and three of his neighbors approached the POCO about getting access to 3-phase and were told it would cost $400,000 EACH!?
 
Vfd

Vfd

I just installed a VFD for a 3hp lathe in a machine shop. It was only $115 on Amazon. Single PH input, 3PH out and it works great. The guy loves the fact that he has speed control above and beyond the machine. I couldn't believe these are that cheap now.
 
Sparky1999 said:
I just installed a VFD for a 3hp lathe in a machine shop. It was only $115 on Amazon. Single PH input, 3PH out and it works great. The guy loves the fact that he has speed control above and beyond the machine. I couldn't believe these are that cheap now.
Click to expand...
WTG!
 
meternerd said:
Based on my limited experience, Roto-Phase and similar are good if the load is a motor, but not very good if there are electronics that need a true sine wave three phase source, such as those with phase monitoring of loss of phase protection. But the last ones I connected were built in the '90's, so times change.
Click to expand...

Yes, and one should make sure that machine control voltage is supplied by the "input" lines and not from a "derived third phase" with a rotophase or even static phase converter, voltage/current on that line will not be same as it is on a true three phase system. Motor currents won't balance either, and can be a problem if running the motor near full load rating most of the time.
 
Size of rotary 3-phase converter?

Size of rotary 3-phase converter?

In an effort to understand what the previous electrician had in mind (before skipping town);

_If you have a 3-phase, 200 amp panel that was to be fed by a rotary converter, how would you go about sizing that converter?

Would it be sized based on the size of the panel? (200 amps equivalent)
Or based on the actual load?

I'm not sure if it's a main breaker panel...
I'm kinda guessing he was going to have a 200 amp service disconnect that feeds the converter, and then feeds 3-phase into the panel (and that the panel is a MLO)?

Does that sound like the correct layout?

Thanks!
 
sw_ross said:
In an effort to understand what the previous electrician had in mind (before skipping town);

_If you have a 3-phase, 200 amp panel that was to be fed by a rotary converter, how would you go about sizing that converter?

Would it be sized based on the size of the panel? (200 amps equivalent)
Or based on the actual load?

I'm not sure if it's a main breaker panel...
I'm kinda guessing he was going to have a 200 amp service disconnect that feeds the converter, and then feeds 3-phase into the panel (and that the panel is a MLO)?

Does that sound like the correct layout?

Thanks!
Click to expand...
I'd size it per actual load. But at same time nearly every phase conversion application I ever encountered was for a single load (or multiple loads all on same machine, in particular center pivot irrigation machines) and was installed on the branch circuit and not on a feeder.
 
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