Benchtop 3 phase power supply

[I^2R]

Not sure if this is the best forum for this, but it seems to attract panel shop questions...

Trying to come up with a way to power up 3 phase control panels on the benchtop for testing before they leave the shop. We only have 1ph 120/240 available. Don't need much power, just enough to fire up the control circuits, etc.
Right now we just power up the two legs that supply the control circuit, however this doesn't allow complete testing of phase rotation, instrumentation, etc.

A rotary phase converter wold be okay, but they are big and expensive. I only figure I need around 250VA. I thought about picking up a cheap 1ph in --> 3ph out VFD (less than $100) and set the output to 60hz, but I assume the output waveform would be too nasty. Perhaps with the right capacitors the output could be cleaned up enough.

I see some swanky 3ph lab power supplies but they are thousands.

Any ideas? How do you guys deal with bench testing?

Thanks.

 

[zog]

I see some swanky 3ph lab power supplies but they are thousands.

Any ideas? How do you guys deal with bench testing?

Thanks.

We spend thousands

 

[kwired]

The problem with using a VFD is that they don't play well with switching loads on the output side, and they don't get along with capacitors on the output either.

 

[BPoindexter]

Besides the output waveform another thing you do not want to do is have no load on the output of a VFD and then put a load on it while it is running. Not sure what type of load you would be looking at it but it could definitely burn up the VFD due to inrush.

 

[fmtjfw]

Could you couple a 1-phase and a 3-phase motor mechanically together and energize two of the leads into the 3-phase, then take the load off the three leads of the 3-phase? If you only need a little current that might work.

 

[I^2R]

Load would be minimal. Just enough to fire up a panel and energize the controls, cycle the relays, whatever. 250VA or so?

 

[kwired]

Load would be minimal. Just enough to fire up a panel and energize the controls, cycle the relays, whatever. 250VA or so?

Do you normally use all three phases for controls? Quite often all that is needed is a single voltage to input to a control power transformer and all controls are supplied by the transformer.

 

[I^2R]

Do you normally use all three phases for controls? Quite often all that is needed is a single voltage to input to a control power transformer and all controls are supplied by the transformer.

Yup, but as I said in the OP:

Right now we just power up the two legs that supply the control circuit, however this doesn't allow complete testing of phase rotation, instrumentation, etc.

Some of our stuff has 3 phase power meters, phase loss monitoring, 3-phase SCR controls, Etc. that can't be fully tested / set up without 3 phase input. I would like the panels to leave the bench 100% tested.