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120VAC input to variable 3 phase output PSU?
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neverendingstudent:
TL;DR: I'm looking for a power supply that has standard US 120VAC input and gives variable voltage 3-phase output (say, from 200V to 480V).

Hi all, I'm soon going to be picking up a large auction lot from a closed-down industrial facility and there's lots of mid-high voltage 3-phase equipment which I would like to test so I can sell it as 'used/tested powers on' instead of having to sell it for 'parts / not working' status.

I don't have 3-phase service and there's no way I could get it - my power is all 120VAC US standard - I can access 240V from the plug my dryer uses if need be, though I would prefer not to.

I'm not expecting to find anything that can supply much amperage, and I'm not going to worry about load-testing anything that has a high-amperage draw, but I would like to be able to power-on test equipment like 400V 3-phase to 24VDC power supplies and the like, to verify they are functional before resale.

I'm having a hell of a time finding anything like this, because when I try searching for any keyword combination including 'power supply' and '3 phase' I get power supplies that use 3 phase as the input, not the output - which makes sense as that would be the far more common use-case.

Any ideas?
NiHaoMike:
You should be able to salvage a 480V to 120V "control transformer" which you can use backwards to get 480V single phase. Most 3 phase switching supplies will start up on single phase although they won't be able to run at full power.
neverendingstudent:
Interesting.  I did not know I could get power-on with a single phase.  I'll keep an eye out for a suitable transformer, it this works it will be a very cost-effective solution, thank you.

Edit: well then... it seems one of the lots I won includes 2 240/480 to 120 control transformers...  Cool.  The (potential) solution just happens to accompany the problem.
WattsThat:
Understand you’ll have to try all three different possible single phase connection possibilities.

I routinely use a universal 150va transformer to power up variable frequency drives at 230/460/575 for testing. Checking inputs with a DMM in diode mode will find shorted input diode bridges thereby saving your expensive transformer fuses. You will fuse it, right?:-DD
edpalmer42:
This situation frequently arises for people who buy old lathes, milling machines, shapers, etc.  The solution is a 'phase converter'.  Old ones are rotary converters that just look like a big motor.  Newer ones are solid-state and are frequently called a VFD (Variable Frequency Drive).  You might actually have one in your auction haul.

Search on Youtube for 'phase converter' or VFD to learn more about them and how to improvise something.
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