30KVA wye configured Autotransformer to a source from a rotary phase converter

[Joe Electrician]

We are in the process of replacing some equipment in a woodworking shop. One of them being a 15hp 600V 3/ph compressor.

The existing compressor is a 240V 3phase unit.
Currently the 3ph power is supplied from a rotary phase converter which is supplied from a 120/240V 600A split service.
As is the 3 phase would mimic a delta source and the 3rd manufactured phase would have no direct (Indirectly through the phase converter) reference to ground/neutral.

Customer has a 30KVA Autotransformer not being used. The transformer - 600Y-240Y configuration. I would think best not to use and to recommend a new D-Y or D-D connected transformer.. or a different compressor. Any thoughts?

 

[waross]

1: If the rotary converter is wye wound, you may be able to extract a neutral from the wye point.
This will be the cheapest and best. You don't often see those terms together.
Don't ground the neutral from the phase converter.

2: If you are unable to extract a wye point, consider an artificial neutral.
You need three small transformers. I suggest 2 KVA or 3 KVA.
Your wye point voltage will be near 140 volts so I suggest 240 Volt primaries.
Connect the secondaries in delta and forget them.
The delta winding will stabilize the wye point of the primary windings.
Use the primary wye point as your neutral.

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Ohm's law
Not just a good idea;
It's the LAW!