Using a delta generator to obtain 120/208

[George Stolz]

This has been an interesting week. Next up:

Suppose the premises wiring is 120/208. The elevator guy shows up and needs power, but the permanent power is not going to be on for weeks.

So, the GC aquires a generator. It comes with three settings: "120/240 1?, 139/240 3?, and 277/480". The generator comes with a dial to adjust the voltage, so the line-line voltage can be dialed down to 208.

Could it damage the 208V (actually, namplate says 200V) elevator motor to run it at 208V from a delta source? There are no L-N loads in this temp (or perm) feeder.
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That was my question from two days ago, I never got a chance to ask.

Now, I realized something as I was typing this - the generator must be a Wye generator, due to the availability of 277/480 and the weird lower 3? (139/240) voltage. Why would they call the middle setting "139/240" instead of "120/208"?

I'm leaving the first part of my question up there, because I'm still curious if it would cause damage to a motor to give it the right voltage from the wrong transformer type.

 

[mdshunk]

Voltage is voltage. The motor won't care where it comes from, as long as it remains reasonably constant.

 

[infinity]

Now, I realized something as I was typing this - the generator must be a Wye generator, due to the availability of 277/480 and the weird lower 3? (139/240) voltage. Why would they call the middle setting "139/240" instead of "120/208"?

139 X 1.73=240 volts

I have seen this voltage when 240 was needed and fed from a Wye voltage regulator. Don't ask me why they used a Wye. Only Liebert can answer that.