I frequently need 120 volt delta power. It's always temporary for about a week and loads very from 1 to 30 kW. I usually simulate this by re-wiring a 480 volt delta to 208Y/120 transformer so that the primary is Y with the neutral ungrounded. I end up with 69 volts to ground on my grounded Y...
Can I use a 60 Hz dry type transformer for 400 Hz power? What if I derate the transformers? What would happen?
We are a testing lab that typically sets up equipment for a week and monitors operation continuously.