I recently purchased a used 75kva 208v delta to 208v Y transformer and have some concerns about some strange results. We would like to use this transformer to create separate (isolated) service between audio and lighting systems.
I wired up the ground and then wired the H1, H2 and H3 terminals to the three hots coming out of my buildings 3 phase 208v service. I disregarded the neutral as its not used in delta. I didn't think the phase order would matter, but I tripped the breakers when I turned it on. After swapping phases the transformer came to life with a lovely buzz like they always do.
I took out my meter and got some strange results. I was happy with my 3 hot to hot results (between 208v-210v) and hot to neutral results (between 121v-122v), but For some reason I have 7 volts between ground and neutral. I also got strange results between hots and ground. X1 reads 110volts while X2 and X3 both read between 120-122volts. I could bond the ground and neutral, but it kind of defeats the purpose of why I bought the transformer.
Lastly, I metered the current draw with no load. Black phase (H3)reads 14.32amps, red phase (H1) reads 11.08amps and blue (H2) reads 9.47amps. I would think they would all be the same.
In summary, I've never hooked up a transformer before so I don't know if the results I got are to be expected. Seems like something is wrong on the H1/X1 phase. Kinda feel like I was sold a lemon. Thoughts?