backfed transformer

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220wire

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I have a 3 phase 240/208-120 transformer that i backfed and reatapped it to get closer to 230v. I have normal voltage (119v and 120v on the other two)readings under no load at the transformer, but soon as a load is put to the transformer the voltage goes up to 135v on two legs and 130v on the other. The transformer is an 75kva Acme TP-53364-4S. There is no center tap either. It feeds two 30hp Vfd's that controls two pumps that are setup for a lead/lag. Not that it makes any difference but the pumps pump poo to the City's poo pond. The vfd's are going into overload protection. It has been almost 3 months since the install. The amperage on the motors seems to be slowly climbing too. I am pretty sure I had the transformer wired correctly but now I am second guessing reversing the primary and secondary and also am wondering about the tap reduction I did to lower the voltage. ANY help would be great
 
It is not grounded. YOu are reference to ground. Ground one corner and take readings. Also if this is a 24- delta to 208y/120 you will NOT get 120 VAc on the 240 secondary.
 
that makes sense. phase to phase readings are 227 227 224. I am about 700 miles from the site so I am communicating with a maintenance guy. When I left almost 3 months ago the voltage was 229 229 230.
 
The taps should not have need to be adjusted. In the US, 230V motors are intended to be installed on 240V nominal services. The primary side, your 208V, should not have any connection to the X0 terminal.

As Brian mentioned, it sounds like you are running your 240V delta side ungrounded. This is normally not ideal for VFDs, but it should not be the cause of your 'climbing motor amps'.
 
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