Dedicated equipment transformer

[Nelson electric]

A dedicated equipment transformer has 480 volt line voltage with 120/220 secondary voltage.
Phase 1 reads 118
Phase 2 reads 131
Phase 3 reads 118
Why would the middle phase read 131?

 

[ActionDave]

Because the XO isn't bonded would be my first guess. What is the application? Is this a Delta secondary and you truly have 120/240V or is it actually 120/208V?

 

[just the cowboy]

unbalanced loads

unbalanced loads

What is the current on them?
How far is the feed.

You can have a large single phase load on a-c phase and no load on b phase. If the feeders were too small this is how voltage drop would show up.

 

[infinity]

A dedicated equipment transformer has 480 volt line voltage with 120/220 secondary voltage.
Phase 1 reads 118
Phase 2 reads 131
Phase 3 reads 118
Why would the middle phase read 131?

As Dave stated the secondary voltage would be either 240/120 or 208Y/120. If it's 3Ø, 4W Delta your secondary voltages should be 120-208-120 to ground.