Transformer Issues

[laketime]

We installed a 75kva 120/208 primary to 120/240v secondary and our phase to neutral reading is 136v and phase to phase is 238v after tapping all the way down. Incoming is 125v phase to neutral and 214v phase to phase. My thoughts are we have utility drop their incoming phase to neutral if possible. Thoughts?

 

[hillbilly1]

Single phase or three phase?

 

[laketime]

Single phase or three phase?

Three phase

 

[hillbilly1]

Delta or wye secondary?

 

[laketime]

Delta or wye secondary?

Delta

 

[synchro]

Your measured 136V phase to neutral voltage sounds like a wye secondary instead of a high leg delta secondary.

 

[laketime]

Your measured 136V phase to neutral voltage sounds like a wye secondary instead of a high leg delta secondary.

Just talked to my journeyman and the secondary is wye in the field. The cut sheet I was holding said it was supposed to be delta secondary.

 

[texie]

Your measured 136V phase to neutral voltage sounds like a wye secondary instead of a high leg delta secondary.

Yep, the math says you would have 138 volts on a 240 Wye secondary so it indicates a wye.

 

[jim dungar]

We installed a 75kva 120/208 primary to 120/240v secondary and our phase to neutral reading is 136v and phase to phase is 238v after tapping all the way down. Incoming is 125v phase to neutral and 214v phase to phase. My thoughts are we have utility drop their incoming phase to neutral if possible. Thoughts?

Why???
You already have the proper nominal output voltage. What else are you expecting?

 

[laketime]

Why???
You already have the proper nominal output voltage. What else are you expecting?

The customer bought all 240v equipment...

 

[jim dungar]

The customer bought all 240v equipment...

And your post says you have 238V. That is as close as you can get given normal +/- 5% tolerance from the utility.