Main Transformer Change 1

Old Xformer New Xformer
3 Phase
Fault Current 10,561 Amps 11,400 Amps

Phase to Gnd
Fault Current 12,151 Amps 13,300 Amps

Given:
The electricity supplier is wanting to change out an old transformer with a newer one. This is the main xformer feeding our manufacturing facility. The fault current levels are depicted above.

My question is how will these higher fault current levels affect the switchgear operated at 4160 Volts (LV side of the main xformer) outside the plant? There are two of these medium voltage breakers feeding each side of our plant.
What should I look for?

 

[dpc]

This is a pretty modest increase, so you may not have any problems.

You need to determine the short circuit rating of the breakers. This data should be stamped on the breaker nameplate.

To be really sure, you may want to have a short circuit study done for your entire system. Fault currents for the entire system will increase slightly.