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Main Transformer Change

Main Transformer Change

Main Transformer Change

(OP)


       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?

RE: Main Transformer Change

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.  

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