Transformer protection

[prdpks2000]

For Distribution Transformer HV primary side , how the HV breaker sized, I need rules for sizing with referring some standers IEC/IEEE/IS/BS/VDE , from following link I got about NEC code.

 

[electrofelon]

This is an NEC forum, so from that standpoint 450.3(A) will be your reference. There are a few MV and utility guys on here that may be able to expand on MV transformer protection practices a little.