Re: 34.5 kv breaker
What is the application for this equipment? Does this feed a large manufacturing plant?
I am assuming it is owned privately and not the local utility. This transformer is big!!
I am also curious as to why you are asking. If you are involved in designing, installing or updating the protection schemes, get professional help. If you are simply curious than here is some general information.
The protection schemes designed for this equipment may include any of the following; Transformer differential protection, Transformer overload protection, and/or bus differential protection.
The breaker itself would not have any protection, it would be used to protect other equipment such as the transformer or the equipment it is feeding.
The bus generally does not have overload protection because it would have been designed and built based on a short circuit study and capable of with standing current up to at least that amount. The transformer would be the limiting factor here.
Bus differential protection would monitor all the current entering and leaving the bus and trip all breakers attached to the bus whenever a discrepancy occurred.
A transformer this large may have a differential protection scheme fed by CT's on the high side transformer bushings and the low side bank breaker. However if the breaker does not have ct's than this clearly wasn't intended.
It would also have some type of overload protection scheme that could be as simple as fuses.
The list could go on and on but suffice it to say the package would be professionally designed with the big picture in mind.
