Generator Circuit Breaker vs. Station Transformer

Dear Mr. Rajesh,

Station Transformer (Any Transformer) meant for Distribution (means you can use it for HIgh voltage or Low voltage and for step down or step up application). The Circuit Breaker meant for Protection.

So both are impartant in a electrical netwrok.

ST is used to supply power to certain critical auxillary load (Certain loads should be in operation even when the power plant is not fully in operation) in a power plant....

GT is a protection device for generator

GCB and Station transformer can be substitute of each other. station transformer supply power to the auxillaries of power plant which are essential to start the generation.

in case of GCB, of initial charging of auxillary the GCB is open and power is suply to axillaries through auxillary transformer and once the voltage reach to required value through synchronisation it is close.

whereas in case of station transformer it supply directly to the station load.

Ya I know but in the operation point and performance point of you which one is best and is there any effect on generator if GCB is used directly connected from Switchyard.

I would like to mention that GCB is used for two purposes :

1. to protect Generator transformer

2. to enable the unit auxiliary transformers to receive power directly from the grid during plant startup

3. it reduces the burden on the station transformer and in some cases station transfomer can be completely eliminated