User:Prakash2009india/Switch yard of powerplant

SWITCHYARD- Switch yard & associated control room is serves the purpose of distribution of station power and acts as communication medium between control agency and station decision makers.Transmission line allows to flow power in both the directions (export &import). For on load connecting and disconnecting of any transmission lines with any unit to 400 KV bus, circuit breaker are used. Heavy arc quenching medium in modern circuit breakers are generally SF6. Isolators are used on both side of circuit breakers for off load engagement / disengagement isolation of circuit breakers (maintenance purpose). Apart from circuit breakers & isolators, switchyard is equipped with current transformers (CT), potential transformer (PT) & mainly used in measuring and protective circuits.Tie transformers are located at switchyard & are basically step down transformers designed to supply station & unit auxiliary power requirements in case of initial start up &extraordinary crisis situation.