What is circuit breaker PPT?

CIRCUIT BREAKERS Definition: A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow.

How does a SF6 circuit breaker work?

In an SF6 Circuit breaker, sulphur hexafluoride gas is used as the arc quenching medium. The contacts of the breaker are opened in a high-pressure flow sulphur hexafluoride (SF6) gas and an arc is struck between them. The gas captures the conducting free electrons in the arc to form relatively immobile negative ions.

What is SF6 circuit breaker PDF?

A circuit breaker in which SF6 under pressure gas is used to extinguish the arc is called SF6 circuit breaker. SF6 (sulphur hexafluoride) gas has excellent dielectric, arc quenching, chemical and other physical properties which have proved its superiority over other arc quenching mediums such as oil or air.

What are the advantages and disadvantages of SF6 circuit breakers?

The gas has is inflammable and chemically stable. Their decomposition products are on explosive ad hence there is the risk of fire or explosion. Electric clearance is very much reduced because of the high electric strength of SF6. Its performance is not affected due to variations in atmospheric conditions.

What are the properties of SF6 circuit breaker?

Properties of Sulphur hexafluoride Circuit Breaker 1 It is colourless, odourless, non-toxic, and non-inflammable gas. 2 SF 6 gas is extremely stable and inert, and its density is five times that of air. 3 It has high thermal conductivity better than that of air and assists in better cooling current carrying parts.

Which is more effective arc quenching medium or SF6 circuit breaker?

It is 100 times more effective as compared to arc quenching medium. Its dielectric strength is 2.5 times than that of air and 30% less than that of the dielectric oil. At high pressure the dielectric strength of the gas increases. Moisture is very harmful to SF 6 circuit breaker.

What kind of gas is used in a circuit breaker?

A circuit breaker in which the current carrying contacts operate in sulphur hexafluoride or SF6 gas is known as an SF6 circuit breaker. SF6 has excellent insulating property. SF6 has high electro-negativity.

What are the duties of a SF 6 circuit breaker?

It requires less maintenance and no costly compressed air system is required. SF 6 performs various duties like clearing short-line faults, switching, opening unloaded transmission lines, and transformer reactor, etc. without any problem. SF 6 gas is suffocating to some extent.