What are the advantages of static relay over electromagnetic relay? Give the two methods of arc interruption? Introduction to Differential Relays Electric switchgear is necessary at every switching point in the electrical power system. What are the problems in bus zone differential protection? The saturation introduces ratio error.
But in high voltage and extra high voltage system, this switching and protective scheme becomes complicated one for high fault current interruption in safe and secure way. Arial-blast type What are the advantages of air blast circuit breaker over oil circuit breaker?
An effective although more costly form of switchgear is the gas-insulated switchgear GISwhere the conductors and contacts are insulated by pressurized sulfur hexafluoride gas SF6. What do you mean by current chopping? This is called as electro negativity of SF6 gas.
What are the methods of capacitive switching?
Besides the power system network, electrical switchgear is also required in industrial works, industrial projects, domestic and commercial buildings. When the fault occurs very near to the neutral point of the transformer, the voltage available to drive the earth circuit is very small, which may not be sufficient to activate the relay, unless the relay is set for a very low current.
The combination of equipment within the switchgear enclosure allows them to interrupt fault currents of thousands of amps. When the contacts of the breaker are separated, an arc is struck between them.
SF6 has high affinity for electrons. Hence can be used in vessels ie, ships, aircrafts etc. It has good dielectric strength and excellent arc quenching property.
It is restricted earth fault relay. The power frequency rms voltage appearing across the breaker contacts after the arc is extinguished and transient oscillations die out is called recovery voltage.
What are faults associated with an alternator?Switchgear and Protection Notes Switchgear and Protection Notes - SGP Notes - SGP Pdf Notes UNIT – I Circuit Breakers-1 Circuit Breakers: Elementary princip.
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A switchgear or electrical switchgear is a generic term which includes all the switching devices associated with mainly power system protection.
It also includes all devices associated with control, metering and regulating of electrical power system/5(15). What are the functions of protective relays To detect the fault and initiate the operation of the circuit breaker to isolate the defective element from the rest of the system, thereby protecting the system from damages consequent to the fault.
Give the consequences of short circuit. Whenever a short-circuit occurs, the current flowing through the.Download