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Circuit breakers are essentially current carrying contacts called electrodes.

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The following is/are the characteristics of SF6 circuit breakers:  (A) It does not need an auxiliary breaking chamber (B) Short break time of 2 to 2.5 cycles (C) All of the above (D) None of the above

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The following is/are the characteristics of SF6 circuit breakers:  (A) It does not need an auxiliary breaking chamber (B) Short break time of 2 to 2.5 cycles (C) All of the above (D) None of the above

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Air blast circuit breakers for 400 kV power system are designed to operate in 50 millisecond.

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Which of the following circuit breakers has high reliability & minimum maintenance?  (A) Bulk oil type CB (B) Air blast CB (C) Vacuum CB (D) Sulphur hexafluoride CB 

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Which of the following circuit breakers has high reliability & minimum maintenance?  (A) Bulk oil type CB (B) Air blast CB (C) Vacuum CB (D) Sulphur hexafluoride CB 

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The time of closing the cycle, in modern circuit breakers is 0.003 sec.

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The current zero interruption, in oil and air blast circuit breakers, is achieved by?

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The current zero interruption, in oil and air blast circuit breakers, is achieved by lengthening of the gap, cooling and blast effect.

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Answer :

Circuit breakers usually operate under transient state of short-circuit current.

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Magnetic circuit breakers use _________ A) Permanent magnets B) Earth magnets C) Solenoid D) All the above

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Magnetic circuit breakers use Solenoid 

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What is the maximum number of circuit breakers in a panel?

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It depends on that which type of panel is this.

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The arcing contacts in a circuit breaker are made of copper tungsten alloy.

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If the % reactance upto the fault point is 20%, then the short circuit current will be

Answer :

If the % reactance upto the fault point is 20%, then the short circuit current will be 5 times the full load current

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The arc temperature in Oil Circuit Breaker may reach up to_______.  (A) 5,000° K (B) 8,000° K (C) 10,000° K (D) None of the above

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The arc temperature in Oil Circuit Breaker may reach up to 5,000° K 

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The number of cycles in which a high speed circuit breaker can complete its operation is  (A) 3 to 8 (B) 10 to 18 (C) 20 to 30 (D) 40 to 50

Answer :

The number of cycles in which a high speed circuit breaker can complete its operation is 3 to 8

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A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

Answer :

A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

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The Minimum Oil Circuit Breaker (MOCB) is named because of :  (A) Reduced requirement of oil (B) Reduced requirement of air (C) All of the above (D) None of the above

Answer :

The Minimum Oil Circuit Breaker (MOCB) is named because of : Reduced requirement of oil 

Description :

For selecting a circuit breaker, ______ should be determined.  (A) initial current that flows on occurrence of a short circuit only (B) transient current that flows at the time of circuit interruption only (C) resonant frequency only (D) (A) and (B) 

Answer :

For selecting a circuit breaker, ______ should be determined. (A) initial current that flows on occurrence of a short circuit only (B) transient current that flows at the time of circuit interruption only (C) resonant frequency only (D) (A) and (B) 

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ln a minimum oil circuit breaker the oil is used

Answer :

ln a minimum oil circuit breaker the oil is used to act as circuit breaking medium only

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A fuse in a motor circuit provides protection against short-circuit and overload.

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Answer :

Arc in a circuit breaker is interrupted at zero current.

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The short circuit in any winding of the transformer is the result of impulse voltage.

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The arc voltage produced in A.C. circuit breaker is always in phase with the arc current.

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In a circuit breaker the basic problem is to transmit large power.

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Ionization in circuit breaker is facilitated by high temperature, increase of mean free path, increasing field strength.

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The voltage appearing across the contacts after opening of the circuit breaker is called recovery voltage.

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Air blast circuit breaker is used for repeated duty.

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Magnetic circuit breaker has instantaneous trip action.

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Thermal circuit breaker has delayed trip action.

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Arc in a circuit behaves as?

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Arc in a circuit behaves as a resistance decreasing with voltage rise across the arc.

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In which fault the maximum short circuit current occurs?

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In three phase bolted fault the maximum short circuit occurs.

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A circuit breaker in which SF6 under pressure gas is used toextinguish the arc is calledSF6 circuit breaker. SF6 (sulphur hexafluoride) gas has excellent dielectric , arc quenching, chemical and other physical properties and has proved its ...

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Insulation resistance of high voltage circuit breakers is more than 100 mega ohms.

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A series R-L-C Circuit has a resonant frequency of 1000 Hz. If the values of R, L and C are doubled, the new resonant frequency is

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A series R-L-C Circuit has a resonant frequency of 1000 Hz. If the values of R, L and C are doubled, the new resonant frequency is 500 Hz

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Which of the following are known as the short circuit parameters of a 2- port network? (A) Z- parameters. (B) H- parameters. (C) Y- parameters. (D) A,B,C,D, parameters.

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Which of the following are known as the short circuit parameters of a 2- port network? (A) Z- parameters. (B) H- parameters. (C) Y- parameters. (D) A,B,C,D, parameters.

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The circuit whose properties are same in either direction is known as?

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