Switchgear Protections

91. When a wave propagates on a transmission line, it suffers reflection several times at

1. tapping
2. load end
3. sending end
4. sending and other end

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92. Which of the following circuit breakers has high reliability and minimum maintenance?

1. Air blast circuit breakers
2. Circuit breaker with SF6 gas
3. Vacuum circuit breakers
4. Oil circuit breakers

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93. Which of the following devices will receive voltage surge first travelling on the transmission line?

1. Lightning arresters
2. Relays
3. Step-down transformer
4. Switchgear

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94. Which of the following is the least expensive protection for overcurrent is low voltage system?

1. Rewireable fuse
2. Isolator
3. Oil circuit breaker
4. Air break circuit breaker

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95. Which of the following medium is employed for extinction of arc in air circuit breaker?

1. Water
2. Oil
3. Air
4. SF6

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96. Which of the following parameter can be neglected for a short line?

1. Inductance
2. Capacitance
3. Resistance
4. Reactance

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97. Which of the following statements is incorrect?

1. Station batteries are used to operate relay only
2. The lightning arresters are basically surge diverters
3. An impedance relay has maximum fault current when fault occurs near the relay
4. A high speed relay has an operation of 1 to 2 cycles

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98. With which of the following, a circuit breaker must be equipped for remote operation?

1. Inverse time trip
2. Time-delay trip
3. Shunt trip
4. None of the above
5. All of the above

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