Multiple Choice Tests on Switchgear Protections - ObjectiveBooks

Multiple Choice Tests on Switchgear Protections

Practice Test: Question Set - 03


1. Protective relays are devices that detect abnormal conditions in electrical circuits by measuring
    (A) Current during abnormal condition
    (B) Voltage during abnormal condition
    (C) Constantly the electrical quantities which differ during normal and abnormal conditions
    (D) None of the above

2. Overheating of relay contacts or contact born out is due to
    (A) Slow making and breaking of load circuit contacts
    (B) Foreign matter on the contact surface
    (C) Too low contact pressure
    (D) All of the above

3. An efficient and a well designed protective relaying should have
    (A) Good selectivity and reliability
    (B) Economy and simplicity
    (C) High speed and selectivity
    (D) All of the above

4. D.C. shunt relays are made of
    (A) Few turns of thin wire
    (B) Few turns of thick wire
    (C) Many turns of thin wire
    (D) Many turns of thick wire

5. Arc in a circuit behaves as
    (A) A capacitive reactance
    (B) An inductive reactance
    (C) A resistance increasing with voltage rise across the arc
    (D) A resistance decreasing with voltage rise across the arc

6. The main function of a fuse is to
    (A) Protect the line
    (B) Open the circuit
    (C) Protect the appliance
    (D) Prevent excessive currents

7. The current zero interruption, in oil and air blast circuit breakers, is achieved by
    (A) Lengthening of the gap
    (B) Cooling and blast effect
    (C) Both (A) and (B)
    (D) Deionising the oil with forced air

8. Ionization in circuit breaker is facilitated by
    (A) High temperature
    (B) Increase of mean free path
    (C) Increasing field strength
    (D) All of the above

9. The delay fuses are used for the protection of ________.
    (A) Motors
    (B) Power outlet circuits
    (C) Fluorescent lamps
    (D) Light circuits

10. When a wave propagates on a transmission line, it suffers reflection several times at
    (A) Tapping
    (B) Load end
    (C) Sending end
    (D) Sending and other end

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