Switchgear & Protection Test Question - Set 9

1)   When a transmission line is energized, the wave that propagates on it is____________?

a. current wave only
b. voltage wave only
c. Both (A) and (B)
d. power factor wave only
Answer  Explanation 

ANSWER: Both (A) and (B)

Explanation:
No explanation is available for this question!


2)   Burden of a protective relay is the power______________?

a. required to operate the circuit breaker
b. absorbed by the circuit of relay
c. developed by the relay circuit
d. none of the above
Answer  Explanation 

ANSWER: absorbed by the circuit of relay

Explanation:
No explanation is available for this question!


3)   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. deionizing the oil with forced air
e. none of the above
Answer  Explanation 

ANSWER: both (A) and (B)

Explanation:
No explanation is available for this question!


4)   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. deionizing the oil with forced air
e. none of the above
Answer  Explanation 

ANSWER: both A. and B

Explanation:
No explanation is available for this question!


5)   The relay operating speed depends upon_________________?

a. the spring tension
b. the rate of flux built up
c. armature core air gap
d. all of the above
Answer  Explanation 

ANSWER: all of the above

Explanation:
No explanation is available for this question!


6)   Relays can be designed to respond to changes in________________?

a. resistance, reactance or impedance
b. voltage and current
c. light intensity
d. temperature
e. all above
Answer  Explanation 

ANSWER: all above

Explanation:
No explanation is available for this question!


7)   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
Answer  Explanation 

ANSWER: all of the above

Explanation:
No explanation is available for this question!


8)   A differential relay measures the vector difference between_________________?

a. two currents
b. two voltages
c. two or more similar electrical quantities
d. none of the above
Answer  Explanation 

ANSWER: two or more similar electrical quantities

Explanation:
No explanation is available for this question!


9)   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
Answer  Explanation 

ANSWER: constantly the electrical quantities which differ during normal and abnormal conditions

Explanation:
No explanation is available for this question!


10)   In a circuit breaker the basic problem is to________________?

a. maintain the arc
b. extinguish the arc
c. transmit large power
d. emit the ionizing electrons
Answer  Explanation 

ANSWER: transmit large power

Explanation:
No explanation is available for this question!


11)   The voltage appearing across the contacts after opening of the circuit breaker is called__________voltage

a. recovery
b. surge
c. operating
d. arc
e. none of the above
Answer  Explanation 

ANSWER: recovery

Explanation:
No explanation is available for this question!


12)   Large internal faults are protected by_______________?

a. merz price percentage differential protection
b. mho and ohm relays
c. horn gaps and temperature relays
d. earth fault and positive sequence relays
Answer  Explanation 

ANSWER: merz price percentage differential protection

Explanation:
No explanation is available for this question!


13)   Directional relays are based on flow of____________?

a. power
b. current
c. voltage wave
d. all of the above
Answer  Explanation 

ANSWER: power

Explanation:
No explanation is available for this question!


14)   Air blast circuit breaker is used for_____________?

a. over currents
b. short duty
c. intermittant duty
d. repeated duty
Answer  Explanation 

ANSWER: repeated duty

Explanation:
No explanation is available for this question!


15)   Circuit breakers usually operate under______________?

a. transient state of short-circuit current
b. sub-transient state of short-circuit current
c. steady state of short-circuit current
d. after D.C. component has ceased
Answer  Explanation 

ANSWER: transient state of short-circuit current

Explanation:
No explanation is available for this question!


16)   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
Answer  Explanation 

ANSWER: many turns of thin wire

Explanation:
No explanation is available for this question!


17)   Circuit breakers are essentially____________?

a. current carrying contacts called electrodes
b. arc extinguishers
c. circuits to break the system
d. transformers to isolate the two systems
e. any of the above
Answer  Explanation 

ANSWER: current carrying contacts called electrodes

Explanation:
No explanation is available for this question!


18)   Circuit breakers are essentially______________?

a. current carrying contacts called electrodes
b. arc extinguishers
c. circuits to break the system
d. transformers to isolate the two systems
e. any of the above
Answer  Explanation 

ANSWER: current carrying contacts called electrodes

Explanation:
No explanation is available for this question!


19)   In order that current should flow without causing excessive heating or voltage drop, the relay contacts should_________________?

a. have low contact resistance
b. be clean and smooth
c. be of sufficient size and proper shape
d. have all above properties
Answer  Explanation 

ANSWER: have all above properties

Explanation:
No explanation is available for this question!


20)   Thermal overload relays are used to protect the motor against over current due to____________?

a. short-circuits
b. heavy loads
c. grounds
d. all of the above
Answer  Explanation 

ANSWER: heavy loads

Explanation:
No explanation is available for this question!