Q.1 _____ and ____ mechanism should be earthed through separate branch.
A. Circuit breaker, earth switch
B. Isolators, circuit breaker
C. Isolators, earth switch
D. Relay, earth switch
Ans.: C
Q.2 The poles of the transmission line are kept in ground their earthing is automatically done, even though a separate earthing has to be made when the ____.
A. soil has less resistivity
B. soil has more resistivity
C. Soil has high conductivity
D. none of the above
Ans.: B
Q.3 Earth wire of the overhead line should be earthed at every ____ distance by preparing independent earth pit.
A. 10 km
B.5.5 km
C. 6.5 km
D. 15 km
Ans.: C
Q. 4 Earth wire of the over head line gives protection against ___also.
A. Earth fault
B. line to line fault
C. breakdown of conductor
D. lightening
Ans.: D
Q. 5 Earthing of neutral in power system can be provided by which of the following?
A. solid earthing and transformer earthing
B. resistance and reactance earthing
C. Peterson coil or suppression coil earthing
D. all of the above
Ans.: D
Q.6 Solid earthing system is employed up to___.
A. 11 kV
B. 33 kV
C. 66 kV
D. 132 kV
Ans.: B
Q.7 The resistance earthing method is used for the system having voltages of ____ and the capacity of power source is more than___.
A. 2.2 kV to 33 kV, 5 MVA
B. 22 kV to 33 kV, 10 MVA
C. 33 kV to 66 kV, 5 MVA
D. 132 kV to 400 kV, 500 MVA
Ans.: A
Q.8 Reactance earthing method can be employed where the value of the ______ is more.
A. Fault current
B. Charging current
C. Earth fault current
D. leakage current
Ans.: B
Q.9 In ____ type earthing system the other healthy phases can supply power when a ground fault occurs on one phase.
A. reactance earthing
B. Resistance earthing
C. Peterson coil
D. any of the above
Ans.: C
Q.10 Peterson coil is also called as__.
A. Arc suppression coil
B. ground fault neutralizer
C. Both A and B
D. None of the above
Ans.: C
Q.11 The grounding obtain by Peterson coil is called as___.
A. resonant grounding
B. neutral grounding
C. system grounding
D. all of the above
Ans.: A
Q.12 In which type of earthing system tapings are provided so if there is change in the length of the line or in the capacitance of the line, the value of inductance can be adjusted with the help of taping?
A. reactance earthing method
B. Resistance earthing method
C. Peterson or arc suppression method
D. Solid earthing method
Ans.: C
Q.13 Neutral is not available when system is___.
A. star connected
B. delta connected
C. star-delta
D. none of the above
Ans.: B
Q.14 IF we double the radius of an electrode, the resistance would decreases only by __.
A. 20 %
B. 30 %
C. 10 %
D. 25 %
Ans.: C
Q.15 Which of the following is/are correct regarding soil resistivity?
A. Rock = 1000- 1000 ohm-m
B. Ice = 10000 – 100000 ohm-m
C. Sea water = 0.1 – 10 ohm-m
D. all of the above
Ans.: D