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Free download in PDF Switchgear and Protection Multiple Choice Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
(1)
The main function of a fuse is to
[A]
protect the line
[B]
open the circuit
[C]
protect the appliance
[D]
prevent excessive currents
Answer: prevent excessive currents
(2)
SF6 gas
[A]
is yellow in colour
[B]
is lighter than air
[C]
is nontoxic
[D]
has pungent small
(3)
With which of the following, a circuit breaker must be equipped for remote operation ?
[A]
Inverse time trip
[B]
Time-delay trip
[C]
Shunt trip
[D]
None of the above
(4)
Arc in a circuit behaves as
[A]
a capackive 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
Answer: a resistance decreasing with voltage rise across the arc
(5)
Relays can be designed to respond to changes in
[A]
resistance, reactance or impedance
[B]
voltage and current
[C]
light intensity
[D]
all above
(6)
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: many turns of thin wire
(7)
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: transient state of short-circuit current
(8)
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
(9)
Directional relays are based on flow of
[A]
Power
[B]
Current
[C]
Voltage Wave
[D]
All Of The Above
(10)
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: two or more similar electrical quantities
(11)
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
(12)
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
(13)
Shunt capacitance is neglected while considering
[A]
short transmission line
[B]
medium transmission line
[C]
long transmission line
[D]
medium and long transmission lines
Answer: short transmission line
(14)
The time of closing the cycle, in modern circuit breakers is
[A]
0.003 sec
[B]
0.001 sec
[C]
0.01 sec
[D]
0.10 sec
(15)
Which of the following is the least expensive protection for overcurrent is low voltage system ?
[A]
Rewireable fuse
[B]
Isolator
[C]
Oil circuit breaker
[D]
Air break circuit breaker
(16)
The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to
[A]
lubricate the contacts
[B]
insulate the contacts from switch body
[C]
extinguish the arc
[D]
all of the above
Answer: extinguish the arc
(17)
To protect most of the electrical equipment handling low power, the types of relays used are
[A]
Thermocouple
[B]
Electronic And Bimetallic
[C]
Both (A) And (B)
[D]
None Of The Above
(18)
The reflection co-efficient at the open circuited end of a transmission line.
[A]
Zero
[B]
Infinity
[C]
Unity
[D]
None Of The Above
(19)
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
Answer: Sending And Other End
(20)
Discrimination between main and back up protection is provided by the use of relays which are
[A]
Fact
[B]
Sensitive
[C]
Slow
[D]
None Of The Above
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