Switchgear and Protection MCQs | Switchgear and Protection MCQs and Answers for competitive exams

Questions
81 The fuse blows off by
A burning
B arcing
C melting
D none of the above

Answer: melting
82 On which of the following effects of electric current a fuse operates ?
A Photoelectric effect
B Electrostatic effect
C Heating effect
D Magnetic effect

Answer: Heating effect
83 An isolator is installed
A to operate the relay of circuit breaker
B as a substitute for circuit breaker
C always independent of the position of circuit breaker
D generally on both sides of a circuit breaker

Answer: generally on both sides of a circuit breaker
84 A fuse in a motor circuit provides protection against
A overload
B short-circuit and overload
C open circuit, short-circuit and overload
D none of the above

Answer: short-circuit and overload
85 Protection by fuses is generally not used beyond
A 20 A
B 50 A
C 100 A
D None Of The Above

Answer: 100 A
86 Oil switches are employed for
A low currents circuits
B low voltages circuits
C high voltages and large currents circuits
D none of the above

Answer: high voltages and large currents circuits
87 The fuse wire, in D.C. circuits, is inserted in
A negative circuit only
B positive circuit only
C both (a) and (b)
D all of the above

Answer: both (a) and (b)
88 Air blast circuit breaker is used for
A over currents
B short duty
C intermittent duty
D repeated duty

Answer: repeated duty
89 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

Answer: all of the above
90 The short circuit in any winding of the transformer is the result of
A mechanical vibration
B insulation failure
C loose connection
D impulse voltage

Answer: impulse voltage
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