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This set of Switch Gear and Protection Multiple Choice Questions & Answers (MCQs) focuses on Switch Gear And Protection Set 4
Q1 | Which of the following circuit breakers has high reliability andminimum maintenance ?
- Air blast circuit breakers
- Circuit breaker with SF6 gas
- Vacuum circuit breakers
- Oil circuit breakers
Q2 | Arc in a circuit breaker is interrupted at
- zero current
- maximum current
- minimum voltage
- maximum voltage
Q3 | transmission line has reflection coefficient as one.
- Open circuit
- Short-circuit
- Long
- None of the above
Q4 | What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ?
- Zero
- Unity
- Infinity
- None of the above
Q5 | The inverse definite mean time relays are used for over current and earth fault protection of transformer against
- heavy loads
- internal short-circuits
- external short-circuits
- all of the above
Q6 | Over voltage protection is recommended for
- hydro-electric generators
- steam turbine generators
- gas turbine generators
- all of the above
Q7 | Air blast circuit breakers for 400 kV power system are designed tooperate in
- 100 microsecond
- 50 millisecond
- 0.5 sec
- 0.1 sec
Q8 | Overfluxing protection is recommended for
- distribution transformer
- generator transformer of the power plant
- auto-transformer of the power plant
- station tr
Q9 | Series capacitors are used to
- compensate for line inductive reactance
- compensate for line capacitive reactance
- improve line voltage
- none of the above
Q10 | Admittance relay is _______ relay.
- impedance
- directional
- non-directional
- none of the above
Q11 | The material used for fuse must have
- low melting point and high specific resistance
- low melting point and -low specific resistance
- high melting point and low specific resistance
- low melting point and any specific resistance
Q12 | If the fault occurs near the impedance relay, the VII ratio will be
- constant for all distances
- lower than that of if fault occurs away from the relay
- higher than that of if fault occurs away from the relay
- none of the above
Q13 | The torque produced in induction type relay (shaded pole structure) is
- inversely proportional to the current
- inversely proportional to the square of the current
- proportional to the current
- proportional to square of the current
Q14 | The steady state stability of the power system can be increased by
- connecting lines in parallel
- connecting lines in series
- using machines of high impedance
- reducing the excitation of machines
Q15 | The inductive interference between power and communication linecan be minimized by
- transposition of the power line
- transposition of the communication line
- both (a) and (b)
- increasing the distance between the conductors
Q16 | The power loss is an important factor for the design of
- transmission line
- motor
- generator
- feeder
Q17 | A fuse is connected
- in series with circuit
- in parallel with circuit
- either in series or in parallel with circuit
- none of the above
Q18 | H.R.C. fuse, as compared to a rewirable fuse, has
- no ageing effect
- high speed of operation
- high rupturing capacity
- all of the above
Q19 | The fuse rating is expressed in terms of
- current
- voltage
- VAR
- kVA
Q20 | The fuse blows off by
- burning
- arcing
- melting
- none of the above
Q21 | On which of the following effects of electric current a fuse operates ?
- Photoelectric effect
- Electrostatic effect
- Heating effect
- Magnetic effect
Q22 | An isolator is installed
- to operate the relay of circuit breaker
- as a substitute for circuit breaker
- always independent of the position of circuit breaker
- generally on both sides of a circuit breaker
Q23 | A fuse in a motor circuit provides protection against
- overload
- short-circuit and overload
- open circuit, short-circuit and overload
- none of the above
Q24 | Protection by fuses is generally not used beyond
- 20 A
- 50 A
- 100 A
- 200 A
Q25 | A fuse is never inserted in
- neutral wire
- negative of D.C. circuit
- positive of D.C. circuit
- phase dine