McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 51. |
Which of the following statements is incorrect? |
| A. | Station batteries are used to operate relay only |
| B. | The lightning arresters are basically surge diverters |
| C. | An impedance relay has maximum fault current when fault occurs near the relay |
| D. | A high speed relay has an operation of 1 to 2 cycles |
| Answer» A. Station batteries are used to operate relay only | |
| 52. |
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 |
| Answer» C. slow | |
| 53. |
Induction cup relay is operated due to changes in |
| A. | current |
| B. | voltage |
| C. | impedance |
| D. | all of the above |
| Answer» D. all of the above | |
| 54. |
A.C. network analyser is used to solve problems of |
| A. | load flow |
| B. | load flow and short-circuit |
| C. | load flow and stability |
| D. | load flow, short-circuit and stability |
| Answer» D. load flow, short-circuit and stability | |
| 55. |
Which of the following statements is incorrect ? |
| A. | Lightning arrestors are used before the switchgear |
| B. | Shunt reactors are used as compensation reactors |
| C. | The peak short current is (1.8 xV2) times the A.C. component |
| D. | The MVA at fault is equal to base MVA divided by per unit equivalent fault |
| Answer» A. Lightning arrestors are used before the switchgear | |
| 56. |
To reduce short circuit fault currents are used. |
| A. | reactors |
| B. | resistors |
| C. | capacitors |
| D. | none of the above |
| Answer» A. reactors | |
| 57. |
Bus coupler is very essential in arrangement |
| A. | single bus |
| B. | double bus, double breaker |
| C. | main and transfer bus |
| D. | all of the above |
| Answer» C. main and transfer bus | |
| 58. |
For cost and safety, the outdoor substations are installed for voltages above |
| A. | 11 kV |
| B. | 33 kV |
| C. | 60kV |
| D. | 110kV |
| Answer» B. 33 kV | |
| 59. |
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» D. impulse voltage | |
| 60. |
relays are used for phase faults on long line. |
| A. | Impedance |
| B. | Reactance |
| C. | Either of the above |
| D. | None of the above |
| Answer» A. Impedance | |
| 61. |
For which of the following protection from negative sequence currents is provided ? |
| A. | Generators |
| B. | Motors |
| C. | Transmission line |
| D. | Transformers |
| Answer» A. Generators | |
| 62. |
relay is preferred for phase fault on short transmission line. |
| A. | Induction type |
| B. | Reactance |
| C. | Impedance |
| D. | None of the above |
| Answer» B. Reactance | |
| 63. |
Distance relays are generally |
| A. | split-phase relays |
| B. | reactance relays |
| C. | impedance relays |
| D. | none of the above |
| Answer» B. reactance relays | |
| 64. |
For which of the following ratings of the transformer differential protection is recommended ? |
| A. | above 30 kVA. |
| B. | equal to and above 5 MVA |
| C. | equal to and above 25 MVA |
| D. | none of the above |
| Answer» D. none of the above | |
| 65. |
A _______ is used to measure the stator % winding temperature of the generator. |
| A. | thermocouple |
| B. | pyrometer |
| C. | resistance thermometer |
| D. | thermometer |
| Answer» C. resistance thermometer | |
| 66. |
The relay with inverse time characteristic will operate within |
| A. | 1.5 sec |
| B. | 5 to 10 sec |
| C. | 5 to 20 sec |
| D. | 20 to 30 sec |
| Answer» B. 5 to 10 sec | |
| 67. |
The single phasing relays are used for the protection of |
| A. | single phase motors only |
| B. | two phase motors only |
| C. | two single phase motors running in parallel |
| D. | three phase motors |
| Answer» D. three phase motors | |
| 68. |
Which of the following devices will receive voltage surge first travelling on the transmission line ? |
| A. | Lightning arresters |
| B. | Relays |
| C. | Step-down transformer |
| D. | Switchgear |
| Answer» A. Lightning arresters | |
| 69. |
Which of the following parameter can be neglected for a short line ? |
| A. | Inductance |
| B. | Capacitance |
| C. | Resistance |
| D. | Reactance |
| Answer» B. Capacitance | |
| 70. |
Series reactors should have |
| A. | low resistance |
| B. | high resistance |
| C. | low impedance |
| D. | high impedance |
| Answer» A. low resistance | |
| 71. |
Which of the following circuit breakers has high reliability and minimum maintenance ? |
| A. | Air blast circuit breakers |
| B. | Circuit breaker with SF6 gas |
| C. | Vacuum circuit breakers |
| D. | Oil circuit breakers |
| Answer» B. Circuit breaker with SF6 gas | |
| 72. |
Arc in a circuit breaker is interrupted at |
| A. | zero current |
| B. | maximum current |
| C. | minimum voltage |
| D. | maximum voltage |
| Answer» A. zero current | |
| 73. |
transmission line has reflection coefficient as one. |
| A. | Open circuit |
| B. | Short-circuit |
| C. | Long |
| D. | None of the above |
| Answer» A. Open circuit | |
| 74. |
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 ? |
| A. | Zero |
| B. | Unity |
| C. | Infinity |
| D. | None of the above |
| Answer» A. Zero | |
| 75. |
The inverse definite mean time relays are used for over current and earth fault protection of transformer against |
| A. | heavy loads |
| B. | internal short-circuits |
| C. | external short-circuits |
| D. | all of the above |
| Answer» B. internal short-circuits | |
| 76. |
Over voltage protection is recommended for |
| A. | hydro-electric generators |
| B. | steam turbine generators |
| C. | gas turbine generators |
| D. | all of the above |
| Answer» D. all of the above | |
| 77. |
Air blast circuit breakers for 400 kV power system are designed to operate in |
| A. | 100 microsecond |
| B. | 50 millisecond |
| C. | 0.5 sec |
| D. | 0.1 sec |
| Answer» B. 50 millisecond | |
| 78. |
Overfluxing protection is recommended for |
| A. | distribution transformer |
| B. | generator transformer of the power plant |
| C. | auto-transformer of the power plant |
| D. | station transformer of the power plant |
| Answer» B. generator transformer of the power plant | |
| 79. |
Series capacitors are used to |
| A. | compensate for line inductive reactance |
| B. | compensate for line capacitive reactance |
| C. | improve line voltage |
| D. | none of the above |
| Answer» A. compensate for line inductive reactance | |
| 80. |
Admittance relay is _______ relay. |
| A. | impedance |
| B. | directional |
| C. | non-directional |
| D. | none of the above |
| Answer» B. directional | |
| 81. |
The material used for fuse must have |
| A. | low melting point and high specific resistance |
| B. | low melting point and -low specific resistance |
| C. | high melting point and low specific resistance |
| D. | low melting point and any specific resistance |
| Answer» A. low melting point and high specific resistance | |
| 82. |
If the fault occurs near the impedance relay, the VII ratio will be |
| A. | constant for all distances |
| B. | lower than that of if fault occurs away from the relay |
| C. | higher than that of if fault occurs away from the relay |
| D. | none of the above |
| Answer» B. lower than that of if fault occurs away from the relay | |
| 83. |
The torque produced in induction type relay (shaded pole structure) is |
| A. | inversely proportional to the current |
| B. | inversely proportional to the square of the current |
| C. | proportional to the current |
| D. | proportional to square of the current |
| Answer» B. inversely proportional to the square of the current | |
| 84. |
The steady state stability of the power system can be increased by |
| A. | connecting lines in parallel |
| B. | connecting lines in series |
| C. | using machines of high impedance |
| D. | reducing the excitation of machines |
| Answer» A. connecting lines in parallel | |
| 85. |
The inductive interference between power and communication line can be minimized by |
| A. | transposition of the power line |
| B. | transposition of the communication line |
| C. | both (A) and (B) |
| D. | increasing the distance between the conductors |
| Answer» C. both (A) and (B) | |
| 86. |
The power loss is an important factor for the design of |
| A. | transmission line |
| B. | motor |
| C. | generator |
| D. | feeder |
| Answer» A. transmission line | |
| 87. |
A fuse is connected |
| A. | in series with circuit |
| B. | in parallel with circuit |
| C. | either in series or in parallel with circuit |
| D. | none of the above |
| Answer» A. in series with circuit | |
| 88. |
H.R.C. fuse, as compared to a rewirable fuse, has |
| A. | no ageing effect |
| B. | high speed of operation |
| C. | high rupturing capacity |
| D. | all of the above |
| Answer» D. all of the above | |
| 89. |
The fuse rating is expressed in terms of |
| A. | current |
| B. | voltage |
| C. | VAR |
| D. | kVA |
| Answer» A. current | |
| 90. |
The fuse blows off by |
| A. | burning |
| B. | arcing |
| C. | melting |
| D. | none of the above |
| Answer» C. melting | |
| 91. |
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» C. Heating effect | |
| 92. |
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» D. generally on both sides of a circuit breaker | |
| 93. |
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» B. short-circuit and overload | |
| 94. |
Protection by fuses is generally not used beyond |
| A. | 20 A |
| B. | 50 A |
| C. | 100 A |
| D. | 200 A |
| Answer» C. 100 A | |
| 95. |
A fuse is never inserted in |
| A. | neutral wire |
| B. | negative of D.C. circuit |
| C. | positive of |
| D. | C. circuit |
| Answer» A. neutral wire | |
| 96. |
Which of the following circuit breakers is used for the railway electrification? |
| A. | Air blast circuit breaker |
| B. | SF6 circuit breaker |
| C. | Bulk oil circuit breaker |
| D. | Minimum oil circuit breaker |
| Answer» A. Air blast circuit breaker | |
| 97. |
The stability of arc in vacuum depends on _________. |
| A. | The contact material only. |
| B. | The circuit parameters only. |
| C. | The contact materials and its vapour pressure. |
| D. | Both (b) and (c) |
| Answer» D. Both (b) and (c) | |
| 98. |
SF6 is which type of gas? |
| A. | Electro positive |
| B. | Electro negative |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 99. |
What is the average rate of rise of restriking voltage upto the first peak? |
| A. | 525 * 103kV / sec |
| B. | 453 * 103kV / sec |
| C. | 582 * 103 kV / sec |
| D. | 467 * 103 kV / sec |
| Answer» B. 453 * 103kV / sec | |
| 100. |
Circuit breakers usually operate under |
| A. | Steady short circuit current |
| B. | Sub transient state of short circuit current |
| C. | Transient state of short circuit current |
| D. | None of these |
| Answer» B. Sub transient state of short circuit current | |
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