MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 129 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
_ Oil switches are employed for$? |
| A. | low currents circuits |
| B. | low voltages circuits |
| C. | high voltages and large currents circuits |
| D. | all circuits |
| Answer» D. all circuits | |
| 52. |
_ Air blast circuit breaker is used for$? |
| A. | over currents |
| B. | short duty |
| C. | intermittant duty |
| D. | repeated duty |
| Answer» E. | |
| 53. |
_Overheating of relay contacts or contact born out is due to$? |
| A. | slow making and breaking of load circuit contacts |
| B. | foreign matter on the contact surface |
| C. | too low contact pressure |
| D. | all of the above |
| Answer» E. | |
| 54. |
_In Railway applications ______ circuit breaker is used.$? |
| A. | SFe |
| B. | bulk oil |
| C. | minimum oil |
| D. | air break |
| Answer» E. | |
| 55. |
_An efficient and a well designed protective relaying should have$? |
| A. | good selectivity and reliability |
| B. | economy and simplicity |
| C. | high speed and selectivity |
| D. | all of the above |
| Answer» E. | |
| 56. |
_Induction cup relay is operated due to changes in$? |
| A. | current |
| B. | voltage |
| C. | impedance |
| D. | all of the above |
| Answer» E. | |
| 57. |
_The reflection co-efficient at the open circuited end of a transmission line.$? |
| A. | zero |
| B. | infinity |
| C. | unity |
| D. | none of the above |
| Answer» D. none of the above | |
| 58. |
_If the fault occurs near the impedance relay, the VII ratio will be$? |
| 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» C. higher than that of if fault occurs away from the relay | |
| 59. |
The arcing contacts in a circuit breaker are made of$? |
| A. | copper tungsten alloy |
| B. | porcelain |
| C. | electrolytic copper |
| D. | aluminium alloy |
| Answer» B. porcelain | |
| 60. |
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» B. sub-transient state of short-circuit current | |
| 61. |
Interruption of large currents by relay requires |
| A. | arc suppressing blow out coils |
| B. | wide separation of the opened contacts |
| C. | high speed opening of contacts |
| D. | all of the above |
| Answer» E. | |
| 62. |
Insulation resistance of high voltage circuit breakers is more than |
| A. | 1 mega ohms |
| B. | 10 mega ohms |
| C. | 100 mega ohms |
| D. | 500 mega ohms |
| Answer» D. 500 mega ohms | |
| 63. |
Ungrounded neutral transmission system is not recommended because of system |
| A. | insulation being overstressed due to over voltages |
| B. | insulation overstress may lead to failure and subsequent phase to phase faults |
| C. | being inadequately protected against ground fault |
| D. | all of the above |
| Answer» E. | |
| 64. |
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» B. in parallel with circuit | |
| 65. |
The fuse blows off by |
| A. | burning |
| B. | arcing |
| C. | melting |
| D. | none of the above |
| Answer» D. none of the above | |
| 66. |
In a circuit breaker the basic problem is to |
| A. | maintain the arc |
| B. | extinguish the arc |
| C. | transmit large power |
| D. | emit the ionizing electrons |
| Answer» D. emit the ionizing electrons | |
| 67. |
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» E. | |
| 68. |
A.C. network analyzer 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» E. | |
| 69. |
Series reactors should have |
| A. | low resistance |
| B. | high resistance |
| C. | low impedance |
| D. | high impedance |
| Answer» B. high resistance | |
| 70. |
The delay fuses are used for the protection of ________ . |
| A. | motors |
| B. | power outlet circuits |
| C. | fluorescent lamps |
| D. | light circuits |
| Answer» B. power outlet circuits | |
| 71. |
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» E. | |
| 72. |
Magnetic circuit breaker has ______ trip action. |
| A. | delayed |
| B. | instantaneous |
| C. | both of the above |
| D. | none of the above |
| Answer» C. both of the above | |
| 73. |
A _______ is used to measure the stator % winding temperature of the generator. |
| A. | thermocouple |
| B. | pyrometer |
| C. | resistance thermometer |
| D. | thermometer |
| Answer» D. thermometer | |
| 74. |
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» C. 0.5 sec | |
| 75. |
Transmission line has reflection coefficient as one. |
| A. | Open circuit |
| B. | Short-circuit |
| C. | Long |
| D. | None of the above |
| Answer» B. Short-circuit | |
| 76. |
Arc in a circuit breaker is interrupted at |
| A. | zero current |
| B. | maximum current |
| C. | minimum voltage |
| D. | maximum voltage |
| Answer» B. maximum current | |
| 77. |
A balanced 3-phase system consists of |
| A. | zero sequence currents only |
| B. | positive sequence currents only |
| C. | negative and zero sequence currents |
| D. | zero, negative and positive sequence currents |
| Answer» C. negative and zero sequence currents | |
| 78. |
For cost and safety, the outdoor substations are installed for voltages above |
| A. | 11 kV |
| B. | 33 kV |
| C. | 60 kV |
| D. | 110 kV |
| Answer» C. 60 kV | |
| 79. |
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 |
| Answer» D. power factor wave only | |
| 80. |
A fuse is never inserted in |
| A. | neutral wire |
| B. | negative of D.C. circuit |
| C. | positive of D.C. circuit |
| D. | phase dine |
| Answer» B. negative of D.C. circuit | |
| 81. |
By which of the following methods major portion of the heat generated in a H.R.C. fuse is dissipated ? |
| A. | Radiation |
| B. | Convection |
| C. | Conduction |
| D. | All of the above |
| Answer» D. All of the above | |
| 82. |
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» D. all of the above | |
| 83. |
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» B. compensate for line capacitive reactance | |
| 84. |
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 |
| E. | All of the above |
| Answer» D. None of the above | |
| 85. |
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 |
| E. | none of the above |
| Answer» B. 0.001 sec | |
| 86. |
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» E. | |
| 87. |
The line insulation is the insulation level of the station equipment. |
| A. | less than |
| B. | same as |
| C. | more than |
| D. | proportional to |
| E. | not directly related with |
| Answer» F. | |
| 88. |
Thermal overload relays are used to protect the motor against over current due to |
| A. | short-circuits |
| B. | heavy loads |
| C. | grounds |
| D. | all of the above |
| Answer» C. grounds | |
| 89. |
Protective relays are devices that detect abnormal conditions in electrical circuits by measuring |
| A. | current during abnormal condition |
| B. | voltage during abnormal condition |
| C. | constantly the electrical quantities which differ during normal and abnormal conditions |
| D. | none of the above |
| Answer» D. none of the above | |
| 90. |
Relays are used for phase faults on long line. |
| A. | Impedance |
| B. | Reactance |
| C. | Either of the above |
| D. | None of the above |
| Answer» B. Reactance | |
| 91. |
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» C. auto-transformer of the power plant | |
| 92. |
To limit short-circuit current in a power system are used |
| A. | earth wires |
| B. | isolators |
| C. | H.R. fuses |
| D. | reactors |
| Answer» E. | |
| 93. |
A switchgear is device used for |
| A. | interrupting an electrical circuit |
| B. | switching an electrical circuit 111 |
| C. | switching and controlling an electrical circuit |
| D. | switching, controlling and protecting the electrical circuit and equipment |
| Answer» E. | |
| 94. |
Wave trap is used to trap waves of |
| A. | power frequencies |
| B. | higher frequencies entering generator or transformer units |
| C. | either of the above |
| D. | none of the above |
| Answer» C. either of the above | |
| 95. |
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» D. Magnetic effect | |
| 96. |
The voltage appearing across the contacts after opening of the circuit breaker is called______voltage. |
| A. | recovery |
| B. | surge |
| C. | operating |
| D. | arc |
| E. | none of the above |
| Answer» B. surge | |
| 97. |
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» D. none of the above | |
| 98. |
Which of the following medium is employed for extinction of arc in air circuit breaker ? |
| A. | Water |
| B. | Oil |
| C. | Air |
| D. | SF6 |
| Answer» D. SF6 | |
| 99. |
Over voltage protection is recommended for |
| A. | hydro-electric generators |
| B. | steam turbine generators |
| C. | gas turbine generators |
| D. | all of the above |
| E. | none of the above |
| Answer» E. none of the above | |
| 100. |
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 |
| E. | none of the above |
| Answer» D. all of the above | |