Power System Question Bank

1. In which of the following cases shunt capacitance is negligible ?

(a) Short transmission lines
(b) Medium transmission lines
(c) Long transmission lines
(d) All transmission lines


Answer: (a) Short transmission lines
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2. A lightning arrester is usually located nearer to

(a) transformer
(b) isolator
(c) bus-bar
(d) circuit breaker
(e) none of the above


Answer: (a) transformer
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3. The material used for the manufacture of grounding wires is

(a) cast iron
(b) aluminum
(c) stainless steel
(d) galvanized steel


Answer: (d) galvanized steel
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4. Surge absorbers protect against……….oscillations.

(a) high voltage high frequency
(b) high voltage low frequency
(c) low voltage high frequency
(d) low voltage low frequency


Answer: (c) low voltage high frequency
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5. Skin effect is noticeable only at ………… frequencies.

(a) audio
(b) low
(c) high
(d) all


Answer: (c) high
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6. Power system stability is least affected by

(a) reactance of generator
(b) input torque
(c) losses
(d) reactance of transmission line


Answer: (c) losses
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7. In medium transmission lines the shunt capacitance is taken into account in

(a) T-method
(b) π-method
(c) Steinmetz method
(d) all of the above.


Answer: (d) all of the above.
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8. System grounding is done so that

(a) inductive interference between power and communication circuits can be controlled.
(b) the floating potential on the lower voltage winding for a transformer is brought down to an insignificant value .
(c) the arcing faults to earth would not set up dangerously high voltage on healthy phases.
(d) for all above reasons.


Answer: (d) for all above reasons.
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9. Which of the following can be used for bus-bars?

(a) Tubes
(b) Rods
(c) Bars
(d) Any of the above.


Answer: (d) Any of the above.
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10. If the height of transmission tower is increased, which of the following parameters is likely to change ?

(a) Capacitance
(b) Inductance
(c) Resistance
(d) All of the above.


Answer: (a) Capacitance
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11. A.C.S.R. conductor having 7 steel strands surrounded by 25 aluminum conductors will be specified as

(a) 25/7
(b) 7/25
(c) 50/15


Answer: (b) 7/25
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12. Impedance relay is used on …… transmission lines.

(a) short
(b) medium
(c) long
(d) all


Answer: (b) medium
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13. Corona is likely to occur maximum in

(a) transmission lines
(b) distribution lines
(c) domestic wiring
(d) all of the above.


Answer: (a) transmission lines
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14. The effect of wind pressure is more predominant on

(a) supporting towers
(b) neutral wires
(c) transmission lines
(d) insulators.


Answer: (a) supporting towers
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15. As compared to cables, disadvantage of overhead transmission lines is

(a) inductive interference between power and communication circuits
(b) exposure to lightning.
(c) exposure to atmospheric hazards like smoke, ice, etc.
(d) all of the above.


Answer: (d) all of the above.
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16. In overhead transmission lines the effect of capacitance can be neglected when the length of line is less than

(a) 80 km
(b) 110 km
(c) 150 km
(d) 210 km.


Answer: (a) 80 km
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17. The effective resistance of a conductor will be the same as ‘ohmic resistance’ when

(a) power factor is unity
(b) current is uniformly distributed in the conductor cross-section.
(c) voltage is low
(d) current is in true sine wave form.


Answer: (b) current is uniformly distributed in the conductor cross-section.
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18. To increase the capacity of a transmission line for transmitting power which of the following must be decreased ?

(a) Capacitance
(b) Line inductance
(c) Voltage
(d) All of the above.


Answer: (b) Line inductance
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19. By using bundled conductors which of the following is reduced ?

(a) Power loss due to corona
(b) Capacitance of the circuit
(c) Inductance of the circuit
(d) All of the above.


Answer: (a) Power loss due to corona
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20. Which of the following short-circuits is more dangerous ?

(a) Dead short-circuit
(b) Line to ground short-circuit
(c) Line to line short-circuit
(d) Line to line and ground short-circuit.


Answer: (a) Dead short-circuit
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21. In case of transmission line conductors with the increase in atmospheric temperature

(a) length decreases but stress increases
(b) length increases but stress decreases
(c) both the length and streets increase
(d) both the length and stress decrease.


Answer: (b) length increases but stress decreases
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22. Skin effect exists only in

(a) AC transmission
(b) high voltage DC overhead transmission
(c) low voltage DC overhead transmission
(d) cables carrying DC current.


Answer: (a) AC transmission
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23. Floating neutral, in 3-phase supply, is undesirable because it causes

(a) low voltage across the load
(b) high voltage across the load
(c) unequal line voltages across the load
(d) none of the above.


Answer: (c) unequal line voltages across the load
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24. The ground ring transmission lines are used to

(a) reduce the transmission losses
(b) reduce the earth capacitance of the lowest unit
(c) increase the earth capacitance of the lowest unit
(d) none of the above.


Answer: (b) reduce the earth capacitance of the lowest unit
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25. The string efficiency of an insulator can be increased by

(a) correct grading of insulators of various capacitances
(b) reducing the number of strings
(c) increasing the number of strings in the insulator
(d) none of the above.


Answer: (a) correct grading of insulators of various capacitances
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26. High voltages for transmitting power is economically available from

(a) d.c. currents
(b) a.c. currents
(c) carrier currents
(d) none of the above.


Answer: (b) a.c. currents
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27. High voltage is primarily used, for long distance power transmission, to

(a) reduce the time of transmission
(b) reduce the transmission losses
(c) make the system reliable
(d) none of the above.


Answer: (b) reduce the transmission losses
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28. By using bundle conductors, the critical voltage for the formation of corona will

(a) remain same
(b) decrease
(c) increase
(d) not occur.


Answer: (c) increase
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29. If the voltage is increased x times, the size of the conductor would be

(a) reduced to 1/x2 times
(b) reduced to 1/x times
(c) increased x times
(d) increased to x2 times


Answer: (a) reduced to 1/x2 times
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30. In the cables sheaths are used to

(a) prevent the moisture from entering the cable
(b) provide strength to the cable
(c) provide proper insulation
(d) none of the above.


Answer: (a) prevent the moisture from entering the cable
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31. Ground wire is used to

(a) avoid overloading
(b) give the support to the tower
(c) give good regulation
(d) connect a circuit conductor or other device to an earth-plate.


Answer: (d) connect a circuit conductor or other device to an earth-plate.
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32. Earthing is necessary to give protection against

(a) danger of electric shock
(b) voltage fluctuation
(c) overloading
(d) high temperature of the conductors.


Answer: (a) danger of electric shock
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33. Resistance grounding is used for voltage between

(a) 3.3 kV to 11 kV
(b) 11 kV to 33 kV
(c) 33 kV to 66 kV
(d) none of the above.


Answer: (a) 3.3 kV to 11 kV
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34. Solid grounding is adopted for voltages below

(a) 100 V
(b) 200 V
(c) 400 V
(d) 860 V


Answer: (d) 860 V
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35. The size of the earth wire is determined by

(a) the atmospheric conditions
(b) the voltage of the service wires
(c) the ampere capacity of the service wires
(d) none of the above.


Answer: (c) the ampere capacity of the service wires
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36. Transmission lines link

(a) generating station to receiving end station
(b) receiving end station to distribution transformer
(c) distribution transformer to consumer premises
(d) service points to consumer premises.


Answer: (a) generating station to receiving end station
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Power System Question Bank

 

  1. Power System MCQ With Answers
  2. Power System Multiple Choice Questions
  3. MCQ on Power System
  4. Power Systems Questions and Answers
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