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SUBSTATION Multiple Choice Questions :-
1. Stones are provided in the substation to
a) To avoid fire accident by draining oil from transformer if leaks
b) To avoid growing of weeds and plants
c) To provide insulation
d) All the above
2. In order to improve the power factor ___ device is employed in the substation
a) Synchronous condenser
b) Synchronous reactor
c) Series Capacitors
d) None of the above
3. What is the minimum phase to phase clearance required for 400kV conductors in substation
a) 3500 mm
b) 4200 mm
c) 5000 mm
d) 4500 mm
4. In substation which of the device is a carrier communication device
a) CVT
b) Earth conductor
c) Wave trap
d) Lightning arrestor
5. Which of the device is employed in substation to limit the short circuit current in the power system
a) Shunt condenser
b) Reactor
c) Series capacitor
d) Shunt capacitor
6. Which of the following busbar arrangement is generally employed in distribution system
a) One-and-half breaker arrangement
b) Main and transfer arrangement
c) Ring main distribution system
d) Single busbar arrangement system
7. Earthing conductivity is affected by
a) Moisture content in the soil
b) Chemical composition
c) Concentration of salts in the soil
d) All the above
8. Emulsifier protection is associated with
a) Grounding protection
b) Dielectric strength protection of cables and conductors
c) Lightning protection
d) Fire protection
9. The size of Gas Insulated Substation is significantly small compared to conventional substation because
a) High electronegative property of SF6 gas
b) High dielectric property of SF6 gas
c) High Insulation property of SF6 gas
d) All the above
10. What is Marshalling Kiosk in power transformer
a) It provides alarms, trips, controls and indications from main transformer
b) It is the base on which transformer rail is provided to pull and push transformer
c) It is the pressure device ruptures when temperature inside transformer increases
d) None of the above
11. Which is the first equipment seen in the substation while coming from transmission system
a) Circuit breaker
b) Lightning arrester
c) Current transformer
d) Transformer
12. Gas Insulated Substation is employed where
a) Where there is less space available
b) For high altitude substations
c) In terrain region
d) All the above
13. A bus coupler circuit breaker is utilized in a substation for
a) Joining the transmission line with station bus-bar
b) Joining main and transfer bus in a substation
c) Joining the generator with transfer
d) Joining the neutral of the generator with earth
14. Which of the gas is used in gas insulated substation
a) Nitrogen + SF6
b) Hydrogen + SF6
c) SF6
d) None of the above
15. Which of the following bus-bars arrangement is more reliable and flexible
a) Main and transfer bus scheme
b) One-and-half breaker scheme
c) Double main busbar scheme
d) Single busbar scheme
16. What is the maximum transmission voltage substation in India
a) 400 kV
b) 500 kV
c) 750 kV
d) 1000 kV
17. A busbar is rated by
a) Current only
b) Voltage only
c) Current, voltage and frequency
d) Current, voltage, frequency and short circuit current
18. In a substation current transformers are used to
a) Measuring purpose
b) Protection purpose connecting to relays
c) Both (a) and (b)
d) None of the above
19. Step potential and Touch potential is associated with
a) High voltage transmission
b) Earthing of the substation
c) Voltage rise in the substation
d) Communication systems
20. It is the minimum clearance required between the live conductors and maintenance operators limit
a) Ground clearance
b) Phase cearance
c) Sectional clearance
d) None of the above
21. Voltage in Primary distribution system is___
A. 220KV
B. 33 KV
C. 11 KV
D. 400KV
22. In primary distribution the voltage is __for supplying to the consumers
A. step down to 400V, 3-phase 4wire
B. step up to 765KV, 3-phase 3wire
C. step down to 11KV, 3-phase 3 wire
D. step down to 220 V, 1-phase 2 wire
23 The voltage between any two phases of a 400V 3-phase 3 wire system is ____
A. 220V
B. 110V
C. 400V
D. 250V
24 The voltage between any phase and neutral of a 400V 3-phase 3 wire system is ____
A. 230V
B. 110V
C. 400V
D. 250V
25. Residential light load is connected between___
A. any two phase
B. any one phase and neutral
C. any two phase and neutral
D. 3-phase
26. Majority of distribution substation are___
A. underground type
B. indoor type
C. Outdoor type
D. any of the above
27. A 3-phase 400V load is connected across__
A. 3-phase lines directly
B. 2-phase and neutral lines directly
C. 3-phase and neutral directly
D. 1-phase and neutral directly
28. The ______ lines runs along the road sides having RCC pole.
A. 33KV
B. 11 KV
C. 132KV
D. 66KV
29. Which of the following is not changed in transformer substation?
A. Frequency
B. power
C. power factor
D. all of the above
30. Why neutral is provided in secondary distribution?
A. for single phase supply
B. for unbalance load
C. neither A nor B
D. Both A and B
31. Power factor correction substations__
A. Which is improve the power factor of the system
B. which is improve the voltage profile of the system
C. reduce the losses in the transmission line
D. all of the above
32. Power factor correction substations are located at___
A. stating of the transmission line
B. receiving end of the transmission line
C. at intermediate of the transmission line
D. Both Sending end and receiving end of transmission line
33. Which of the following device is used for power factor correction in power factor correction substation?
A. Synchronous Condenser
B. Induction motor
C. Slip ring induction motor
D. DC series generator
34. A converting substation which change
A. DC into AC
B. AC into DC
C. AC to AC
D. DC to DC
35. A converting substation which receive AC and convert into DC power to supply for___
A. electroplating purpose
B. traction purpose
C. electric welding purpose
D. all of the above
36. A frequency substation may be required for___
A. domestic consumers
B. commercial consumers
C. Industrial consumers
D. traction
37. A substation which perform the switching operations of power transmission lines are called___
A. Transformer substation
B. Switching substation
C. Industrial substation
D. intermediate substation
38. What are the advantages of indoor substation over outdoor substation?
A. less space required
B. operation is easy
C. chances of fault is less
D. all of the above
39. A pole mounted substations are__
A. placed overhead on the poles
B. cheapest form of substation
C. does not requires building works
D. all of the above
40. Capacity of a pole mounted substations is generally up to___.
A. 500KVA
B. 200KVA
C. 400KVA
D. 1000KVA
41. The structure of pole mounted substation is of ____type.
A. H-type
B. I-type
C. A-type
D. T-type
42. Fault location in indoor type substation is____
A. easy
B. difficult
C. depend on type of fault
D. none of the above
43. Capital cost of outdoor substation is ____ than indoor substation of the same rating.
A. low
B. high
C. same as
D. none of the above
44. In which of the following substation the future expansion is possible?
A. Underground type
B. Indoor type
C. Outdoor type
D. pole mounted type
45. In which of the following, time require for erection is less?
A. Underground type
B. Indoor type
C. Outdoor type
D. pole mounted type
46. Underground substation is located at____
A. scarcity of land
B. price of land is high
C. high population density
D. all of the above
47. Which of the following is/are requirement of underground substation?
A. good ventilation system
B. size of substation is minimum as possible
C. provision of emergency lighting and protection against fire
D. all of the above
48. A____ is common electrical component for incoming and outgoing of electrical lines in substation?
A. Bus-bars
B. Isolating switches
C. Insulators
D. Circuit breakers
49. Which of the following bus-bar arrangement is commonly used?
A. Single bus bar system with sectionalisation
B. Double bus bar arrangement
C. Single bus bar arrangement
D. all of the above
50. Bus-bars are of ____ material.
A. Copper
B. Aluminium
C. Both A or B
D. Iron or steel
51. Bus-bars are operated at___
A. Constant voltage
B. variable voltage
C. Depend upon requirement
D. none of the above
52. The cross section of bus bar is of ___ shape.
A. Rectangular
B. Circular/round
C. triangular
D. Both A or B
53. Which of the following used for clearance between ground and live conductor in substations?
A. Isolating switch
B. Insulators
C. Circuit breakers
D. all of the above
54. Which of the following material commonly used for manufacturing of insulators?
A. Porcelain
B. Cement
C. Ceramics
D. all of the above
55. The insulators serves the purpose of___
A. support the conductors
B. Confine current to the conductor
C. provide clearance from ground
D. all of the above
56. The types of insulators are
A. Pin type
B. Suspension type
C. Strain type or post type
D. all of the above
57. ______ is used to disconnect the system for maintenance and repairs purpose?
A. Insulators
B. Isolating switch or isolators
C. Bus bars
D. none of the above
58. Isolator is designed to open a circuit or live system under___
A. on load
B. under no load
C. Either A or B
D. Neither A nor B
59. Isolator is open
A. After opening of circuit breaker
B. after closing of circuit breaker
C. under closing position of circuit breaker
D. any of the above
60. Isolator is used ____
A. After circuit breaker in line
B. before circuit breaker in line
C. Both A and B
D. after or before bus bars
61. A power transformers used in substations to__
A. change frequency
B. step up or step down the voltage
C. to improve the power factor
D. to convert AC into DC
62. For rating up to 10MVA____ transformers is used.
A. Naturally cooled oil immersed
B. naturally cooled oil forced
C. air forced oil immersed
D. air force oil circulated
63. Which of the following instrument transformer is used in substations
A. CT
B. PT
C. Both A and B
D. neither A nor B
64. Which of the following is more prone to fault?
A. Indoor type substation
B. Underground type substation
C. Outdoor type substation
D. all of the above
65. Indoor substation are usually for a voltage ____.
A. up to 66 KV
B. up to 11 KV
C. up to 33 KV
D. up to 132 KV
66. If the surrounding atmosphere is contaminated with impurities like fumes, dust and metal corroding, the indoor substations are erected for voltage up to___
A. 33 KV
B. 66 KV
C. Both A and B
D. 132 KV
67. Foundation mounted sub-stations, transformers of capacity __ is used.
A. below 250 KVA
B. up to 10KVA
C. up to 200 KVA
D. above 250 KVA
68. Pole mounted substations, transformers of capacity ____ is employed.
A. up to 25 KVA
B. up to 125 KVA
C. Up to 250 KVA
D. all of the above
69. Substations for primary and secondary transmission are ____
A. pole mounted Indoor type
B. foundation mounted outdoor type
C. foundation mounted indoor type
D. pole mounted outdoor type
70. Selection and location of site for a substations is depends on___
A. availability of suitable and sufficient land
B. Type of substations
C. Atmospheric conditions and
D. all of the above
71. Why aluminum is used for numerous switchgear installation over copper?
A. higher conductivity on weight basis
B. lower cost for equal current carrying capacity
C. excellence corrosion resistance
D. all of the above
72. In substations the bus bars are painted or coated with enamel paints because of ____
A. to indicate different phases in three phase systems
B. to indicate positive and negative in DC system
C. Both A and B
D. to reduce the effective cooling
73. Why hollow bus bar conductors are used instead of solid one?
A. due to skin effect
B. proximity effect
C. Ferranti effect
D. all of the above
74. The bus bar conductors are supported on___
A. Pin type insulators
B. Post type insulators
C. Strain type insulators
D. Both B or C
75. ______ which combines the function of the isolators and a switch.
A. Circuit breaker
B. load interrupter switches
C. Earth switches
D. Line trap unit
76. Earth switch is connected between
A. line and earth
B. two lines
C. line and neutral
D. circuit breaker and isolators
77. Which of the following is normally open in substations?
A. Circuit breaker
B. Earth switch
C. Isolators
D. none of the above
78. A power transformers are designed to have maximum efficiency ___
A. at full load
B. near to full load
C. Both A or B
D. at 50% of full load
79. Power transformers usually designed to make use of flux density of __
A. 1.5 to 1.77
B. 0.5 to 1.5
C. 1 to 1.5
D. 0.5 to 7.7
80. The voltage regulation of power transformer is ranging from___
A. 5 to 8%
B. 6-10%
C. 10-12%
D. 10-15%
81. The control system in substations generally operated at__
A. 110V
B. 220 V
C. Both A or B
D. 400V
82. Carrier current equipment is installed in substations for___
A. relaying
B. Communication
C. Telemetering or supervisory control
D. all of the above
83. The indicating and metering instruments used in substations are___
A. Ammeters, Voltmeters
B. Wattmeter, power factor meters
C. KWh and KVARh meters
D. all of the above
84. Batteries are used in substation for the purpose of__
A. emergency lighting
B. to supply operating and control circuits
C. to supply protective relaying systems
D. all of the above
85. Which of the following is closed after line is disconnected from the supply?
A. isolators
B. Earth switch
C. Circuit breakers
D. relays
86. Which of the following is closed first for supplying power after repairs or maintenance?
A. isolators
B. Earth switch
C. Circuit breakers
D. relays
87. Which of the following is secondary transmission voltage?
A. 66 KV
B. 33 KV
C. 400 KV
D. Both A or B
88. Which of the following is primary transmission voltage?
A. 132 KV
B. 400KV
C. 765 KV
D. all of the above
89. Which of the following is remains open during normal operation of power system?
A. Earth switch
B. Circuit breaker
C. Isolators
D. indicating instruments
90. A charging current is discharge through_____ after the line is disconnected from the main supply?
A. Earth switch
B. Circuit breaker
C. Isolators
D. indicating instruments
91. Primary grid type substation is ____substation
A. step down type
B. step up type
C. distribution type
D. none of the above
92 In step up substation the electric power is transmitted by____
A. 3-phase 3 wire system
B. 3-phase 4 wire system
C. 2-phase 3 wire system
D. 2-phase mid-point earthed system
93. Primary substation is generally__
A. Indoor type
B. outdoor type
C. pole mounted type
D. any of the above
94. Electric power received by the primary grid substation at receiving end which is reduces the voltage level of 66KV for__
A. primary distribution purpose
B. secondary transmission purpose
C. secondary distribution purpose
D. primary transmission purpose
95. The generating voltage at generating station is step up for transmission is___
A. 11KV
B. 66KV
C. 33KV
D. any of the above
96. Secondary substation, electric power is transmitted at__
A. 132 KV
B. 66 KV
C. 220 KV
D. 33 KV
97. From a secondary substation, electric power is transmitted by___
A. 3-phase 3 wire system
B. 3-phase 4 wire system
C. 2-phase 3 wire system
D. 2-phase mid-point earthed system
98. At receiving end of secondary transmission, voltage is ____.
A. stepped up to 220 KV
B. step down to 66 KV
C. step down to 11 KV
D. step down to 440V
99. A consumers having demand more than 50KW are distributed by__
A. 11KV
B. 33 KV
C. 66 KV
D. 440 V
100. The secondary substation is generally ____ substations
A. Indoor type
B. Outdoor type
C. Underground type
D. any of the above