Switchgear Protections

61. The delay fuses are used for the protection of _________ .

1. motors
2. power outlet circuits
3. fluorescent lamps
4. light circuits

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62. The fuse blows off by

1. burning
2. arcing
3. melting
4. none of the above

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63. The fuse rating is expressed in terms of

1. current
2. voltage
3. VAR
4. kVA

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64. The ground wire should not be smaller than No _________ copper.

1. 2
2. 4
3. 6
4. 10

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65. The inductive interference between power and communication line can be minimized by

1. transposition of the power line
2. transposition of the communication line
3. both (a) and (b)
4. increasing the distance between the conductors

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66. The interaction between a transmission line and communication line is minimized by

1. transposing transmission as well as communication lines
2. increasing the height of the trans-mission line tower
3. increasing the distance between the two lines
4. all of the above

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67. The inverse definite mean time relays are used for over current and earth fault protection of transformer against

1. heavy loads
2. internal short-circuits
3. external short-circuits
4. all of the above

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68. The line insulation is the insulation level of the station equipment.

1. less than
2. same as
3. more than
4. proportional to
5. not directly related with

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69. The main function of a fuse is to

1. protect the line
2. open the circuit
3. protect the appliance
4. prevent excessive currents
5. none of the above

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70. The material used for fuse must have

1. low melting point and high specific resistance
2. low melting point and -low specific resistance
3. high melting point and low specific resistance
4. low melting point and any specific resistance

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