Underground Cables MCQ

Test your knowledge with important Underground Cables MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30 + more Underground Cables MCQs at Bissoy

• How can one think of reducing the earth capacitance of line?
  ক

  Using guard ring

  খ

  Using special designed earth capacitances

  গ

  Implementing parallel insulator lines

  ঘ

  Any of the mentioned
• For a 400 kV, 50 Hz five pin insulator setup provides the protection with an efficiency of 87.4%. The same setup is now meant to be used at the frequency of 60 Hz, the updated string efficiency of the system will be ____________
  ক

  87.4

  খ

  91

  গ

  82%

  ঘ

  86%
• If the frequency of the transmission line is changed from 50 Hz to 100 Hz, then the string efficiency ____________
  ক

  remains unchanged

  খ

  increases

  গ

  decreases

  ঘ

  May or may not increase depending on the parameters
• The pin type insulators are generally not used for the voltage range exceeding ____________
  ক

  33kV

  খ

  66kV

  গ

  25kV

  ঘ

  11kV
• For a line-man while measuring the string efficiency of the insulator installation done, observes that it shows a reading of 100%. This means ___________________
  ক

  equal potential across each insulator disc

  খ

  one of the insulator disc is shorted

  গ

  zero potential across each disc

  ঘ

  none of the mentioned
• A string of insulators consisting of 7 units. The voltage across the bottom most unit is 25% of the total voltage. The string efficiency of this system will be
  ক

  57.14 %

  খ

  50.6 %

  গ

  80.4 %

  ঘ

  67.7 %
• The capacitance grading method is one of the most practical and most widely used method in Indian transmission system.
  ক

  True

  খ

  False
• How does grading neutralize the potential distribution across the units of the suspension insulators?
  ক

  By forming capacitances to cancel the charging current from link pins

  খ

  By forming capacitances with link pin to cancel the charging current from them

  গ

  By increasing the capacitance of lower insulator units

  ঘ

  By decreasing the capacitance of lower insulator units
• For a string of five suspension insulators is to be fitted with a grading ring. If the pin to earth capacitances are equal to C, then the value of line to pin capacitance of first and last capacitance(from top) is
  ক

  0.25C, 4C

  খ

  0.667C, 3C

  গ

  1.5C, 1.5C

  ঘ

  4C,0.25
• For a string of five suspension insulators is to be fitted with a grading ring. If the pin to earth capacitances is equal to C, then the value of line to pin capacitance of first capacitance is
  ক

  0.25C

  খ

  0.667C

  গ

  1.5C

  ঘ

  4C
• Dielectric power loss of a transmission line cable operating for ‘V’ volts, ‘f’ Hz having a capacitance of ‘C’ Farads with the tangent loss angle of δis ____________
  ক

  ωCV2 tanδ

  খ

  ωCV2/tanδ

  গ

  (tanδ/ωCV)2

  ঘ

  ωCV2 tanδ2
• Consider a system having a cable of capacitance 5 nF, with 765 kV star connected at 50 Hz having a power loss in the cable as 82.1 kW. Then the dielectric loss angle is _________(in degrees).
  ক

  15

  খ

  7.5

  গ

  20

  ঘ

  4.9
• The resistance of the insulation used for the cables is 40 ohms for a length of ‘x’ km. If the proposed plan needs to extend the transmission line cable to extra ‘2x’ m then the resistance of the cable offered will be _____________ (in ohms).
  ক

  13.33

  খ

  20

  গ

  120

  ঘ

  40
• Grading of the cables is performed in order to achieve ____________ (i) uniform stress (ii) reduction in quantity of insulation (iii) reduction in quality of insulation
  ক

  (i), (ii)

  খ

  (ii)

  গ

  (i),(iii)

  ঘ

  (ii), (iii)
• For a transmission system of voltage ‘765 kV’ volts having the core radius of ‘5’ cm and outer radius of ‘0.40’ m. The maximum dielectric stress on single core cable is _________
  ক

  7357.7 kV

  খ

  919.7 kV

  গ

  4247 kV

  ঘ

  530 kV
• Single core cables for ac systems are provided with armouring.
  ক

  True

  খ

  False
• Single core cables for AC systems are not provided with armouring.
  ক

  True

  খ

  False