Potential Distribution & String Efficiency of Insulator - MCQs with Answers

Potential Distribution & String Efficiency of Insulator - MCQs with Answers

Q1. The voltage across the various discs of a string of suspension insulator having identical discs is different due to

a. Surface leakage currents.
b. Series capacitance.
c. Shunt capacitance to ground.
d. Series and shunt capacitance.

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Q2. On what factor does the string efficiency of a string of suspension insulators dependent?

a. Size of the insulator.
b. Number of discs in the string.
c. Size of tower.
d. None of these.

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Q3. The maximum voltage of the disc type insulators is at

a. Same at all points
b. Near the tower or starting of the insulator.
c. Near to the conductors.
d. None of these.

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Q4. The string efficiency of a high voltage line is around

a. 100 %
b. 80 %
c. 40 %
d. 10 %.

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Q5. What is the voltage across the second unit from the top in case of a suspension type insulator?

a. V₂ = V₁ (3 + 4K)
b. V₂ = V₁ (1 + K)
c. V₂ = V₁ (1 + K²)
d. None of these.

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Q6. Voltage across the string is ___________ times the line voltage.

a. √3
b. √2
c. 1 / √3
d. 1 / √2

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Q8. A 3 phase over head transmission line is supported by three discs of suspension insulators. The potentials across the first and second insulator are 8 and 11 kV respectively. What is the line voltage and string efficiency?

a. 0.654 and 63.5%
b. 0.375 and 68.3 %
c. 0.527 and 56.34 %
d. 0.287 and 65.258 %

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