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Overhead Lines Insulator MCQ Questions & Answers

Overhead Lines Insulator MCQs : This section focuses on the "Overhead Lines Insulator". These Multiple Choice Questions (MCQs) should be practiced to improve the Overhead Lines Insulator skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

A suspension string have 3 units. Voltage across topmost and lower most unit of string are 6.71 volts and 11 volts respectively. What is the voltage across middle string, if voltage across whole string is 25.76 volts?

A. 103.47 volts
B. 8.05 volts
C. 83.6 volts
D. 25.76 volts

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Question 2

A transmission line consists of 9 discs of suspension insulator in each string. What is the operating voltage of the transmission line?

A. 11 KV
B. 33 KV
C. 66 KV
D. 132 KV

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Question 3

Arcing horns are used for ______________

A. protecting insulators from birds
B. protecting insulators from cracking or breaking due to flash over
C. improving string efficiency
D. protecting insulator from deposition of dirt

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Question 4

By using which of the following method hundred percent string efficiency can be achieved?

A. Using long cross arms
B. Capacitance grading
C. Static shielding
D. 100% string efficiency cannot be achieved

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Question 5

If a string of suspension insulator has three units, each can withstand a maximum 11 KV and total string can withstand 25.76 KV. What is the string efficiency?

A. 234.10%
B. 46.30%
C. 68.75%
D. 78%

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Question 6

If voltage across lowermost unit of a string is 34.8% of voltage across whole string and string efficiency is 57.46%. What is the voltage across whole string.

A. 100%of line voltage
B. 43.64% of line voltage
C. 75.2% of line voltage
D. 92.26% of line voltage

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Question 7

Glass insulator cannot be used for voltage above __________

A. 25 KV
B. 11 KV
C. 33 KV
D. 50 KV

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Question 8

Suspension insulator are made up of _____________

A. glass
B. porcelain
C. steatite
D. epoxy resin

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Question 9

Pin type insulator are mostly subjected to which type of mechanical stress?

A. Compressive stress
B. Tensile stress
C. Both tensile and compressive stress
D. Twisting stress

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Question 10

The unequal voltage distribution across individual unit of string of suspension insulator is __________

A. desirable and expressed by string efficiency
B. undesirable and expressed by string efficiency
C. desirable and expressed by impulse ratio
D. undesirable and expressed by impulse ratio

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Question 11

Voltage distribution across disc of strings of suspension insulator assembly is ______

A. same for all disks
B. maximum for unit nearest to the line
C. maximum for unit nearest to the tower
D. equal to transmission line voltage rating

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Question 12

What is the effect of rain on string efficiency?

A. It becomes very low
B. It reduces slightly
C. It does not changes
D. It is improved

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Question 13

What is the most common cause of failure of overhead line insulators?

A. Flashover
B. Mechanical stress
C. Porosity of materials
D. Improper vitrification

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Question 14

What is the reason for unequal distribution of voltage among different unit of suspension insulator?

A. Unequal capacitance of different units
B. Unequal distribution of charging current caused by stray capacitance
C. Unequal resistivity of different units
D. Dirt deposited over the insulator disc

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Question 15

Which of the following insulator is similar to pin type insulator?

A. Suspension insulator
B. Post insulator
C. Strain insulator
D. Shackle insulator

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Question 16

Which of the following insulator is used for insulating stay wire from pole?

A. Pin type insulator
B. Shackle insulator
C. Suspension insulator
D. Stay insulator

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Question 17

Which of the following is the main field of application of pin type insulator?

A. Distribution system
B. Transmission system
C. Transmission and distribution system
D. EHV transmission system

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Question 18

Which of the following location is suitable to use shackle insulator?

A. Sharp Turn in transmission line
B. Dead end of low voltage distribution line
C. For bearing High Voltage transmission line conductor
D. Dead end of EHV transmission line

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Question 19

Which of the following material is not used for overhead line insulators?

A. Porcelain
B. Glass
C. PVC
D. Steatite

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Question 20

Which type of insulator is used where there is dead end of the line or there is a corner or a sharp curve, for high voltage line?

A. Pin type insulator
B. Shackle insulator
C. Strain insulator
D. Stay insulator

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