MCQs of Mechanical Features and Design of Overhead Transmission Line (Power System - I - 3140914)

Power System - I (3140914) MCQs

MCQs of Mechanical Features and Design of Overhead Transmission Line

Showing 71 to 80 out of 108 Questions

71.

The non uniform distribution of voltage across the units in a string of suspension type insulator is due to

(a)	Unequal self-capacitance of the unit
(b)	Non-uniform distance of separation of the units from the tower body
(c)	Existence of stray capacitance between metallic junction of the units and tower body
(d)	Non uniform distance between the cross arms and the units

72.

Voltages across the various disc of string of suspension insulator having identical discs is different due to

(a)	Surface leakage current
(b)	Series capacitance
(c)	Shunt capacitance to ground
(d)	Series and shunt capacitance

73.

String efficiency of a string of suspension insulators is dependent on

(a)	Size of the insulators
(b)	Number of discs in string
(c)	Size of tower
(d)	All of above

74.

100% string efficiency means

(a)	One of the insulator discs is shorted
(b)	Zero potential across each insulator disc
(c)	Equal potential across each insulator disc
(d)	None of the above

75.

In a suspension type insulator potential difference is

(a)	Maximum across the lowest disc
(b)	Maximum across top most disc
(c)	Uniformly distributed over the disc
(d)	None of the above

76.

If the frequency of a transmission system is changed from 50 Hz to 100 Hz, the string efficiency

(a)	Increases
(b)	Decreases
(c)	Remains unchanged
(d)	May increase or decrease depending on line parameters

77.

String efficiency of a HV line is around

(a)	100%
(b)	80%
(c)	40%
(d)	10%

78.

66 kV system has string insulator having 5 disc and earth to disc capacitance ratio of 0.1. The string efficiency will be

(a)	89%
(b)	75%
(c)	67%
(d)	55%

79.

The string efficiency of insulators can be increased by

(a)	Reducing the number of strings
(b)	Increasing the number of strings
(c)	Correct grading of insulators of various capacitance
(d)	Changing the orientation of strings

80.

Consider the following statements: In the case of suspension type insulators, the string efficiency can be improved by
1. Using a longer cross-arm
2. Using a guard ring
3. Grading the insulator disc
4. Reducing the cross arm length

(a)	1, 2 and 3 are correct
(b)	2, 3 and 4 are correct
(c)	2 and 4 are correct
(d)	1 and 3 are correct

Showing 71 to 80 out of 108 Questions