MCQs of Underground Cables (Power System - I - 3140914)

Showing 51 to 60 out of 112 Questions

51.

Power factor of an open-ended cable can be improved by

(a)	Increasing the capacitance
(b)	Decreasing the capacitance
(c)	Increasing the conductor resistance
(d)	Increasing the insulation resistance

52.

The capacitance of a cable increases

(a)	Linearly with the increase in cable length
(b)	Linearly with the decrease in cable length
(c)	Exponentially with the increase in cable length
(d)	None of above

53.

The capacitance of a cable depends upon

(a)	The length of the cable
(b)	Relative permittivity of dielectric used in cable
(c)	Ratio of sheath diameter and core diameter
(d)	All of above

54.

The charging current drawn by the cable

55.

In the underground cables, electrostatic stress is

(a)	Maximum at conductor surface and minimum at the sheath
(b)	Minimum at conductor surface and maximum at the sheath
(c)	Same at the conductor and sheath
(d)	Zero at the conductor as well as on the sheath

56.

In a cable of conductor diameter d and overall diameter with dielectric material D, the maximum dielectric stress

(a)	Occurs at the conductor surface and is proportional to d
(b)	Occurs at the conductor surface and is proportional to 1/d
(c)	Occurs at the middle of dielectric and is proportional to 1/D
(d)	Occurs at the outer surface of dielectric and is proportional to D

57.

To obtain the minimum value of stress in cables, the ratio (R/r) should be

58.

The Surge impedance of 50 miles long underground cable is 50Ω. For a 25 miles length it will be

59.

The breakdown of insulation of a cable can be avoided economically by using

(a)	Insulation layer of different dielectrics
(b)	Inter sheath
(c)	Either (a) or (b)
(d)	None of above

60.

In capacitance grading of cables, the dielectric used is

Showing 51 to 60 out of 112 Questions