Power System - I (3140914) MCQs

MCQs of Underground Cables

Showing 101 to 110 out of 112 Questions
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101.
If r is the radius of the conductor and R the radius of the sheath of the cable, the cable operates stably from the view point of dielectric strength if
(a) r/R > 1.0
(b) r/R < 1.0
(c) r/R < 0.632r
(d) r/R < 0.368
Answer:

Option (d)

102.
Three insulating materials with same maximum working stress and permittivity 2.5, 3.0, 4.0 are used in a single core cable. The location of the materials with respect to the core of the cable will be
(a) 2.5, 3.0, 4.0
(b) 3.0, 2.5, 4.0
(c) 4.0, 3.0, 2.5
(d) 4.0, 2.5, 3.0.
Answer:

Option (c)

103.
Three insulating materials with breakdown strengths of 250 kV/cm, 200 kV/cm, 150 kV/cm and permittivity of 2.5, 3.0 and 3.5 are used in a single core cable. If the factor of safety for the materials is 5, the location of the materials with respect to the core of the cable will be
(a) 2.5, 3.0, 3.5
(b) 3.0, 2.5, 3.5
(c) 3.5, 3.0, 2.5
(d) 3.5, 2.5, 3.0.
Answer:

Option (a)

104.
The insulation resistance of a cable of length 10 km is 1 MΩ, its resistance for 50 km length will be
(a) 1 MΩ
(b) 5 MΩ
(c) 0.2 MΩ
(d) None of the above
Answer:

Option (c)

105.
The capacitance of a 3-core cable between any two conductors with sheath earthed is 2 μF. The capacitance per phase will be
(a) 1 μF
(b) 4 μF
(c) 0.667 μF
(d) 1.414 μF
Answer:

Option (b)

106.
If δ is the loss angle of the cable, its power factor is
(a) sin δ
(b) cos δ
(c) Power factor is independent of δ
(d) Power factor depends upon δ but it is not as per (a) and (b)
Answer:

Option (a)

107.
The effect of bonding the cable is
(a) To increase the effective resistance and inductance
(b) To increase the effective resistance but reduce inductance
(c) To decrease the effective resistance and inductance
(d) To decrease the effective resistance but increase the inductance
Answer:

Option (b)

108.
In order to eliminate sheath losses, a successful method is
(a) To transpose the cable along with cross bonding
(b) Transpose the cables only
(c) Cross bonding the cables is enough
(d) None of the above is effective
Answer:

Option (a)

109.
In a three phase EHV cable, a metallic screen around each core insulation is provided to
(a) Facilitate heat dissipation
(b) Give mechanical strength
(c) Obtain radial electric stress
(d) Obtain longitudinal electric stress
Answer:

Option (c)

110.
The insulation resistance of a 20 km long underground cable is 8 MΩ. Other things being the same, the insulation resistance of a 10 km long cable will be
(a) 16 MΩ
(b) 32 MΩ
(c) 4 MΩ
(d) 2 MΩ
Answer:

Option (a)

Showing 101 to 110 out of 112 Questions
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