Download PDF
Free download in PDF Underground Cables Multiple Choice Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
(1)
The insulating material for a cable should have
[A]
high mechanical strength
[B]
low cost
[C]
high dielectric strength
[D]
all of the above
(2)
Which of the following insulation is used in cables ?
[A]
Paper
[B]
Varnished cambric
[C]
Rubber
[D]
Any of the above
(3)
In a cable immediately above metallic sheath _____ is provided.
[A]
Armouring
[B]
Earthing Connection
[C]
Bedding
[D]
None Of The Above
(4)
In single core cables armouring is not done to
[A]
avoid excessive sheath losses
[B]
make it flexible
[C]
either of the above
[D]
none of the above
Answer: avoid excessive sheath losses
(5)
Dielectric strength of rubber is around
[A]
200 kV/mm
[B]
30 kV/mm
[C]
5 kV/mm
[D]
15 kV/mm
(6)
PVC stands for
[A]
post varnish conductor
[B]
positive voltage conductor
[C]
polyvinyl chloride
[D]
None of the above
Answer: polyvinyl chloride
(7)
In the cables, the location of fault is usually found out by comparing
[A]
the inductance of conductors
[B]
the capacitances of insulated conductors
[C]
the resistance of the conductor
[D]
all above parameters
Answer: the capacitances of insulated conductors
(8)
The relative permittivity of rubber is
[A]
between 2 and 3
[B]
between 5 and 6
[C]
between 8 and 10
[D]
between 12 and 14
(9)
Solid type cables are considered unreliable beyond 66 kV because
[A]
there is a danger of breakdown of insulation due to the presence of voids
[B]
of corona loss between conductor and sheath material
[C]
insulation may melt due to higher temperature
[D]
skin effect dominates on the conductor
Answer: there is a danger of breakdown of insulation due to the presence of voids
(10)
In cables the charging current
[A]
leads the voltage by 90°
[B]
leads the voltage by 180°
[C]
lags the voltage by 90°
[D]
lags the voltage by 180°
Answer: leads the voltage by 90°
(11)
In the cables, sheaths are used to
[A]
prevent the moisture from entering the cable
[B]
provide proper insulation
[C]
provide enough strength
[D]
None Of The Above
Answer: prevent the moisture from entering the cable
(12)
In a cable the voltage stress is maximum at
[A]
core of the conductor
[B]
surface of the conductor
[C]
sheath
[D]
insulator
Answer: core of the conductor
(13)
Underground cables are laid at sufficient depth
[A]
to avoid being unearthed easily due to removal of soil
[B]
to minimise the effect of shocks and vibrations due to gassing vehicles, etc.
[C]
for all of the above reasons
[D]
to minimise temperature stresses
Answer: to minimise the effect of shocks and vibrations due to gassing vehicles, etc.
(14)
The thickness of metallic shielding on cables is usually
[A]
0.04 mm
[B]
40 to 60 mm
[C]
0.2 to 0.4 mm
[D]
None Of The Above
(15)
The underground system is ...........costly then the equivalent overhead line system
[A]
Greater than
[B]
Less
[C]
More
[D]
Same
(16)
Metallic shielding is provided on underground cables to
[A]
Control the electrostatic voltage stress
[B]
Reduce thermal resistance
[C]
Reduce corona effect
[D]
All of the above
(17)
The materials used for armouring of an underground cable is
[A]
Galvanised steel wire
[B]
Steel tape
[C]
Aluminium
[D]
Either A or B
(18)
In underground cables the electrostatic stress is
[A]
Zerothe contactor as well as on the sheath
[B]
Minimum at contactor surface and maximum at the sheath
[C]
Maximum at contactor surface and minimum at the sheath
[D]
Same at the conductor and sheath
Answer: Maximum at contactor surface and minimum at the sheath
(19)
Underground cables are laid at sufficient depth so as to
[A]
Minimise temperature stresses
[B]
Minimise effects of shocks and vibrations owing to passing vehicles etc.
[C]
Avoid being unearthed easily owing to removal of soil
[D]
Both A and C
Answer: Minimise effects of shocks and vibrations owing to passing vehicles etc.
(20)
A layer similar to bedding is provided on the armouring to protect the whole cable from all atmospheric conditions. Which layer is this?
[A]
Serving.
[B]
Sheath
[C]
Insulation
[D]
A layer of jute
Take Mock Tests