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Free download in PDF Underground Cables Objective Type 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.
(21)
Why are the inter sheaths in cables used?
[A]
Provides proper stress distribution.
[B]
Minimises the stress.
[C]
Provides protection against moisture, current and voltage surges.
[D]
To improve the insulation.
Answer: Provides proper stress distribution.
(22)
Armouring is provided above the bedding. The armouring consists of one or two layers of which wire or tape?
[A]
Thin wires of copper.
[B]
Wire made of both copper and cadmium.
[C]
Galvanised steel wire.
[D]
Wires of aluminium.
Answer: Galvanised steel wire.
(23)
What is the purpose of bedding on the underground cables?
[A]
To avoid leakage of current.
[B]
To protect the sheath against corrosion.
[C]
To protect the sheath from mechanical injury due to armouring.
[D]
Both (b) and (c)
(24)
The breakdown voltage of a cable depends on
[A]
time of application of the voltage
[B]
working temperature
[C]
presence of moisture
[D]
all of the above
(25)
The disadvantage with paper as insulating material is
[A]
it is an organic material
[B]
it has high capacitance
[C]
it is hygroscopic
[D]
none of the above
Answer: it is hygroscopic
(26)
The advantage of oil filled cables is
[A]
no ionisation, oxidation and formation of voids
[B]
more perfect impregnation
[C]
smaller overall size
[D]
all of the above
(27)
The insulating material should have
[A]
high dielectric strength
[B]
low permittivity
[C]
high resistivity
[D]
all of the above
(28)
Copper as conductor for cables is used as
[A]
hard drawn
[B]
annealed
[C]
hardened and tempered
[D]
alloy with chromium
(29)
If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be
[A]
50 cm
[B]
10 cm
[C]
2 cm
[D]
400 cm
(30)
Cables for 220 kV lines are invariably
[A]
compressed oil or compressed gas insulated
[B]
paper insulated
[C]
mica insulated
[D]
none of the above
Answer: compressed oil or compressed gas insulated
31
The advantage of cables over overhead transmission lines is
[A]
easy maintenance
[B]
low cost
[C]
can be used in congested areas
[D]
can be used in high voltage circuits
Answer: can be used in congested areas
32
Capacitance grading of cable implies
[A]
use of dielectrics of different permeabilities
[B]
grading according to capacitance of cables per km length
[C]
cables using single dielectric in different concentrations
[D]
none of the above
Answer: use of dielectrics of different permeabilities
33
A cable carrying alternating current has
[A]
hysteresis and leakage losses only
[B]
hysteresis, leakage, copper and friction losses
[C]
hysteresis losses only
[D]
hysteresis, leakage and copper losses only
Answer: hysteresis and leakage losses only
34
The insulation of the cable decreases with
[A]
the decrease in the length of the insulation
[B]
the increase in length of the insulation
[C]
either (a) or (b)
[D]
none of the above
Answer: the increase in length of the insulation
35
The breakdown of insulation of the cable can be avoided economically by the use of
[A]
inter-sheaths
[B]
insulating materials with different dielectric constantswork
[C]
both (a) and (b)
[D]
none of the above
36
The electrostatic stress in underground cables is
[A]
maximum at the conductor and minimum at the sheath
[B]
minimum at the conductor and maximum at the sheath
[C]
same at the conductor and the sheath
[D]
none of the above
Answer: maximum at the conductor and minimum at the sheath
37
The intersheaths in the cables are used to
[A]
provide proper stress distributionformula
[B]
avoid the requirement of good insulation
[C]
minimize the stress
[D]
none of the above
Answer: provide proper stress distribution
38
A certain cable has an insulation of relative permittivity 4. If the insulation is replaced by one of relative permittivity 2, the capacitance of the cable will become
[A]
one half
[B]
double
[C]
four times
[D]
None
39
If the length of a cable is doubled, its capacitance
[A]
becomes double
[B]
becomes one-half
[C]
becomes one-fourth
[D]
remains unchanged
40
Cables, generally used beyond 66 kV are
[A]
oil filled
[B]
armoured
[C]
S.L. type
[D]
belted
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