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Free download in PDF 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)
The electrostatic stress in underground cables is
[A]
same at the conductor and the sheath
[B]
minimum at the conductor and maximum at the sheath
[C]
maximum at the conductor and minimum at the sheath
[D]
zero at the conductor as well as on the sheath
Answer: maximum at the conductor and minimum at the sheath
(22)
The insulation of the cable decreases with
[A]
the increase in length of the insulation
[B]
the decrease in the length of the insulation
[C]
either (a) or (b)
[D]
none of the above
Answer: the increase in length of the insulation
(23)
A cable carrying alternating current has
[A]
hysteresis losses only
[B]
hysteresis and leakage losses only
[C]
hysteresis, leakage and copper losses only
[D]
hysteresis, leakage, copper and friction losses
Answer: hysteresis and leakage losses only
(24)
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
(25)
In case of three core flexible cable the colour of the neutral is
[A]
blue
[B]
black
[C]
brown
[D]
none of the above
(26)
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
(27)
Cables for 220 kV lines are invariably
[A]
mica insulated
[B]
paper insulated
[C]
compressed oil or compressed gas insulated
[D]
rubber insulated
Answer: compressed oil or compressed gas insulated
(28)
Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ?
[A]
Polyvinyle chloride
[B]
Vulcanised rubber
[C]
Impregnated paper
[D]
Compressed SFe gas
Answer: Compressed SFe gas
(29)
Copper as conductor for cables is used as
[A]
annealed
[B]
hardened and tempered
[C]
hard drawn
[D]
None of the Above
(30)
The insulating material should have
[A]
low permittivity
[B]
high resistivity
[C]
high dielectric strength
[D]
all of the above
31
The advantage of oil filled cables is
[A]
more perfect impregnation
[B]
smaller overall size
[C]
no ionisation, oxidation and formation of voids
[D]
all of the above
32
The disadvantage with paper as insulating material is
[A]
it is hygroscopic
[B]
it has high capacitance
[C]
it is an organic material
[D]
none of the above
Answer: it is hygroscopic
33
The breakdown voltage of a cable depends on
[A]
presence of moisture
[B]
working temperature
[C]
time of application of the voltage
[D]
all of the above
34
If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be
[A]
2 cm
[B]
10 cm
[C]
50 cm
[D]
400 cm
35
Underground cables are laid at sufficient depth
[A]
to minimise temperature stresses
[B]
to avoid being unearthed easily due to removal of soil
[C]
to minimise the effect of shocks and vibrations due to gassing vehicles, etc
[D]
for all of the above reasons
Answer: to minimise the effect of shocks and vibrations due to gassing vehicles, etc
36
The thickness of metallic shielding on cables is usually
[A]
0.04 mm
[B]
0.2 to 0.4 mm
[C]
3 to 5 mm
[D]
40 to 60 mm
37
In a cable the voltage stress is maximum at
[A]
sheath
[B]
insulator
[C]
surface of the conductor
[D]
core of the conductor
Answer: core of the conductor
38
In the cables, sheaths are used to
[A]
prevent the moisture from entering the cable
[B]
provide enough strength
[C]
provide proper insulation
[D]
none of the above
Answer: prevent the moisture from entering the cable
39
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 of the above
40
Cables, generally used beyond 66 kV are
[A]
oil filled
[B]
S.L. type
[C]
belted
[D]
armoured
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