Some of the questions personal interviews
Some of the questions personal interviews
1 -- Why cables are not used for
long distance
transmission?
Cables are not used for long
distance transmissions due to their large charging currents.
2 -- Mention the 3 main parts of
the cable?
Conductor, dielectric, sheath
3 -- What is the function of
conductor?
Conductor provides the conducting
path for the current.
4 - .What is the function of
sheath in cables?
The sheath does not allow the
moisture to enter and protects the cable from all external influences like
chemical or electrochemical attack, fire etc.
5 -- Mention the conductor
materials in cables?
Copper, Aluminium
All occupies greater space than copper for a given conductance.
Both are high electrical conductivity.
All occupies greater space than copper for a given conductance.
Both are high electrical conductivity.
6 -- What is the purpose of
stranding of conductors?
Stranding increases the cable. It
has flexibility. Resistance of the
7 -- Define the segmental
conductors.
The stranded wires which are
compacted by the rollers to minimize the air spaces between the individual
wires are called segmented conductors. Here the conductor size is reduced for a
given conductance.
8. State the properties of
insulating materials.
It should have high insulation
resistance, high dielectric strength, and good mechanical properties,
non-hygroscopic, capable of being operated at high temperatures, low thermal
resistance and low power factor.
9. Mention the commonly used
power cables.
Impregnated paper, Polyvinyl
chloride, polyethylene
10. Mention the advantages of PVC
over paper insulated cables.
Reduced cost and weight,
Insulation is resistant to water, Simplified jointing, increased flexibility No
plumbing required.
11. State the merits of paper
insulated cables.
High current carrying capacity,
long life and greater reliability
12. Where polythene cables are
used?
-being non-hygroscopic used in
cables for submarines and damp soil.
- being lighter used as aerial cables for vertical installations.
- being lighter used as aerial cables for vertical installations.
13. State the advantages of
polythene insulators.
They are non-hygroscopic, light
in weight, low dielectric constant, low loss factor and low thermal resistance.
14. By what materials cable
sheaths are made?
Lead sheaths and Aluminums
sheaths.
15. In what way Al sheaths are
superior to lead sheaths?
Al sheaths are smaller in weight,
high mechanical strength, greater conducyivity, cheap, easy to manufacture and
install, withstands the required gas pressure without reinforcement.
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