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.

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.

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.