Interview Questions.

Question 1. What Do You Mean By Underground Cable And Where Is It Used ?

Answer :

The cable buried in floor for transmission and distribution of electrical strength is referred to as underground cable. These are used in huge cities and different densely populated regions wherein overhead construction in such vicinity is nearly impossible.

Question 2. What Are The Advantages Of Used Cables For Transmission Of Electrical Power As Compared To Overhead Lines ?

Answer :

The advantages of the underground cable are as follows :-

Being exposed to ecosystem cables are loose from the interruptions of supply resulting from lightning or thunderstorm or birds or different extreme climate conditions.
It reduces twist of fate because of breaking of conductors.
Maintenance fee is low.
It does no longer damage the splendor of the cities.
These are very a good deal beneficial in densely populated areas.
Cable Gland Interview Questions
Question three. When Is A Cable Termed As L.T. Mains And L.T. Submains ?

Answer :

When a there segment, 4 center cable is used as a distributor it's far known as L.T. Mains and when a single segment two center cable is used as a distributor it's miles called L.T. Sub mains.

Question 4. What Are The Different Types Of Cables Used In Transmission & Distribution System ?

Answer :

For low & medium voltage lines P.V.C cables are used.
For excessive voltage strains XLPE and PILC cables are used.
For more excessive voltage strains XLPE, oil filled, gasoline crammed and gas stress or compression cables are used.
Question five. What Are The Classifications Of The Underground Cables According To The Voltage Range ?

Answer :

Low anxiety cables : (1) 250-440 volts (2) 650-1100 volts.
High anxiety cables : (1) upto 3.Three kV. (2) up to 6.6 kV (three) up to 11 kV.
Super tension cables : (1)66 kV. (2) 132 kV.
Extra high-quality voltage strength cables : above 132 kV.
Question 6. What Are The Full Names Of Pvc, Pilcswa, Pilcdsta & S, Xlpe And Mind Cables ?

Answer :

P.V.C. Cable: Poly Vinyl Chloride insulated cable.
P.I.L.C. Cable: Paper Insulated Covered cable.
P.I.L.C.S.W.A. Cable : Paper Insulated Lead Covered Steel Wire Armoured cable.
P.I.L.C.D.S.T.A. Cable: Paper Insulated Lead Covered Double Steel Tape Armoured cable.
XLPE cable: Cross Linked Polyethylene Insulated cable.
M.I.N.D. Cable : Mass Impregnated Non Draining cable.
Question 7. What Are The Essential Elements Of An Underground Cable ?

Answer :

The vital of an underground cable are the conductor, the insulation, the screening, the sheathing, the bedding, the protection and the serving.

Question 8. Why Are Stranded Conductors Used In The Cable Of Sizes Above 16 Sq Mm. ?

Answer :

Stranded conductors are used to growth the floor vicinity of the conductor and additionally to make the cable bendy and more plausible.

Question nine. What Are The Advantages Of Circular And Sector Shaped Conductor In Cable ?

Answer :

The interstices among the cores and common diameter are decreased.

Question 10. What Do You Mean By The Terms ‘the Nominal Cross Section’, ‘the Actual Cross Section’ And ‘the Equivalent Cross Section’ Of The Spiral Stranded Conductors Of A Cable ?

Answer :

The ordinary cross segment is the vicinity of the move section of 1 conductor in a plane perpendicular to its duration accelerated by means of the range of conductors.

The actual cross section is the area of the oblique go phase of a conductor produced by means of cutting the stranded conductor by way of a aircraft perpendicular to the middle of the cable improved through the range of conductors, which is also more than the nominal move phase.

The equal pass phase is the move section of a strong conductor of the equal period as the cable and having the same resistance at the same temperature, which is much less than the nominal pass section because of the incase in resistance because of spiraling.

Question 11. What Are The Insulating Materials Used In Underground Cable ?

Answer :

P.V.C. Impregnated paper, Vulcanized rubber, Varnished cambric are utilized in L.T. Cables at the same time as Impregnated paper, Cambric, XLPE are used in H.T. Cables.

Question 12. What Do You Mean By The Belt Paper Insulation ?

Answer :

Belt paper is an oil impregnated paper, the essential insulating part of the cable, which is essentially composed of cellulose fibres felted to from a robotically sturdy sheet.

Cable Gland Interview Questions
Question 13. What Is The Purpose Of Metallic Sheath In Underground Cable ?

Answer :

To shield the insulation against ingress of moisture.

Question 14. What Materials Are Generally Used For Metallic Sheath ?

Answer :

Lead, Lead alloy and Aluminium are normally used for metallic sheath.

Question 15. What Do You Mean By Bedding Of A Cable ?

Answer :

Bedding means a layer of compounded jute or hessian carried out over the lead sheath.

Question 16. Why Is A Layer Of Bedding Provided Over Metallic Sheath In Underground Cable ?

Answer :

To shield the steel sheath towards the corrosion and from mechanical damage from the armouring.

Question 17. What Do You Mean By The Armouring Of A Cable ?

Answer :

Armouring of a cable method the availability of layers of galvanized or galvanised metallic wires or metallic wires or metallic tapes over the bedding.

Question 18. Why Is Armouring Provided In Cable ? Under What Operating Conditions Unarmoured Cables Are Used ?

Answer :

Armouring is furnished to shield the cable in opposition to mechanical damages due to direct blows, abrasion, pink-axing, vibration and longitudinal stresses or any unintended digging. If there is no chance of mechanical damages whatsoever the unarmoured cables may be used.

Question 19. What Are The Different Types Of Armouring Used In Cable ?

Answer :

The distinctive styles of armouring are as follows :

Galvanised or ungalvanised metal tape
Galvanised spherical metal cord
Galvanised flat metallic strip and
Hare drawn aluminium cord armour.
Question 20. What Are The Merits And Demerits Of (a) Double Steel Tape Armour & (b) Single Wire Armour ?

Answer :

Double steel tape armour :

Merits : It is gives a great safety in opposition to effect, mechanical harm and any penetration of sharp bodies.

Demerits : It is inflexible. It has more loss in place of twine armour.

Single twine armour :

Merits : It is higher longitudinal energy, greater flexibility and more electric conductivity with minimum loss instead of metal tape armour. It may be without problems treated with brief bend.

Demerits : Mechanical protection is terrible in preference to steel tape armour.

Question 21. What Type Of Armour Will You Expect In A Single Core 11 Kv Cable ?

Answer :

Hard drawn aluminium cord armour is found.

Question 22. Why Can Wire Armoured Cables Take Bends Of Shorter Radius Than Tape Armoured Ones ?

Answer :

Wire armoured cables can take bends of shorter radius because of higher longitudinal power of cord armouring than that of tape armouring.

Question 23. What Are The Applications Of Single Steel Tape, Double Steel Tape, Singal Wire Armoured Ones ?

Answer :

Single metallic tape armouring:Single metallic tape armouring is used mainly for freeway cables, cables suspended on a messenger or clamped at durations in shaft and tunnel set up or cables buried immediately underground in which a mechanical outer safety is required however longitudinal are not involved.

Double metallic tape armouring: Double metallic tape armouring is used especially for low anxiety cables installed interior or aerially outside or at once buried underground wherein a terrific safety in opposition to crushing or penetration by using sharp bodies is needed and now not likely to be subjected to tensile stresses.

Single wire armouring: Single cord armouring is utilized in cables where the armouring is subjected to have longitudinal energy consisting of for cables pulled into duct, used for river crossing, laid in marshy ground or in colliery districts wherein soil subsidence may additionally arise, vertical cable runs and for cables held on brackets alongside facet railways or tunnels and so forth.

Double wire armouring: Double cord armouring is used chiefty for vertical run of large size cables as in a mine shaft, submarine or dredger wherein smooth handling and greater flexibility for the identical conductivity with excessive longitudinal energy is required.