Cables Multiple Choice Questions And Answers In English -2

1. High tension cables are generally used up to
(A) 11kV
(B) 33kV
(C) 66 kV
(D) 132 kV
Ans: A

2. PVC stands for
(A) polyvinyl chloride
(B) post varnish conductor
(C) pressed and varnished cloth
(D) positive voltage conductor
(e) none of the above
Ans: A

3. If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be
(A) 5 kV/mm
(B) 10 kV/mm
(A) 15 kV/mm
(D) 30 kV/mm
Ans: B

4. In the cables, sheaths are used to
(A) prevent the moisture from entering the cable
(B) provide enough strength
(e) provide proper insulation
(D) none of the above
Ans: A

5. Solid type cables are considered unreliable beyond 66 kV because
(A) insulation may melt due to higher temperature
(B) skin effect dominates on the conductor
(C) of corona loss between conductor and sheath material
(D) there is a danger of breakdown of insulation due to the presence of voids
Ans: D

6. If the length of a cable is doubled, its capacitance
(A) becomes one-fourth
(B) becomes one-half
(C) becomes double
(D) remains unchanged
Ans: C

7. The material for armouring on cable is usually
(A) steel tape
(B) galvanised steel wire
(C) any of the above
(D) none of the above
Ans: C

8. Cables, generally used beyond 66 kV are
(A) oil filled
(B) S.L. type
(C) belted
(D) armoured
Ans: A

9. 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
Ans: D

10. 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
Ans: C

11. In cables the charging current
(A) lags the voltage by 90°
(B) leads the voltage by 90°
(C) lags the voltage by 180°
(D) leads the voltage by 180°
Ans: B

12. 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
(6) double
(C) four times
(D) none of the above
Ans: A

13. The intersheaths in the cables are used to
(A) minimize the stress
(B) avoid the requirement of good insulation
(C) provide proper stress distribution
(D) none of the above
Ans: C

14. 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
Ans: C

15. The breakdown of insulation of the cable can be avoided economically by the use of
(A) inter-sheaths
(B) insulating materials with different dielectric constants
(C) both (A) and (B)
(D) none of the above
Ans: C

16. 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
Ans: A

17. Cables for 220 kV lines are invariably
(A) mica insulated
(B) paper insulated
(C) compressed oil or compressed gas insulated
(D) rubber insulated
Ans: C

18. 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 SF6 gas
Ans: D

19. The insulating material should have
(A) low permittivity
(B) high resistivity
(C) high dielectric strength
(D) all of the above
Ans: D

20. 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
Ans: D