Transmission and distribution mcq - electrical Multiple Choice Questions - Electrical input

## Sunday, August 5, 2018

Transmission and distribution mcq

transmission and distribution electrical Multiple Choice Questions :-

1. The usual spans with R.C.C. poles are -
(a) 30—40 meters
(b) 90—100 meters
(c) 80—100 meters
(d) 400—500 meters
Ans: c
2. Which of the following materials is not used for transmission and
distribution of electrical power ?

(b) Aluminium
(c) Nickel
(d) Tungsten
Ans: d

3. The wooden poles well impregnated with creosite oil or any preservativecompound have life-----
(a) from 5 to 8 years
(b) 25 to 30 years
(c) 10 to 30 years
(d) 50 to 70 years
Ans: b

4.  If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to the annual cost of electrical energy wasted in the conductors the total annual cost will be minimum and the corresponding sizeof conductor will be most economical. This statement is known as –
(a) Lenz'z law
(b) Ohm’s law
(c) Kirchhoffs law
(d) Kelvin’s law
Ans:- d

5.  By which of the following systems electric power may be transmitted?
(a) Underground system
(c) only (b)
(d)  both (a) and (b)
Ans- d

6. The underground system cannot be operated above
(a) 66 V
(b)132kV
(c) 11 kV
(d)33kV
Ans:- a

7. Overhead system can be designed for operation up to
(a)132kV
(b)11 kV
(c) 66 kV
(d) 400 kV
Ans:- write  in  comment  box

8. 310 km line is considered as
(a) a short line
(b) a medium line
(c) a long line
(d) none of the above
Ans: c

9. Which of the following are the constants of the transmission lines----
(a) Resistance
(b) Inductance
(c) Capacitance
(d) none of the above
Ans: d

10. The corona is affected by which of the following?
(a) Size of the conductor
(b) Shape of the conductor
(c) Surface condition of the conductor
(d) All of the above
Ans: d

11. Galvanised steel wire is  used as -
(a) stay wire
(b) earth wire
(c) structural components
(d) All of the above
Ans:- d

12. The square root of the ratio of line impedance and shunt admittance is called
(a)  conductance of the line
(b) surge impedance of the line
(c) regulation of the line
(d) all of the above
Ans: b

13. The phenomenon qf rise in voltage at the receiving end of the open-circuited or lightly loaded line is called
(a)  Ferranti effect
(b) Doppler  effect
(c) Raman effect
(d) all of the above
Ans:- a

14.  conductors, which connect the consumer’s terminals to the distribution
(a) Feeders
(b) Distributors
(c) Service mains
(d) None of the above
Ans:c

15. The operating voltage of supertension cables is up to
(a) 1.1 kV
(b) 6.6 kV
(c) 33 kV
(d) 11 kV
Ans:- c

16. Which of the following methods is used for laying of underground cables
(a) Solid system
(b)Direct laying
(c) Draw-in-system
(d) All of the above
Ans: d

17. The operating voltage of extra high tension cables is upto
(a) 6.6 kV
(b) 66 kV
(c) 33 kV
(d) 132 kV
Ans: b

18. Which of the following is the source of heat generation in the cables
(a) Dielectric losses in cable insulation
(b) losses in the conductor
(c) Losses in the metallic sheathings and armourings
(d) All of the above
Ans: - write in comment box

19. Which of the following D.C. distribution system is the simplest and lowest in first cost?
(a) Ring system
(b) Inter-connected system
(d) None of the above
Ans:- a

20. A booster is a --
(a) synchronous generator
(b) shunt wound generator
(c) series wound generator
(d) All of the above
Ans: c

21. The voltage of the single phase supply to residential consumers is
(a) 200 V
(b) 120 V
(c) 440 V
(d) 230 V
Ans:- d

22. Which of the following faults is most likely to occur in cables
(a) Cross or short-circuit fault
(b) Open circuit fault
(c) Breakdown of cable insulation
(d) All of the above
Ans:  d

23. The distributors for residential areas are
(a) single phase
(b) three-phase four wire
(c) three-phase three wire
(d) all of the above
Ans: b

24. The cause of damage to the lead sheath of a cable is
(a) mechanical damage
(b)  chemical action on the lead when buried in the earth
(c)  crystallisation of the lead through vibration
(d) all of the above
Ans: d

25. The conductors of the overhead lines are
(a)  Stranded
(b)  Solid
(c) both solid and stranded
(d) all  of the above
Ans: a

26. Multicore cables generally use
(a) square conductors
(b) circular conductors
(c) sector-shaped conductors
(d)  rectangular conductors
Ans:- c

27. High voltage transmission lines use
(a)  pin insulators
(b)  suspension insulators
(c) both (a) and (b)
(d) all of the above
Ans:- b

28. The material commonly used for insulation in high voltage cables is
(a) paper
(b)  rubber
(d) graphite
Ans:- a

29. The loads on distributors systems are
(a) balanced
(b) unbalanced
(c) both balanced and unbalanced
(d) none of the above
Ans: b

(a) copper conductors
(b) All aluminium conductors
(c) Aluminium conductor steel-reinforcement
(d) Nickel coated copper
Ans: c

31. The power factor of industrial loads is generally
(a)   zero
(c)    unity
(d)   lagging
Ans:- d

32. Transmission line insulators are made of
(a) porcelain
(b) iron
(C) glass
(d) P.V.C.
Ans: a

33. The material generally used for armour of high voltage cables is
(a) copper
(b) brass
(c) aluminium
(d)  steel
Ans:- d

34. The minimum clearance between the ground and a 220 kV line is about
(a) 7.0m
(b) 7.5 m
(c) 8.0m
(d) 8.5 m
Ans: a

35. Large industrial consumers are supplied electrical energy at
(a) 132 kV
(b) 33 kV
(c) 400 kV
(d) 66 kV
Ans:- d

36. For an overhead line, the surge impedance is taken as
(a) 10-30 ohms
(b) 100—200 ohms
(c) 300—400 ohms
(d) 700—1000 ohms
Ans: b

37. A feeder, in a transmission system, feeds power to
(a) service mains
(b) generating stations
(c) distributors
(d) none of the above
Ans:- c

38. In aluminium conductors, steel core is provided to
(a) increase the tensile  strength
(b) reduce line inductance
(c ) compensate for skin effect
(d) neutralise proximity effect
Ans:- a

39. Aluminium has a specific gravity of
(a) 2.5
(b) 2.6
(c) 2.7
(d) 2.8
Ans:- c

40. Pin type insulators are generally not used for voltages beyond
(a) 33 kV
(b) 66 kV
(c) 132 kV
(d) 400 kV
Ans:- a

41. For transmission of power over a distance of 200 km, the transmission voltage should be
(a) 11 kV
(b) 33 kV
(c) 66 kV
(d) 132 kV
Ans:- d

42. Series capacitors on transmission lines are of little use when the load VAR requirement is
(a) small
(b) large
(c) fluctuating
(d) none of the above
Ans: a

43. When a conductor carries more current on the surface as compared to core, it is due to
(a) unsymmetrical fault
(b)  skin effect
(c) corona
(d) permeability variation
(e) all of the above
Ans:- b

44. The skin effect of a conductor will reduce as the
(a) frequency increases
(b) resistivity of conductor material increases
(c) diameter increases
(d) permeability of conductor material increases
Ans:- b

45. The angular displacement between two interconnected stations is mainly due
(a) reactance of the interconnector
(b) armature reactance of both alternators
(c) synchronous reactance of both the alternators
(d) none of the above
Ans: b

46.  When the interconnector between two stations has large reactance
(a)  the stations will fall out of step because of large angular displacement between the stations
(b)  the transfer of power will take place with voltage fluctuation and noise
(c)  the transfer of power will take place with least loss
(d) all of the above
Ans:- a

47. Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical
(a) Booster transformer
(b) Synchronous condenser
(c) Tap changing transformer
(d) Static condenser
Ans:- a

48. The current drawn by the line due to corona losses is
(a) non-sinusoidal
(b) sinusoidal
(c) triangular
(d) square
Ans:- a

49. Corona usually occurs when the electrostatic stress in air around the conductor exceeds
(a) 33 kV (r.m.s. value)/cm
(b) 11 kV (r.m.s. value)/cm
(c) 66 kV (maximum value)/cm
(d) 30 kV (maximum value)/cm
Ans: d

50. Which of the following characteristics should the line supports for transmission lines possess ------
(a) Low cost
(b) High mechanical strength
(c) Longer life
(d) all of the above
Ans:- d