Electrical questions, Written test technical questions

1. In treated Earth wire, Earth wire is treated with following things?

Ans. charcoal & salt

2. In one and a half bus bar system ___ no. of CBs are used in diameter?

Ans. 3

    

3. skewing in IM motor is for?

Ans. To reduce noise

    

4. In a core of Transformer, stamping is provided to reduce?

Ans. eddy current losses

5. p.f. variation of alternator is?

Ans. lagging to leading

     

6. In alternator for fix input if field excitation is increased then ?

Ans. active power increase

7. Gravel is provided in substation for?

Ans. to increase resistance between ground to worker's foot

8. The standard current rating of an electromagnetic relay are?
Ans. 1A and 5A

9. A distance relay is said to be inherently directional if its characteristics on R-X diagram?
Ans. is a circle that passes through the origin

10. Load flow study is carried for....
Ans. System Planning

11. The effect of ice deposition on conductor is...
Ans. Increased in Weight

12. At load bus in the power system, the quantities specified are..
Ans. P and Q

13. Purpose of back-up protection is?
Ans. To guard against failure of primary

14. The advantage of neutral earthing is...
 Ans. Elimination of arcing ground

15. Dielectric strength is normally expressed in?
Ans. kV/mm

16. Outdoor type switchgear is generally used for voltage beyond?
Ans. 66kV

17. Graphite is used in Nuclear power station as...
Ans. moderator

18. The motor used in celling fans is?
Ans. Capacitor Start motor

19. Which motor is used to start heavy loads?
Ans. Series motor

20. A Mho relay is a
Ans. Voltage restrained directional relay

21. The positive and negative sequence impedance of  transmission line are?
Ans. Equal

22. The insulation coordination for UHV lines (above 500 kV) is done based on?
Ans. Switching surges

23. Sequence operator is given by _______
Ans. 1 magnitude with angle 120

24. An ideal voltage source has zero _____
Ans. internal resistance

25. The capacity of a cell is measured in
Ans. ampere-hours

26. The maximum efficiency of a distribution transformer is
Ans. at 50% full load

27. Slip of the induction motor at starting is
Ans. one

28. Thermal relays are often used in
Ans. Motor starters

29. The surge  impedance of a 500 km long transmission line is 400 ohms. For 250 km length of same line the surge impedance will be.....
Ans. 400 ohms

30. protection by fuses is generally not used beyond
Ans. 200 Amp

31. In a step up transformer which ratio has value of one?
Ans. F2/F1 (F represents frequency)

32. In Scott connection, the neutral point divides the teaser winding in the ratio
Ans. 1:2


33. An exciter for an alternator is a small dc _______ generator.
Ans. Shunt or Compound

34. Rotor of an alternator has ________ slip ring.
Ans. 2

35. When the load (inductive) is thrown off, the terminal voltage will 
Ans. increase

36. The regulation of a synchronous motor is
Ans. 0%

37.  In a double cage induction motor the under cage has
Ans. Low R and High X

38. The slip in actual induction motor is generally
Ans. 3% to 5%

39. The shaft of an induction motor may be unbalanced due to
Ans. uneven air gap

40. The frequency of the induced e.m.f in the rotor circuit is maximum at
Ans. stand still

41. A terminal where three or more branches meet is known as
Ans. Node

42. The Super-position theorem is applicable to
Ans. Linear responses only

43. Fuse protection is used for current rating upto
Ans. 100 A

44. Which relay is used for feeders?
Ans. Translate relay

45. Solid grounding is used for voltages
Ans. below 660V

46. Extra high tension cables are meant for operation upto
Ans. 66kV

47. The current drawn by the line due to corona losses is
Ans. non-sinusoidal

48. Material generally used for bus bar is
Ans. aluminium

49. The protection against direct lighting stokes and high voltage steep waves is provided by
Ans. lighting arresters and ground wires

50. ACSR conductor having 7 steel stands surrounded by 25 aluminium conductors will be specified as
Ans. 25/7