- In a star-delta transformer, the delta side phase voltage leads the star sides phase voltage by an angle + 30°.
- The phase shift is the angular displacement between the maximum positive value of the alternating quantities having the same frequency.
- In other words, the angular displacement between high voltage and the low voltage terminal and the corresponding neutral points (real or imaginary), expressed with reference to high voltage side is known as phase displacement (or shift) of the transformer.
1. Under overexcitation synchronous phase modifier works as
2. The neutral of the power system may be connected to earth
3. A 100 Ah capacity battery should deliver a current of 10 A for approximately _____ hrs.
4. For the 400KV line, The Spacing Between phase conductors is around
5. Shunt capacitors in a sub-station
6. An alternator is said to be over-excited when it is operating at
7. Series capacitors are used to
8. Disadvantage of low power factor is
9. The color of neutral three core flexible cable is
10. The location of ground faults in underground cables can be found by
11. Fault location in an HV cable is done by
13. Which of the following is not a valid advantage of bundle conductor?
14. The surge resistance of cables is
15. Skin effect is only noticeable at _______ frequencies.
16. When transmission voltage is increased, the line losses are
17. Var compensators are used to
18. High voltage transmission lines use
19. The material used for insulators are
20. Isolator in substation is open under ------------- condition?
21. The surge impedance value of overhead lines is
22. Surge impedance loading of a transmission line is also known as
23. Cables used for underground services from 33 kV to 60 kV are
24. The minimum clearance distance that equipment should be kept away from 50 kV power lines is
25. The cheap and temporary system of the internal wiring is?
27. To improve power factor and feeder voltage controller, which compensation is required
28. Method of voltage control adopted for transmission lines in AC systems is
29. The skin effect in a transmission line is affected by
30. What is the result of the Skin Effect?
31. Transmission efficiency increases as
32. An isolator in Hv substation is used for
33. For a short tie line fed at both end , what is the best choice of protection?
34. For protection of transformer, restraint used to guard against
36. Pin insulators are used up to voltage of about
37. Corona effect can be detected by
39. The effect of wind pressure is more predominant on
40. Transposition of the transmission line is adopted to make ......... uniform throughout the line.
41. The Power Transmitted will be maximum when
42. In a substation the equipment used to limit short circuit current level is
43. In order to increase the limit of the distance of transmission line
44. In series R - L - C circuit the condition for resonance is
45. The most commonly used method for the protection of three phase feeder is
46. Power station and substations are protected against Direct strokes lightning using
48. Simultaneous tripping of the circuit breaker at both ends of transmission line is achieved by
49. Interposing current transformer is used in differential protection of a transformer to
50. The magnitude of generator earth fault current is limited by
51. A wire pilot is Generally economical for distance up to
52. An overhead transmission line is provided with earth wire for protection against
55. The statutory limit for voltage variation at the consumer's terminal is
56. A line from which loads are tapped off is called
57. The bulk power consumers are supplied at
58. By which of the following a bus-bar is rated?
60. By which of the following systems electric power may be transmitted?
Transformer Most asked Mcqs With Full Explanation and Exam Notes
1. The secondary winding of which of the following transformers is always kept closed?
3. Star-star power transformer is protected by current transformer having
4. In the case of transformer Buchholz relay is used to protect from
5. During short-circuit test of transformer, which winding of transformer is short-circuited
6. Natural air cooling is usually restricted for transformers up to
7. The distribution transformer is rated in
8. A core type transformer provides
9. The temperature rise of transformer is directly proportional to
10. When secondary of the transformer is short-circuited, the primary inductance
11. With the increase in load, the eddy current
28. The rate of rise of re-striking voltage is dependent upon
29. The time to open the circuit breaker contact is called as
30 . Earthing switch is used for
31. A thermal protection relay provides protection against what?
31. Mho relays are used for the protection of which of the following lines?
34. If sag in an overhead line increases, the tension in the line
More Earthing MCQs with Full Explanation and Important Notes
1. The neutral of the power system may be connected to the earth
2. Grounding of substation provides
3. Earthing is necessary to give protection against
4. Standard wire gauge used for earthing lead should not be thinner than
5. What should be the value of earthing resistance for large power stations?
6. The earthing wire should have
7. The size of the earth wire is determined by
8. The minimum length of pipe electrode used for earthing should not be less than
10. Earth resistance in a typical domestic wiring is
11. From the point of view of safety, the resistance of the earthing electrode should be
Induction Motor Most asked MCQs with Full Explanations and Exam Notes
1. If frequency of 3-phase supply to the stator of 3-phase induction motor is increased. What happens to synchronous speed. It