# Chapter 3 : Electromagnetism

1. Scalar or dot product and B indicated by A of two vectors A(Sin B) of Where is the angle between the vector A

AB sin

2. Vector or cross product of two vectors A and B indicated by A X B equals where is the angle between the two vectors A and B

AB sin

3. Line integral around a closed path is

A.

4. Surface integral of a surface is

5. Volume integral of a volume is

...

6. D . (V x A) is equal to

7. Electric flux inside a conducting spere is

8.. Electric field on equipotential surface is

A.

9. Surface integral of the electric intensity is

10. Displacement density D and electric field strength E are related by

/

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# Chapter 5 : Harmonics and Transients

41. Harmonics in transformer result in

42. Which fractional pitch will eliminate the seventh harmonic from the voltage waveform of an alternator?

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# Chapter 5 : Harmonics and Transients

31. The magnetising-inrush-current in a transformer is rich in

32. The in-rush current of a transformer at no load is maximum if the supply voltage is switched on

33.  Pure inductive circuit takes power (reactive) from the a.c. line when

Both (b) & (c)

34. With 100% series compensation of lines

35. In a pure LC parallel circuit under resonance condition, current drawn from the supply mains is

...

36.  While rising and falling if a wave is not symmetrical, it contains

37. The main reason for generation of harmonics in a transformer could be

38. While rising and while falling, if a wave is symmetrical, it contains

A.

39. The principal information obtained from load flow studies in a power system are 1. magnitude and phase angle of the voltage at each bus. 2. reactive and real power flows in each of lines. 3. total power loss in the network. 4. Transient stability limit of the system Select the correct answer from the codes given below

40. Shunt compensation in an EHV line is used to improve

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# Chapter 5 : Harmonics and Transients

21. The positive sequency component of voltage at the point of fault is zero when it is a :

22. A wave-trap is used at the termination of a HVAC overhead line to a station switchyard to

23.  Transient current in electrical circuits are associated with

9 × 108 metre/sec
108 metre/sec

24. Earth wire on EHV overhead transmission line is provided to protect the line against

25. One current transformer (CT) is mounted over a 3-phase 3-core cable with its sheath and armour removed from the portion covered by the CT. An ammeter placed in the CT secondary would measure

...

26.  Consider the following statements : The transient stability of the power system under unbalanced fault conditions can be effectively improved by 1. Excitation control 2. phase-shifting transformer 3. single-pole switching of circuit breakers 4. increasing the turbine input. Of these statements

A.

27. Lightning arresters are used in power systems to protect electrical equipments against

28. A lightning arrestor connected between the line and earth in a power system

A.

29. Tick out the correct statement :

30. The order of the lightning discharge current is :

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# Chapter 5 : Harmonics and Transients

11. In an R-L circuit connected to an alternating sinusoidal voltage, size of transient current primarily depends on

12. The transients which are produced due to sudden but energetic changes from one steady state of a circuit to another are called transients.

13.  Transient current in electrical circuits are associated with

14. There are no transients in pure resistive circuits because they

A.

15. For measuring positive, negative and zero sequence voltages in a system, the reference is taken as :

...

16.  The most economic load on an underground cable is :

A.

17. In case of a 3-phase short circuit is a system, the power fed into the system is

18. If cc is the angle of voltage wave at which an R-L circuit is switched in and 0 is the impedance angle of the R-L circuit, there will be no transient when the circuit is switched in, if:

A.

19. An RLC series circuit remains predominantly inductive

20. A generator is connected to a synchronous motor. From stability point of view it is preferable to have

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# Chapter 5 : Harmonics and Transients

1. Non-sinusoidal waveforms are made of

2. The positive and negative halves of a complex wave are symmetrical when

3.  The rms value of the complex voltage given by v = 162 sinωt + 12 sin 3ωt is

4. In a 3-phase system,the harmonic has negative phase sequence of RBY.

5. Two complex waves will have the same wave-shape if

...

6.  The trigonometric Fourier series for a complex wave will contain positive cosine terms only when

7. Transient current in an R-L-C circuit is oscillatory when

R=0R=2√L/C

8. The transient current in a loss-free L-C circuit when excited from an ac source is a/an sine wave.

A.

9. Double-energy transients are produced in circuits consisting of

10.Tansient disturbance is produced in a circuit whenever

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