electrical engineering MCQs – Page 237

Practise multiple-choice questions from electrical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

electrical engineering Mcqs

1. economics of power generation 2. analog electronics 3. solid state switching circuits 4. parallel circuits 5. switchgear and protection 6. op amp circuits 7. transistor audio power amplifiers 8. electrostatics 9. heating and welding 10. multi stage transistor amplifiers 11. passive filters 12. network theorems 13. regulated d c power supply 14. a c fundamentals circuits and circuit theory 15. electromagnetic induction 16. power electronics 17. magnetism and electromagnetism 18. transformers 19. modulation and demodulation 20. d c generators 21. semiconductor theory 22. single phase induction motors 23. semiconductor diode 24. hybrid parameters 25. digital electronics 26. oscillators 27. earthing or grounding 28. single stage transistor amplifiers 29. d c motors 30. transistor biasing 31. amplifiers with negative feedback 32. basic electrical 33. electronic instruments 34. synchronous motors 35. field effect transistors fet 36. magnetic circuit 37. control systems 38. industrial drives 39. power generation 40. series parallel circuits 41. transistor tuned amplifiers 42. electrical engineering materials 43. rectifiers and converters 44. integrated circuits 45. scr silicon controlled rectifiers 46. cables 47. polyphase induction motors 48. measurement and instrumentation 49. transistors 50. electrical machine design 51. electrolysis and storage of batteries 52. electric traction 53. transmission and distribution

4721. 4 thyristors rated 200 V in series. The operating voltage of the string is 600 V. Derating factor of the string is_____________________?
0

A. 0.2

B. 0.25

C. 0.7

D. 0.75

4722. Rise time is defined by the interval when____________?
0

A. gate current rises from 90 % to 100 % of it final value

B. anode voltage drops from 90 % to 10 % of its initial value

C. anode current rises 10 % to 90 % of its final value

D. both B and C

4723. CB used for over current protection of thyristor operates when the fault current is__________?
0

A. of long period

B. of short duration

C. both (A) and (B)

D. neither (A) nor (B)

4724. In forward blocking mode of a thyristor________?
0

A. Junction J1, J3 is in reverse bias and J2 is in forward bias.

B. junction J3 is in forward bias and J1, J2 is in reverse bias.

C. junction J2 is in reverse bias and J1, J3 is in forward bias.

D. Junction J1 and J2 is in forward bias and J3 is in reverse bias.

4725. In a 3 phase CSI, if the required line output voltages are balanced and 120 degree out of phase, then the chopping angles are used to eliminate only the harmonics at frequencies
0

A. All of these

B. 11

C. 5

D. 7

4726. Harmonics in 3 phase inverters can be reduced by using___________?
0

A. Passive filter

B. Active filter

C. Both passive and active filters

D. None of these

4727. In a flyback converter, the inductor of the buck-boost converter has been replaced by a_____________?
0

A. Flyback transistor

B. Flyback capacitor

C. Flyback resistor

D. Flyback transformer

4728. During gate recovery time_____________?
0

A. charge carriers of J3 junction is removed

B. charge carrier of J1 junction removed

C. charge carriers of J2 junction is swept out

D. charge carriers of J2 junction recombined

4729. The sum of all phase current in a star connected primary winding with no neutral connection is equal to___________?
0

A. Three times the line current

B. Zero at all times

C. Three times the phase current

D. Phase current

4730. Maximum power loss occurs during_________________?
0

A. rise time

B. all

C. delay time

D. spread time

4731. In ac dc conversion, when the switch is closed then the sum of voltages around the loop is____________?
0

A. Non zero

B. Zero

C. Twice of the voltage when switch is open

D. Equal to the sum of voltage when switch is open

4732. Thermal voltage VT can be given by____________?
0

A. (K2/q)(T + 1/T 1)

B. qT/K

C. KT/q

D. Kq/T

4733. A power semiconductor may undergo damage due to____________?
0

A. Low di/dt

B. High dv/dt

C. Low dv/dt

D. High di/dt

4734. A single phase one pulse controlled circuit has a resistance R and counter emf E load 400 sin(314 t) as the source voltage. For a load counter emf of 200 V, the range of firing angle control is _____?
0

A. 30 to 180.

B. 60 to 180.

C. 30 to 150.

D. 60 to 120.

4735. If the firing angle becomes negative, then the rectifier begins to work as_______________?
0

A. A regulator

B. An inverter

C. A rectifier

D. A chopper

A. Identical to phase voltage in CSI

B. Identical to phase voltage in VSI

C. Identical to line voltage in a VSI

D. Identical to line current in VSI

4737. Transformer utilization factor is a measure of the merit of a rectifier circuit. It is the ratio of_______________?
0

A. AC input power to the transformer volt amp rating required by secondary

B. DC output power to the transformer volt amp rating required by primary

C. DC output power to the transformer volt amp rating required by secondary

D. AC input power to the transformer volt amp rating required by primary

4738. The advantage of using free wheeling diode in half controlled bridge converter is that
0

A. There is always a path for the ac current independent of the ac line

B. There is always a path for the dc current independent of the ac line

C. There is always a path for the dc current dependent of the ac line

D. There is always a path for the ac current independent of the ac line

4739. In the operation and control of both naturally commutated and forced commutated SCR base converter, commutation plays an important role. The converters is / are ___________?
0

A. All of these

B. DC AC

C. AC DC

D. DC DC

4740. What is the advantage of HRC fuses over Rewirable fuses?
0

A. All of the above

B. High rupturing capacity

C. High speed operation

D. No ageing effect

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