electrical engineering MCQs – Page 241

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 Review each marked answer and report any item that may be outdated or unclear.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 generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
4801. The ac output voltage waveform of VSI and AC output current waveform of CSI respectively is composed of___________?
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A. High dv / dt, high di / dt

B. High dv / dt, low di / dt

C. Low dv / dt, low di / dt

D. Low dv / dt, high di / dt

4802. For commutation in three phase PAC, normally balanced three phase voltages VR, VY and VB are connected to the three legs of the converter via______________?
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A. Three resistance

B. Three inductances

C. Three transistors

D. Three capacitances

4803. A single phase full bridge inverter can operated in load commutation mode in case load consist of______?
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A. RLC overdamped.

B. RL.

C. RLC underdamped.

D. RLC critically damped

4804. The transfer function of PWM is generally developed in______________?
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A. None of these

B. Frequency domain

C. Either A. or B.

D. Time domain

4805. Ripple factor is the ratio of______________________?
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A. Rms value of the ac component of load voltage to the dc voltage

B. Average value of the ac component of load voltage to the peak value of voltage

C. Peak value of the dc component of load voltage to the ac voltage

D. Average value of the dc component of load voltage to the ac voltage

4806. A thyristor can termed as__________?
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A. AC switch

B. DC switch

C. Both a and B

D. Square wave switch

4807. Double fourier series analysis of PWM is_____________?
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A. Two dimensional functions

B. Three dimensional functions

C. All of these

D. One dimensional functions

4808. The capacitance of reversed bised junction J2 in a thyristor is CJ2 = 20 pF and can be assumed to be independant of the off state voltage. The limiting value of the charging current to turn on the thyristor is 16 mA. What is the critical value of dv/dt?
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A. 600 V/s

B. 1000 V/s

C. 800 V/s

D. 1200 V/s

4809. Why resistor is used in Snubber circuit_________________ ?
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A. To minimize the discharging current

B. All of these

C. To minimize the loss

D. To minimize the charging current

4810. Practical way of obtaining static voltage equalization in series connected SCRs is by the use of____________?
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A. Resistors of the same value across each SCR

B. One resistor across the string

C. Resistors of different values across each SCR

D. One resistor in series with each SCR

4811. The maximum firing angle in the half wave controlled regulator is_____________?
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A. 190 degree

B. 210 degree

C. 180 degree

D. 200 degree

4812. Anode current in an SCR consists of____________?
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A. holes only

B. electrons only

C. either electron or holes

D. Both electron and holes

4813. In a 3 phase bridge rectifier the ripple frequency is _____________?
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A. Twice the input frequency

B. Three times the input frequency

C. Six times the input frequency

D. Equal to the input frequency

4814. Leakage current flows through the thyristor in_________?
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A. forward blocking mode

B. reverse blocking mode

C. both forward and reverse blocking mode

D. forward conduction mode

4815. By which one of the following we can measure the reliability of a string_____________?
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A. Derating factor

B. Reliability factor

C. Factor of safety

D. String efficient

4816. In single phase VSI, the harmonic which is not present is____________?
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A. 2nd

B. 5th

C. 3rd

D. 7th

4817. 60 thyrsistors are connected in series and parallel to form a 10 KV and 5.5 KA switch. Each thyristor is rated for 1.2 KV, 1 KA. The no. of parallel path are 6. The efficiency of the switch is______________________?
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A. 76.3 %

B. 83.30%

C. 91.60%

D. 90.90%

4818. Which of following is normally ON device?
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A. IGBT

B. BJT

C. TRIAC

D. SIT
4819. In a 3 phase VSI SPWM to use a single carrier signal and preserve the features of PWM technique, the normalized carrier frequency should be____________?
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A. Odd multiple of seven

B. Odd multiple of three

C. Multiple of two

D. Odd multiple of five

4820. SCRs are used in series to meet_______________?
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A. low voltage demand

B. high current demand

C. low current demand

D. high voltage demand