Power Electronics Questions and Answers | Online Quiz for Practice

46. The input current waveform of a bridge controlled rectifier when the load is perfectly filtered is

1. Trapezoidal wave
2. Square wave
3. Saw - tooth wave
4. Sine wave

47. The most suited gate pulses given to the AC regulator with R - L load can be in the form of

1. None of these
2. Large isolating pulse transformer
3. A train of pulses
4. Continuous signal

48. The normal way to turn on a diac is by ...........................

1. None of the above
2. Gate voltage
3. Breakover voltage
4. Gate current

49. The output power of the cascaded amplifier-attenuator system can be determined using

1. Actual gain of attenuator
2. Actual gain of amplifier and attenuator
3. Gain in dB of amplifier and attenuator
4. Actual gain of amplifier

50. The power MOSFET device is a

1. Voltage controlled bipolar device
2. Voltage controlled unipolar device
3. Current controlled bipolar device
4. Current controlled unipolar device

51. The square wave operation of 3 phase VSI lines contains the harmonics. The amplitudes are

1. None of these
2. Inversely proportional to their harmonic order
3. Not related to their harmonic order
4. Directly proportional to their harmonic order

52. The switching function of semiconductor devices can be characterized with

1. Duty ratio, frequency and time delay
2. Frequency only
3. Duty ratio and frequency
4. Duty ratio only

53. The triac is .....................

1. Answers (1) and (2)
2. A four-terminal device
3. Not a thyristor
4. Like a bidirectional SCR

54. The UJT may be used as ............................

1. None of the above
2. A sawtooth generator
3. A rectifier
4. Am amplifier

55. The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of ........................ in its first quadrant

1. none of the above
2. SCR
3. UJT
4. Transistor

56. To turn on UJT, the forward bias on the emitter diode should be ...................... the peak point voltage

1. None of the above
2. Equal to
3. More than
4. Less than

57. TRIAC is a semiconductor power electronic device which contains

1. Two BJTs connected in series
2. Two SCRs connected in parallel
3. Two SCRs connected in series
4. Two SCRs connected in reverse parallel

58. Under harmonic free load voltages, the 3 phase VSI

1. Does not contains seventh harmonic
2. Does not contains third harmonic
3. Does not contains fifth harmonic
4. Does not contains second harmonic

59. Unipolar modulation is generally used in

1. DC - DC converters
2. AC - DC converters
3. DC - AC converters
4. AC - AC converters

60. Very large values of modulation index (greater than 3.24 lead to)

1. Trapezoidal AC output voltage
2. Sine AC output voltage
3. Triangular AC output voltage
4. Square AC output voltage