power electronics MCQs – Page 5

Practise focused power electronics questions with marked answers for exam preparation and subject revision.

power electronics Mcqs

81. 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

82. An SCR is made up of silicon because?
0

A. silicon has small leakage voltage than germanium

B. silicon has small leakage current than germanium

C. silicon has large leakage voltage than germanium

D. silicon has large leakage current than germanium

83. The turn-on time of an SCR with inductive load is 20 s. The puls train frequency is 2.5 KHz with a mark/space ratio of 1/10, then SCR will___________?
0

A. Turn on if pulse frequency us increased to two times

B. Not turn on

C. Turn on

D. Turn on if inductance is removed

84. Which one is most suitable power device for high frequency (>100 KHz) switching application?
0

A. BJT

B. Schottky diode

C. Microwave transistor

D. Power MOSFET

85. In variable frequency, PWM gain
0

A. Phase lead helps to increase the phase margin of the control loop

B. Phase lag helps to decrease the phase margin of the control loop

C. Phase lag helps to increase the phase margin of the control loop

D. Phase lead helps to decrease the phase margin of the control loop

86. A thyristor is basically________?
0

A. A set of SCRs

B. PNPN device

C. A set if SCR,diac and triac

D. A combination of diac and triac

87. A carrier based PWM technique in CSI is composed of____________?
0

A. A switching and shorting pulse combination

B. All of these

C. A switching pulse generator and a shorting pulse generator

D. A shorting pulse distributor

88. Under harmonic free load voltages, the 3 phase VSI_____________?
0

A. Does not contains fifth harmonic

B. Does not contains seventh harmonic

C. Does not contains second harmonic

D. Does not contains third harmonic

89. Dynamic equalising circuit is useful____________?
0

A. To limit di / dt of SCR

B. To limit dV / dt of SCR

C. For voltage equalisation

D. Both B and C

90. A single phase ac dc converter is also known as____________?
0

A. rectifier

B. regulator

C. chopper

D. inverter

91. A MOSFET, for its conduction uses_____________?
0

A. Only minority carriers

B. Only majority carriers

C. Both minority and majority carriers

D. None of these

92. The power demand can be estimated approximately by____________?
0

A. Mathematical method

B. Load survey method

C. Statistical method

D. Economic parameters

93. In a load commutated DC DC chopper, the capacitor has a_____________?
0

A. Symmetric trapezoidal voltage across itself

B. Symmetric rectangular voltage across itself

C. Symmetric triangular voltage across itself

D. Symmetric sinusoidal voltage across itself

94. AC power in a load can be controlled by using____________?
0

A. Three SCRs in series

B. Two SCRs in parallel opposition

C. Four SCRs in series

D. Two SCRs in series

95. If all the SCRs of 3 phase PAC is replaced by diodes, they would be triggered_____________?
0

A. 120 degree after the zero crossing of the corresponding line voltages

B. 60 degree after the zero crossing of the corresponding line voltages

C. 60 degree before the zero crossing of the corresponding line voltages

D. 120 degree before the zero crossing of the corresponding line voltages

96. As the breakdown voltage reached, the DIAC exhibits?
0

A. All of these

B. Goes into avalanche condition

C. Voltage drop snaps back

D. Negative resistance characteristics

97. The square wave operation of 3 phase VSI lines contains the harmonics. The amplitudes are____________?
0

A. None of these

B. Directly proportional to their harmonic order

C. Inversely proportional to their harmonic order

D. Not related to their harmonic order

98. In a square wave operation of 3 phase CSIs, the power values are on for___________?
0

A. 90 degree

B. 150 degree

C. 120 degree

D. 60 degree

99. In a push pull converter, the filter capacitor can be obtained as____________?
0

A. Cmin= ( 1 2 D ) V / 32 ( Vr L f2 )

B. Cmin= ( 1 2 D ) V / 42 ( Vr L f2 )

C. Cmin = V / ( Vr L f2 )

D. Cmin= ( 1 D ) V / ( Vr L f2 )

100. DIAC and TRIAC both are semiconductors devices and conduct in____________________?
0

A. DIAC conducts in forward direction and TRIAC conducts in reverse direction

B. Both conducts in forward direction

C. Both conducts in reverse direction

D. Both conducts in either direction

Previous Next

Showing 81 to 100 of 227 mcqs