Power Electronics Questions and Answers in Quiz Form 8 for Practice

106. Power electronics essentially deals with control of a.c. power at …………

1. Frequencies above 1000 kHz
2. Frequencies less than 10 Hz
3. Frequencies above 20 kHz
4. 50 Hz frequency

107. Silicon controlled rectifier can be turned on

1. And turned off by applying gate pulse
2. By applying a gate pulse and turned off by removing the gate pulse
3. By applying a gate pulse and turned off only when current becomes zero
4. By making current non zero and turned off by making current zero

108. Single phase VSI are mainly used in

1. Ups
2. Multilevel configuration
3. Power supplies
4. All of these

109. The advantage of using free – wheeling diode in half controlled bridge converter is that

1. There is always a path for the ac current independent of the ac line
2. There is always a path for the dc current dependent of the ac line
3. There is always a path for the dc current independent of the ac line
4. There is always a path for the ac current independent of the ac line

110. The conduction losses in IGBT is

1. Lower than that of MOSFET
2. Equal to that of MOSFET
3. More than that of MOSFET
4. Equal to that of BJT

111. The device that does not have the gate terminal is ……………….

1. FET
2. SCR
3. Triac
4. Diac

112. The device that exhibits negative resistance region is ………………..

1. Triac
2. Transistor
3. Diac
4. UJT

113. The effects of EMI can be reduced by

1. Reducing the efficiency of the coupling path
2. Reducing the susceptibility of the receptor
3. Suppressing emissions
4. All of these

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

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

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

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

116. The normal way to turn on a diac is by ………………..

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

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

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

118. The power MOSFET device is a

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

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

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

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

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