Top 250+ Solved Power Electronics MCQ Questions Answer
Q. A forward voltage can be applied to an SCR after its:
a. anode current reduces to zero
b. gate recovery time
c. reverse recovery time
d. anode voltage reduces to zero
Q. In a thyristor, the magnitude of the anode current will:
a. increase if the gate current is increased
b. decrease if the gate current is decreased
c. increase if gate current is decreased
d. no change with the variation of the gate current
Q. Once SCR starts conducting a forward current, its gate lossescontrol over:
a. anode circuit voltage only
b. anode circuit current only
c. anode circuit voltage and current
d. none of the above
Q. On state voltage drop across thyristor used in a 230 V supplysystem is of the order:
a. 110-115V
b. 250 V
c. 1- 1.5 V
d. none of the above
Q. Silicon controlled rectifier can be turned on
a. By applying a gate pulse and turned off only when current becomes zero
b. And turned off by applying gate pulse
c. By applying a gate pulse and turned off by removing the gate pulse
d. By making current non zero and turned off by making current zero
Q. TRIAC is a semiconductor power electronic device whichcontains
a. Two SCR’s connected in reverse parallel
b. Two SCR’s connected in parallel
c. Two SCR’s connected in series
d. Two BJT’s connected in series
Q. An SCR can be used
a. as static conductor
b. for power control
c. for speed control of dc shunt motor
d. all of these
Q. A crowbar is a circuit which is used to protect a
a. voltage sensitive load from excessive dc power supply output voltages
b. current sensitive load from excessive dc power supply output voltages
c. voltage sensitive load from excessive ac power supply output voltages
d. current sensitive load from excessive ac power supply output voltages
Q. The input current waveform of a bridge controlled rectifier when theload is perfectly filtered is
a. Sine wave
b. Square wave
c. Saw – tooth wave
d. Trapezoidal wave
Q. The advantage of using free – wheeling diode in half controlled bridge converter is that
a. There is always a path for the dc current independent of the ac line
b. There is always a path for the ac 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
Q. Harmonics in 3 phase inverters can be reduced by using
a. Passive filter
b. Active filter
c. Both passive and active filters
d. None of these
Q. The most suited gate pulses given to the AC regulator with R – L load can be in the form of
a. Continuous signal
b. Large isolating pulse transformer
c. A train of pulses
d. None of these
Q. With increase in firing angle,
a. Both harmonic distortion and quality of input current increases
b. Harmonic distortion increases and quality of input current decreases
c. Harmonic distortion decreases and quality of input current increases
d. Both harmonic distortion and quality of input current decreases
Q. The power MOSFET device is a
a. Current controlled unipolar device
b. Voltage controlled unipolar device
c. Current controlled bipolar device
d. Voltage controlled bipolar device