Explore topic-wise MCQs in Power Electronics and Drives.

This section includes 109 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics and Drives knowledge and support exam preparation. Choose a topic below to get started.

101.

In order to obtain static voltage equalization in series-connected SCRs, connections are made of

A. one resistor across the string
B. resistors of different values across each SCR
C. resistors of the same value across each SCR
D. one resistor in series with the string.
Answer» D. one resistor in series with the string.
Discussion
102.

In a conventional reverse blocking thyristor

A. external layers are lightly doped and internal layers are heavily doped.
B. external layers are heavily doped and internal layers are lightly doped
C. the p-layers are heavily doped and the n-layers are lightly doped
D. the p-layers are lightly doped and the n-layer are heavily doped.
Answer» E.
Discussion
103.

Optocouplers combine

A. SITs and BJTs
B. IGBTs and MOSFETs
C. Power transformers and silicon transistor
D. Infrared light-emitting diode and a silicon phototransistor
Answer» E.
Discussion
104.

A lossy capacitor C

A. 10 W and 0.0002
B. 10 W and 0.0025
C. 20 W and 0.025
D. 20 W and 0.04
Answer» D. 20 W and 0.04
Discussion
105.

Circuit turn-off time of an SCR is defined as the time

A. taken by the SCR to turn off
B. required for the SCR current to become zero
C. for which the SCR is reverse biased by the commutation circuit
D. for which the SCR is reverse biased to reduce its current below the holding current
Answer» D. for which the SCR is reverse biased to reduce its current below the holding current
Discussion
106.

An ac induction motor is used for a speed control application. It is driven from an inverter with a constant V/f control. The motor name-plate details are as follows :

A. 2400 rpm
B. 2280 rpm
C. 2340 rpm
D. 2790 rpm
Answer» D. 2790 rpm
Discussion
107.

A solar cell of 350 V is feeding power t o an ac supply of 440 V, 50 Hz through a 3-phase fully controlled bridge converter. A large inductance is connected in the dc circuit to maintain the dc current at 20 A. If the solar cell resistance is 0.5 Ω, then each thyristor will be reverse biased for a period of

A. 125
B. 120
C. 60
D. 55
Answer» B. 120
Discussion
108.

Consider the following statements regarding speed control of induction motors by means of external rotor resistors :

A. 1 and 3
B. 2 and 3
C. 1 and 3
D. 1, 2 and 3
Answer» B. 2 and 3
Discussion
109.

In an inverter with fundamental output frequency of 50 Hz, if third harmonic is eliminated, then frequencies of other components in the output voltage wave in Hz would be

A. 250, 350, 500, high frequencies
B. 50, 250, 350, 500, high frequencies
C. 50, 50, 350, 550
D. none of these
Answer» C. 50, 50, 350, 550
Discussion