Explore topic-wise MCQs in Power Electronics.

This section includes 16 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.

1.

The thermal resistance between junction & the SCR (θjc) has the unit

A. Ω/°C
B. W/Ω
C. has the unita) Ω/°Cb) W/Ωc) °C/W
D. ΩW/°C
Answer» D. ΩW/°C
Discussion
2.

The maximum rms current of an SCR is 50 A. For a 120° sine wave conduction the form factor (FF) = 1.878Find the average on-state current rating (ITAV).

A. 93.9 A
B. 174 A
C. 26.62 A
D. 68.52 A
Answer» D. 68.52 A
Discussion
3.

The amp2-sec rating of the SCR specifies

A. The power dissipated by the device when fault occurs
B. The energy dissipated by the device when fault occurs
C. The energy that the device can absorb before the fault is cleared
D. The energy that the device can absorb while operating in the forward blocking mode.
Answer» D. The energy that the device can absorb while operating in the forward blocking mode.
Discussion
4.

For an SCR the average & rms values of current are I/4 & I/2 respectively. Calculate the average on-state current rating (ITAV). Take maximum RMS on-state current = 35 A.

A. 8.78 A
B. 10.10 A
C. 17.5 A
D. 24.74 A
Answer» D. 24.74 A
Discussion
5.

For a SCR the maximum rms on-state current is 35 A. If the SCR is used in a resistive circuit for a rectangular wave with conduction angle of 90°. Calculate the average & rms currents respectively.

A. I/4, I/2
B. I/2, I/√2
C. I/4, I2/2
D. I/4, I/√2
Answer» B. I/2, I/√2
Discussion
6.

The voltage safety factor (VSF) for an SCR is the ratio of

A. peak working voltage & peak reverse repetitive voltage
B. dv/dt & di/dt
C. peak repetitive reverse voltage & maximum value of input voltage
D. peak repetitive reverse voltage & rms value of input voltage
Answer» D. peak repetitive reverse voltage & rms value of input voltage
Discussion
7.

THE_THERMAL_RESISTANCE_BETWEEN_JUNCTION_&_THE_SCR_(‚ÂÀ√≠‚ÄÖ√†√®JC)_HAS_THE_UNIT?$#

A. Ω/°C
B. W/Ω
C. °C/W
D. ΩW/°C
Answer» D. ‚Äö√Ñ√∂‚àö√´¬¨‚àÇW/¬¨¬®‚Äö√†√ªC
Discussion
8.

THE_MAXIMUM_RMS_CURRENT_OF_AN_SCR_IS_50_A._FOR_A_120¬¨ àû_SINE_WAVE_CONDUCTION_THE_FORM_FACTOR_(FF)_=_1.878?$#

A. .
B. 93.9 A
C. 174 A
D. 26.62 A
Answer» D. 26.62 A
Discussion
9.

The amp2-sec rating of the SCR specifie?

A. The power dissipated by the device when fault occurs
B. The energy dissipated by the device when fault occurs
C. The energy that the device can absorb before the fault is cleared
D. The energy that the device can absorb while operating in the forward blocking mode.
Answer» D. The energy that the device can absorb while operating in the forward blocking mode.
Discussion
10.

For an SCR the average & rms values of current are I/4 & I/2 respectively. Calculate the average on-state current rating (ITAV). Take maximum RMS on-state current = 35 A.

A. 8.78 A
B. 10.10 A
C. 17.5 A
D. 24.74 A
Answer» D. 24.74 A
Discussion
11.

For a SCR the maximum rms on-state current is 35 A. If the SCR is used in a resistive circuit for a rectangular wave with conduction angle of 90°. Calculate the average & rms currents respectively.$

A. I/4, I/2
B. I/2, I/‚àö2
C. I/4, I<sup>2</sup>/2
D. I/4, I/‚àö2
Answer» B. I/2, I/‚Äö√Ñ√∂‚àö‚Ć‚àö‚àÇ2
Discussion
12.

An SCR has half cycle surge current rating of 3000 A for 50 Hz. Calculate its one-cycle surge current rating

A. 3121.32 A
B. 2121.32 A
C. 3131.32 A
D. 2131.32 A
Answer» C. 3131.32 A
Discussion
13.

Which among the following anode current waveforms will have the minimum junction temperature?

A. 100 % DC
B. 25 % DC
C. 50 % DC
D. AC
Answer» C. 50 % DC
Discussion
14.

The finger voltage of an SCR is

A. minimum value of Vak to turn on the device with gate triggering
B. maximum value of Vak to turn on the device with gate triggering
C. minimum value of Vak to turn on the device without gate triggering
D. maximum value of Vak to turn on the device without gate triggering
Answer» B. maximum value of Vak to turn on the device with gate triggering
Discussion
15.

The forward dv/dt rating of an SCR

A. increases with increase in the junction temperature
B. decreases with increase in the junction temperature
C. increases with decrease in the rms value of forward anode-cathode voltage
D. decreases with decrease in the rms value of forward anode-cathode voltage
Answer» B. decreases with increase in the junction temperature
Discussion
16.

The voltage safety factor (VSF) for an SCR is the ratio of

A. peak working voltage & peak reverse repetitive voltage
B. dv/dt & di/dt
C. peak repetitive reverse voltage & maximum value of input voltage
D. peak repetitive reverse voltage & rms value of input voltage
Answer» D. peak repetitive reverse voltage & rms value of input voltage
Discussion