Test: Thyristors Ratings & Thyristors Protection - Electrical Engineering (EE) MCQ

peak working voltage & peak reverse repetitive voltage

dv/dt & di/dt

peak repetitive reverse voltage & maximum value of input voltage

peak repetitive reverse voltage & rms value of input voltage

increases with increase in the junction temperature

decreases with increase in the junction temperature

increases with decrease in the rms value of forward anode-cathode voltage

decreases with decrease in the rms value of forward anode-cathode voltage

minimum value of Vak to turn on the device with gate triggering

maximum value of Vak to turn on the device with gate triggering

minimum value of Vak to turn on the device without gate triggering

maximum value of Vak to turn on the device without gate triggering

100 % DC

25 % DC

50 % DC

AC

3121.32 A

2121.32 A

3131.32 A

2131.32 A

I/4, I/2

I/2, I/√2

 I/4, I²/2

I/4, I/√2

8.78 A

10.10 A

17.5 A

24.74 A

The power dissipated by the device when fault occurs

The energy dissipated by the device when fault occurs

The energy that the device can absorb before the fault is cleared

The energy that the device can absorb while operating in the forward blocking mode.

93.9 A

174 A

26.62 A

68.52 A

Ω/°C

W/Ω

°C/W

ΩW/°C

connecting an inductor in parallel across the load

connecting an inductor in series with the load

connecting an inductor in parallel across the gate terminal

connecting an inductor in series with the gate

reducing the junction temperature

applying gate current nearer to the maximum gate current

using only R loads

proper mounting of the SCR on heat sink

limit the power loss

reduce the junction temperature

avoid accidental turn-on of the device

avoiding sudden large voltage across the load

connecting a capacitor in parallel with the load

connecting an inductor in series with the load

connecting a capacitor & resister in parallel with the device

connecting an inductor & resister in parallel with the device

 I(1 – e^-t/τ)

I(1 + e^-t/τ)

I(1 – e^t/τ)

none

RL circuits

Circuit breakers

Varistors

di/dt inductor

Varistors

Snubber Circuits

F.A.C.L.F & C.B.

Zener diodes

F.A.C.L.F & C.B

Shielded cables & twisted gate leads

Snubber circuits

di/dt inductor in series with the gate terminal

8 μH

80 μH

16 μH

160 μH

high surge current capabilities

high amp ²-sec rating

less switching losses

voltage clamping properties