250+ TOP MCQs on Other Thyristor Members-1 and Answers

Power Electronics Multiple Choice Questions on “Other Thyristor Members-1”.

1. _________ device from the thyristor family has its gate terminal connected to the n-type material near the anode.
A. SCR
B. RCT
C. PUT
D. SUT
Answer: C
Clarification: PUT is Programmable Unijunction Transistor which is a p-n-p-n device just like the SCR with its gate connected to the n-type material.

2. The Programmable Unijunction Transistor (PUT) turns on & starts conducting when the
A. gate voltage exceeds anode voltage by a certain value
B. anode voltage exceeds gate voltage by a certain value
C. gate voltage equals the anode voltage
D. gate is given negative pulse w.r.t to cathode
Answer: B
Clarification: The device only starts to conduct when the forward anode to cathode voltage exceeds the applied gate to cathode voltage.

3. The equivalent circuit of SUS (Silicon Unilateral Switch) consists of
A. a diode in series with a PUT
B. a diode in parallel with a PUT
C. a diode in anti-parallel with a PUT
D. two diodes
Answer: C
Clarification: It is a diode connected in anti-parallel with a PUT.

4. From the following list of devices, choose the device that only turns-on for a fixed-value of anode-cathode voltage
A. PUT
B. SCR
C. SUS
D. BJT
Answer: C
Clarification: Unlike the other devices the SUS only turns-on for a fixed value of anode to cathode voltage.

5. The SCS (Silicon Controlled Switch) is a
A. two terminal device
B. three terminal device
C. four terminal device
D. five terminal device
Answer: C
Clarification: The SCS is a four terminal device A,K,KG & AG.

6. The SCS is a four layer, four terminal thyristor. Can be turned on by
A. the anode gate
B. the cathode gate
C. either of the gates
D. gating both the gates together
Answer: C
Clarification: The SCS has two gates, anode-gate and cathode-gate. Either of the gates could be used to turn on the device.

7. The SCS (Silicon Controlled Switch) can be turned on by two methods, by applying __________ and __________
A. positive pulse to the anode gate, positive pulse to the cathode gate
B. positive pulse to the anode gate, negative pulse to the cathode gate
C. negative pulse to the anode gate, positive pulse to the cathode gate
D. negative pulse to the anode gate, negative pulse to the cathode gate
Answer: C
Clarification: Either of the gates could be used to turn on the device.

8. Which of the following devices provide complete isolation between triggering circuit and power circuit?
A. PUT
B. LASCR
C. SUS
D. DIAC
Answer: B
Clarification: Complete Isolation between triggering circuit & power circuit is the major advantage of using LASCR as they are light activated or light trigged.

9. The DIAC can be represented by
A. two SCRs in anti-parallel
B. two SCRs in parallel
C. two diodes in anti-parallel
D. two diodes in parallel
Answer: C
Clarification: The DIAC is nothing but a bi-directional diode.

10. The TRIAC can be represented by
A. two SCRs in anti-parallel
B. two SCRs in parallel
C. two diodes in anti-parallel
D. two diodes in parallel
Answer: A
Clarification: The TRIAC is a bidirectional SCR.