Power/trigger devices: Match each device with a characteristic application or control property. List I List II A. GTO 1. Widely used as switches in digital computers B. UJT 2. Used for freewheeling (commutation) paths C. Power diode 3. Can be turned off by a negative gate signal D. MOSFET 4. Used in generating triggering pulses (relaxation oscillator)
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AA-1, B-2, C-3, D-4
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BA-4, B-2, C-3, D-1
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CA-3, B-4, C-2, D-1
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DA-2, B-1, C-3, D-4
Answer
Correct Answer: A-3, B-4, C-2, D-1
Explanation
Introduction / Context:Power electronics integrates devices with distinct control behaviors. Recognizing their hallmark uses is essential for converter and trigger design.
Given Data / Assumptions:
- GTO = Gate Turn-Off thyristor.
- UJT = Unijunction transistor.
- Power diode used in rectifiers and freewheeling paths.
- MOSFET commonly used as the basic switch in digital logic.
Concept / Approach:
Map each device’s well-known control trait: GTO’s gate-off capability, UJT’s relaxation oscillation for triggering, power diode’s freewheeling role, and MOSFET’s ubiquity in digital switching.
Step-by-Step Solution:
GTO → can be turned off by negative gate signal ⇒ A-3.UJT → used to generate trigger pulses ⇒ B-4.Power diode → freewheeling path across inductive loads ⇒ C-2.MOSFET → widely used as digital computer switch ⇒ D-1.Verification / Alternative check:
Converter schematics show freewheeling diodes across inductors; UJT timers in classic firing circuits; GTO datasheets specify gate-off conditions; MOSFETs populate logic ICs and CPUs (CMOS).
Why Other Options Are Wrong:
- Swapping GTO with diode ignores their fundamentally different control.
- Assigning “freewheeling” to MOSFETs mislabels the role; the intrinsic body diode is not the primary freewheel device in all designs.
Common Pitfalls:
Assuming SCRs can all be turned off by gate—only GTOs have gate turn-off capability; standard SCRs require current fall below holding current or forced commutation.
Final Answer:
A-3, B-4, C-2, D-1