Assertion–Reason (inverters and commutation): Assertion (A) “An inverter does not require forced commutation.” Reason (R) “A series inverter is a forced-commutation inverter.” Determine the correct choice.
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ABoth A and R are correct and R is correct explanation of A
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BBoth A and R correct but R is not correct explanation of A
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CA is correct but R is wrong
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DA is wrong but R is correct
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E—
Answer
Correct Answer: A is wrong but R is correct
Explanation
Introduction / Context:Thyristor inverters require means to turn devices off. Depending on topology, commutation can be natural (line-commutated), forced using auxiliary circuits, or inherent via self-commutated switches (IGBT/MOSFET). This item checks clarity on forced commutation in classical SCR inverters and the nature of series inverters.
Given Data / Assumptions:
- Assertion says “inverter does not require forced commutation” (general claim).
- Reason states “series inverter is a forced-commutation inverter.”
Concept / Approach:
Many SCR-based inverters away from a stiff AC grid must force current to zero to turn off the SCRs. Series inverters are prime examples using resonant LC paths for forced commutation. Therefore the universal statement in A is wrong; R is true.
Step-by-Step Solution:
Evaluate A: incorrect as a general claim; numerous inverters require forced commutation.Evaluate R: correct—series inverters use resonant commutation to force SCR current to zero.Mapping to choices → “A wrong, R correct”.Verification / Alternative check:
Textbook classifications: line-commutated vs forced-commutated; series/parallel inverters are under forced commutation families.
Why Other Options Are Wrong:
- Options A/B/C assume Assertion is true; it is not.
Common Pitfalls:
Generalizing from self-commutated IGBT inverters (gate turn-off) to all inverter types; here “forced commutation” is a specific SCR technique.
Final Answer:
A is wrong but R is correct