Assertion–Reason on gate turn-off thyristor (GTO) Assertion (A): A GTO can be turned ON and turned OFF by gate pulses. Reason (R): A GTO can be turned OFF by applying a sufficiently strong negative gate pulse.

Introduction / Context:
Gate Turn-Off Thyristors (GTOs) are controllable power devices that can be both turned on and turned off using gate signals. This distinguishes them from conventional SCRs, which require forced commutation or line commutation for turn-off.

Given Data / Assumptions:

• A: GTO supports gate-controlled turn-on and turn-off.
• R: Negative gate current actively extracts carriers to commutate the device off.

Concept / Approach:
In a GTO, the gate structure is designed to provide substantial reverse gate current to remove stored charge from the device’s base regions. This suppresses the regenerative action responsible for conduction, thereby achieving turn-off without external commutation networks.

Step-by-Step Solution:
Turn-ON: Apply positive gate current to inject carriers and trigger conduction.Turn-OFF: Apply a strong negative gate pulse; this extracts carriers, disabling the regenerative feedback.Therefore, A is true and R correctly explains how turn-off is achieved.

Verification / Alternative check:
Manufacturer datasheets specify peak negative gate current requirements and di/dt limits for reliable GTO turn-off, confirming gate-controlled turn-off capability.

Why Other Options Are Wrong:

• (b) Incorrect because R directly explains A.
• (c) and (d) contradict well-known GTO operation.
• (e) Both statements are known to be true.

Common Pitfalls:

• Using insufficient negative gate current during turn-off leads to failure to commutate and potential device damage.
• Confusing GTOs with standard SCRs, which cannot be turned off via gate.

Final Answer:
Both A and R are correct and R is correct explanation of A