Transient Stability Improvement

Correct Answer

B — Improves the system stability

Concept and Reasoning

Fast fault clearing reduces the duration of severe electrical-power imbalance during a disturbance, limiting rotor-angle acceleration and increasing the critical clearing margin. High-speed circuit breakers therefore improve power-system transient stability, making option B correct.

Calculation / Key Relation

Shorter clearing time → smaller rotor-angle excursion → better transient stability

Exam Takeaway

Fast protection improves stability by removing the fault sooner.

Common Mistake

A circuit breaker does not reduce the prospective short-circuit current before interruption; it reduces fault duration.