If the torque angle ‘delta’ increases indefinitely, the system indicates
- A. Steady state stability
- B. Permanent stability
- C. Instability
- D. None of the above
Answer: C. Instability
Explanation: Stable operation requires dPe/dδ > 0. If the power angle δ increases beyond 90° indefinitely, synchronizing torque vanishes and the system loses synchronism (instability).