Breaker-failure protection serves to protect the system by which means?

• A. Tripping a backup breaker if the primary fails to clear the fault.
• B. Reducing the fault current by increasing impedance.
• C. Disconnecting all sources except one during faults.
• D. Providing remote signaling without tripping any breaker.

Answer: (A)

Breaker-failure protection is a safeguard that stays in place to keep the system safe if the first line of protection doesn’t operate. When a fault happens, the primary protection should trip the main breaker and interrupt the fault current. If that breaker fails to trip or fails to open, the breaker-failure scheme detects that the primary device did not clear the fault and then sends a trip signal to a backup breaker. This backup breaker opens to isolate the faulty section, preventing the fault from persisting and helping to avoid equipment damage, overheating, and cascading outages. It’s a second line of defense designed to ensure the fault is cleared even when the main protection malfunctions. This concept isn’t about reducing fault current by changing impedance, nor about disconnecting all sources during faults, nor about signaling remotely without tripping—its purpose is to guarantee that the fault is cleared by tripping a backup breaker if the primary fails.