What is the purpose of circuit breakers in an aircraft electrical system?

• A. To store electrical energy.
• B. To protect circuits from overload by interrupting current.
• C. To measure voltage across circuits.
• D. To provide manual switching of circuits.

Answer: (B)

Circuit breakers are protective devices that interrupt current when a fault or overload occurs. In an aircraft electrical system, they monitor the current flowing to each circuit and trip open if the current becomes too high, preventing overheating of wiring, insulation damage, or fire. This rapid interruption helps isolate faults and protect essential systems. They can be reset after the fault is cleared, which is why they’re preferred over fuses in many aviation applications. They may also be operated manually to disconnect a circuit, but their primary purpose is safety and fault isolation, not energy storage, voltage measurement, or normal switching.