Compare fuses and circuit breakers used in aircraft electrical protection.

Compare fuses and circuit breakers used in aircraft electrical protection.

• A. Circuit breakers are one-time protection by melting; fuses are resettable devices that trip on overcurrent or faults.
• B. Fuses provide one-time protection by melting; circuit breakers are resettable devices that trip on overcurrent or faults.
• C. Both devices reset automatically.
• D. Fuses regulate voltage.

Answer: (B)

The main idea is how overcurrent protection devices behave after a fault. A fuse provides one-time protection by melting its conductor when current exceeds the rating; once blown, the circuit is open and you must replace the fuse. Circuit breakers are resettable devices that trip when the current is too high or a fault occurs, and after the fault is cleared they can be reset to restore power without replacing components. In aircraft systems this distinction matters because circuit breakers allow quick isolation and re-energizing of circuits, while fuses are fixed, non-resettable protections. The notion that both reset automatically isn’t correct, and fuses don’t regulate voltage—they simply open the circuit when overcurrent occurs.

The main idea is how overcurrent protection devices behave after a fault. A fuse provides one-time protection by melting its conductor when current exceeds the rating; once blown, the circuit is open and you must replace the fuse. Circuit breakers are resettable devices that trip when the current is too high or a fault occurs, and after the fault is cleared they can be reset to restore power without replacing components. In aircraft systems this distinction matters because circuit breakers allow quick isolation and re-energizing of circuits, while fuses are fixed, non-resettable protections. The notion that both reset automatically isn’t correct, and fuses don’t regulate voltage—they simply open the circuit when overcurrent occurs.