What is the purpose of a fuse in an aircraft electrical system?

• A. To protect conductors and components from overcurrent by breaking the circuit.
• B. To store electrical energy for backup.
• C. To regulate voltage.
• D. To increase circuit current.

Answer: (A)

A fuse is a protective device in an aircraft electrical system that opens the circuit when current exceeds the fuse’s rating. This action prevents overheating of wires and components and helps avoid damage or fire by isolating the faulty path. In flight, faults can cause sudden overcurrents, and the fuse reacts by melting its internal element to stop the flow of electricity, keeping the rest of the system safe.

Storing electrical energy for backup is the job of a battery or capacitor, not a fuse. Regulating voltage is handled by voltage regulators or power management equipment, not by a fuse. A fuse does not increase current; it does the opposite—interrupts current to prevent harm.