What is the function of circuit breakers in an aircraft's electrical system?

• A. They regulate voltage in circuits.
• B. They interrupt current to protect circuits from overload.
• C. They store energy for emergency use.
• D. They convert AC to DC.

Answer: (B)

Circuit breakers protect electrical circuits by interrupting current when a fault or overload occurs. In an aircraft, each circuit has a breaker that pops out when the current exceeds its rating, either due to a fault, short circuit, or excessive draw. This automatic opening stops current flow to prevent overheating of wires, damage to insulation, or fires. Once the issue is fixed, the breaker can be reset to restore power. They don’t set or regulate voltage, store energy for emergencies, or convert AC to DC—that’s the job of voltage regulators, energy storage devices, and rectifiers, respectively.