What are circuit breakers primarily used for in the electrical system of an aircraft?

Circuit breakers are primarily used in aircraft electrical systems to prevent electrical overloading. Their main function is to interrupt the flow of electrical current when it exceeds a predetermined level, which helps to protect the wiring, components, and the overall electrical system from damage that could be caused by excessive current. This feature is vital in aircraft, where electrical systems are critical for operation and safety.

When a circuit experiences an overload—either due to excessive draw from electrical devices or short circuits—the circuit breaker will "trip," cutting off the electrical flow to that circuit. This quick response minimizes the risk of fire and equipment damage, ensuring that the aircraft remains safe during operation. Other options mentioned in the question do not pertain to the primary function of circuit breakers; they either relate to different systems within the aircraft or do not accurately describe what circuit breakers are designed to do.