What protective device is used to interrupt a fault in an electrical circuit?

The protective device specifically designed to interrupt a fault in an electrical circuit is the circuit breaker. Circuit breakers are critical components in electrical systems because they detect fault conditions, such as short circuits or overloads, and automatically disconnect the electrical supply to prevent damage to the system, protect equipment, and ensure safety for personnel.

While oil circuit reclosers also provide a form of protection by disconnecting circuits during fault conditions, they are typically more specialized and used for higher voltages in outdoor applications. In contrast, a circuit breaker can be used in various applications, both residential and commercial, making it a more universally applicable answer for the specific question of interrupting faults in electrical circuits.

Transformers and control relays do not serve as protective devices for interrupting faults. Transformers are used to transfer electrical energy between circuits via electromagnetic induction, while control relays are intended for controlling other devices or equipment but do not interrupt fault conditions directly. Thus, the most accurate choice for a device that interrupts a fault in an electrical circuit is the circuit breaker.