Which device is used to interrupt the electrical current in case of a fault?

• A. Fuse
• B. Circuit breaker
• C. Transformer
• D. Relay

Answer: (B)

The device that interrupts the electrical current in the event of a fault is a circuit breaker. Circuit breakers are designed to automatically disconnect the electrical circuit when they detect an overload or short circuit condition, which helps to prevent damage to the electrical system and reduces the risk of fire hazards. They serve as a safety mechanism, ensuring that the flow of electricity is stopped in response to issues that could lead to unsafe conditions.

While fuses also serve the purpose of interrupting current to protect circuits, they do so by melting a wire when excessive current flows through them, which requires replacement after they have operated. Circuit breakers, on the other hand, can be reset and reused after they trip, making them a more flexible and convenient option in many applications.

Transformers are used to change the voltage level in AC circuits and do not interrupt current flow, while relays are used to control the operation of other devices but do not act as primary current interrupting devices in the event of faults like a circuit breaker does.