What does a circuit breaker do in an electrical system?

A circuit breaker plays a crucial protective role in an electrical system by interrupting current flow during a fault. When a fault occurs, such as a short circuit or an overload condition, the normal flow of current can increase significantly, potentially leading to damage or hazards like overheating, fires, or even equipment failure.

The circuit breaker detects this abnormal condition through its sensing mechanism and automatically opens the circuit, stopping the flow of electricity to prevent these dangerous outcomes. By interrupting the current, the circuit breaker thus protects both the electrical infrastructure and any connected devices from damage.

The other options describe functions that are not part of a circuit breaker's operation. For instance, circuit breakers do not amplify signals or increase voltage, nor do they maintain a constant current; instead, their primary function is to provide safety by controlling current in response to fault conditions.