Circuit Breaker

A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating.

Informational Note: The automatic opening means can be integral, direct-acting with the circuit breaker, or remote from the circuit breaker.

A qualifying term indicating that the circuit breaker can be set to trip at various values of current, time, or both, within a predetermined range.

A qualifying term indicating that no delay is purposely introduced in the tripping action of the circuit breaker.

A qualifying term indicating that there is purposely introduced a delay in the tripping action of the circuit breaker, which delay decreases as the magnitude of the current increases.

A qualifying term indicating that the circuit breaker does not have any adjustment to alter the value of the current at which it will trip or the time required for its operation.

The value of current, time, or both, at which an adjustable circuit breaker is set to trip.

A switching device capable of making, carrying, and interrupting currents under normal circuit conditions, and also of making, carrying for a specified time, and interrupting currents under specified abnormal circuit conditions, such as those of short circuit.