MINIATURE CIRCUIT BREAKER

摘要

A miniature circuit breaker having a pair of operable contacts in a main current path between a line terminal and load terminal, a trip mechanism for opening the contacts if an overcurrent condition occurs, and an electric motor to close the contacts via a contact closing mechanism. The trip mechanism includes a trigger mechanism and a contact opening mechanism, a current sensor arranged to detect current through the main current path, and a control unit. The trigger mechanism triggers the contact opening mechanism if a trip signal is produced. The control unit produces a trip signal to operate the trigger mechanism if it determines a short circuit condition occurs based on output of the current sensor; and the control unit is arranged to operate the electric motor to trigger the contact opening mechanism into opening the contacts independently of the trigger mechanism if it determines that an overload condition occurs.