Patent ID: 7026894

Claim:
An apparatus for interrupting an electrical short circuit current in an electrical distribution system having a plurality of phases, the apparatus comprising: a housing; a plurality of separable conduction paths; an operating mechanism in operable communication with the plurality of conduction paths; an electronic trip unit in signal communication with each of the plurality of conduction paths and in operable communication with the operating mechanism; and an electromagnetic trip unit in electromagnetic field communication with each of the plurality of conduction paths and in operable communication with the operating mechanism; wherein the electromagnetic trip unit is configured to be operably responsive to a first half-cycle waveform of the short circuit current prior to the electronic trip unit being operably responsive to a subsequent second multi-cycle waveform of the short circuit current, each of the electromagnetic trip unit and the electronic trip unit being operably responsive by being capable of sending a trip signal to the operating mechanism in response to the first half-cycle waveform and the second multi-cycle waveform, respectively.