Passive triggering mechanisms for use with switching devices incorporating pyrotechnic features

An electrical system 900 comprises an operating power circuit 902, a pyrotechnic trigger circuit, and a pyrotechnic actuator 912. The operating power circuit comprises an operating power source 904 coupled to an operating load 906 by a current path and a contactor 908. The pyrotechnic trigger circuit comprises a trigger switch 914 which closes in response to elevated current in the operating power circuit. When the trigger switch closes, it conducts the elevated current in the operating power circuit for sufficient time to activate the pyrotechnic actuator, which operates on the contactor to interrupt the current path. The trigger switch is destroyed by the elevated current after activation of the pyrotechnic actuator. The system may further comprise a secondary power source 816 (figure 12), and the trigger circuit may use the secondary power source to activate the pyrotechnic actuator. The secondary power source may comprise a battery, capacitor circuit, or low voltage power source. The passive trigger switch may comprise a reed switch. The contactor may be a fuse.