Low energy memory metal actuated latch

A method of tripping an electric switch in response to a trip condition, the electric switch including a trip bar, a plunger mechanism, and memory wire, the plunger mechanism being positioned to move the trip bar from a reset state to a trip state, the memory wire being coupled to the plunger mechanism, the method comprising steps of:

• providing an electric signal to the memory wire;
• contacting the length of the memory wire from a first shape to a second shape in response to the electric signal;
• and
• moving the trip bar from the reset state to the trip state with the plunger mechanism in response to the memory wire changing from the first shape to the second shape.

A circuit breaker comprising:

• a set of contacts;
• a trip means, operatively mechanically coupled to the set of contacts, for disengaging the set of contacts in response to a mechanical motion;
• a plunger means for providing the mechanical motion to the trip means so that the set of contacts are engaged when the plunger means is in a released state;
• a latch means, mechanically couplable to the plunger means, for preventing the plunger means from attaining the released state when the latch means is in a latched state, the latch means allowing the plunger means to attain the released state when the latch means is in an unlatched state;
• and
• a length of memory wire that changes lengthwise in response to a change in the wire and that is mechanically coupled to the latch means, the memory wire moving the latch means to the unlatched state by acting on the latch means in a direction along which the wire changes in length in response to a change of length resulting from a change in the memory wire.