Patent ID: 8860534

Claim:
An overcurrent switching device for an electric circuit to be monitored, which has interrupter contact means ( 14 ) constructed in such a manner that an interruption of the electric circuit is effected as a reaction to the exceeding of a predetermined current threshold, wherein the interrupter contact means have an expansion unit ( 16 ) realised by means of a magnetically active shape memory alloy material, which is loaded by a magnetic field ( 18 ) of a current flowing in the electric circuit, wherein the expansion unit ( 16 ; 30 ; 32 ; 34 ) mechanically driving a contact, particularly an interrupter contact ( 14 ), is provided adjacently to a coil-free current-carrying conductor section ( 10 ) of the electric circuit for magnetic interaction in such a manner that above the predetermined current threshold, a current flow in the coil-free current-carrying conductor section ( 10 ) generates a magnetic field which effects an expansion movement of the expansion unit which interrupts the electric circuit, and wherein an entire length of said current-carrying conductor section ( 10 ), which is adjacent to said expansion unit ( 16 ; 30 ; 32 ; 34 ) is coil-free.