Protective switch with magnetic and thermal release for e.g. motor or circuit protection, is made from alloy with combined thermal- and magnetic shape memory

摘要

Release armature (24) is made of a material with combined thermal- and magnetic shape memory (MSM). It is released by a magnetic field and/or heating. Should a short-circuit current flow, the magnetic field from the release solenoid (22) causes deformation of the armature, so opening the point of contact (4). Similarly, a temperature increase on overcurrent, also causes deformation and contact opening. The ferromagnetic shape memory alloy contains nickel, manganese and gallium. Various expanding, bending or twisting configurations of the armature are feasible.