Abstract: A relay including a control circuit which via a movement creating or actuating arm and a transmission mechanism activates a contact means in order to switch on or switch off a main circuit. The actuating arm includes two elongated parallel parts which are separated by a thermally and electrically insulated layer. The two parallel parts each have a first end fastened to a housing or holder. The two parallel parts each have a second end fixed to each other, forming a movable end of the arm. One or both parallel parts of the arm are provided with a heat creating or producing element. The actuating arm, attached at one end and movable at the other end, together with the heat producing element, constitutes the first part of the control circuit or relay. When a control current flows through the heat producing element, one of the two parallel parts of the arm is heated thereby causing a movement of the movable end of the arm to thereby activate the control means through the transmission mechanism.

Abstract: An arm preferably for electric switches, the arm being controlled by electricity, and having a first fixed end the other end of which is movable perpendicular to the length direction of the arm. The arm comprises two parallel portions (47) separated by an air gap (17) or some other heat insulating material, and which are secured to each other at each end. At least one of the portions, being heated by electricity and, through longitudinal differential expansion with respect to the other portion, achieves said movement. The portions are so shaped that, adjacent the fixed end (at 45) with respect to the rest of the portions, they have a reduced bending resistance about an axis which is perpendicular to the length direction of the arm and with respect to said direction of movement.