Abstract: The present invention relates to an actuating mechanism for actuating the moving contact of a protective interrupting chamber which is installed on a high-voltage or medium-voltage power line and which is to be opened when a current in excess of a surge current threshold flows through line, the mechanism including a drive member for driving a displacement device for displacing the contact. The drive member is a conductive helical spring made of a shape memory alloy and electrically coupled to the line, a current in excess of said surge current threshold passing through the spring heating said spring to such an extent that said alloy goes from its martensitic phase to its austenitic phase. The mechanism enables the interrupting chamber to be re-closed by means of a sequencer device associated with the displacement device, and providing an adjustable and timed opening and closing cycle.

Abstract: A female contact, in particular for a high tension section switch, the female contact comprising two interleaved thimbles, a metal first thimble made by extruding a block of metal and then machining it, said first thimble having metal contact fingers designed for co-operating electrically with a male contact, the other thimble including fingers of an insulating material, the insulating fingers limiting the displacement of the metal contact fingers in a radial direction and in a lateral direction to predetermined values that are less than the elastic limit of deformation of the metal contact fingers, and serving in particular to prevent contact between the metal contact fingers.