Abstract: An interrupter includes a vacuum enclosure for a set of high voltage contacts and end contact assemblies are secured to the end walls. High voltage terminals are connected to the contact assemblies. A solid insulating shell intimately attaches to the vacuum enclosure and extends axially therefrom to enclose the contact assemblies, with a contact shaft passageway in one end of the shell. One of the contact assemblies includes a movable contact shaft extending through the passageway in the insulating shell to an operating mechanism for rapid opening of the contacts. The passageway is sealed at the outer end to the shaft with a rolling diaphragm and defines a chamber encompassing the contact assembly. A deaerated insulating oil fills the chamber and significantly increases the impulse voltage rating of the interrupter. The chamber may alternatively be filled with a non-pressurized sulfur hexafluoride or other suitable gaseous medium to prevent contamination.

Abstract: Multiple portions exhibiting relatively different heat conductance characteristics, and so arranged that heat is concentrated in the fusible element, are used to control the heat transfer in a fusible element to achieve preselected time-current fusion characteristics. A portion of the fusible element may also be made of a material exhibiting a relatively high temperature coefficient of resistance for additional control definition of the time-current characteristics.