Electric fuse having large cycling ability and gas-evolving means

An electric fuse comprising a tubular casing of electric insulating material;

• a pulverulent arc-quenching filler inside said casing;
• a pair of terminal elements having axially inner end surfaces closing said casing;
• a pair of fusible elements conductively interconnecting said pair of terminal elements;
• said pair of fusible elements comprising axially outer, parallel, substantially planar sections;
• and said pair of fusible elements further comprising axially inner substantially planar converging sections, said axially inner sections converging in opposite directions from the axially inner ends of said axially outer sections and intersect at substantially straight lines, each of said axially outer sections and each of said axially inner sections having points of reduced cross-sectional area arranged at points thereof remote from the intersections of the planes defined by said axially outer sections and the planes defined by said axially inner sections;
• wherein the improvement comprises a sheet of electric insulating material evolving gas under the action of an electric arc inserted into the gap formed between said pair of fusible elements, said sheet of electric insulating material having a length but slightly shorter than the spacing between said axially inner end surfaces of said pair of terminal elements so as to be substantially prevented from moving relative to said pair of fusible elements in a direction longitudinally of said casing, and said sheet of electric insulating material having a width but slightly less than the inner diameter of said casing so as to be substantially prevented from moving relative to said pair of fusible elements in a direction transversely of said casing.