Arrester apparatus

An arrester, comprising:

• an insulating tubular member;
• a pair of main electrodes air-tightly coupled to respective open ends of said insulating tubular member;
• a ground electrode attached to a central portion of said insulating tubular member;
• and
• a springy, electrically-conductive short-circuiting element having a substantially cylindrical shape essentially conforming to the shape of said insulating tubular member, said short-circuiting element being fitted around an outer wall of said ground electrode by utilization of spring characteristics of said short-circuiting element to allow electrical connection between said short-circuiting element and said ground electrode, said short-circuiting element including extension portions extending along an outer wall of said insulating tubular member to respective main electrodes, said extension portions facing said main electrodes with a certain gap maintained when a thermally-fusible spacer is unfused;
• wherein if said arrester is overheated, said spacer is thermally fused by heat and said extension portions electrically contact said main electrodes due to spring characteristics, short-circuiting said main electrodes to said ground electrode;
• and wherein said spacer has a central hole and is sandwiched between said short-circuiting element and said ground electrode, with a terminal of said ground electrode fitted in said central hole, and said extension portions of said short-circuiting element are made to face said main electrodes by utilization of spring characteristics, with said certain gap maintained.