Cut-out fuse is made of insulating base, live and fixed contact and fuse tube. Fixed contact installed on both sides of insulating base, and live contact installed on both sides of fuse tube , and out Bakelite paper tube or epoxy –glass fiber fabric tube . Load-off cutout fuse is used for breaking &making load current with adding spring auxiliary contacts and arc-quenching cover. When cutout fuse under normal working condition . Fuse tube forms close location with help of tight for fuse link.
When any fault come out in system, fault current make fuse link melt promptly , and form arcing , arc-quenching tube heated by arc , decompose lot of gas ,produce great pressure inside of tube, and blow vertically in high strength, the electric arc would be lengthened and quenched quickly. After melting of fuse link, fixed contact below turn down due to lost of tension, it makes locking mechanism to release fuse tube to fall down, it forms obvious breaking off location.
When necessary to pull-off load, unhinge contact with insulating link, live and fixed contacts are still connected , to pull contacts continuous with insulating link , auxiliary switch also would be apart , it make electric arc between auxiliary switches ,arc would be lengthened in narrow slot of arc-quenching cover , which produce gas at same time, to quench the arc when current over zero.