The expulsion fuse

THE EXPULSION fuse is an extremely simple device used quite extensively for interrupting a-c. circuits of moderate voltage and power. In spite of its apparent simplicity and widespread use, the principles upon which it functions are not at all generally understood. Comparisons of interrupting capacities of a soapstone fuse tube and a fiber fuse tube, support the view that the expulsion fuse depends upon the gas blast produced by rapid decomposition of fuse tube material under the heat of the arc. The effectiveness of the gas blast is stated to be due to the high degree of turbulence it introduces into the confined arc space.