Electric fuse for elevated circuit voltages capable of interrupting

Abstract

An electric fuse adapted to form multibreaks at the occurrence of small protracted overload currents includes a first fusible element having a relatively small resistance which supports at a predetermined point thereof means for causing formation of a break at the occurrence of small protracted overloads. The fuse includes a second fusible element having a relatively high resistance shunted across said predetermined point of said first fusible element and has ends adapted to initiate arcing at small current intensities at points thereof located immediately adjacent said first fusible element. Blocks of metal are arranged in spaced relation from said first fusible element in the zone of arcing established by fusion of said ends of said second fusible element to increase the contamination of said zone by products of arcing resulting from vaporization of said blocks. A rod member of electric insulating material is arranged parallel to, but spaced from, the axis of the casing of the fuse. This rod member engages and supports full turns of the first and of the second fusible element which are each formed by a helical winding only at one single point of the particular turn. This rod member of electric insulating material forms also a support for the aforementioned arc product generating blocks.