Abstract A quick acting current limiting, high voltage fuse comprising a tubular casing made of an insulating material; one or more relatively long fusible elements wound helically on an insulating core which is located inside the casing coaxially therewith; a pair of metallic terminals which close the ends of the casing and are connected to the ends of the fusible elements; and a granular arc extinguishing material which completely fills the casing and embeds the elements and core. Each element consists of a very thin, narrow and long strip of a fusible metal such as silver having along its length in one edge a plurality of spaced notches made by cutting out small segments of strip. Each notch appears in outline on the flat side of the strip as an arc of a circle. These notches define regions of reduced cross section for initiating fusion of the strip. Their configuration and arrangement reduces the tendency of the arcs to run together as they enlarge. Their presence also produce a rapid rise in arc voltage, short melting time, and low I2t.
A quick acting fuse comprising: a. a tubular casing; b. a terminal structure closing each end of the casing; c. a core located inside said casing coaxially therewith, said core being slender enough that a significant radial space is left between it and said casing; d. at least one fusible element wound helically on said core with the turns of the helix spaced from one another, said element having its ends connected to the respective terminal structures, said element comprising: i. a relatively long strip of fusible conducting material having a plurality of notches along its length, the first notch in each end of said strip is spaced a significant distance from the respective terminal structure and a somewhat lesser distance from the next adjoining notch and the remaining notches are spaced even closer together at approximately equal intervals; and e. a granular arc extinguishing material filling the casing and embedding the fusible element.
Claim 2
Dependent Claim
154 words
A quick acting fuse comprising: a. a tubular casing; b. a terminal structure closing each end of the casing; c. a core located inside said casing coaxially therewith, said core being slender enough that a significant radial space is left between it and said casing; d. at least one fusible element wound helically on said core with the turns of the helix spaced from one another, said element having its ends connected to the respective terminal structures, said element comprising: i. a relatively long strip of fusible conducting material having a plurality of notches along its length, the first notch in each end of said strip is spaced a significant distance from the respective terminal structure and a somewhat lesser distance from the next adjoining notch and the remaining notches are spaced even closer together at approximately equal intervals; and e. a granular arc extinguishing material filling the casing and embedding the fusible element.
Claim 3
Dependent Claim
43 words
The quick acting fuse as specified in claim 1 wherein a plurality of said strips are wound flatwise on said core in parallel and spaced relatively close to one another and with a much greater spacing left between the turns of the strip.
Claim 4
Dependent Claim
46 words
The quick acting fuse as specified in claim 6 wherein the notches in each of said strips are all located along only one edge of the strip and said strips are so wound on said core that all of their notches face in the same direction.