CURRENT LIMITING FUSE

• US 3,838,375 A
• Filed: 01/29/1973
• Issued: 09/24/1974
• Est. Priority Date: 01/29/1973
• Status: Expired due to Term

• Current Assignee: Ben Lee Damsky, Gerhard Frind, Michael Owen
• Original Assignee: Ben Lee Damsky, Gerhard Frind, Michael Owen
• Inventors: Frind, Gerhard, Owen, Michael, Damsky, Ben Lee
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Bell, Fred E.
• Application Number:
  US05/327,744
• Time in Patent Office: 603 Days
• Field of Search: 337/273,276,158,246,293 200/144C
• US Class Current: 337/276
• CPC Class Codes: H01H 85/18 Casing fillings, e.g. powder

Abstract

Cartridge type current limiting fuses contain a fusible element within an appropriate cartridge connected to electrically conducting terminals at respective ends thereof. The fusible element is surrounded by a packed particulate mass of high resistivity high dielectric strength arc-constricting media which surrounds the fusible elements and is bound into a selfsupporting rigid but porous mass by an inorganic binder which maintains good electrical and mechanical characteristics at temperatures to which the bound particulate mass is subjected to during operation of the fuse to interrupt an electrical current.

Claims

2. The fuse of claim 1 wherein said particulate matter is characterized by a density at least 10 percent greater than the density of a gravity filled cartridge.

3. The fuse of claim 1 wherein said particulate matter is selected from the group consisting of the oxides and nitrides of silicon, magnesium, aluminum, beryllium, calcium, and strontium.

4. The fuse of claim 1 wherein said particulate matter is silica sand.

5. A current limiting fuse having a rating of at at least 1000 volts and comprising:

a. at least one electrically insulating cartridge having a minimum cross-sectional dimension of approximately one inch;

b. a pair of electrically conductive terminals at opposed ends of said cartridge;

c. at least one fusible element within said cartridge in electrical contact with said terminals;

d. a filling of packed particulate matter of high electrical resistivity and high dielectric strength within said cartridge surrounding and in intimate contact with said fusible element and providing a porous arc-constricting enclosure therefor, d1. said packed particulate being bound into a rigid self supporting adherent body by a silica binder added thereto, d2. said binder being present in sufficient quantity to substantially coat the entire surface of each particle of said particulate matter, but insufficient to substantially impair the porosity thereof, d3. said binder having an electrical resistivity characteristic which does not degrade the electrical resistivity characteristic of said packed particulate matter at temperatures up to the temperature of said matter during arcing after fusion of said fusible element and which maintains its binding characteristic at said temperatures.

6. The fuse of claim 5 wherein a plurality of fusible elements are connected between said terminals and individually surrounded by said bound particulate matter.

7. The fuse of claim 5 wherein a plurality of said cartridges are connected electrically in parallel.

8. The fuse of claim 7 wherein the diameter of the cylinders of said cartridges is the same.

9. The fuse of claim 5 wherein said fuse cartridge diameters are within the range of approximately 1 to 4 inches.

10. The fuse of claim 5 wherein said particulate matter is selected from the group consisting of the oxides and nitrides of silicon, magnesium, aluminum, beryllium, calcium, and strontium.