US3256412A - Rapid acting fuse - Google Patents

Description

June 14, 1966 A. R. DAVIS 3,256,412

RAPID ACTING FUSE Original Filed March 15, 1961 I NVENTOR.

49/62 4. DAV/S United States Patent 3,256,412 RAPID ACTING FUSE Ariel R. Davis, Salt Lake City, Utah, assignor to BJ.

Management Corporation, Salt Lake City, Utah, a corporation of Utah Original application Mar. 15, 1961, Ser. No. 95,952. Divided and this application June 16, 1964, Ser. No.

1 Claim. (Cl. 200123) This is a division of my co-pending application Serial No. 95,952 filed March 15, 1961 and entitled, Solid State Control System.

This invention relates to rapid acting fuses and is directed particularly to the means for storing and connecting rapid acting fuse wire. The I T fuse Wire carries normal currents Without deterioration but on an overload current rapidly accumulates heat to melt the wire within a few cycles to disrupt the circuit and protect the electrical elements. In the case of sensitive electrical elernents, such as silicon controlled rectifiers, the fuse Wire can be selected that will melt below the destructive current values of the silicon controlledrectifiers.

An object of the invention is to provide a support and storage means for fuse wire that maintains the wire at normal currents and provides simple means for re-establishing the fuse after destruction by overload currents.

Other and further objects will be apparent from the following description taken in connection with the drawing respectively illustrating the fuse with the clamping members sectionally illustrated.

The fusecomprises two spaced base members 160 and 161. The base members are each made of one-half inch diameter silver plated copper cylinders which serve as heat sinks. These bases are fastened to conducting strips 118a, b and 123a, b respectively. The bases are spaced a distance A apart to form a small air gap preferably one-sixteenth of an inch between them. The bases have flat clamping or gripping surfaces 162, 163 with threaded holes 164, 165 to receive bolts 166, 167. On the base 161 a bobbin member is held in place by the bolt 167 and has an open ended inner chamber 169. A bobbin of pure silver wire is wound in a coil and placed in the chamber of the bobbin to freely rotate about bolt 167. About three-quarters of an inch of Wire is pulled out and extends from base 160 to base 161 and is held in place by the bobbin or clamping member 168 under the pressure of the bolt 167 and the cylindrical "ice and open the circuit. On a sudden high overload it will fuse before the current reaches the burn out point of the silicon controlled rectifiers. This point selected is above the point that the trigger retarder, air choke and breaker combination fuses, but below the fusing of the rectifiers. Thus the fuse is a safety device in case the air core choke or trigger retarder is not functioning or the circuit breaker is not operative. In view of the bobbin form of the fuse wire, the fuse is easily renewed by unrolling the wire and reclamping it between the cylindrical members and the bases 160 and 161.

As seen from the foregoing description the fuse wire will rapidly disintegrate on overload to protect sensitive electrical elements and the fuse is readily and easily reestablished by loosening the screws and unreeling the wire for fastening of the block 171. This can be done quickly so that the equipment is immediately returned to service as soon as the overload conditions are removed.

The invention is set forth in the appended claim.

I claim:

A fuse comprising first and second base members having good heat and electrical conducting properties and having gripping surfaces thereon, first and second clamping members having good heat conducting properties and having gripping surfaces facing the gripping surfaces of said base members for holding fuse wire therebetween, means removably attaching said clamping members to said base members in clamping relation, said first clamping member having an inner chamber housing a coil of fuse Wire and having an opening from said chamber in the gripping surface of the first clamping member With an extension of the fuse wire from said chamber between the gripping surfaces of said first base and clamping members to and between the gripping surfaces of said second base and clamping members for conduction of current from one base member to the other and said first base and clamping members and said second base and clamping members being spaced apart a distance in the order of $4 of an inch to form heat sinks for removal of heat under normal currents while permitting accumulation of heat in the wire to destroy the wire on excessive currents.

References Cited by the Examiner UNITED STATES PATENTS 292,713 l/l884 Weston 200l35 301,030 6/1884 Weston 200l35 1,173,962 2/1916 Hensell 200125 1,374,368 4/1921 Drake 200125 2,794,097 5/1957 Jacobs 200123 3,002,071 9/1961 Storsand 200 3,020,370 2/1962 Swain 200120 FOREIGN PATENTS 197,089 5/ 1923 Great Britain.

BERNARD A. GILHEANY, Primary Examiner.

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