US2514163A

US2514163A - Load-break fuse switch

Info

Publication number: US2514163A
Application number: US20480A
Authority: US
Inventors: Ralph R Pittman
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-04-12
Filing date: 1948-04-12
Publication date: 1950-07-04
Anticipated expiration: 1967-07-04

Description

July 4, 1950 PlTTMAN 2,514,163

LOAD-BREAK FUSE SWITCH Filed April 12, 1948 IN V EN TOR.

Patented July 4, 1950 UNITED STATES PATENT OFFICE LOAD-BREAK FUSE SWITCH Ralph E. Pittman, North Little Rock, Ark. Application April 12, 1948, Serial No. 20,480

1 Claim. 1

This invention relates generally to fuse switches adapted for connection to electrical circuits, and particularly to a fuse switch construction suitable for interrupting load current by appropriate manipulation, which in addition functions as a fuse operable upon predetermined excess current.

Among the objects of the invention may be noted the provision of means for manually causing operation of the fuse and interruption of normal load current when desired; the provision of a fuse switch which may be opened and closed as desired without operation of the fuse, together with the automatic overload protection inherent in a fused device. Other objects will be obvious or pointed out hereinafter.

The invention comprises the elements and combinations thereof, features of construction and arrangement of parts to be exemplified in the description to follow, and the scope of the invention will appear in the accompanying claim.

Fig. 1 of the drawing is a side elevational view of the device, shown partly in section; Fig, 2 is an end view of the switch. Similar reference characters indicate corresponding parts in the figures of the drawing.

Load-break switches are well known and widely used in electrical construction; fuse constructions are also common. However, in situations requiring both interruption of load current and interruption of overload current, one structure is often supplied for load breaking and another and separate structure for overload interruption in response to the fusing of a fusible element. The advantages of accomplishing both of these functions by means of a single, simple structure, from the standpoint of the lower cost of the apparatus in addition to the lower cost of mounting, are obvious.

The manner in which my invention meets the foregoing requirements will be clear from the following description.

Referring to the drawing, the insulator Ill has secured at its upper end the upper conducting contact member l3 and at its lower end the lower conducting contact member 14, to which are respectively attached the line terminal I! and the load terminal I2. A fuse tube 15, of insulating material, spans the space between the upper end and lower contact members, the upper fuse tube contact 26 conductively engaging the upper contact member 53, and the lower fuse tube contact 21 conductively engaging the lower contact memher It.

The fuse link is extends through the fuse tube 15, and electrically connects the upper contact member I3 to the lower contact member l4, through its engagement at the button-head end with the upper fuse tube contact 26, and through the engagement of its outwardly extending end with the downwardly biased fuse link extractor l8. Within the tube l5, and between the lower open end thereof and the top of the tube, the fuse link 16 is provided with a mechanically weakened fusible element ll, of such tensile strength that the fuse link will rupture at the element ll when the fuse link is subjected to a predetermined tension.

The fuse tube 15 is mounted on the lower contact member I4 by the pivot l9, and is provided with an eye 20 for convenient opening and closing of the fuse switch by means of an insulated switch stick, in which operations the upper fuse tube contact 26 disengages the upper contact member 13 as the tube I5 is rotated on the pivot I9.

At the lower end of the tube l5 and on the lower fuse tube contact 21 is pivotally mounted, for rotation about the pivot 22, the fuse link rupturing lever 2|. Thi lever includes the arms 24, which straddle the fuse tube 15, and which are joined at their inwardly extending ends by the laterally extending fuse-extractor engaging portion 25, which is so positioned that it engages the fuse extractor [8 in its path of movement and urges the latter in the direction to tension the fuse link It when the fuse link rupturing lever 2| is urged in counterclockwise direction about the pivot 22.

Preferably the fuse link rupturing lever 2| extends outwardly and downwardly from the open end of the fuse tube l5, and is provided with a recess 23 for receiving an insulated switch stick to urge the lever 2| in the direction to rupture the fuse link IS. The dotted lines indicate the position of the parts immediately after the fuse link rupturing lever 2| has been urged to the position to rupture the fuse link, but before the link has been completely extracted from the open end of the fuse tube.

From the above description, it will be seen that the circuit from the line terminal H to the load terminal l2 may be opened in either of two ways as desired, one by pulling the fuse tube l5 to open position, in which event only air break circuit interruption is available, or alternately by tensioning the fuse link to rupture, in which event the much more effective expulsion fuse interrupting ability i utilized.

If the magnitude of the current is such that the arc cannot be interrupted by air-break, as

may be readily determined by trial, then the fuse link rupturing lever 2| may be employed. In so doing, it will be observed that the force applied to tension the link to rupture is in the direction to close the switch. This is a most important consideration from the standpoint of avoiding unwanted air-break interruption and in addition providing assurance that the switch is in the fully closed position before the blast attending expulsion action is initiated by rupture of the mechanically weakened section within the tube. It is in this respect that the recess 23 is provided, instead of an eye, at the outer end of the fuse link rupturing lever 2i.

The end of the fuse link rupturing lever 2i which is intended to be manipulated to cause breakage of the fuse link preferably extends outwardly beyond the pivot 22 for a distance greater than that from the other end of the lever to the pivot, to facilitate breakage of the higher amperage fuse links which, to handle rated current, are inherently of relatively high tensile strength. In the absence of the mechanical advantage so provided, such large amperage links are extremely diificult to fracture.

It will be apparent that changes and modifications may be made in the specific embodiment of the invention here shown and described and it is intended that the description herein will be regarded as illustrative rather than limiting.

I claim, as my invention:

In a fuse switch having an open position and a closed position, a fuse tube open at the lower end and swingable in upward direction for movement from open to closed position, a fuse link within said fuse tube, and a pivotally mounted fuse link rupturing lever on said tube at the open end and arranged to withdraw said fuse link from the open end of said tube in response to a predetermined movement of said lever in said upward direction, said lever extending respectively inwardly and outwardly beyond said fuse tube, the inwardly extending portion moving downwardly when the outwardly extending portion moves upwardly whereby said fuse tube is held in closed position while the fuse link is withdrawn from the open end of said tube.

, RALPH R. PI'I'I'MAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,899,915 Matthews et a1. Feb. 28, 1933 2,133,139 Hermann Oct, 11, 1938 2,150,102 Lemmon Mar. 7, 1939 2,175,328 Walsh Oct. 10, 1939 2,310,466 Schultz et a1 Feb. 9, 1943