US2496759A - Circuit breaker - Google Patents

Description

Feb. 7, 1950 A. WARSH-ER 2,

CIRCUIT BREAKER Filed Jan. 11, 1945 'TTE J.

rig. 21 49 43. g.\ 19

INVENTOR Adaljnk Wars/54m ATTORNEY Patented Feb. 7, 1950 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Adolph Warsher, Maywood, N. J. Application January 11, 1945, Serial No. 572,296

6 Claims.

The present invention relates to circuit breakers, more especially of the resettable type, operating by thermal expansion under overload.

It is among the objects of the invention to provide a device of the above type, which may be substituted for the ordinary fuse, without any alteration in the conventional fuse terminal installation, which will operate reliably to interrupt a sustained overload, which is thoroughly proof against fire hazard, which effectively indicates even in thedark an interrupted circuit condition, which may be readily reset by a simple manual thrust, and which utilizes substantially the conventional fuse cartridge or fuse plug casing for housing the thermally responsive circuit interrupter, the resetting as well as the indicating instrumentalities.

In the accompanying drawings in which is shownone of various possible embodiments of the several features of the invention,

Fig. 1 is an enlarged view in longitudinal cross section through a fuse plug embodiment of the invention;

Fig.2 is a plan view thereof;

Fig. 3 is a view in transverse cross section taken on line 3-3 of Fig; 1; and

Fig. 4 is a side elevation of the interrupter subassembly.

Referring now to the drawings, there is a fuse plug housing or casing of generally conventional construction including a main or outer insulating fuse .body ID with an upper rim ll, presenting a peripheral shoulder i2 against which abuts the upper end of the screw shell terminal contact i3 soldered in place as at it and rolled under the base of the body as at it, the body having the usual frusto-conical inner end it mounting the central contact H to which is connected the conductor strip i8 extending along the inner wall of the body Telescoped into this generally conventional outer fuse body is the insulating inner fuse body 19 which includes the cover 20 and the cylindrical body that is snugly telescoped into the outer shell. The inner shell has a contact 2i frictionally coacting with the screw shell conductor strip 22 and a second contact 23 similarly coacting with the conductor strip ll forthe central conductor. To assure registry of the contacts of the inner and outer plugs,-they are keyed as at 24.

According to the invention, the circuit breaker and associated elements are mounted within the fuse plug in lieu of the usual fuse strip between the terminals. In general the invention involves the use of a switch comprising a movable preloaded spring contact element 25 and a coacting thermally responsive catch element 26 electrically connected in series between the terminals 2| and 23. The device also includes the reset button 21 accessible through the cover 20 for relatching the device after it is sprung on overload. Preferably the device also includes a miniature vapor electric lamp 28 with the associated series connected ballast coil 29, the said two series connected elements also being connected between the terminals 2i and 23 and lets, rivets or screws 33 to an angle bracket 3!,

, desirably with a locating nub 35 to depend from the cover 20 to which said bracket is aflixedby eyelets, screws or rivets 36. The insulating plate 32 depends from the cover to one side of the axis of the fuse plug and is spaced at both faces and preferably also at its edges from the wall of the casing.

Preferabl the releasable spring contact element 25 is an elongated phosphor bronze or beryllium copper strip rivets in place as by eyelet 31. The spring contact is bent in a U-shaped loop 39 through a window slot 40 to protrude from the other face of the mounting plate. The lower edge of the window slot extends but little below the lower arm of the U in the spring contact and extends well thereabove to permit the snapping release of said spring contact as indicatedin dotted lines in Fig. 1.

Coacting with the spring contact element is the thermally responsive element 26 preferably in the form of a bimetallic catch mounted at its lower end by eyelet ll, upon the same face as the spring contact and keyed against rotation about said eyelet by bending its lower end alt-33 about the lower edge of the plate 32. Catch 26 is formed with a latching end 42 normally locking the horizontal extremity 43 of the spring contact in lower or stressed position, as shown in the drawings. Preferably an insulating essence plate N isinterposed between the carrying plate 32 and the bimetallic catch 28 and is held in place by eyelet 4i and extends over eyelet 31 to prevent arcing over. Preferably also plate 32 has an upstanding rib ll to prevent arcing over between eyelets 81 and II. Connector wires ll and il are aillxed to the respective eyelets 31 and ii and extend to the respective contacts 2! and 23 to which they are desirably soldered as shown.

The U-looped portion is of the spring contact preferably extends, as shown, to the axial line of the plug into the path of movement of the enlarged lower end 4| of a reset rod having the button 21 protruding upwardly through the center of the window ii in the cover of the fuse. Preferably a leaf spring on the under face of the cover resiliently retains the button in elevated position.

In use of the circuit breaker as thus far described, the current will pass from terminal ll through strip ll, contact 23, lead 41, eyelet Ii, bimetallic catch 2, spring contact fl, eyelet 31, lead 46, and contact 2| to the screw terminal It. A transient overload, that is, one of the type not injurious to the circuit, will not heat the bimetallic strip sufllciently to change the relation shown in Fig. 1. Upon a suflciently sustained overload, however, said catch ll will move outwardly and release the preloaded spring contact 2| which then snaps upwardly as shown. By reason of the preloading set forth, the snapping, when it occurs, is so vigorous that no arc will be maintained and the circuit is sharply interrupted.

The device affords an inherent safety lag and will not snap open on every short and harmless surge of abnormal current, but only on sustained overloads of predetermined time-current product which will produce suflcient heat in the bimetallic element to release the spring catch member and allow the circuit contacts to separate. The bimetallic catch will remain in deflected position after it trips until it cools sufficiently to return. Accordingly it would be impossible to reset the circuit breaker prematurely. Thus adequate time is aflorded for the wires of the previoguuslcyuoverloaded circuit to cool down before the t can be reclosed. This is to be distinguished from the conventional melting type of fusible link which is apt to blow if replaced too promptly.

The miniature vapor electric lamp may be filled with any suitable noble gas, such as argon,

, and its electrodes are spaced so that it will glow under a predetermined voltage materially below that of the line. The miniature lamp and the series connected ballast resistance aredisposed in the inner fuse plugin the space to one side of the plate 32 and reset button 21.

Even though little or no arcing occurs when the circuit breaker snaps open, the flow through the ballast resistance 20 and miniature lamp ll will cause the latter to light at least for an incorporated in any desired size or shape of casing As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A circuit breaker comprising a fuse plug casing having a central and a screw shell contact, a cover, a bracket aflixed to the inner wall of said cover, an insulating plate afllxed to said bracket and depending into said casing at a distance from the lateral wall thereof and having a window opening therein, a movable spring contact strip and a bimetallic catch element both affixed at'the lower ends thereof to the same side of the insulating plate, the spring contact strip presenting a loop extending through said window to the face opposite the side on which the contact strip and catch element are affixed, the free end of said spring contact strip being maintained in depressed pomtion by said catch, and a central reset button in said cover, spring urged upward through the cover, registering at its lower end with the looped portion of said spring contact strip and adapted to reset the same.

2. A circuit breaker comprising a fuse plug casing having a central and a screw contact, a cover, an insulating plate depending from said cover, a pair of metallic mounting elements through said plate, a spring contact element amxed to said plate at one end thereof by one metal mounting element, and a coactlng bimetallic catch aillxed to said plate by the other metal mounting member, a miniature glow discharge lamp and an associated ballast within said casing connected in series between said metallic mounting members, a phosphorescent paint spot exposed to said lamp and means connecting the respective metallic mounting members to the terminals of the plug.

3. A circuit breaker comprising a fuse plug casing, having a central and a screw contact, a cover, an insulating plate depending from said cover, a pair of metallic mounting elements through said plate, a spring contact element affixed to said plate at one end thereof by one metal mounting element, and a coacting bimetallic catch afllxed to said plate by the other metal mounting member, a reset button, a miniature glow discharge lamp and an associated ballast within said casing connected in series between said metal mounting members, and means connecting the respective metal mounting members to the terminals of the plug, said plug having a translucent window in its cover through which the reset button extends, said window having an area covered with phosphorescent paint and exposed to the radiation from said miniature lamp.

4. A circuit breaker comprising a fuse plug casing, including an outer body having a central and a screw shell contact a cover having an inner body telescoped into said outer body, an insulating mount carried by said cover, a releasable spring contact element, and a bimetallic catch, both amed to said mount at one face thereof, said catch being adapted to latch said spring contact, said spring contact element having a loop extending fromthe other face of said mount, a reset button extending through the cover to coact r an with said loop for relatching the same, conducting leads from the spring contact and the catch respectively, contact members carried by the inner body to which said leads are respectively amxed, said contact members coacting respectively in the assembled body with the central and the screw shell contacts of the outer body.

5. The combination recited in claim 4 in which a miniature glow discharge lamp with an associated ballast resistance in series therewith are disposed within the inner body between the insulating mount and one of said contacts, the terminals of said series connected elements being electrically connected respectively to the contact members of the coacting catch and spring contact elements and a phosphorescent paint spot exposed to said lamp.

6. A circuit breaker comprising a fuse plug casing including a cover, an insulating plate mounted on said cover and depending therefrom, a releasable spring contact strip eyeleted to said plate at one end thereof and extending in a reverse U-bend through a window in said plate with the loop of the U protruding from the other face thereof and the free end 01' said strip protruding from the face on which said strip is mounted, an insulating sheet overlapping the mounted end of said strip, a bimetallic catch superposed over said insulated sheet, an eyelet connecting said sheet and said catch to said plate, said catch having a conformation at its upper end to maintain the spring contact strip depressed, said plate having an insulating rib intervening between the two eyelets, and a reset button through the cover of the plug to coact with said loop for resetting the same.

ADOLPH WARSHER.

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

UNITED STATES PATENTS Cook Dec. 25, 19 5

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