US2836680A - Fuse cutout construction - Google Patents

Description

May 27, 1958 A. a. BALE, JR, ET AL 2,836,630

FUSE CUTOUT CONSTRUCTION Filed Aug. 8, 1955 25072 6. BaZe Jr: fawczr'd L. San/(ear INVENTORS.

BY Z M/ 4 United States Patent Ofiice 2,836,680 Patented May 27, 1958 FUSE CUTOUT CONSTRUCTION Alton G. Bale, Jr., South Milwaukee, and Edward L. Sankey, Milwaukee, Wis., assignors t McGraw-Edison Company, a corporation of Delaware Application August 8, 1955, Serial No. 527,084

3 Claims. (Cl. 200-114) The present invention relates to a fuse cutout construction, and particularly relates to a cutout characterized by its ability to safely close an electric circuit even though fault conditions may exist thereon.

When a fault condition develops on a distribution circuit causing the fusible element of a fuse cutout to rupture, large mechanical forces may develop in the cutout. Conventional housed cutouts are constructed with sufiicient strength to counteract any expulsive forces caused by rupture of the fuse link when all of the cooperating members are in secure mechanical engagement relative to one another. This is true even in the relatively confined space provided in conventional cutout housings.

However, when an attempt is made to reclose conventional cutouts after replacement of a ruptured fuse link, and on the existence of alow impedance fault, violent arcing'between contacts often occurs with consequent profused evolution of hot gases. Inasmuch as the gases are relatively confined, they will act immediately to force an incompletely closed cutout door open with such violence as to injure or burn a lineman servicing the fuse. In many cases,'there is even the possibility of the porcelain housing being blown tion of relatively confined gases. 7

The present invention contemplates the modification of conventional cutouts to include an auxiliary electrical circuit including an auxiliary circuit-closingmeans for completing the electrical circuit through the fusible element afterthe various cooperating parts have been placed in secure mechanical relationship with one another. l V o It isa particular object of the invention to provide a housed cutout utilizing conventional operating parts with a modified'terminal construction including an insulating gap in said terminal having means for electrically and mechanically bridging said gap to complete the elec tric circuit through said terminal to the cutout fuse link, said bridging means being actuated externally of said cutout after complete 'mechanical closure of the cutout door has been insured.

It is a further object of the present invention to provide an auxiliary switching means for completing the electrical circuit from a line terminal of a fuse cutout to the fuse cartridge after mechanical sccurement of all cooperating movable parts, wherein said means cornprises a pair of cooperable' contacts, one of which is biased towards closure with the other and is withheld from such movement by means of a detent-pawl arrangement and which is preferably releasably operable exterrially of said cutout'by means of a hook stick or other means engageable therewith and which may be manipulated by a lineman or operator safely positioned remotely therefrom. o I

It is still another object of this invention to provide an improved cartridge-door assembly for enclosed cutouts which assembly may be inserted in standard cutout boxes for testing theline circuit to, determine if a fault exists apart by the evolu in the system prior to insertion of the original re-fused cartridge-door assembly.

An embodiment of the invention is shown in the accompanying drawing, in which:

Fig. 1 is a side elevational view, in section, of a housed cutout embodying the present invention with the various cooperating parts being in mechanical securement relative to one anotner and being shown with the electrical circuit being in non-conductive arrangement;

Fig. 2 is a cross sectional view taken on lines 2-4 of Fig. l with the housing and door removed.

Referring to the drawing, it will be seen that the fuse cutout comprises an insulating housing 1 which is supportedon a metallic bracket 2, and includes a door 3. The door is also of insulating material, such as reinforced Bakelite, and is hingedly supported on the housing by means of trunnions 4 which extend laterally from the lower edge of the door, and are removably seated within the spaced apart hook-like portions of a rigid bracket 5 affixed to the housing.

The door 3 is adapted to pivot into closed relation with the housing 1, as shown in Fig. l and to be removed from the bracket The construction of the hinge assembly is well-known, and has been illustrated here in dotted portions for convenience and minimum of confusion in disclosing the novel features of the present structure.

It will be seen that the insulating door 3 fixedly carries on it a fuse cartridge assembly, indicated generally by the reference numeral it}. When the door 3 is closed with respect to housing It, as illustrated in Fig. l, the upper terminal cap ii of the cartridge 1% contacts and becomes electrically engaged with an upper stationary terminal 12 affixed within the housing in electrical association with a pair of U-shaped yiclo'able contact clips 13 serving to guide the cap it. into alignment with the spring-type terminal 12. Members 12 and 13 are connected to an incoming electric line conductor 14 by means of a screw-type connector 15.

The outgoing line conductor 19 is spaced from the conductor 14 and is connected in a conventional manner through the medium of the screw-type connector 20 to a lower contact clip in the form of a U-shaped resilient member 21.

When the door 3 is swung to closed position, as shown in Fig. l, the lower stationary terminal clips or members 21 are adapted to electrically receive therebctween,

a conductive contact 22, which in turn supports the cartridge assembly 1%. rigidly ZliilXQd to the door by means of screws 23 to prevent the cartridge assembly 10 from sliding with re- Mounted at the far lower end of the fuse tube 27, there,

is a conducting terminal member 30, which is preferably a casting and includes an integral ferrule portion 31circumjacent to the tube and which is pinned'in place by means of the straight thru pin 32. The member 30 includes a conventional threaded stud 33 0 preferably staked thereto, and to which a leader portion of a fuse link 34 is electrically connected by means of a knurled thumb screw 35. The leader of the fuse link 34 extends from the lower end ofthe fuse tube 2'7 and is pulled tightly over the conventional flip-out lever 36 pivotally mounted on the terminal member 30. The lever 36 is biased for clockwise movement with reference to Fig. 1,

, ture of the fusible element (not shown).

The fuse tube contact 22 is,

H The present invention is best described in connection with the illustration of Fig. 2 and with reference to the lower portion of the cartridge assembly 10 of Fig. l. The invention is directed particularly to the provision of an auxiliary switch means for completing the,electric'al circuit from the fuse link 34 through the terminal member 30 to the contact 22 and from there to the line conductor 19. This circuit is to be completed after complete closure of the cutout door 3 and secure mechanical engagement of the cap 11 on the cartridge assembly 10 and the upper terminal 12.

The various components of the switch means include cooperable auxiliary contacts 40 and 41. The auxiliary stationary contact 40 is preferably an integral part of the fuse tube contact 22 and is bevelled at its outer edge 42 to engageably receive the movable contacts 41. The movable contacts 41 preferably comprise companion members 41a and 41b (see Fig. 2) mounted at the extremity of the movable contact assembly generally designated by the reference numeral 43. The assembly 43 comprises two cooperating contact supports biased towards one another by means of compression coil springs 44 at either side thereof. The springs 44 are preferably circumjacent to a headed thrupin 45. The assembly 43 is pivotally mounted on the terminal member 30 by means of a pivot pin 46 and is biased for clockwise rotation as viewed in Fig. l by means of the torsion spring 47.

As shown in Fig. l, the movable contact assembly 43 is prevented from rotating by means of a pawl-detent arrangement comprising the pawl portion 50 of the assembly engageable with the detent portion 51 of the trigger assembly, denoted generally by the reference character 52. The trigger assembly 52 is pivotally attached to the terminal member 39 by means of the pivot pin 53, which also pivotally supports the flip-out lever 36. The trigger assembly 52 preferably extends exteriorly of the cutout for purposes hereinafter described.

The operation of the device is as follows:

As has been stated earlier, it is intended that the improved cartridge assembly be used either as a permanently installed component of the fuse cutout, or in the alternative, as a temporary safety device for testing an electrical line subsequent to replacement of a blown fuse link assembly. In illustrating the operation of the invention, it will be assumed that the cartridge assembly 10 and the door 3 are mechanically secured in'operating position cooperating with the spaced apart terminals within the housing 1. If it is desired to replace a ruptured fuse link 34, the door 3, and likewise the cartridge assembly 10, are swung outwardly on the trunnions 4 and removed from the hook-like bracket 5. After removal of the assembly from the housing 1, the cap 11 is unscrewed and the ruptured portions of the fuse link 34 are removed from the fuse tube 27. The lower portion of the link 34 is also removed from the stud 33.

After a new fuse link has been installed in the cartridge assembly 10 and fastened around the lever 36 and the stud 33 in the conventional manner, the lineman makes such that the auxiliary movable contact assembly 43 is placed in rotative non-conducting position, as shown in Fig. 1, with the pawl portion 50 engaging the detent 51 of the trigger assembly 52. This insures that the electrical circuit from the terminal member 30 to the contact 22 is interrupted.

Since the said circuit is interrupted, the door and attached cartridge assembly 10 may be replaced on the bracket and swung into closed position as shown in Fig. 1 with the cap 11 being placed in secure mechanical engagement with the terminal 12. Thus, the door may be fully mechanically closed without completing the electrical circuit through the cutout. Consequently, even though a fault should remain on the electric ciruit, no arcing or flashing will occur, nor will any danger ensue to the lineman closing the fuse box, because the cartridge 10 is in non-conductive position during this time.

After the lineman has removed himself from the immediate vicinity of the fuse cutout, he may engage the trigger assembly 52 by means of an insulated stick and rock the trigger clockwise, as shown in Fig. 1, to release the detent portion 51 from the pawl portion 50 of the movable contact assembly 43. This action permits the torsion spring 47 to urge the movable contacts 41 towards secure electrical engagement with the bevelled edge of the auxiliary contact 40. Obviously, the switch may be closed by other means, such as by means of a pull-cord (not shown) tied to the trigger assembly and hanging below the cutout.

The circuit is now complete through the fuse cartridge assembly, and should a fault have remained on the line after the fuse assembly is closed in, and after the trigger assembly 52 has been actuated, the fusible element (not shown) of the fuse link 34 may rupture due to the overcurrent. However, no serious consequences will result because all arcing will be confined to the interior of the cartridge assembly 10, which is designed for that duty. Hence, it is to be appreciated that the invention completely eliminates premature arcing between the terminals of the cutout construction, which arcing would occur when merely closing a faulted system when conventional cutouts are employed. Moreover, the lineman may close the improved cutout door without apprehension as to whether a violent flashing may occur before the door has been fully closed.

As implied hereinbefore, it is not necessary to secure the benefit of this invention by requiring every cutout and electrical system to be provided with a novel cartridge door assembly herein described. Rather, the invention is adapted to be used in a cutout having any proper corresponding current rating. Thus, if need be, at line crew truck may carry only one such device for each conventionally rated cutout in a system, and whenever it is desired to re-fuse a cutout, and where there may be a reasonable doubt as to whether or not a fault has been cleared, the present cartridge-door assembly may be temporarily installed and actuated to determine whether or not the fusible element therein will rupture. If it does not, of course, the door 3 carrying the cartridge assembly 10, may be removed and the standard cutoutdoor assembly substituted therefore. The circuit may then be safely and confidently closed.

In addition, the auxiliary switch means is entirely out of the path of any hot gases following interruption of the fusible element. Thus, none of the cooperating members are subject to erosion or other detrimental effects taking place under fault conditions.

It will be apparent that a novel fuse cutout assembly has been provided of easily operated, simplified, parts which will permit the assembly to be operated to closed circuit position without danger to the lineman, and wherein premature uncontrolled arcing is precluded. In addition, it will be appreciated that little or no modification of present type cutouts, other than the lower terminal assembly is required for adapting the cutout to include the preferred embodiment of the present invention.

. We claim:

1. In an enclosed fuse cutout having spaced apart line terminals, a closure assembly for said enclosed cutout including a fuse cartridge assembly arranged to mechanically bridge said terminals, pivot means pivotally supporting one end of said cartridge assembly for rotative movement in to and out of bridging engagement with said terminals, and a fuse link contained within said cartridge assembly and normally electrically connecting said line terminals; auxiliary switch means interposed between said fuse link and one of said terminals and comprising a pair of auxiliary contacts externally of said fuse cartridge assembly and biased for normal electrical engagement with one another, restraining means normally preventing said electrical engagement, and a manually operable trigger adapted for releasing said restraining means to permit said electrical engagement of said auxiliary contacts after said fuse cartridge assembly has been pivotally rocked into mechanically secure bridging relationship with said line terminals.

2. In an enclosed fuse cutout having spaced apart line terminals, a closure assembly for said enclosed cutout including a fuse cartridge assembly arranged to mechanically bridge said terminals, pivot means pivotally supporting one end of said cartridge assembly for rotative movement into and out of bridging engagement with said terminals, and a fuse link contained within said cartridge assembly and normally electrically connecting said line terminals; auxiliary switch means interposed between said fuse link and one of said terminals and comprising a pair of auxiliary contacts externally of said fuse cartridge assembly, one of said contacts being pivotally mounted and biased for movement towards electrical en gagernent with the other, and a manually operable trigger assembly having a portion normally restraining said pivoted contact from said biased movement, said trigger assembly adapted for said manual operation after said fuse cartridge assembly has been pivotally rocked into mechanically secure bridging relationship with said line.

3. In an enclosed fuse cutout having spaced apart line terminals, a closure assembly for said enclosed cutout including a fuse cartridge assembly arranged to mechanically bridge said terminals, pivot means pivotally supporting one end of said cartridge assembly for rotative movement into and out of bridging engagement with said terminals, and a fuse link contained within said cartridge assembly and normally electrically connecting said line terminals; auxiliary switch means interposed between said fuse link and one of said terminals and comprising a pair of auxiliary contacts externally of said fuse cartridge assembly, one of said contacts being positioned at one end of a pivotally mounted lever, spring means urging said lever towards movement of said one of said contacts into electrical engagement with the other contact, the opposite end of said lever including a pawl, and a manually operable trigger assembly having a detent portion normally engaging said pawl to prevent movement of said lever, said trigger assembly adapted for said manual operation for releasing said pawl from, said detent portion after said fuse cartridge assembly has been pivotally rocked into mechanically secure bridging relationship with said line terminals.

References Cited in the file of this patent UNITED STATES PATENTS 1,288,951 Matthews et al. Dec. 24, 1918 2,249,662 Matthews July 15, '1941 2,272,717 Ludwig et al. Feb. 10, 1942 2,438,746 Garrison Mar. 30, 1948 2,716,681 Smith Aug. 30, 1955 2,734,966 Schneider Feb, 14, 1956 U. S. DEPARTMENT OF COMMERCE PATENT OFFI CE CERTIFICATE OF CORRECTION Patent No, 2,836,680 Alton Bale Jr 'et alo May 27, 1958 Column 5, line 25 after "the word "line? and before the period insert terminals o Signed and sealed this 29th day of July 1958a (SEAL) At'fiest:

KARL 11L, AXLINE ROBERT C WATSON Attesting Officer Commissioner of Patents U. S. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 2,836,680 Alton G0 Bale, Jr et alo May 27, 1958 Column 5, line 25 after tho Word "line and before the period insert terminals 0 Signed and sealed this 29th day of July 19580 (SEAL) Atiest:

KARL Ha MINE ROBERT C. WATSON Attesting Officer Commissioner of Patents

Images