US2086028A - Fuse switch - Google Patents

Description

July 6,1937. w. A. HEINRICH ET AL FUSE SWITCH Filed. my 20, 1935 A TTa/ EY Patented July 6, 1937 PTENT aoeaeze Fuss swrren Walter A. Heinrich and Charles Allin Fox, Louis, Mo., assignors to .lames R. Kearney (dor poration, St. Louis, Mo., a corporation of mnsouri Application Itiay 2, 1935, No. 1% Claims. (Cl. soo -rm This invention relates generally to fuse switches of the type employed in connection with electrical service distribution, and more specif= ically to an improved tensloned fuse switch of 5 this type winch is of greatly simplified construction, the predominant object of the invention be ing to provide a tensioned fuse switch of the type referred to which, while of extremely simple construction and mechanical arrangement, is

capable of performing its intended function in a highly emcient manner.

Fuse switches of the type heretofore in gen= eral use comprised a switch mounting, a fuse cartridge, and a fuse link. The switch mount= 1? ing consisted of a base suitably designed to be bolted or clamped to a cross-arm, pole, or other support, and included parts adapted to provide for permanent attachment to the line terminals. The switch mounting was so arranged as to support the fuse cartridge in such manner that it might be put in and taken out with the aid of an insulated switch stick or fuse puller. The fuse cartridge consisted essentially of an arc expulsion tube equipped with necessary castings and terminal parts to properly hold the fuse link and to permit the cartridge assembly to be put in and taken out of the switch mounting by means of the insulated switch stick or fuse puller referred to above. This fuse tube had to be of 30 'the proper length and had to have the proper wall thickness relative to its internal diameter,

so as to interrupt the loads for which it was de-- signed, and also the fuse tube necessarily had to possess sufllcient mechanical rigidity to support 35 and maintain proper alinement of its parts with the partsof the switch mounting with which they co-operated. The fuse link consisted of a flexible conductor provided with a relatively short reduced section between its ends, which either 40 meltedor separated when the current exceeded the capacity of the fuse link, and said fuse link included end portions adapted to be secured to the fuse cartridge so that the reduced portion of the fuse link was located within the tube, 45 The fuse link when blown was replaced by a new fuse. link by taking the fuse cartridge out .of the mounting by means of an insulated switch stick or fuse puller, it being necessary to ma-.

nipulate certain terminal screws in order to re- 60 lease the blown fuse link and substitute a new a fuse link therefor.

The improved fuse switch disclosed herein combines the-fuse cartridge andthefuse link in a single fuse assembly, eliminating entirely 55 the necessity for the conventional fuse cartridge and its associated parts. in accordance with invention the expulsion tube is held in suspen== sion away from the switch mounting, and there fore the mechanical forces prcducedby heavy, short circuits are not transmitted to the swltoi'i 5 mounting, as in the type of fuse switch hereto= fore employed. Also, the screw contacts for the fuse link are eliminated in the improved struc= ture and this permits reduction in the number of parts as weli as in the weight of the structures, 10 making reat economies possible in the mantl facture of improved structure. By construct= ing the expulsion tube of the structure of the present invention sothat it is relieved of ail mechanics-.1 duties and serves to perform expul is sion duties only, said tube may be of substan tially reduced internal diameter. permits the use of a shorter and thinner walled tube, and

allows such a reduction in the cost of the tube that it may be thrown away with the discarded 20 or blown fuse link.

The fuse switch mounting of the improved structure is very greatly simplified when compared with the mountings employed with fuse switches of the construction heretofore used. This results from the fact that the conventional fuse cartridge iseliminated in the improved structure, and therefore the mounting of the structure disclosed herein need not include the more or less complex mechanical means heretofore present for supporting the conventional fuse cartridge in a manner to permit ready and convenient attachment and detachment of the fuse cartridge with the aid of a switch stick or fuse puller.

Fig. 1 is a side elevation of the improved fuse switch. v a

Fig. 2 is a front elevation of the fuse switch illustrated in Fig. 1.

Fig. 3 is an enlarged section of the combined 40 expulsion tube and fuse link assembly.

Fig. 4 is a, plan view of the improved fuse switch with a portion of the insulator broken away to conserve space.

Fig. 5 is an enlarged section on line 5-4 of Fig. 4.

In the drawing, wherein is shown for the purpose of illustration, merely, one embodiment of the invention, A designates the mounting of the improved fuse switch, B designates the expulsion tube thereof, and C designates the fuse link of the improved structure. I designates a suitable insulator to which is attached adjacent to its upper end an upper terminal 2, which is adapted to have suitably connected thereto a section of an electrical'conductor (not shown) which constitutes a part of the electrical circuit with which the fuse switch is associated. The upper terminal 2 includes a base portion 2 which is provided with a curved, inner face that contacts with the correspondingly curved outer face of the insulator, and an upwardly and rearwardly extended portion 2 to which the electrical conductor is attached, said upper terminal being secured to the insulator by suitable means such as a bolt 3.

Associated with the upper terminal 2 is an upper contact 4 which preferably is formed from a sing e length of relatively heavy wire. The contact 4 includes a downwardly extended, looped portion 6, through which the bolt 3 is extended, there being a washer 8 interposed between the head portion of the bolt and the looped portion 5 of the contact 4, and said bolt, in addition to acting to secure the terminal 2 to the insulator, serving also to secure the contact to the terminal. Extended outwardly from the upper portion of the looped portion 5 of" the contact 4 are contact portions which converge toward each other for a short distance forwardly of the looped portion, as indicated at I in Fig.4, and then extend forwardly from said convergent portions in more or less parallelism. At the forward ends of the forwardly extended legs of the contact 4 said legs are turned rearwardly upon themselves, as indicated at 8 in Fig. 4, and are then bent outwardly to provide angularly disposed portions 9. At a point immediately adjacent to the forward end of the convergent portions of the contact 4 a sleeve I0 is provided which embraces the forwardly extended legs of said contact so as to prevent undue separation of the forwardly extended legs of the contact.

.Adjacent to the lower end of the insulator I a lower terminal I I is fixed thereto.

This terminal is provided with a base portion I I which is provided with a curved inner face that contacts with the correspondingly curved outer face of the insulator, and said terminal includes a downwardly and rearwardly. extended portion II to which is attached a section of the electrical conductor with which the fuse switch is associated. The lower terminal I I is secured to the insulator by suitable means, such as a bolt I2. Associated with the lower terminal II is a lower contact I3, which preferably is formed from a single length of relatively heavy wire which is provided with an upwardly extended, looped portion I4. The bolt I2 is extended through the looped portion I4 of the lower contact I3, there being a washer I5 interposed between the head portion of the bolt I2 and said looped portion of the contact l3. Because of this arrangement, the bolt I 2 serves both to secure the terminal I I to the insulator and to attach the lower contact to said terminal I I.

The lower contact I3 includes substantially parallel portions I6 which extend forwardly from the lower portion of the looped portion I4 thereof and merge into oppositely disposed, helically arranged portions II which serve to greatly increase the resiliency of the contact. From these helically arranged portions the continuous length of wire which produces the lower contact extends forwardly in the form of a pair of convergent leg portions I8 to a point inwardly of the forward end of the contact, from which point the forwardly extended legs of the contact extend in more or less parallelism for a distance, after which said legs'are flared outwardly as indicated at I9 in Fig. 4. At the approximate forward ends of the convergent leg portions I8 of the lower contact I3 9.

sleeve 20 is provided, which embraces said leg portions and prevents undue spreading thereof.

vided at their outer ends with loops 2:. Also, the

cable sections 2| and 22 have soldered, or otherwise secured thereto, flanged collars 24, which serve a purpose to be hereinafter set forth. The inner end portions of the cable sections 2i and 22 .are extended into the opposite end portions of the expulsion tube B, and the opposite end portions of the fuselink C are coiled about said inner end portions of said cable sections and are secured thereto, said fuse link including a meitable or separable portion C which is located within the expulsion tube. The expulsion tube B is interposed between suitable washers 25 which are soldered or otherwise securely fixed to the cable sections 2I and 22, said washers contacting'closely with the end faces of the expulsion tube,vthere being no positive attachment between the washers and the expulsion tube.

In applying the expulsion tube and fuse link assembly to the upper and lower contacts of the improved structure in the fusing position, the prong at one end of an ordinary insulated switch stick is inserted through one of the loops 23 of the assembly, and the cable section at the lower end of v the assembly is guided between the flared portions I9 of the lower contact I 3. At this time the lower contact is in its lowered position, as suggested by dotted lines in Fig. 1. The assembly is then raised against the restraining force exerted by the helical portions ll of the lower contact and the inherent resiliency of said lower contact, and as this is done the lower cable section of the assembly is crowded between the parallel portions of the lower contact located rearwardly of the portions II thereof, thus making secure and positive connection between the fuse assembly and the lower contact. Raising of the fuse assembly is continued until the cable section at the upper end of the assembly is guided between one of the rearwardly extended portions 8 of the upper contact 4 and the adjacent forwardly extended parallel leg portion of the contact, theassociated angular portion 9 aiding in introducing the upper cable section 2| into the position described. The fusing operation is then completed and the switch stick is removed. It is obvious that the fuse assembly may be removed by reversing the operation Just described. When the fuse assembly is in the fusing position, the flanged collars 24 are in close contact with upper and lower faces of the upper and lower contacts 4 and I3, respectively. This results in the fuse link C being under tension, and therefore when the fuse link is ruptured by a fault in the circuit the relieved lower contact will immediately swing downwardly, thus jerking the lower portion of the fuse link out of the expulsion tube. The lowered position of the lower contact gives visible indication that the fuse link has been ruptured. The contact pressure produced by the more or less V-shaped openings in the upper and lower contacts is a function of the tension on the fuse link divided by the coefficient of friction. This makes it possible to obtain adequate contact pressure with very small permanent tension on the fuse link.

It is obvious that the cable section 2I at the upper end of the fuse assemblymay be introduced into place between either of the rearwardly turned portions 8 and the adjacent, for- .wardly extended, parallel portion of the upper contact. .Also, the double fuse assembly grips of the uppercontact l are important when it is desired to remove a fuse assembly, and manual removal of the fuse assembly is objected to because of the are which would be created in'the air when the fuse assembly would be pulled free from the upper contact. By providing the upper A tube of the blown fuse assembly.

In order to prevent the lower portions of the fuse assemblies from being dislodged from the lower contact and falling to the ground when the fuse assemblies blow, with the possible chance of injuring persons or causing fires, we make the cable section 22 of such length that it may be twisted about one leg portion of the lower contact, as shown most clearly in Fig. 5 This twisting operation of the cable section 22 may be conveniently done with a switch stick, and because the twisted portion of the cable section is gripped by the gripping portion of the lower contact there is very little danger that it will fall away from said contact. If desired, the cable section need not be so twisted with relationto the lower contact, and in this event it will hang as suggested by dotted lines in Fig.

An important feature of the invention is that the expulsion tube B of the fuse assembly is held in suspension out of direct contact with the switch mounting. Because of this arrangement mechanical forces produced by heavy, short circuits are not transmitted to the switch mounting.

We claim:

1. A fuse switch comprising a supporting structure including spaced apart terminals, contact members associated with said terminals, one of said contacts being maintained in a substantially fixed position and the other contact being provided with a coiled portion to give increased resiliency thereto and being movable in a direction away from the other contact, gripping portions at the outer ends of said contacts, and a fuse link frictionally gripped by said gripping portions of said contacts and maintained under tension while in the fusing position by the tendency of said resilient contact to move in a direction away from the other contact.

2. A fuse switch comprising a supporting structure including spaced apart terminals, contact members associated with said terminals, said contact membersbeing formed of heavy wire which is characterized by being inherently resilient, one of said contact members being maintained in a substantially fixed position and the other contact member being provided with a coiled portion so as to be possessed of greater resiliency than the associated contact member and being movable because of its greater resiliency in a direction away from said associated contact member, frictional gripping portions at the outer ends of said contact members, and a fuse link gripped by said frictional gripping portions and maintained under tension while in the fusing position by the tendency of the contact member possessed of greater resiliency to move in a direction away from the other contact member.

3. A fuse switch comprising a supporting struc ture including spaced apart terminals, contact members. associated with said terminals, said contact members being formed of heavy wire which is characterized by being inherently resilient and each contact member including a pair of substantially parallel, outwardly extended leg portions, one of said contact members being maintained in a substantially fixed position and the other contact member being provided with a coiled portion so as to be possessed of greater resiliency than the associated contact member and being movable because of its greater resiliency in a direction away from said associated contact member, frictional gripping portions at the outer ends or" said contact members, and a fuse link gripped by said frictional gripping portions and maintained under tension while in the fusing position by the tendency of the contact member possessed of greater resiliency to move in a direction awayirorn the other contact member.

A fuse switch comprising a supporting structure including spaced apart terminals, contact members associated with said terminals, said contact members being formed of heavy wire which is characterized by being inherently resilient and each contact member being formed of a single length of material bent double to provide a pair of substantially parallel, outwardly extended leg portions, one of said contact members being maintained in a substantially fixed position and the other contact member being provided with a coiled portion so as to be possessed of greater resiliency than. the associated contact member and being movable because of its greater resiliency in a direction away from said associated contact member, frictional gripping portions at the outer ends of said contact members, and a fuse link gripped by said frictional gripping portions and maintained under tension while in the fusing position by the tendency of the contact member possessed of greater resiliency to movelin a direction away from the ture including spaced -apart terminals, contactmembers associated with said terminals, one of said contacts being formed of inherently resilient, heavy wire provided with a coiled portion to give increased resiliency thereto and being movable in a direction away from the other contact, and a fuse link connected to said contacts and maintained under tension while in the fusing position by the tendency of said resilient contact to move in a direction away from the other contact, one of said contacts being provided with a pair of fuse link gripping portions disposed at opposite sides thereof.

6. A fuse switch comprising a supporting structure including spaced apart terminals, contact members associated with said terminals, one of said contacts being formed of inherently resilient, heavy wire provided with a coiled portion to give increased resiliency thereto and being movable in a direction away from the other contact, and a fuse link connected to said contacts and maintained under tension while in the fusing position by the tendency of said resilient contact to move in a direction away from the other contact, the upper contact being provided with a pair of fuse link gripping portions disposed at opposite sides thereof.

7. A fuse switch comprising an insulating supporting structure, contact members supported by said supporting structure, said contact members being formed of inherently resilient material and being adapted for relative movement away from each other, and a fuse link connected atits opposite ends to said contact members and held under tension thereby, said fuse link comprising a pair of flexible cables spaced apart at their inner adjacent ends to provide a gap, a fusible element connected to said cables and disposed in said gap, and a tube which encloses said gap and is disposed in a position out of direct rigid connection with said supporting structure and said contact members.

8. A fuse switch comprising an insulating supporting structure, contact members supported by said supporting structure, said contact members being formed of inherently resilient material and being adapted for relative movement away from each other, and a fuse link connected at its opposite ends to said contact members and held under tension thereby, said fuse link comprising a pair of flexible cables spaced apart at their inner adjacent ends to provide a gap, a fusible element connected to said cables and disposed in said gap, a tube which encloses said gap and is disposed in a position out of direct rigid connection with said supporting structure and said contact members, and loops.at the outer ends of said flexible cables adapted to receive a tool employed in applying the fuse link to the contact members.

9. A fuse switch comprising an insulating supporting structure, contact members supported by said supporting structure, said contact members being formed of inherentlyresilient wire material and being adapted for relative movement away from each other, and a fuse link connected at its opposite ends to said contact members and held under tension thereby, said fuse link comprising a pair of flexible cables spaced apart at their inner adjacent ends to provide a gap, a fusible element connected to said cables and disposed in said gap, and a tube which encloses said gap and is disposed in a position out of direct rigid connection with said supporting structure and said contact members.

10. A fuse switch comprising an insulating supporting structure, contact members supported by said supporting structure, said contact members being formed of inherently resilient wire material and being adapted for relative movement away from each other, one of said contact members including oppositely disposed portions which converge toward each other as the forward end of the contact member is approached, and a fuse link connected at its opposite ends to said contact members and held under tension thereby, said fuse link comprising a pair of flexible cables spaced apart at their inner adjacent ends to provide a gap, a fusible element connected to said cables and disposed in said gap, and a tube which encloses said gap and is disposed in a position out of direct rigid connection with said supporting structure and said contact members.

11. A fuse switch comprising an insulating supporting structure, contact members supported by said supporting structure, said contact members being formed of inherently resilient wire said fuse link comprising a pair of flexible cables spaced'apart at their inner adjacent ends to provide a gap, a fusible element connected to said cables and disposed in said gap, and a tube which encloses said gap and is disposed in a position out of direct rigid connection with said supporting structure and said contact members.

12. A fuse switch comprising an insulator, a contact member secured to said insulator adjacent to its upper end, a second contact member secured to said insulator adjacent to its lower end, said contact members being formed of inherently resilient wire material and being adapted for movement away from each other, and a fuse link connected at its opposite ends to said contact members and held in tension thereby, said fuse link comprising a pair of flexible cables spaced apart at their inner adjacent ends to provide a gap, a fusible element connected to said cables and disposed in said gap, and a tube which encloses said gap and is disposed in a position out of direct rigid connection with said insulator and said contact members.

13. A fuse switch comprising an insulating supporting structure, contact members supported by said supporting structure, said contact members being formed of inherently resilient material and being adapted for relative movement away from each other, and a fuse link connected at its opposite ends to said contact members and held under tension thereby, said fuse link comprising a pair of flexible conductors spaced apart at their inner adjacent ends to provide a gap, 8. fusible element connected to said flexible conductors and disposed in said gap, and a tube which encloses said gap and is disposed in a posi tion out of direct rigid connection with said supportng structure and said contact members.

14. A fuse switch comprising a supporting r structure, contact members supported by said supporting structure, said contact members being formed of inherently resilient material, a fuse link connected to said contact members and maintained under tension while in the fus ing position by the tendency of one of said contact members to move in a direction away from the other contact member, and fuse link gripping portions forming parts of said contact members,

said gripping portions being formed by adjacently disposed parts of said contact members which are forced toward each other by the inherent resiliency of the contact members so as to grip portions of the fuse link therebetween.

WALTER a HEINRICH. CHARLES ADIN FOX.

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