US2938093A - Electrical contact for fuse cutout - Google Patents

Description

May 24, 1960 G. R. Mcc ouo ELECTRICAL CONTACT FOR FUSE CUTOUT Filed Dec. 20, 1956 u ln 'Fa'g. 2

D W T 5 mom a m Jr 4 AW/ I. if R m 6y B United States Patent Ofiice 2,938,093 Patented May 24, 1960 2,938,093 ELECTRICAL CONTACT FOR FUSE CUTOUT George R. McCloud, Cudahy, Wis., assignor to McGraw- Edison Company, a corporation of Delaware Filed Dec. 20, 1956, Ser. No. 629,544 8 Claims. (Cl. 200-133) This invention relates to an electrical contact for a fuse cutout and particularly to a generally U-shaped metal clip adapted to resiliently grasp the contact of a fuse tube.

U-shaped clips as presently made, comprise a single resilient, current-conducting U-shaped member or a combination of a resilient U-shaped backing member and a separate U-shaped current carrying member with the connection to a line conductor being made through a connector attached to the base of the U-shaped clip.

With either of the above constructions, a current tends to flow around the base of the backing member as well as to the current-conducting member. The current in the base of these members tends to weaken and eventually destroy the resiliency of the backing member and consequently the clip no longer tightly grasps the contact on the fuse tube.

In accordance with the present invention, a U-shaped contact clip includes a highly resilient backup member and a highly conductive cover or liner which is secured to the inner surfaces of the contact grasping portion of the backup member. This current conducting liner is directly connected to a line conductor forwardly of the base of the backing member and consequently directs the incoming current directly to the fuse tube contact and away from the base portion of the backup member. The line conductor is connected directly to the conducting liner by an in-line connection to establish a minimum of current interchange points and to reduce the necessary height of an enclosure, if employed, while maintaining the required flashover distance between the incoming line connections.

The present invention thus provides a long-life contact clip adapted to resiliently grip a contact and to maintain such grip without loss of resiliency caused by overheating due to carrying current.

The drawing furnished herewith illustrates the best mode presently contemplated for carrying out the invention.

In the drawing:

Figure 1 is a view in section through a housed typed fuse cutout employing a contact clip constructed in accordance with the present invention;

Fig. 2 is a front view looking into the housing of Figure 1 with the pivoting door removed;

Fig. 3 is an enlarged elevational view of a contact clip shown in Figures 1 and 2;

Fig. 4 is a side elevational view of the clip shown in Fig. 3; and

Fig. 5 is a view taken on line 55 of Fig. 3.

Referring to the drawing and particularly to Figure 1, the housed type fuse cutout is shown as comprising a housing 1 having upper and lower contact assemblies 2 and 3 mounted within the housing and electrically connected by a fuse tube assembly 4. A pivotal door or cover 5 carries the fuse tube assembly 4 to permit removal thereof from the contact assemblies 2 and 3.

' The housing 1 is porcelain or other suitable insulating material and is generally a rectangular box type having an open front closed by the door 5 and a partially open bottom adjacent the open front to permit pivoting of the door. A mounting bracket 6 is cemented within a recess in the back exterior surface of the housing 1 as by cement 7 and permits mounting of the cutout in place. The housing is made generally rectangular to provide relatively large spacing between the upper and lower contact assemblies 2 and 3 to thereby eliminate internal flashover. A barrier 8 projects from the rear interior wall into the housing between the contact assemblies 2 and 3 to further protect against flashover.

To support the contact assemblies 2 and 3 within the housing, a recess is formed on the internal face of the backwall adjacent the top and bottom of the housing, and metal mounting brackets 9 are cemented one within each recess as by cement 10. As most clearly shown in Fig. 2, lateral openings 11 are formed in the side walls of the housing immediately adjacent the contact assemblies 2 and 3 to permit the extension of incoming and outgoing line conductors 12 into the housing from either side and the connection of the conductors to the contact assemblies 2 and 3.

The contact assemblies 2 and 3 are connected electrically by the fuse tube assembly 4 which comprises an insulating tubular body 13 which carries an upper contact cap 14 and a lower contact sleeve 15. A fuse lead 16, of which only the lower portion is shown, is connected to the contact cap 14 in any suitable manner and extends through and out of the bottom of the fuse tube body 13 and around a fuse link extractor 17 to a stud and nut clamp 18 carried by the lower sleeve contact 15.

The fuse or link extractor 17 is a spring loaded member which is adapted to rapidly and positively withdraw the fuse lead 16 to electrically disconnect the fuse cap 14 from the fuse sleeve 15 in the event the fuse melts, as more fully described in United States Patent No. 2,409,077.

The contact sleeve 15 is secured to the bottom end of the fuse tube 13 in a suitable manner such as by a locking pin 19 which extends through a transverse opening in the sleeve, which opening is aligned with a recess in the fuse tube 13 in assembled relation. The contact sleeve 15 is also secured to the inner surface of the pivoting door 5 in a suitable manner such as by mounting bolts 20 which extend through lateral flanges 21 on the sleeve, of which only one is shown, to removably support the fuse assembly 4 within the housing.

The door 5 is pivotally supported on housing 1 by laterally extending trunnions 22 on sleeve 15 which are journaled within suitable hook-like bearing members 23 rigidly secured to the sidewall of the housing 1 adjacent the bottom of the housing.

A generally hairpin-shaped spring includes an upper leg 24 which is secured to the upper contact assembly 2 by a vertically depending portion 25 and an integral lower leg 26 extending inwardly and downwardly within the housing in the path of the contact cap 14 when the door is open, as shown by phantom lines, in Figure 1. When the door 5 is closed, the depending leg 26 is bent upwardly by the fuse tube into a generally horizontal position as shown in Figure l. The spring has no function in the fuse cutout, as illustrated. The spring functions if the fuse cutout includes a drop-out fuse assembly such as shown and described in United States Patent No. 2,458,753 or some other similarly functioning assembly.

Door 5 is provided with a manipulating eyelet or handle 27 to allow manual control of the door for refusing and the like, such as by inserting a conventional switch stick, not shown, into the eyelet.

The upper and lower contact assemblies 2 and 3 are similar in construction with the exception that the upper contact assembly 2 includes the hairpin spring secured thereto by depending portion 25. Similar elements in the two contact assemblies are given the same number.

Each assembly includes a generally Ushaped backup member 28 secured in any suitable manner to the mounting brackets 9 as by small mounting bolts 29 which extend through suitable openings in the base portion 39. Side arms 31 extend outwardly from the base toward the door with the forward portions 32 of the arms 31 being reduced in width and releasably grasping the contact cap 14 or sleeve 15 of the fuse tube assembly 4. The backup member 28 is formed of any highly resilient metal, such as stainless steel, and the side arms 31 are spaced less than the diameter of the cap or sleeve so as to provide a tight grip of the latter elements. The side arms 31 have their tips 33 bent away from each other to provide a guide for the incoming contact cap or sleeve. Openings 34 are provided in each side arm 31 immediately adjacent the base 30 of the backup member 28. The openings are slightly wider than the reduced front arm portion 32.

Generally flat conducting contact liners or members 35 extend outwardly over the inner surface of each of the side arms 31 and have a projection 36 which extends laterally through the respective openings 34. The conducting members 35 are formed of a highly conductive material such as silver-plated, soft copper or the like and are the same width as the respective arm portions 32 and therefore completely cover the arm portions 32. Laterally extending ears 37 on each member 35 are crimped over the edges of the associated side arm 31 to secure the respective member 35 to the arm. The outer end portions of contact members 35 also extend around and are clamped to the outer end or tip of each of the side arms 31 as at 38.

To directly connect each contact member '35 to a lineconductor 12, a movable collar 39 is disposed on each projection '36 of the contact member 35 and the line condoctor 12 is clamped between the collar 39 and the projection 36 by a small bolt 49 which threads through a tapped opening in the collar and bears on the respective projection 36. The projection 36 thus functions as keeper bars to prevent the clamping bolts 40 from cutting the conductors 12 and also to distribute the clamping force.

Each collar 39 is guided between a pair of guides 41 which extend laterally one each from opposed longitudinal edges of each opening 34 in the backup member. The guides 41 are preferably integrally formed with the backup member 28 by suitably stamping out the opening 34. Each collar 39 is maintained between the guides 41 and on the respective conducting member projection 36 by lateral cars -42 on the end of each projection 36.

In operation, the current flows essentially directly through the soft copper cont-act member 35 between the line conductor 12 and the contact cap 14 and contact sleeve 15, respectively, because of the much greater conductivity of the member 35. As a direct connection is made to the conducting member 35 contactwise of the base portion '38, that is, intermediate the base portion 30 and the point of current transfer from the contact member 35, the current is effectively directed from the base 30 of the backup member 28, and consequently, the backup member 28 remains resilient and maintains a tight grip on the associated contact cap 14 and contact sleeve 15 even after long periods of operation.

The terminals formed by the projections 36 and collar 39 are at the same height as the clip arms 31 within the housing 1 and thus permit a predetermined flashover distance between the contact assemblies 2 and 3 with a minimum housing height. Further, the incoming conductors 12 are connected directly to the contact liner or member 35 and thus establish a very minimum number of current interchange or transfer points.

Although the contact clip is described with a single piece backup member having a base portion and integrally projecting arms, the clip may be made as a separate base member and have separate contact arms or members attached thereto in any suitable manner which provides or includes a resilient junction. Thus, if separate parts are used, either or both may be formed of resilient material such that the arms are biased into engagement with the contact on the fuse tube. 01', if desired, both the base member and the contact member may be made of rigid material with a separate resilient member securing them in operative relation.

To maintain the resiliency within the connection between the base member and the contact member, the connection to the incoming line is made intermediate the base portion and the contact member such that essentially no current flows in the resilient portion or junction of the base member and the attached contact member.

Although the described embodiment employs a pair of spaced arms adapted to grasp a contact within the arms, the invention is equally applicable to other forms of resilient contact members employed in fuse cutouts and the like.

The present invention provides an easily fabricated clip which may be rapidly and conveniently assembled with the fuse housing. The disposition and the connection of a contact member provides a compact fuse cutout having a direct and short current path through a minimum number of current interchange points as well as a rugged and long-life resilient contact clip.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctively claiming the subject matter which is regarded as the invention.

I claim:

1. An electrical contact clip mounted on a contact sup port and adapted to resiliently engage a contact, which comprises a metallic base member adapted to be secured to said contact support, a contact member having an electrical conductivity greater than the base member and resiliently joined to the base member to form a continuation of the base member, said contact member extending from the base member and being adapted to be disposed in operative spaced relation with respect to the contact to provide resilient engagement between the contact member and the contact in spaced relation to said base member, said conducting liner having a conductivity greater than the conductivity of the metallic base member, and terminal means intermediate said contact member and said base member to connect the contact member to a line conductor in spaced relation with respect to said base member and the resilient connection to the contact member to substantially direct current flow from the line conductor directly to the contact through the contact member and away from said base member and to thereby maintain said resilient engagement of the contact by said contact members.

2. A contact clip adapted to resiliently engage a contact at two generally opposite surfaces, which comprises a metallic base member having a pair of parallel arms of a highly resilient metal extending therefrom and disposed in laterally spaced relation with respect to the contact to provide an inherent bias of said arms toward the contact, a conducting liner secured to the inner surface of at least one of said arms and terminating in spaced relation to the opposite arm to engage said contact when the clip is mounted on the contact, said conducting liner having a conductivity greater than the conductivity of the metallic base member, and terminal means disposed intermediate the length of said arms and in alignment with said arms to establish in-line terminal connection between the conducting liner and a line conductor to substantially direct current flow between the line conductor and the contact directly through the conducting liner and through a minimum number of current interchange points.

3. A contact clip adapted to resiliently engage a contact member, which comprises a resilient metallic member having a base portion and having aligned parallel side arms extending from said base portion and adapted to engage generally opposite surfaces of said contact member, said arms being spaced less than the diameter of said contact member which bends the side arms outwardly from said non-engaged spaced relation to establish a positive grip therebetween, non-engaging individual conducting liners secured to the surface of each side arm adapted to engage the contact member and having a relatively high electrical conductivity compared to the electrical conductivity of the side arms, and means intermediate the length of each of said side arms to selectively connect the conducting liners in circuit in spaced relation to said base portion whereby current flow is directed through the conducting liner and away from the base portion and through a minimum of current interchange points.

4. A contact clip for a housed type fuse cutout adapted to graspingly engage a fuse contact in a fused position, which comprises a channel member formed from a highly resilient metal to tightly grip a fuse contact between the side portions of the member, a low resistance lining secured to an inner side surface of the member in spaced relation to the base of the member and disposed in engagement with the fuse contact in a fused position, said channel member having an opening adjacent the innermost end of the lining, and means to connect the liner to a line conductor through said opening and in spaced relation to the base of the channel member to provide an electrically low resistance path between the conductor and the fuse contact.

5. A contact clip for a housed type fuse cutout including an insulating fuse housing and a removable fuse contact, which comprises a generally U-shaped member of a highly resilient material having a base portion with means adapted to connect the member to said fuse housing and having integrally extending side arms adapted to receive and tightly clamp said fuse contact between the tips of the side arms, said member having an opening in at least one of the side arms adjacent the base portion of the member, an inner liner of a low resistance material on the tip of the side arm having said opening, and connector means adapted to be attached to an electrical conductor and having low resistance means extending through said opening into engagement with the liner to provide a low resistance path between the electrical conductor and the fuse contact.

6. A stationary contact clip adapted to be secured within the housing of a housed type cutout fuse for engagement with a fuse tube contact, which comprises a channel member formed of a highly resilient metal and adapted to tightly grip said fuse tube contact between the extending side portions of the member, means associated with the base of the channel member to secure the channel member to the housing, aligned openings in the side portions of the channel member outwardly of the base of the channel member, low resistance liners secured one to each of the inner side portions of the channel member and covering the inner side portions outwardly of the openings with an integral transverse extension of said liners extending through the openings, and connector means adapted to selectively connect the extensions of said liners to a conductor to provide a low resistance path between the conductor and the fue tube contact.

7. A compact housed type fuse cutout having a removable wall, which comprises an upper generally U- shaped contact clip assembly and opening toward said movable wall adjacent upper line conductor opening means in the housing, a lower generally U-shaped contact clip assembly opening toward said movable wall adjacent lower line conductor opening means in the housing, said contact clips being generally U-shaped and spaced in accordance with a predetermined fiashover spacing requirement and having projecting contact arms aligned across the opening means, and terminal means secured one each to the contact clips in alignment with said projecting arms and said openings, said means being adapted to be connected to a line conductor extended through said opening.

8. A compact housed type fuse cutout, which comprises a housing having upper and lower incoming line terminal openings disposed in minimum fiashover spaced relation, a pair of contact clips secured within the housing one adjacent said upper openings and the other adjacent said lower openings, said clips having spaced arms extended transversely of said openings and having apertures aligned with said openings, and terminal means disposed between said spaced arms and adapted to connect said clips to an incoming line conductor extended through an aligned housing opening and clip aperture.

References Cited in the file of this patent UNITED STATES PATENTS 1,864,283 Steinmayer June 21, 1932 2,011,391 Bennett Aug. 13, 1935 2,011,543 Meyer Aug. 13, 1935 2,016,099 Sandin Oct. 1, 1935 2,081,813 Hermann May 25, 1937 2,433,666 Hermann Dec. 30, 1947 2,681,963 Fahnoe June 22, 1954 2,792,472 Koch May 14, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,938,093 May 24, 1960 George R. McCloud It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, lines 46, 47, and 48, strike out "said conducting liner having a conductivity greater than the conductivity of the metallic base member,"; column 6, line 14, for "fue" read fuse Signed and sealed this 15th day of November 1960.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner "of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,938,093 May 24 1960 George R. McCloud It is hereby certified that error appears in the printed specification of theabove numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, lines 46, 47, and 48, strike out "said conducting liner having a conductivity greater than the conductivity of the metallic base member,"; column 6 line 14 for "fue" read fuse Signed and sealed this 15th day of November 1960.

(SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents

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