US3299240A - Hinge contact for disconnect switch - Google Patents

Description

Jan. 17, 1967 A. FoTl HINGE CONTACT FOR DISCONNECT SWITCH 2 Sheets-Sheet l Filed May 25, 1965 onocu ococn INVP Jan. 17, 1967 A. FOTI HINGE CONTACT FOR DISCONNECT SWITCH 2 Sheets-Sheet 3 Filed May 25. 1965 L s :No ZI/M//VUM E Cap/fe e uw f L vvv INVENTOR. 6795/14 F07/ United States Patent Office 3299,24@ Patented Jan. 17, 1967 3,299,240 HINGE CONTACT FR DHSCNNECT SWITCH Arem Foti, Greensburg, Pa., assigner to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed May 25, 1965, Ser. No. 458,595 8 Claims. (Cl. 20G-166) This invention relates to outdoor high-voltage switches which are of dual metal construction and, more particularly, is directed to novel contact structure for providing an electrical path between a dual motion and the hinge member upon which said blade is rotatably secured.

ln co-pending application Serial No. 114,271 entitled Dual Metal Electric Switch, assignedlto the assignee of the instant invention, and now issued as U.S. Patent 3,266,568 on September 14, 1965, there is shown a highvoltage outdoor disconnect switch in which portions having relative movement therebetween are constructed of copper or copper bearing material while the remaining portions are made of aluminum. The aluminum portions of the switch are secured to the copper portions by welding or pressure bonding to create a metallurgical bond which eliminates the possibility of corrosion at the inner face. This dual metal construction allows those parts of the switch, which have relative movement therebetween to have the highly desirable characteristics of copper, such as high thermal and electrical conductivity, and a material which remains substantially constant in its characteristics; while those parts of the swit-ch which have no relative movement therebetween have the highly desirable characteristics of aluminum which include light weight, high strength, excellent corrosion resistance, ease of fabrication, low erection and maintenance cost, good electrical and thermal conductivity, non-magnetic characteristics, and also a relatively low cost per pound as a raw material. A detailed description of the advantages and operation of the dual metal, dual motion electric switch may be had by referring to the aforementioned patent and such description is incorporated herein by reference thereto.

For purposes of this invention, it is suiiicient to note that in the dual metal electric switch of Patent 3,206,568 there existed the problem of making an electrical-mechanical transition from the aluminum tubing of the switch blade to the hinge support member, upon which the blade is rotatably secured. As will be further described in the specification, this transition is accomplished by hash-welding a short copper tube to the aluminum tubing, the lower end of the copper tube having axial slots to define a plurality of contact lingers.v These contact fingers rotatably engage a protrusion carried by the basic frame casting and provide an electrical path therebetween. The protrusion is of a copper material and has a silver annular surface formed thereon.

Electrical contact from the lower end of the copper tube is achieved by causing the individual contact ngers thereof to be biased inwardly toward engagement with the silvered surface of the protrusion on the hinge whereby in accordance with the teachings of the aforementioned application, the desired silver-to-copper interchange is formed between surfaces having relative movement with respect to one another.

Functionally, the flash-welded joint of the short copper tube to the aluminum blade tubing provides an excellent electrical transition between the two members. However, the method is costly, entails considerable handling and transportation of material from factory and material suppliers to special purpose flash-welding facilities,` and back to the factory for machining. Furthermore, the flash-welding requires special purpose equipment which is costly and scarce.

In View of the above problems, the instant invention contemplates novel structure for providing a metallurgically sound transition from the aluminum switch blade tubing to the hinged support contact member upon which the blade rotates in a manner which minimizes material handling, eliminates specialty manufacturing processes, results in a product improvement, and substantially reduces total manufacturing costs.

The basic concept of the instant invention is that of forming the central and lower end portieri of the switch blade of an integral tubular aluminum member (as contrasted with the above identified application wherein the lower portion is a copper tube flash-welded to the central portion) and spot welding of a plurality of contact points or buttons radially around the lower section of the aluminum blade at precisely the same point where the copper contact fingers of the previous design engage the cooperating hinge support member. Such contact points or buttons are rivet-like in appearance and have a shank portion which is spot-welded within resilient lingers of the lower aluminum portion, and a head portion which engages the exterior surface of the hinge support member. The contact point or button is preferably of silver and consequently provides the desired silver to copper Contact (the silver head of the button to the copper hinge support member) without the necessity of silvering the copper hinge support member.

The contact structure of the instant invention provides many advantages over the flash-welded copper tube structure of the aforementioned application.

The flash-welding process used for joining the short copper tube to the aluminum blade dictates the use of a high-purity aluminum with limited mechanical strength. However, since dash-welding has been eliminated, the instant invention makes possible the use of higher strength aluminum alloys. All processes associated with the manufacturing of the blade tubes of the instant invention are performed in one factory, thus eliminating time consuming handling and transportation of materials from suppliers to ash Welder and finally back to the factory for machining operations. Also, the flash-welding of tubes requires special purpose equipment which is costly and scarce whereas the spot-Welding equipment to place the contact buttons within apertures in the lower portion of the aluminum tube is, by comparison, light duty, readily available, and low cost. A further advantage exists because the silver Contact buttons permit the retaining of a silver to copper contact at the blade hinge, and yet eliminates the silver plating operation required in the above mentioned design.

Accordingly, it is an object of the instant invention to provide a dual motion disconnect switch comprising an elongated body having a central portion and first and second end portions, the rst end portion being movable into and out of engagement with a cooperating contact, the second end portion rotatably and electrically engaging a cooperating hinge support member, the second end portion including a plurality of contact points which engage the hinge support member to provide a vpath for electrical conduction therebetween.

Another object of the instant invention is to provide a metallurgically sound transition between an aluminum blade tubing and its associated hinge support member which minimizes material handling, eliminates specialty manufacturing processes, and is of low manufacturing cost.

Still another object of the instant invention is to provide novel contact structure for making a metallurgically sound transition from an aluminum blade tubing to its 3 associated hinge support member which makes possible the use of higher strength aluminum for the aluminum blade tubing than was capable with prior art structures.

Still another object of the instant invention is to provide a silver to copper contact between a switch blade and its associated hinge support member while eliminating a silver plating operation on the hinge support member which was necessary in the prior art.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings in which:

FIGURE l is a side view of an outdoor high voltage dual motion electrical switch made of dissimilar metals, such switch being the environment in which the instant invention finds application;

FIGURE 2 is a cut-away perspective view of the hinge end of the disconnect switch shown in Patent 3,206,568, and appropriately labelled prior art;

FIGURE 3 is a partial cut-away perspective view of the switch blade of FIGURE l, said switch blade incorporating the structure of th-e instant invention;

FIGURE 4 is a view taken along the arrows 4-4 of FIGURE 3; and

FIGURE 5 is an enlarged view of the button-like contact shown in FIGURE 2.

My invention is illustrated and described in connection with FIGURES 1-5 which show a single pole of an airbrake switch commonly known as a 3-insulator vertical break rotating insulator outdoor high voltage air switch.

Details of the operation of this particular type of switch are set forth in U.S. Patent 2,673,902, issued March 30, 1954 to G. E. Heberlein, entitled Disconnect Switch and assigned to the assignee of the instant invention.

Referring to FIGURE l, it is seen that the switch is comprised of four main sections, mainly the base 11; the insulator columns 12, 13, and 14; the current carrying part 15; and the mechanical operating means 16. For the sake of clarity, the various metals-used in the switch are illustrated by designation so that the figures will be self-explanatory. For example, all portions of the switch made of aluminum are indicated as such by small circles; all portions of the switch made of copper are indicated by a plurality of small xs; all portions of the switch made from metal such as steel are indicated by :t plurality of dots; and all portions of the switch made of silver are indicated by a plurality of small ss.

As explained in detail in the aforementioned Patent 2,673,902, the current carrying part 15 serves as a conductor between the terminalpads 18 and 19 when the switch is closed, such as seen in FIGURE l, and through appropriate operating mechanism 16 operated through the insulator column 12, the blade of the switch can be actuated to the open circuit position, as seen in FIGURE 2, to provide an open gap in the electrical circuit.

Assuming that the blade is to be moved from its open circuit position shown in FIGURE 2 to the closed circuit position of FIGURE l, a brief explanation of its dual movement is as follows. By means of the operating mechanism 16 the blade 20 is first caused to be pivoted in the plane parallel to the paper upon which FIGURE l is drawn -until its beaver-tailed end portion 21 is within the upstanding arms of the jaw 22, the narrow dimension of the beaver-tailed end 21 being parallel lto the upstanding arms of the jaw. Continual activation of the operating mechanism 16 then causes the blade 20 to rotate about its own axis so as to bring the broad dimension of the beaver-tail end 21 into high pressure contact engagement with the upstanding arm of the jaw 22.

Referring to FIGURE 2 there is shown in detail the prior art structure for making an electrical mechanical transition from the lower portion 23 of the aluminum blade to the blade hinge member 26. Specifically, it

4 may be seen that the lower portion 23 of the aluminum blade 20 has a short copper tube 25 fiash-welded thereto to provide a metallurgical bond between the two metals and eliminate corrosion at the conducting inner face.

The lower end of the copper tube 25 has axial slots therein (not shown in FIGURE 2 but of the type shown in FIGURE 3 at 36) to define a plurality of contact iingers in the manner described in the above noted U.S. Patent 2,673,902 where, as will be seen hereinafter, these contact lingers rotatably and electrically engage a protrusion 28 of the hinged casting 26.

The 'hinge casting 26 is of copper material, but its upwardly extending protrusion 28 has a silvered annular surface 30 formed thereon. Electrical contact from the lower portion 23 of blade 20, which has copper tube 2S Hash-welded thereto, is achieved by causing the individual fingers of the tube 25 to be biased inwardly toward engagement with the silvered surface 30 on protrusion 28 through the biasing force of an annular spring 32, which is contained within an annular groove at the end of the copper tube 25 as shown. The desired silver to copper contact is now formed between the blade and its hinge support member, which two elements have relative movement therebetween.

Referring to FIGURE 3 there is shown a preferred embodiment of the instant invention which eliminates the necessity of flash-'welding the copper tube 25 to the lower aluminum portion 23 of the blade 20, while still maintaining the preferred silver to copper Contact between the blade and its hinge support casting 26. Specifically, it will be seen that the central portion 34 and the lower portion 23 of the switch blade 20 is an integral aluminum tube, thus completely eliminating the need for a copper tube 25 of FIGURE 2. The hollow cylindrical lower portion 23 has a plurality of axial slots 36 (see FIGURES 3 and 4) to define a plurality of contact fingers 38 each of which extends below the spring 32 of FIGURE 3 when the blade 20 is assembled on the protrusion 28 of the hinge casting 26. Each of the fingers 33 has an aperture 40 therein for receiving a rivet-like contact point or button 42 which is preferably spot-welded `(using metallic inert gas, MIG) within the apertures 40.

The contact points or buttons are rivet-like in appearance and as indicated in FIGURE 5 are preferably of silver for good contact performance. However, they may be constructed of any material which is a good conductor and a good contact material. The contact points 42 comprise a shank portion 44 which is spotwelded within the respective apertures 40, and a head portion 46 which abuts the interior surfaces of the contact fingers 38 (see FIGURE 4).

With the contact buttons 42 spot-welded within the l apertures 40 of the fingers 38, the blade 20 is slid over the protrusion 28. The garter spring 32 is then placed on the exterior of the fingers 38 to bias the heads 46 of the buttons 42 into firm electrical contact with the protrusions 28. Since the protrusion 28 is of copper material and the buttons 42 of silver, the preferred contact of copper to silver is established without the necessity of silvering the protrusions 28 which was required in the prior art device of FIGURE 2.

The instant structure is generally applicable in disconnect s'witches for all ratings listed in present NEMA standards. The instant invention has been tested and found successful in disconnect switch blades rated at 4,000 amperes on a continual basis and 142,000 amperes on a momentary or short circuit basis,

Thus the instant invention provides structure for establishing a path for electrical conduction between the switch 'blade of a disconnect switch and its associated hinge casting which completely eliminates the necessity of flash-welding a copper tube to the lower portion of the blade. Furthermore, the instant invention provides a preferred copper to silver contact without. the. DCQCSsity of applying additional material on the =hinge support member.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by Way of example and that numerous changes in the examples of construction and the combination arrangement of parts may be resorted to without departing from the sphere and scope of the invention as hereinafter claimed.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A blade for a disconnect switch comprising an elongated body having a central portion and first and second end portions, said first end portion movable into and out of enga-gement with a cooperating contact, said second end portion rotatably and electrically engaging a cooperating hinge support member, said second end portion including a plurality of contact points engaging said hinge support member to provide a path for electrical conduction therebetween, said central portion and said second end portion is an integral cylindrical member of aluminum and said contact points are constructed of a conductive material other than aluminum.

2. The blade of claim 1 wherein said contact points are constructed of silver.

3. A blade for a disconnect switch comprising an elongated body having a central portion and first and second end portions, said first end portion movable into and out of engagement with cooperating contact means, said second end portion rotatably and electrically engaging a cooperating hinge support member, said second end portion terminating in a plurality of finger-like extensions, each of said extensions having an aperture located therein, a plurality of contact buttons rigidly secured within respective ones of said apertures, said contact buttons having head portions and shank portions, said head portions engaging said hinge member to provide a path for electrical conduction therebetween.

4. The blade of claim 3 wherein said central portion and said second end portion is a hollow integral cylindrical member of aluminum and said contact buttons are constructed of a conductive material other than aluminum, the shanks of said ycontact buttons welded in said apertures to effect a metallurgical bond which 5 eliminates corrosion at the interfaces of the shanks and the iinger-like extensions.

5. The blade of claim 4 wherein said contact buttons are constructed-of silver.

6. The blade of claim 5 and further including spring means for biasing the heads of said contact buttons into firm electrical and mechanical contact with said hinge mem'ber.

7. An outdoor disconnect switch comprising:

a contact member;

a hinge support member having a copper protrusion thereon;

a dual motion elongated blade member having a central portion and first and second end portions, said first end portion movable into and out of engagement with said contact member, said second end portion rotatably secured about its longitudinal axis to said protrusion, said second end portion terminating in a plurality of finger-like extensions, each of said extensions having an aperture located therein; and

a plurality of contact buttons welded within respective ones of said apertures, said contact buttons having lhead portions extending within the interior of said second end portion and into electrical and mechanical engagement with said protrusion.

8. The blade of claim 7 wherein said central portion and said second end portion is an integral tubular member of aluminum and said contact buttons are constructed of silver. References Cited by the Examiner UNITED STATES PATENTS 2,658,964 11/1953 Heberlein 200-48 ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner.

Claims (1)

1. A BLADE FOR A DISCONNECT SWITCH COMPRISING AN ELONGATED BODY HAVING A CENTRAL PORTION AND FIRST AND SECOND END PORTIONS, SAID FIRST END PORTION MOVABLE INTO AND OUT OF ENGAGEMENT WITH A COOPERATING CONTACT, SAID SECOND END PORTION ROTATABLY AND ELECTRICALLY ENGAGING A COOPERATING HINGE SUPPORT MEMBER, SAID SECOND END PORTION INCLUDING A PLURALITY OF CONTACT POINTS ENGAGING SAID HINGE SUPPORT MEMBER TO PROVIDE A PATH FOR ELECTRICAL CONDUCTION THEREBETWEEN, SAID CENTRAL PORTION AND SAID SECOND END PORTION IS AN INTEGRAL CYLINDRICAL MEMBER OF ALUMINUM AND SAID CONTACT POINTS ARE CONSTRUCTED OF A CONDUCTIVE MATERIAL OTHER THAN ALUMINUM.

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