US3206568A

US3206568A - Dual metal electric switch

Info

Publication number: US3206568A
Application number: US114271A
Authority: US
Inventors: Foti Arem
Original assignee: ITE Circuit Breaker Co
Current assignee: ABB Inc USA; ITE Circuit Breaker Co
Priority date: 1961-04-19
Filing date: 1961-04-19
Publication date: 1965-09-14
Anticipated expiration: 1982-09-14

Description

' sap-g. 14,1965

A. FOTl DUAL METAL ELECTRIC SWITCH 2 Sheets-Sheet l Filed April 19, 1961 U RM 4 m m mam mm W W s ml m A? 7 Sept. 14, 19 65 A. FOTl v DUAL METAL ELECTRIC SWITCH 2 Sheets-Sheet 2 Filed April 19 1951 fllllllull 4z u/wkva/w E 2] COPPEQ 571 5151 I INVENTOR. IRE/I4 F677 3,206,568 DUAL METAL ELECTRIC SWITCH Arem Foti, Greensburg, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Apr. 19, 1961, Ser. No. 114,271 11Claims. (Cl. 200'48) My. invention relates to electrical switches and, more particularly, is directed to out-door high-voltage switches which are of a dual metal construction.

In the construction of electrical switches, many features'must exist in order to provide the necessary and desirable electrical service to customers, It is essential that the electrical switch have strength as'well as high conductivity and that it not change in characteristics with time. Through the years, it has been standard to manufacture electrical switches having most of the components made of copper or copper-bearing metal since the copper has the; characteristic of having high conductivity, strength and condition with time. However, there are numerous drawbacks which exist when the switch is made of copper. In the first place, copper is a relatively high density metal and, thus, there is a substantial weight of the switch in the hinge, blade and jaw portions. This extensive weight must be supported by electrical insulators and, accordingly, the insulators have 'to be fairly large a d strong to withstand this weight.

It would'be desirable to retain the desirable characteristics of copper without having any of the disadvantages that are associated with copper. To this end, Ihave providedin my switch aluminum parts to replace some sections and portions of the switch which were heretofore made of copper. The strength, conductivity and consistency of characteristics with time that exist with copper parts also exist with aluminum parts and yet there is a substantial reduction in the weight of the entire switch.

The use of aluminum as a conducting material as well as a structural material has reached large proportions in the electrical industry. There are numerous characteristics of the aluminum which makeit a particularly desirable metal for use in the electrical field. For example, aluminum has the favorable properties of being'light Weight, having high strength, excellent"co rrosion resistance, ease of fabrication, low erection and maintenance costs, excellent electrical and thermal conductivity, nonsparking and non-magnetic characteristics and also has a relatively low cost per pound as a raw material.

It is an object of my present invention to provide an outdoor high voltage electrical switch which makes the maximum use of the desirable characteristics of aluminum parts includingaluminum terminal pads to thereby make the transition betweenthe aluminum pad and the aluminum conductor without andundesirable electrolytic galvanic corrosion.

Unfortunately, it is not possible to construct an entire switch of aluminum. That is, there are numerous portions of the switch which have relative movement with respect to each other and must carry large magnitudes of current through the relatively movable parts. The oxidation of the aluminum creates an oxide coating which has very highresistivity. Thus, prior art attempts to construct electrical switches of all aluminum have failed due to the high resistivity of the aluminum oxide coating which exists at the relatively movable parts which must conduct current. Although prior attempts have been made to overcome this obstacle, none of them to date have been successful. For example, attempts have been made to silver-plate the aluminum in order to minimize the creation of an aluminum oxide coating. However, silver plating is porous and, hence, oxidation andcorrosion U ited States Patent and remams-substantially constant in its characteristics will occur in the space between the silver plating and the aluminum which will substantially weaken the bond between the plating and the aluminum. I a

. It would be desirable, of course, to have the main portions of the switch made of aluminum and have the conducting portions which are relatively movable made of,

copper to thereby retain the desirable characteristics of both metals in a switch.

It is a primary. object of my invention to provide a cured to the aluminum by a process involving the application of pressure and heat. Normally, there would be a considerable electro-galv-anic corrosion between .the dissimilar metals of copper and aluminum. However, the air-tight alloyed bond created between the aluminum and. copper by the welding process completelyeliminates all corrosive effects at the interface between the copper and aluminum. Although minor corrosion may conceivably exist on the external surface between the copper and alu- A minum, this corrosive effect is minute and does not affect the conductivity. However, I have found that even this minor electro-galvanic corrosion can be substantiallyeliminated by coating external area adjacent to the. metallurgical bond with a synthetic rubber or epoxy paint. In

all prior art structures of out-door electrical switches vwhich were designed to have the desirable characteristics of both the copper and the aluminum, there was always L the undesirable side effect of a galvanic corrosion because of the dissimilar metals. My novel switch virtually eliminates the galvanic corrosion problem.

It is furthermore noted that in the electrical industry involved with the generation transmission and distribution of electrical power, aluminum has been used in ever increasing quantities as electrical conductor. This is particularly true in high voltage transmission lines where aluminum is used as the bus' conductor in generating plants, switch yards and distribution centers. Furthermore, the aluminum has been used extensively for structural materials for supporting out-door air-break switches, bus bars, lightning arresters and other types of heavy electrical apparatus.

The present known types of high voltage electrical switches have had their terminals made of copper. However, this creates a very serious problem because of the ever threatening occurrence of galvanic corrosion when aluminum conductors-are terminated on copper switch terminal parts. The termination of aluminum conductors on copper switch pads has created problems in the past and various attempts have been used to overcome the undesirablecorrosion but none of these have received universal acceptance and, in fact, none of the methods for terminating aluminum conductors on copper switches is, in fact, completely satisfactory.

Some of the prior art methods are as follows:

(A) Having a copper terminal pad but providing an all-aluminum terminal lug to receive the aluminum con-.1

ductor. The aluminum lug is bolted directly to the cop'- per or copper allow switch pad.

(B) Using a copper faced aluminum terminal lug wherein the copper facing is soldered to an'alurninum terminal lug and the lug is bolted to the switch pad.

(C) Hot-dip, tin-plate a terminal pad and bolting an all-aluminum conductor thereto.

3,206,568 Patented Sept. 14, 1965 contacting relatively movable copper part.

' so that thealuminum side of the wafer bears against the aluminum terminal lug and the copper side of the wafer bears against the copper switch pad.

, (E) To provide an aluminum terminal lug and a cadmiumplatedswitch terminal pad with the lug bolted to the pad.

(F) To provide an aluminum terminal lug which is cadmium-plated and thereafter bolted directly on to a copper switch pad;

All of these. prior art methods are objectionable because of the possible undesirable galvanic corrosion which can exist as a result of the unreliable soldering of copper to aluminum as well as failures which result by having the aluminum conductor become loosened from its clamped surface as a result of the thermal racheting caused by the dissimilar metals.

Although these parts of dissimilar metals may intentionally have a relatively low'resistivity, they cannot with stand the test of time in out-door installations where they are constantly exposed to large variations in humidity. The porosity of the various plated parts causes the air moisture to infiltrate and penetrate into the mircoscopic areas or interfaces between dissimilar metals and thus conditions are created for the undesirable electro-galvanic corrosion.

With my novel arrangement, I am able to provide an aluminum terminal pad at both the jaw and the hinge end-f the switch which results in a less costly, more reliable, and more orderly termination of aluminum conductors without any fear or problem of electrolytic cor- IOSlOn.

It is an object of my invention to eleminate the environment which is conducive to this electrolytic corrosion by providing a metallurgical bond between the dissimilar metals which'results in an alloyed interface between the metals wherein the percentage of aluminum in the alloy decreases from 100% to 0% over a discreet distance in a direction away from the aluminum and toward the As a result of the metallurgical bond which exists between the dissimilar metals, all of these advantages are obtained without sacrificing any of the time proven desirable characteristics of a silver to copper contact arrangement.

It is well known in the electrical industry that it is extremely desirable to provide silver surfaced copper to copper current interchange surfaces. Although the bulk of the material is copper, one of the two mating surfaces is either a sliver insert or is silver plated. The details of the construction and advantage of the silver to copper contact is set forth in detail in US. Patent 2,371,755,

issued March 20, 1945, to J. W. Gilson, entitled Disconnecting Switch, and assigned to the assignee of the instant invention. By providing an aluminum switch having portions thereof .made of copper welded to the aluminum, I have made it possible to retain all of the advantages of the copper, all of the advantages of the aluminum, all of the advantages of the silvered-copper contact arrangement and not have any of the disadvantages which arenormally associated with the utilization of dissimilar metals.

As a further unexpected advantage of the invention, it has been found that the counter-weight normally connected to the blade of a high voltage disconnect switch can be either substantially minimized or in some cases completely eliminated. In switches of the type to which the invention applies, the switch blade must be many feet long and considerable weight is saved, particularly inswitches which exceed the 69 kv. rating. Since the lighter aluminum is used, the net weight of the switch blade for a given current rating is decreased, particularly in the voltage ranges of 115, 138 and 161 kv. Thus the counter-weight mechanism always required with such switches can be substantially simplified. Moreover,

' 4 in the case of a switch of the order of 69 kv. rating, the counter-weight mechanism can be completely eliminated.

Throughout this description applicant has referred to I aluminum and aluminum alloy, it being understood that the terms are used in their broadest sense and in fact used interchangeably.

Accordingly, a primary object of my invention is to provide a high voltage out-door disconnect switch in which the main portions of the switch that are utilized for both conducting current and for mechanical functions are made of a light-weight strong alumnium and the remaining portions of the switch in which there is relative movement between the parts are made of copper or copperbearing metals and the copper portions of the switch are secured to the aluminum by welding or pressure-bonding to create a metallurgical bond which eliminates the possibility of corrosion at the interface.

Another object of my invention is to provide a light weight electrical switch of dissimilar metals joined together by an alloy of the dissimilar metals in which maximum use of the desirable characteristics of the metals is obtained.

Another object of my invention is to provide an outdoor disconnect switch such that all components, divided into body portions and contacting portions, are made respectively of an aluminum alloy and copper and these two metals are joined to each other by flash welding to create a metallurgical bond to prevent electrolytic corrosion.

Still another object of my invention is to provide an electrical switch in which all mechanical and electrical parts which do not have conducting cooperating surfaces are made of a first material, such as aluminum or aluminum alloy and all of the portions which have conducting cooperating surfaces are made of a second material, such as a copper, copper-bearing metal, or copper-silver surfaced metal.

A still further object of my invention is to provide an outdoor high voltage switch in which all conducting and mechanical metal parts are made of aluminum alloy and all conducting parts which have movement with respect to each other are made of copper bearing metal whereas mechanical parts which have relative motion but do not carry current are made of aluminum alloy.

Another object of this invention is to provide a novel electrical switch which does not require a counter-weight for the movable switch blade in switches having a rating of the order of 69 kv.

These and other objects of my invention will be apparent from the following description when taken in connection with the drawings, in which:

FIGURE 1 is a side view of an out-door high-voltage electrical switch made of dissimilar metals and incorporating the features of my invention.

FIGURE 2 is a perspective view of the hinge end of the disconnect switch of FIGURE 1 showing a partially cutaway view of my novel switch.

FIGURE 2a is a detailed cross-sectional view of the conducting hinge of FIGURE 2.

FIGURE 2b is a cross-sectional view of the end of the blade of FIGURE 2.

FIGURE 3 is a perspective view of the jaw showing the details of the bi-metallic arrangement.

My invention is illustrated and described in connection with FIGURES 1 through 3 which show a single pole of an air-break switch commonly known as a three-insulator vertichal break rotating insulator outdoor high voltage air switc The details of the operation of this particular type of switch is set forth in detail in US. Patent 2,673,902, issued March 30, 1954, to G. E. Heberlein, entitled Disconnect Switch, and assigned to the assignee of the in stant invention.

The switch is comprised of four main sections, namely, the base 11, the insulator columns 12, 13 and 14, the

, the various metals used in the switch 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 and all portions of the switch made of copper are indicated by a plurality of small x's and all portions of the switch made from metal such as stainless steel are'indicated by a plurality of dots. Although my invention is particularly directed to the current carrying parts and mechanical operating means 31, it is noted that because these portions of the switch are made primarily of aluminum and, therefore, of very light weight, it is now possible to provide a base 11, which has to serve as a structural support, which also is a light-weight'aluminum. Furthermore, the insulators i2, 13 and 14 could also be of a lighter weight, since the load thereon from the current carrying parts 15 and mechanical means 31 is substantially reduced. The disconnect switch can be provided with surge protection gaps 16 and 1.7 which are described in more detail in copending application Serial No. 88,828, filed February 13, 1961, now Patent No. 3,117,192, in the name of James B. Owens, entitled Disconnecting Switch With Surge Protection Gaps, and assigned to the assignee of the instant invention.

As explained in detail in the aforementioned Patent 2,673,902, the current carrying parts 15 serve as a conductor between-the terminal pads 18 and 19. when the switch is closed, such as seen-in FIGURE 1 and, through appropriate operating mechanism 31 operated through the insulator column 12, the blade of the switch can be actuated to the open circuit position, as seen in FIG- URE 2, to provide an 'open gap in the electrical circuit.

Referring first to the jaw end of the switch, the jaw casting 20 of FIGURE 3 is a heat-treated aluminum alloy and, hence aluminum conductors can be terminated on the aluminum terminal pad 19. The

contact fingers

21, 22 are shown as [ii-metallic strips formed into essentially a Ushape with the

inner portion

23, 24 being aluminum -lurgical bonding between the copper and aluminum. In view of the copper-aluminum alloy existing in the inter-face between the copper strips 25, 26 and the aluminum strips 23, 24, there will be no electrolytic galvanic corrosion between these two dissimilar metals at the interface. Hence, there will be a high conductivity at the interface to thereby permit load current to fiow without unduly heating these parts. The contact pressure for the jaw assembly is provided by means of the stainless steel spring 27 which is housed within the bore of the stainless steel bolt 28 with pressure being exerted by the stainless steel plunger 29 .on the inner surface of the aluminum strip, such as strip 24. It will be noted that spring 27 could be external of the bolt and still servethe same function. Thus, the bolt 28 is inthreaded engagement with the jaw casting 20 to thereby secure the bi-metallic strips 24, 26 to the jaw casting 20. Both the stainless steel spring 27 and the stainless steel plunger 29 are captured within the bore of the bolt 28 so that the spring 27 supplies a continuous pressure on U-shaped bi-metallic strips, such as 24, 26, so that the

strips

23, and 24, 26 are urged toward each other and thus provide the necessary contact pressure with the beaver tail of the blade when the switch is in the closed position.

It will be noted that the jaw section of the switch is in the alloyed bonding process.

made primarily of aluminum so that an aluminum lug can now be secured to the terminal pad 19 and thereby permit an aluminum conductor or bus to be connected directly to the switch of my invention without any problems of electrolytic corrosion.

Furthermore, at the point at which there would be relative movement of conductive parts, namely, between the stationary contact and the beaver-tail of the blade, the necessary provisions are made for having a copperto-copper transfer and, if desired, this transfer can be from a silver-plated copper-to-copper..

Furthermore, the arrangement is such that there is an orderly transition from copper to aluminum by means of a metallurgical bond to prevent undesirable corrosion. The details of the blade and blade operating mech anism is best seen by referring to FIGURE 2. The main portion of the blade 30, as well as the main portion of the blade operating mechanism 31, like the jaw, casting 20, is made of heat-treated aluminum alloy. In like manner, the remaining component, such as the frame casting 32, is also made of aluminum so that the terminal pad 18, as heretofore mentioned, is aluminum and thus there is nodifficulty in terminating an aluminumbus or conductor to the hinge end of the switch.

While there are various manners in which the aluminum-to-copper bond can be obtained, a particularly desirable method of bonding which yields an alloy type bonding may be had by a novel cast-weld bonding method. More specifically, the copper member which is to have an aluminum body secured thereto is held within a mold such as a sand mold and molten aluminum is thereafter poured into the mold so that it can at least partially surround portions of the copper member. The molten aluminum supplies the heat required However, in an alloyed bonding process, pressure is also required and is obtained by the shrinkage that occurs when the aluminum solidifies on the copper body. Thus, in this novel castweld bonding technique, the aluminum supplies both the heat and pressure required in obtaining an alloy bond which avoids electro'galvanic corrosion.

It has been found for improved bonding that it is desirable to first coat the copper surface which is to receive the aluminum member with a tin or silver coating. EX-

periments with nickel plating and chromium plating have such as the blade 30, the operating cranks 31 and the frame casting 32, I have been able to retain the above-noted desirable features of having copper at the point of current conduction between relatively movable parts. By

way of example, the blade 30 has a main portion 34 to which the contact section 35 and beaver-tail is secured by means of a welding operation. Thus, the main portion of the hollow blade 34 is made of aluminum butthe forward end of the blade 35 where the contact is located is made of copper. Thus a short piece of copper tubing 35 is flash-welded to the aluminum tubing 34 to create a and current conduction. The sleeve 60 can be undercut,

at its lower outer circumference so that a synthetic rubber or epoxy material 64 can be placed-between the sleeve 60 and the area on blade 34 and portion 35 adjacent to and including area 63 of the metallurgical bond. The material 63 is water excluding and thus prevents any electro- Details of the lytic action on the inside surface of the copper 34 and aluminum 35. With or without the insert 60, a similar synthetic rubber or epoxy 61 is placed around the entire area of the metallurgical bond 63 for the same reason. Thereafter, the silvered portions 36 representing the movable contact surface can be added to the end of member on the beaver-tail as to insure that there will be a silvered copper-to-coppcr engagement between the portions 35 and the stationary contacts 25, 26. Thus, at the portions having relatively movement and which move away from each other, namely, the beaver-tail 35 and the stationary contacts 25, 26 l have been able to retain a silver-surfaced copper-to-copper relationship which is as desired.

The oppositeend of the blade has a portion 37 made of copper which is flash-welded to the tubular portion 34 to provide a metallurgical bond between the two metals and eliminate corrosion at the conducting interface.

The lower end of copper portion 37 has axial slots therein (not shown) to define a plurality of contact fingers in the manner described in the above noted US. Patent 2,673,902 where, as will be seen hereinafter, these contact fingers rotatably electrically engage the hinged casting 33 carried by frame casting 32.

The hinge casting 33 is of copper material and has an upwardly extending protrusion 38 as best seen in FIG- URE 2 which has a silvered annular surface 39 formed thereon, and a stainless steel axial extension 40. The stainless steel axial extension 40 has a threaded upper end 41 which threads into aluminum insert 42 secured within tube 34. Thus the hollow aluminum blade 34 is mechanically secured to hinge casting 33 through the stainless steel rod 40.

During the operation ofthe switch the main blade portion-34 will rotate with respect to hinge casting 33. Electrical contact from the lower end of blade 34 which is formed of the portion 37 is achieved by causing the individual fingers of portion 37 to be biased inwardly toward engagement with the silvered surface 39 on protrusion 38 through the biasing force of annular spring '43,

which is contained within an annular groove in the end of copper portion 37 as shown. The annular groove in the end of copper portion 37 further defines an inwardly extending ridge to assure high contact pressure between the copper fingers defined by tube 37 and the silver ring 39 whereby, in accordance with the teachings of the invention the desired silver surfaced copper-to-copper current interchange is formed between surfaces having relative movement with respect to one another.

The member 44 and the blade contact chamber 44a, to which it is secured, are of cast aluminum and are mechanically pivotally mounted to hinge casting 33 at the lower portion of the hinge casting. The hinge casting 33 may have a hot tin dipped surface 44b to permit pivotal rotation between

members

44 and 44a, and casting 33 with little friction. The forward end of the mechanical bearing may then be swaged inside the blade 2 to prevent relative axial motion between the blade and hinge casting 33, with extending stainless steel member 40 secured to extension 38 as by a threaded connection.

In addition to this motion about its axis, blade 34 will also have a pivotal rotation which makes a further silvered copper-to-copper surface necessary between the frame casting 32 and the hinge casting 33.

More specifically, the hinge casting 33 is secured to the frame casting 32 by a novel pivotal support which includes .a partially aluminum, partially copper threaded

hinge members

45 and 45. Each of these members is constructed in the manner shown in FIGURE 2a which is a sectional view through the hinge for the case of member 45. Thus, the member 45 is composed of an upper aluminum portion 450, and a lower copper portion 45b, which are joined along the surface 450, as by welding under heat and pressure to form an alloyed bonding of the two metals whereby the metals are metallurgically bonded, as is the case throughout the copper to aluminum joints of the novel switch of the invention. The bolt portion 45a has openings therein to receive

bolts

46 and 47 which form a bolted connection between the aluminum portion of bolt 45 and the aluminum frame casting 32. The extending copper section 45b of bolt 45 isthen threaded into tapped openings 49 of hinge casting 33 and presses downwardly on a stainless steel spring 49 captured within opening 48. The threaded portion 45b of bolt 45 may be silvered whereby the spring 49 causes a high pressure engagement between the silvered copper threads of portion 45b and the copper threads within opening 48 whereby a silvered copper-to-eopper contact is provided. Note that this is the case although the area still maintained the bolted aluminum-to-aluminum joint between the frame casting 32 and bolt portion 450 of bolt 45.

, The operating mechanism for the switch as shown in FIGURES 1 and 2 as crank means 31 includes a crank arm 49 which is of aluminum and extends through a hearing structure 59 in frame casting 32. The crank arm 49 which is of aluminum is secured to rotatable insulator 12 through a bolt ring 51 at the top thereof while the opposite end of frame casting 32 is bolted to the top of insulator stack 13 as by bolts 53 and 54 of FIGURE 2. The connection between crank arm 49 and crank arm 55 includes a threaded portion 56 which is described in the above noted Patent 2,673,902 and perimts a rotative motion between the two crank arms during switch operation.

In operation and assuming that the switch is to be moved from the position of FIGURE 2 to the position of FIGURE 1, the crank arm 49 is moved from left to right by causing the insulator stack 12 to rotate as by rotating the lower operating crank 57 of FIGURE 1. This initial rotation causes crank member 55 to exert a force which tends to rotate switch blade 39 about its pivotal arrangement which includes pivotal members 45 and 45a downwardly toward the jaw contact 20. As the beavertail 35 enters the jaw contact, its narrow dimension is almost parallel to the contacting surfaces of the hinge contact and once it reaches a contacting position the crank

arms

49 and 55 are relatively straight. Thecontinued rotation of the crank arms will then cause a rotation of blade 34 about its axis so as to bring the broad dimension of beaver-tail 36 into high pressure contact engagement with the copper surfaces of the opposing

stationary contact members

21 and 22. That is to say, the silvered surfaces 36 of the copper extension 35 of the switch blade will engage the copper surfaces of

contacts

21 and 22, with high pressure, by virtue of the inwardly directed forces on the stationary contact members.

If desired, as shown in FIGURE 1, the switch may be provided with arcing contacts in the usual manner where the arcing contacts may be of stainless steel or of an aluminum coated'steel rod found in the usual manner. Thus, blade 34 as shown in FIGURE 1 may have an extending rod 66 which engages an arcing born 67 which is electrically connected to terminal pad 19 in any desired manner.

A counter-balancing structure such as a dash-pot arrangement including dash-pot 68 may be provided in the usual manner as is also described in aforementioned US. Patent 2,673,902. However, in accordance with the present invention and for switches having ratings of the order of 115, 138 and 161 kv., the switch blade for a given current rating will be lighter whereby the requirements of the counter balancing structure are simplified. In switches rated at approximately 69 kv., it has been found possible to completely eliminate this counter balance structure. Thus as shown in FIGURE 1 where counter balance structures are used, the moment of force on either side of the pivot for blade 30 has been relatively balanced. In accordance with one feature of the invention, however, a moment of force can appear only on one side of the blade pivot.

From the foregoing description it will be noted that those parts which perform chiefly mechanical functions are of aluminum alloy, such as the

cranks

49 and 55 of crank system 31, the counter balancing components which I switch which are to serve a pure current-conducting function are formed of aluminum alloy. Since this accounts for the major portion of the switch, the overall switch construction becomes relatively light in weight for the same electricalduty as would be served by an equivalent copper switch. Moreover, this decrease in weight has other highly advantageous effects for the complete system in that it permits the use of lighter weight insulator columns such as insulator columns 12, 13 and 14.

By way of example, in the case of a 115,000 volt rated switch, it has heretofore been the practice to use five-inch bolt circle NEMA technical reference number 19 insulator columns.- This has been used as the industry standard. Such insulator columns have been comprised of three NEMA TR-140 insulator units. In accordance with the present invention, however, it has now become possible to use a three-inch bolt circle for a high strength alumina porcelain body insulator which will serve the same electrical and mechanical functions as the present standard five-inch bolt circle columns.

In the foregoing, I have described my invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of my invention within the scope of the description herein are obvious. Accordingly, I prefer to be bound. not by the specific disclosure herein, but only by the appending claims.

I claim:

1. An outdoor disconnect switch; said outdoor disconnect switch including a hinge member, an elongated blade member and a contact member; saidhinge member being electrically insulated from said contact member; said hinge member and contact member having body portions and contacting portions; said blade having a body portion and a first and second respective contacting portion at each of its ends; said body portions being comprised of aluminum; said contacting portions ,being of relatively non-oxidizable conductive material with respect to aluminum; one end of said blade being pivotally connected to said hinge member, said first contacting portion of said blade engaging said contacting portion of said hinge member; the other end of said blade being movable between an engaged and disengaged position with respect. to said contact member, said second contacting portion of said blade being engageable with said contacting portion of said contact; said contacting portions being welded to their respective body portions.

2. A blade 'for an outdoor disconnected switch; said blade having an elongated aluminum body and a contacting portion connected to one end of said blade; said contacting portion being a relatively non-oxidizable highly conductive material; said contacting portion being connected to said aluminum body by an intermediate alloy of said aluminum and said relatively non-oxidazable material; the percentage of said aluminum in said alloy decreasing from 100 percent to zero percent over a discrete distance in adirection away from said aluminum body and toward said contacting portion; said relatively non-oxidizable material being copper.

3. An outdoor disconnect switch; said outdoor disconnect switch including conducting members such as a hinge member. an elongated blade member and a contact mem- 1 0 tive material with respect to aluminum; one end of said blade being pivotally connected to said hinge member, said first contacting portion of said blade engaging said contacting portion of said hinge member; the other end of said blade being movable between an engaged and disengaged position with respect to said contact member, said second contacting portion of said blade being engageable with said contacting portion of said contact; said contacting portions being connected to their respective body portions by an intermediate alloy of aluminum and said non-oxidizable conductive material; said relatively non-oxidizable material being copper.

4.' An outdoor disconnect switch; said outdoor disconnect switch including a hinge member, an elongated blade member and a contact member; said hinge member being electrically insulated from said contact member; each of said hinge member and contact member having body portions and contacting portions; said blade having body portion and a first and second respective contacting portion at each of its ends; said body portions being comprised of aluminum; said contacting portions being of a relative y non-oxidizable conductive material with respect to aluminum; one end of said blade being pivotally connected to said hinge member, said first contacting portion of said of aluminum and said non-oxidizable conductive matcrial; said first contacting portion of said blade comprising a silvered surface copper material.

5. A blade for an outdoor disconnect switch; said blade having an elongated aluminum body and a contacting portion connected to one-end of said blade; said contacting portion being a relatively, non-oxidizable highly conductive material; said contacting portion being connected to said aluminum body by an intermediate alloy of said aluminum and said relatively non-oxidizable material; said contacting portion of said blade being of a silvered surface copper.

6. An aluminum jaw contact for an outdoor disconnect switch; said jaw contact having a terminal pad of aluminum extending therefrom for receiving an aluminum conductor; said aluminum jaw having a pair of parallel extending legs; each of said pair of extending legs receiving one leg of a respective U-shaped bimetallic strip in mechanical and electrical engagement; the other leg of each of said bimetallic strips being adjacent one another and spaced from one another; said U-shaped bimetallic strips having an inner layer of aluminum and an outer layer of a highly conductive material other than aluminum; said inner layers of aluminum being metallurgically bonded to their respective outer layers of highly conductive material other than aluminum; and biasing means connected to said other legs; said other legs being biased toward one another by their said respective biasing means.

7. An aluminum jaw contact for an outdoor disconnect switch; said jaw contact having a terminal pad of aluminum extending therefrom for receiving an aluminum conductor; said aluminum jaw having a pair of parallel extending legs; each of said pair of extending legs receiving one leg of a respective U-shaped bimetallic strip in mechanical and electrical engagement; the other leg of each of said bimetallic strips being adjacent one anotherandspaced from one another; said U-shaped bimetallic strips having an inner layer of aluminum and an outer layer of a highly conductive material other than aluminum; said inner layers of aluminum being metallurgically bonded to their rcspective outer layers of highly conductive material other than aluminum; said highly conductive material being copper.

8. A hinge for a disconnect switch blade; said hinge comprising a hinge casting of a first highly conductive maf second portion of said second highly conductive materia said first portion of said hinge pin being pivotally connected to said hinge casting; said second portion of said hinge pin being rigidly secured to said frame casting; said first and second portions of said hinge pin being metallurgically bonded to one another; said second highly conductive material being aluminum. i

9. A hinge for a disconnect switch blade; said hinge comprising a hinge casting of a first highly conductive material for carrying said blade, a frame casting of a second highly conductive material, and a hinge pin formed of a first portion of said first highly conductive material and a second portion of said second highly conductive material; said first portion of said hinge pin being pivotally connected to said hinge casting; said second portion of said hinge pin being rigidly secured to said frame casting; said first and second portions of said hinge pin being metallurgically bonded to one another; said second highly conductive material being aluminum; said first highly conductive material being copper.

10. An outdoor high voltage electrical switch including a blade, a jaw and a hinge; said blade having an elongated aluminum body and a contacting portion connected to one end of said blade; said contacting portion being relatively non-oxidizable highly conductive material; said contacting portion being connected to said aluminum body by an intermediate alloy of said aluminum and said relatively non-oxidizable material; said contacting portion of said blade being of a silvered surface copper; said jaw contact having a terminal pad of aluminum extending therefrom for receiving an aluminum conductor; said aluminum jaw having a pair of parallel extending legs; each ofsaid pair of extending legs receiving one leg of a respective U-shaped bimetallic strip in mechanical and electrical engagement; the other leg of each of said bimetallic strips being adjacent one another and spaced from one another; said U-shaped bimetallic strips having an inner layer of aluminum and an outer layer of a highly conductive material other than alu-- minum; said inner layers of aluminum being metallurgically bonded to their respective outer layers of highly conductive material other than aluminum; said hinge comprising a hinge casting of a first highly conductive material for carrying said blade, a frame casting of a second highly conductive material, and a hinge pin formed of a first portion of said first highly conductive material and a second portion of said second highly conductive material; said first portion of said hinge pin being pivotally connected to said hinge casting; said second portion of said hinge pin being rigidly secured to said frame casting; said first and second portions of said hinge pin being metallurgi-' cally bonded to one another.

11. A blade for an outdoor disconnect switch; said blade having an elongated aluminum body and a contacting portion connected to one end of said blade; said contacting portion being a relatively non-oxidizable highly conductive material; said contacting portion being connected to said aluminum body by an intermediate alloy of said aluminum and said relatively non-oxidizable material; the percentage of said aluminum in said alloy decreasing from 100% to 0% over a discrete distance in a direction away from said aluminum body and toward said contacting portion; the area outside area at and adjacent to said intermediate alloy being covered with an epoxy resin.

References Cited by the Examiner UNITED STATES PATENTS 2,114,837- 4/38 Gillette 219-1 18 2,345,034 3/44 Crabbs 200170 X 2,673,902 3/ 54 He'berlein 200-48 2,703,349 3/55 Sant.

2,830,144 4/58 Fjcllstedt 200-48 2,854,074 9/58 Frank et a1 200-166 X BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAFER, Examiner.

Claims

1. AN OUTDOOR DISCONNECT SWITCH; SAID OUTDOOR DISCONNECT SWITCH INCLUDING A HINGE MEMBER, AN ELONGATED BLADE MEMBER AND A CONTACT MEMBER; SAID HINGE MEMBER BEING ELECTRICALLY INSULATED FROM SAID CONTACT MEMBER; SAID HINGE MEMBER AND CONTACT MEMBER HAVING BODY PORTIONS AND CONTACTING PORTIONS; SAID BLADE HAVING A BODY PORTION AND A FIRST AND SECOND RESPECTIVE CONTACTING PORTION AT EACH OF ITS ENDS: SAID BODY PORTIONS BEING COMPRISED OF ALUMINUM; SAID CONTACTING PORTIONS BEING OF RELATIVELY NON-OXIDIZABLE CONDUCTIVE MATERIAL WITH RESPECT TO ALUMINUM; ONE END OF SAID BLADE BEING PIVOTALLY CONNECTED TO SAID HINGE MEMBER, SAID FIRST CONTACTING PORTION OF SAID BLADE ENGAGING SAID CONTACTING PORTION OF SAID HINGE MEMBER; THE OTHER END OF SAID BLADE BEING MOVABLE BETWEEN AN ENGAGED AND DISENGAGED POSITION WITH RESPECT TO SAID CONTACT MEMBER, SAID SECOND CONTACTING PORTION OF SAID BLADE BEING ENGAGEABLE WITH SAID CONTACTING PORTION OF SAID CONTACT; SAID CONTACTING PORTIONS BEING WELDED TO THEIR RESPECTIVE BODY PORTIONS.