US3727018A

US3727018A - Disk vacuum power interrupter

Info

Publication number: US3727018A
Application number: US00181095A
Authority: US
Inventors: H Wesoloski; A Arns
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1971-09-16
Filing date: 1971-09-16
Publication date: 1973-04-10
Anticipated expiration: 1990-04-10
Also published as: CA960735A

Abstract

A vacuum circuit interrupter comprising a cylindrical envelope having upper and lower ceramic or glass closure insulator plates through which axially aligned relatively movable contact rods having impedance means comprising a pair of relatively shallow cylindrical metallic shields that are concentrically affixed to associated ones of the contact rods.

Description

D United States Patent [191 [111 3,727,018 Wesoloski et a]. 5] Apr. 10, 1973 [54] DISK VACUUM POWER INTERRUPTER 3,280,286 10/1966 Ranheim ..200 144 B [75] Inventors: Henry J. wesoloski, Cohasset; 3,366,825 l/l968 Lafferty ..200/144 B X gust Arns, Jr., North Easton, both f Mass Primary Examiner-Robert S. Macon Att R b rtC. J t [73] Assignee: Allis-Chalmers Corporation, Mil- Omey o e ones 6 a1 waukee, Wis. 57] ABSTRACT [22] Filed: Sept. 16, 1971 A vacuum circuit interrupter comprising a cylindrical PP 181,095 envelope having upper and lower ceramic or glass closure insulator plates through which axially aligned [52] US. Cl. ..200/ 144 B relatively movable Contact rods having impedance [51] Int. Cl. ..H01h 33/66 means comprising a pair of relatively shallow cylindri- [58] Field of Search ..200/ 144 B cal metallic shields that are concentrically affixed to associated ones of the contact rods. [56] References Cited 5 Claim, 3 Drawing Figures UNITED STATES PATENTS 3,087,034 4/1963 Beers et a]. ..200/144 BACKGROUND OF THE INVENTION This invention relates to circuit interrupters and more particularly to interrupters of the vacuum type which include an evacuated housing, or envelope, in which movable circuit contact rods are arranged for make and break operations. The operation of the contacts in the interrupters in interrupting a circuit is accompanied by arcing wherein relatively high temperatures are experienced. The high temperature causes the contact metal to vaporize which is a good conductor of electricity and tends to increase the current flow within the envelope. Also, the metallic particles in the vapor are dispersed in all directions fusing on the interior surface of the envelope and impairs the operation of the interrupter. To overcome the difficulties the envelopes have been made of glass or a ceramic material. With ceramic or glass lined metallic envelopes, the incorporation of the interior arc shields is extremely difficult in view of the complicated mounting arrangements required.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a circuit interrupter wherein the envelope is constructed of metallic material having glass or ceramic insulating end closure plates through which relatively movable contact rods extended, being insulated from the envelope or body by the glass insulating end closure plates. Each contact rod is provided with an arc shield that is fixedly secured to an associated one of the contact rods in a manner to be relatively movable with respect to each other upon the relative movement of the contact rods themselves.

One object of the present invention is to provide a compact, rigid and reliable vacuum circuit interrupter capable of accommodating large contact rods or studs, which are capable of carrying and interrupting higher currents,

Another object of this invention is to provide a compact, rigid and reliable vacuum circuit interrupter comprising relatively fewer parts thereby having fewer seams or joints wherein leakage can occur.

Still another object of this invention is to provide a compact, rigid and reliable vacuum circuit interrupter which includes a compact arc shield fixedly attached to each of the associated contacts, one of which may be movable and the other a fixed contact.

Yet another object of this invention is to provide a compact, rigid and reliable vacuum circuit interrupter having a circular metallic body portion, the ends of which are closed by glass insulating end plates.

Other objects and advantages of the invention will hereinafter appear.

DRAWING FIG. 1 is a view taken through the interrupter being partly in vertical section and partly in elevation showing the assembly as it appears when the contact rods are in closed position.

FIG. 2 is an end view of one of the pair of contact inserts shown in FIG. 1; and

FIG. 3 is a view in section taken in a plane represented by the line 3--3 on FIG. 2.

DESCRIPTION In the drawing, the numeral 10 designates a high voltage vacuum type electrical circuit interrupter or switch. The interrupter 10 comprises an envelope 1] formed as an upper and lower cup 12 and 14, respectively. The cups l2 and 14 are identical in form and each has an inwardly extending flange portion 16 and 17, the inner edge of which is rolled backwardly so as to face radially outwardly. The roller portion 18 and 19 of the flanges operate as reinforcing elements which gives additional strength andrigidity to their associated cups, and by eliminating sharp corners serve the additional function of reducing the electric field gradient.

The lower cup 14 is provided with an insulator and closure plate 21 which is preferably glass but may be a ceramic material if so desired. A circular opening 22 is formed in the glass end plate 21 with its axis being coaxial with the axis of the cup 14. Inserted into the opening 22 of the end plate 21 is a metallic bushing 26 having an axial bore 27 and an outwardly extending radial supporting flange 28. The external diameter of the hub of the bushing 26 is such that a snug fit is obtained between the bushing and the end plate 21.

With the bushing 27 assembled to the glass end plate 21, the plate 21 is inserted into position in the cup 14. The diameter of the end plate 21 is such that a snug fit of the plate in its sealed position in the end plate is effected. In inserting the glass end plate into the cup care is taken to insure that mechanical stresses are not developed between the plate and the cup.

With the cup 14 and closure plate 21 and bushing 26 assembled the entire assembly is subjected to a bonding process so that a leak free bond is obtained between the contacting outer surface of the glass end plate and the supporting inner surface of the cup flange 17 and also between the peripheral edge of the glass end plate and the adjacent inner surface of the cup 14; likewise a leak free bond is obtained between the external surface of the hub of bushing 26 and the adjacent contacting surface of the wall of the opening 22 as well as the contacting surfaces of the glass plate and the radial flange portion 28 of the bushing 26.

The cup 14 and bushing 26 are preferably of an ironnickel-cobalt alloy having a coefficient of thermal expansion which closely matches that of the glass or ceramic end plate 21. A metallic alloy which is preferred, is a commercially available product manufactured by the Carborundum Company and presently sold under the trademark KOVAR.

A contact rod or stud 31 of oxygen-free, high-conductivity copper is disposed within the bore 27 of the bushing 26 and is of a diameter that provides a smooth noninterfering movable fit therein so as to provide for free axial movement of the contact rod in the bushing. At its inner or upper end, the contact rod 31 is provided with a large diameter copper contact 32 which is secured to the end of contact rod for movement therewith as by being brazed thereto. The large diameter contact rod 32 is provided with a flat upper circular surface 33 the peripheral edge of which is contingent to a peripheral beveled surface 34 that slopes downwardly to the peripheral edge of the contact.

As shown in FIGS. 2 and 3 the contact 32 is provided with a plurality of slots 35 which divide the contact into discrete segments 36. The slots 35 are shown as being generally of a spiral configuration and are constructed and arranged so as to overlap one another. An arc initiated on one of the segments 36 is driven outwardly dueto the magnetic effect resulting from the looped path in accordance with well known principles and is also caused to rotate. As the arc rotates, it is forced to jump from segment to segment across an intervening slot 35. The tendency of an arc to hang on at the edge of a slot as its jumps from segment to segment is overcome by filling the slots 35 with a high resistance material 37, such as nickel or iron. The high resistance material 37 is inserted into the slots 35 so that the material is flush with the surface 33 of the contact.

Disposed within an axial recess 38 formed in the upwardly facing flat surface 33 of the contact 32 is a circular contact insert 39 which is secured in position as by brazing. The insert 39 is a metallic material other than pure copper, and preferably of a copper alloy which has good conductivity evidencing a high resistance to welding in a vacuum environment.

Mounted on the contact rod 31 in coaxial relationship is a disk are shield 41 which in cross-section presents a pie-shaped configuration. The are shield 41 is fixedly secured to the contact rod 31 so as to move axially with the rodand is positioned thereon so that its peripheral edge 42 is located in a horizontal plane which is spaced from the horizontal plane in which the bottom surface of the contact 32 is disposed. The diameter of the shield is of a dimension to insure that the peripheral edge 42 of the shield extends well beyond the peripheral edge of the contact rod 31. The construction and arrangement of the shield 41 is such wherein a line of sight line, represented by the broken line 43, is tangent to the peripheral edge 42 of the shield 41 and the upper peripheral edge 44 of a copper contact 96 but does not intersect the surface of the end plate 21. With this arrangement any metallic particles that may be impelled downwardly toward the insulator and plate 21 will be deflected and/orintercepted so that such metallic particles cannot deposit on the insulator end plate 21 to form a conductive path.

The contact rod extends downwardly through the .axial opening 27 in the bushing 26 and through a prounder surface of the flange 28 of the bushing .26. A

sealing washer 52 is mounted about the contact rod 31 and is secured thereto for axial movement with the rod. The depending end of the bellows 51 is secured in a sealed constructional arrangement to the sealing washer 52. The bellows 51 is of a length so as to expand downwardly without strain upon a full operating stroke of thecontact rod 31. The extending end of the contact rod 31 and the bellows 51 are disposed within a tubular mounting collar 56. At its upper end adjacent to the bushing 26 the'collar 56 encompasses the flange 28 of the bushing 26 being fixedly and rigidly secured thereto. The lower depending end of the mounting collar is provided with a circular bolt ring 57 having a plurality of bolt holes 58, two of which are shown; the ring 57 being welded in position to the outer surface of the mounting collar 56. For mounting the interrupter to a support (not shown) a base plate 61 is provided with bolt holes 62 which are axially aligned with associated ones of the bolt holes 58 formed in the ring 57.

The extending lower end of the contact rod 31 is threaded, as at 66, and extends through an opening 67 formed in the base plate 61. As shown in the drawing, the threaded end of the contact rod 31 is provided with an axial extending flat surface 68 that cooperates with a flat wall surface 69 of a semicircular lower portion 71 of the opening 67. With the arrangement disclosed free i axial movement of the contact rod 31 is permitted but the rod 31 is prevented from rotating by operation of the flat surface 68 on the rod 31 cooperating with the flat wall surface 69 of the lower portion of the opening '67. Thus, the danger of inadvertently opening the various sealed joints of the assembly such as between the sealing washer 52 and stud 31, or the lower end of the bellows 51 and the sealing washer 52, or the upper end of the bellows 51 and the bushing 26 is eliminated.

In forming the flat surface 68 on the lower depending end 66 of the contact rod 31 a shoulder 72 is constructed. The portion of the contact rod 31 wherein the shoulder 72 is located is disposed within the circular upper portion 73 of the opening 67. The depth of the circular portion 73 is such that the shoulder 72 on the contact rod 31 will engage a shoulder 74 adjacent to the flat wall surface 69 of the semicircular lower portion 71 of the opening 67. This arrangement actsas a positive stop and effectively establishes the maximum axial travel in a downwardly or outwardly direction permitted to the contact rod 31. In this manner, inadvertent over-travel of the contact rod in a downward separating stroke cannot occur thereby eliminating the dangers of accidentally damaging the assemblies associated with the lower envelope cup unit 14 is avoided.

The upper cup 12 assembly is similar to the lower cup assembly. As shown, the upper cup 12 is provided with an insulator end closure plate 81 similar to the end plate 21 associated with the cup 14. A circular opening 82 having its axis coinciding with the axis of the end plate 81, is formed in the end plate. The diameter of the end plate 81 is dimensioned so that upon assembly of the end plate into a position abutting the flange 16 of the cup 12, a snug fit between the end plate and cup is obtained.

Inserted into the axial opening 82 of the end plate 81 is a bushing 83 having an axial opening 84 and provided a radial outwardly extending flange 86. in assembled condition the axes of the bushing 83, end plate 81 and cup 12 are constructed and arranged so as to coincide. Assembly of the bushing 83 into'position in the end plate 81 is effected prior to effecting the bonding of the end plate to the cup 12. Thus, when bonding is effe'cted, the joint between the periphery of the end plate and contacting interior surface of the wall of the cup 12, as well as the joint between the contacting surfaces of the glass end plate and the flange 16 are sealed to provide a leak-free joint. Likewise, the joint between wall of the opening 82 andgthe exterior contacting peripheral surface of the bushing hub and the contacting surfaces of the glass end plate with the top surface of the flange 86 will also be sealed to provide a leak free joint.

The cup 12 and bushing 83 are of the same type of iron-nickel-cobalt alloy as set forth for the cup 14 and bushing 26. Thus, all of the metallic parts of theenvelope will have a similar thermal coefficient of expansion as well as the same electrical characteristics.

The bushing 83 receives the reduced portion 91 of an upper fixed contact rod 92. A shoulder 93 formed by the reduced portion 91 abuts the bushing 83 to give positive location to the contact rod 92 so that the axis of the rod coincides with axis of the bushing 83. As stated, the rod 92 is a fixed or stationary contact member and is secured in the bushing 83 by being brazed therein, the braze being carried about the entire circumference of the rod both at the lower and upper end surfaces of the bushing as indicated. In this manner the rod 92 is fixedly secured in the bushing 83 and the joint at the shoulder 93 is sealed, as well as, the joint at the upper end face of the bushing is also sealed to provide leak-free joints.

A large diameter copper contact 96 identical in construction and arrangement to the lower contact 32 is secured to lower depending end of the rod 92. A contact insert 97 is brazed in position in an axial recess 98 formed in the contact 96. The contact insert 97 is identical to the contact insert 39 so that when the interrupter is in conducting condition the upper and lower contact inserts 97 and 39 conductively engage. In this manner, since the inserts are of a metallic material other than pure copper, and preferably of a copper alloy which has good conductivity and evidencing a high resistance to welding, welding of the contacts will not occur.

Immediately above the contact 96 there is provided an arc shield 99. The shield 99 is identical to the shield 41 and is mounted about the rod 92 being fixed in position thereon as by being brazed. The diameter of the shield 99 is such that a line of sight line, represented by the broken line 101, is tangent to the peripheral edge 102 of the shield 99 and the lower peripheral edge 103 of the lower contact 32 but does not intersect the surface of the end plate 81. In this manner, the shield 99 will deflect or intercept any metallic particles that are impelled upwards towards the insulator end plate 81. Thus, the likelihood of a layer of metallic particles coating the surface of the insulator plate 81 and providing a conductive path is eliminated.

The two cups l2 and 14 after bonding and assembly of the associated elements therewith are welded or otherwise secured together. To this end, the lower cup 14 is provided with an outwardly extending radial flange 106 and the upper cup 12 is providing with a similar radial outwardly extending flange 107. The flanges 106 and 107 are complementary and are disposed in abutting relationship, thereby forming a stable supporting base which may be easily sealed and welded to rigidly couple the two cup members together with a leak-free joint.

With the two cup assemblies secured together in sealed relationship, the interior chamber 110 of the interrupter 10 is evacuated to provide a vacuum in the chamber. To this end, a vertical passage 111 is formed in the contact rod 92 which has communication with a horizontal passage 112 drilled through the rod 92. The outer end of the passage 111 is provided with a tube 114 which is secured in sealed relationship in the outer end of the passage. When the chamber 110 is evacuated the tube 114 is pinched off to seal the evacuated chamber.

The circuit interrupter set forth presents a compact, rigid and reliable device which is capable of carrying and interrupting a higher current than heretofore possible with comparable sized prior art interrupters. It is also apparent that the manufacture and assembly of the device disclosed is simplified thereby offering a material reduction in the cost of manufacture. Also, the servicing of the device is facilitated for the device may be parted at the joint juncture of the two cup members 12 and 14 to thereby separate the device into its two basic unit components.

The invention is described in detail in a particular form and it will be appreciated that modification can be made without departing from spirit and scope of the illustrated embodiment of the invention set forth and described.

We claim:

1. In a vacuum circuit interrupter;

an envelope comprising identical first and second metallic units each constructed and arranged as metallic rings having radial inwardly extending flanges at one end and radial outwardly extending flanges at the opposite ends, said units being joined with their outwardly extending flanges in abutting sealed relationship;

a first glass insulator flat end plate closure disposed in'the free end of said first unit in bonded sealed engagement with the radial inwardly extending flange thereof;

second glass insulator flat end plate closure disposed in the free end of said second unit in a bonded sealed engagement with the radial inwardly extending flange thereof; first contact rod extending into said first unit through an axial opening in said first glass insulator end plate closure in sealed relationship therewith;

a second contact rod extending into said second unit through an axial opening in said second glass insulator end plate closure;

means operable to effect a seal between said second contact rod and the axial opening in said second glass insulator end plate closure through which said contact rod extends in a manner to permit said second contact rod to move axially in a contact make-or-break path of travel.

2. A vacuum circuit interrupter according to claim 12 including means operable to engage said second contact rod for limiting the axial movement thereof in a circuit interrupting direction of movement.

3. A vacuum circuit interrupter according to claim 13 including means operable to prevent rotation of said movable second contact rod without interfering with the axial movement thereof.

4. A vacuum circuit interrupter according to claim 14 including means carried by said interrupter for mounting said interrupter to an associated structure.

5. In a vacuum circuit interrupter;

a rigid envelope comprising identicalfirst and second metallic units each having both ends open, said sealing means to seal the space between said first contact rod and the opening in said first end plate closure through which said first contact rod extends;

- a second insulating end closure secured in sealed relationshipin the open free end of said second envelope unit, said first insulating end plate closure having an axial opening therein;

a second contact rod extending into said second unit through the axial'opening in said second end plate

Claims

1. In a vacuum circuit interrupter; an envelope comprising identical first and second metallic units each constructed and arranged as metallic rings having radial inwardly extending flanges at one end and radial outwardly extending flanges at the opposite ends, said units being joined with their outwardly extending flanges in abutting sealed relationship; a first glass insulator flat end plate closure disposed in the free end of said first unit in bonded sealed engagement with the radial inwardly extending flange thereof; a second glass insulator flat end plate closure disposed in the free end of said second unit in bonded sealed engagement with the radial inwardly extending flange thereof; a first contact rod extending into said first unit through an axial opening in said first glass insulator end plate closure in sealed relationship therewith; a second contact rod extending into said second unit through an axial opening in said second glass insulator end plate closure; means operable to effect a seal between said second contact rod and the axial opening in said second glass insulator end plate closure through which said contact rod extends in a manner to permit said second contact rod to move axially in a contact make-or-break path of travel.

5. In a vacuum circuit interrupter; a rigid envelope comprising identical first and second metallic units each having both ends open, said units being secured to each other in coaxial sealed relationship; a first insulating flat end plate closure secured in sealed relationship in the open free end of said first envelope unit, said first insulating end plate closure having an axial opening therein; a first contact rod extending into said first envelope unit through the axial opening in said first end plate closure; sealing means to seal the space between said first contact rod and the opening in said first end plate closure through which said first contact rod extends; a second insulating end closure secured in sealed relationship in the open free end of said second envelope unit, said first insulating end plate closure having an axial opening therein; a second contact rod extending into said second unit through the axial opening in said second end plate closure; an axial deflectable bellows operatively arranged to seal the space between said second contact rod and the opening in said second end plate closure through which said second contact rod extends in a manner to permit said second contact rod to move axially relative to said first contact rod in contact make-and-break operations.