GB1595924A - Compressed-gas circuit-interrupters of the puffer-type having supporting shielding and assembly parts - Google Patents

Description

(54) IMPROVED COMPRESSED-GAS CIRCUIT-INTERRUPTERS OF THE PUFFER-TYPE HAVING IMPROVED SUPPORTING, SHIELDING AND ASSEMBLY PARTS (71) We, WESTINHOUSE ELECTRIC CORPORATION, of Westinghouse Building, Gateway Center, Pittsburgh, Pennsylvania, United States of America, a company organised and existing under the laws of the Commonwealth of Pennsylvania, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a circuit-interrupter and in particular to a compressed-gas puffer-type circuit interrupter and in particular to a compressed-gas puffer-type circuit interrupter.

According to the present invention, a circuit interrupter includes contact means separable to establish an arc, said contact means including a stationary contact and a cooperable movable contact, a first substantially cylindrically-shaped metallic electrostatic shield encompassing the stationary contact and ensuring a low-gradient electrostatic field between the separated contacts in the fully open-circuit position of the circuitinterrupter, and an upper-disposed, second, cylindrically-shaped metallic electrostatic shield for encompassing line-terminal connecting means of said stationary contact means and in which a plurality of resilient metallic clips are provided whereby to enable a ready mounting and dismounting of the second metallic electrostatic shield.

The invention will now be described, by way of example with reference to the accompanying drawings in which: Figure 1 is a vertical sectional view taken through an improved tank-type compressedgas circuit interrupter; Figure 2 is a top plan view of the outer metallic grounded tank with the terminalbushings removed; Figure 3 is an enlarged vertical sectional view taken through the subassembly, of two modular gas-units, and operating linkage; Figure 4 is a considerably-enlarged, sideelevational view of the two modular units arranged in electrical series, the left-hand modular unit being shown in side elevation, whereas the right-hand modular, puffertype, interrupting unit is shown in vertical section, the contact structure being illustrated in the fully-open circuit position; Figure 5 is a vertical sectional view taken through the contact structures; Figure 6 is a side-elevational view of the upper conducting shielding cross-bar structure; Figure 7 is a top plan view of the cross-bar shielding structure of Fig. 6; Figure 8 is an end elevational view of the conducting cross-bar structure of Figs. 6 and 7; Figure 9 is a side elevational view of one of the three resilient spring-clips associated with the stationary contact structure to hold the upper shield assembly 96 in place; Figure 10 is a top plan view of the resilient spring-clip structure of Fig. 9; Figure 11 is a top plan view of the relatively-heavy metallic support-plate structure for supporting the two puffer interrupting units of the present invention; Figure 12 is a fragmentary sectional view taken substantially along the line XII-XII of Fig. Il; Figure 13 is a top plan view of the lowerdisposed supporting shielding structure for rigidly supporting the two operating cylinders and for causing their simultaneous movement; Figure 14 is an end elevational view of the lower-disposed shielding cross-bar structure of Fig. 13; Figure 15 is a side elevational view of a spring-clip member fastened to the relatively-heavy metallic support casting, which supports the two puffer units and is adapted to hold into accurate position the two tubular shielding ring members of Figs. 24 and 27; Figure 16 is a fragmentary end elevational view of the spring-clip assembly of Fig. 15; Figure 17 is a side elevational view of a spherical bearing used for connecting the operating rod to the conducting cross-bar structure: Figure 18 is a vertical sectional view taken substantially along the line XVIII-XVIII of Fig. 17; Figure 19 is a horizontal sectional view taken substantially along the line XIXXIX of Fig. 3 with certain parts omitted for clarity; Figure 20 is a top plan view, partly in cutaway section. of the upper-disposed conducting shielding cross-bar structure, illustrating the spherical bearing-pivot connection for the operating rod; Figure 21 is a side elevational view, partly in vertical section, of the capacitor-tube illustrating, in vertical section, the end mounting fittings; Figure 22 is an end elevational view of the right-hand mounting terminal for the capacitor-tube of Fig. 21, illustrating its resilient Ushaped configuration; Figure 23 is a fragmentary top plan view of the left-hand mounting fitting of the capacitor-tube of Fig. 21 showing the association therewith of mounting bolts; Figure 24 shows one of the upper shielding tubes associated with the relatively-heavy horizontally-extending metallic casting support-plate; Figure 25 is a side elevational view of a tubular end tip for the electrostatic tubular shielding members of Figures 24 and 27.

Figure 26 is a fragmentary enlarged sectional view taken through the line XXVIXXVI of Figure 24 of the shieldingtube assembly of Fig. 24, looking in the direction of the arrows; Figure 27 is a top plan view of the lowerdisposed shielding tube disposed at the lower end of the insulating upstanding supporting cylinder member of Fig. 3; Figure 28 is a fragmentary sectional view taken substantially along the line XXVI II-XXVIII of Fig. 27. looking in the direction of the arrows; Figure 29 is a considerably-enlarged vertical sectional view taken through the lefthand stationary contact assembly of Fig. 1, illustrating the resilient supporting arrangement for the upper-disposed cylindrical shield member 96 for removably supporting the same; Figure 30 is a top plan view of the resilient conductor strap associated with the left-hand stationary contact assembly of Fig. 1, indicating its manner of connection to the lower ends of the terminal-studs of the terminalbushings; and, Figure 31 illustrates an alternate modifiedtype of electrical line connection for the improved interrupting structure of the present invention, wherein the terminal-bushings 58, 59 of Fig. 1 are omitted, and in their place. electrical connection is alternatively connected to a "pipes" type of gas-insulated transmission-line system.

Figures 1--3 illustrate a subassembly 1 comprising a pair of conjointly-acting gasmodules 2 electrically and mechanically tied together by a horizontally-extending bridging-bar construction 4 having pivotally connected thereto, as at 5, an upstanding main insulating operating rod 6.

The operating rod 6 is, as shown, pivotally connected at 7 to a bell-crank lever 8, which is affixed to a rotatable main operating shaft 9. A lever box 10 is affixed, as by welding 3 (Fig. 3), for example, to the lower surface 11 of the main metallic support-plate 12.

Each of the gas-modular units 2 comprises an upper stationary contact structure 13 including a cluster of annularly-arranged main stationary contact fingers 14, which, in the closed-circuit position of the interrupter, as indicated in Figure 1, make good contacting engagement with an. annular movable main contact 15 affixed to an operatingcylinder assembly 17.

Centrally disposed within the cluster of relatively-stationary main contact fingers 14 is a tubular stationary arcing contact 20, which makes engagement with a plurality of secondary movable arcing contact fingers 22, the movable arcing rod-shaped contact 23 extending therewithin.

Constituting a part of the movable operating-cylinder assembly 17 is an insulating hollow orifice 25, which directs the gas flow emanating from the compression space 30 (Fig. 5), interposed between the stationary piston structure 18 and the outer-disposed movable operating cylinder 17. This gas flow strikes the established arc 35, as indicated in Figure 3, and effects the rapid extinction thereof.

The two modular gas-units 2 operate simultaneously by their downward cooperative movement, and. in electrical series, constitute an electrical piece of interrupting equipment having a voltage rating of 242 Kv with an interrupting capacity of 50 to 63,000 amperes, for example. The full-load continuous current rating of the circuit-interrupter, for example, would be 2,000 to 4,000 amperes.

As illustrated in Figure 3, the two modular units 2 are collectively supported by an upstanding insulating support cylinder 40, which, in turn, is fixedly bolted to the relatively-heavy metallic support-plate 12, referred to hereinbefore.

Following subassembly of the interrupting equipment 1, illustrated in Figure 3, the grounded metallic tank structure 41 is lifted up and dropped over the subassembly. The heavy metallic support-plate 12 is secured by a plurality of circumferentially-disposed bolts 45 (Fig. 1) to the underside of a heavy mounting ring 46, which, in turn, is welded, for example, to the inner side walls 48 of the outer metallic tank structure 41.

The flexible connectors 60, 61, connected respectively to the upper stationary contact structures 13, may be manually secured to the lower terminal-studs 66, 67 of the two terminal-bushings 58, 59 by means of the manhole service opening 70 provided in the side wall of the tank structure 41. Thus, the major portion of the assembly operations may be conducted externally of the tank 41 with plenty of working space. Following the subassembly, as mentioned, the tank 41 is dropped over the subassembly 1 to secure the two assemblies together. It will be noted that attached to the side of the metallic tank is the mechanism housing 75, together with its internally-located pneumatic mechanism 77 (Fig. 1). Generally, this is of the type which, when operated, will effect opening of the circuit-breaker 53. Thus, suitable valve structure 80 will admit high-pressure gas to a piston 81, which will effect downward movement of a piston-rod 82, consequent clockwise rotation of a bell-crank lever 83 having an arm 84, which is pivotally connected. as at 85, by an operating link 86 to a second bell-crank lever 87.

A second arm 89 of the second bell-crank lever 87 has pivotally connected thereto, as at 91 a connecting rod 92 having secured thereto a spring seat 93, which is biased toward the right, as viewed in Figure 1, in a direction to close the circuit-breaker 53.

The connecting rod 92 is pivotally connected to the bell-crank lever assembly 95, which operates the main operating shaft 9.

The construction is such that the compression spring 100 effects closing of the circuitinterrupter 53, a closing shock-absorber 101 (Fig. 1) being provided to limit the dosing travel of the circuit-breaker 53.

During the opening operation, the valve mechanism 80 is actuated to effect, through the piston 81 and the aforesaid interconnecting linkage the downward opening movement of both movable contact structures 15 to the position illustrated in Figure 3.

Where the terminal-bushings 58 and 59 are not utilized for certain applications, the construction. as illustrated in Figure 31, may be employed, wherein the terminal straps 110. Ill, affixed to the flexible connectors 60.

61, may be fixedly secured secured to conductors 115, which constitute a part of a gasinsulated transmission system 116. A fragmentary portion of such a gas-insulated system 116, is illustrated in Figure 31.

Figure 4 more clearly illustrates the electrical and mechanical interconnection between the two modular puffer units 2, including an upper generally U-shaped shielding crossbar structure 4 and a lower-disposed similar U-shaped shielding structure 27. The upper shielding structure 4 has a pair of lateral bearing holes 28 provided therein accommodating a horizontally-disposed pivot-pin 5, which accommodates a partially spherical bearing 31 more clearly illustrated in Figures 17, 18 and 19 of the drawings. By so using the partially spherical bearing 31, compensation is provided for inaccuracies of manufacture of the several parts.

As illustrated in Figure 4, each of the movable operating cylinders 17 is guided by a steel rod 33, for example, slidable within guides 34 and 36 provided in the stationary puffer pistons 18, and serving to guide the movable operating cylinders 17. The pistons 18 are mounted upon a central mounting plate 32, on which are also mounted electrostatic shielding ring-shields 73, 74, 76 and 78 for relieving the critical voltage regions and half-circle shaped support insulators 79, which support the upper terminals 66, 67, shields 96, 97 and arcing contacts 20 of the interrupter 53. Figure 19. illustrates a hon- zontal sectional view taken through the side semi-circular, upstanding, insulating support members 79, The main current passing through the circuit-interrupter 53 is transferred by means of copper alloy finger clusters 14, for example, forming part of the upper stationary contact terminal 13, and which transfer current to the annular outside main movable contact 15 of each movable puffer, or operating cylinder 17. Secondary contacts 22 are provided inside of each moving operating cylinder 17 to initiate the arc 35 during circuit-interruption.

Two electrostatic shields 96, 97 are supported upon the top stationary contact termi- nals 13. The lower shield 97 acts as a voltage shield and also deflects much of the hot, ionized gas, created during interruption, into regions 88 in the breaker 53 having relatively low-voltage stress and a large gas volume to mix with the hot gas. The upper shield 96 hides the top terminal bolts 94 and the connectors 60, 61, which are connected, in the final assembly to the breaker entrance bushings 58, 59. Special spring clips 98 (Figs.

9, 10) hold the shield 96 in place, and allow easy and fast removal of the shield 96 to access for the connectors 60. 61 and bolting hardware 94. Capacitor tubes 37 are provided across the interrupter assembly 1 to aid in current interruption. The top terminal 13 and shield arrangement 96, 97 is independent of the type of bushing 58,59 which is used on the complete circuit-breaker 53. The breaker 53 may thus be used in free-standing, or gasinsulated substation applications, as shown in Fig. 31 The circuit-interrupter 53 of the present application is particularly capable of operating on a 242 Kv transmission-line, and, moreover, is capable of continuously passing currents of the order of 3,000 to 4,000 amperes, for example. The interrupting capacity may be of the order of 50,000 amperes, for example.

In mounting the capacitor tubes 37, it will be observed that each capacitor-tube 37 has a lower stud-portion 38 (Fig. 21), which fits into a recess 39 (Fig. 11) provided in the metal central cast support-plate 32, with a spring-clip 42 to make good contact therebetween. The upper end of the capacitortube 37 is located on the side of the lower electrostatic shield 97, as illustrated in Figure 3.

The upper electrostatic shield 96 is readily mounted and disassembled by the utilzation of three equally-spaced spring-clips 98, more clearly illustrated in Figures 9, 10. When the modular circuit-interrupting structure 53 is desired to be utilized in a circuit-interrupter of the type of Figure 1, it will be observed that no tensile or compressive stresses are imposed upon the lower ends of the terminalbushings 58, 59, but merely a flexible connector 60 or 61 is provided therebetween. The sole support for the stationary contact structure 13 is thereby provided by the upstanding supporting insulating cylindrical supports 79.

The central mounting plate 32 is a cast aluminium member. for example. shaped to provide high mechanical strength and support for the piston pressure loading during breaker operation and to provide electrical shielding of the electrically poorly-shaped guide rods 33 and main insulating tube mounting bolts. In general, the more smooth, continuous or round a shape is, the higher an electrical stress it can sustain or be allowed to be near. The oval rib 32A on the mounting plate 32 is the main shielding for the abovementioned poor shapes.

The side vertical support-plates 79 are very important, inasmuch as they must have the requislte strength for supporting the upperdisposed relatively-stationary contact assemblies 13. Additionally these vertical sidesupport plates 79 have an additional function of keeping the arc and hot arcing products awav from the side-walls 48 of the outer grounded metallic tank 41. Of the utmost importance. however, is the fact that the sideinsulating support-plates 79 support the upper stationary contact structures 13. so that the upper terminal members are completely supported independently from the terminalbushings SX, 59. when the latter are used. As a result. the stationary contact structures 13 may merely be electrically connected by a flexible conductor 60, 61 to the lower. respective, interior ends of the terminal-studs 66. 67 of the terminal-bushings 58, 59 when they are used; and when they are not used, electrical connection may, alternatively, be made to the interior live "hot" conductors 115 of "pipes" utilized in "pipe-type", gasinsulated transmission-line equipment 116 (Fig. 31).

By utiliiir:ug the side-support plates 79 there is no net essity for having any supporting cross-member (not shown) between the two laterally-spaced stationary contact structures 13. This has the advantage that there are no surface creepages, which would be encountered, and advantage is taken of the high insulating qualities of the sulfur-hexafluoride (SF6) gas 16 disposed within the outer tank structure 41.

An additional advantageous result of the foregoing arrangement is that it allows the interrupter assembly 1, which is completely supported from the lower, relatively-heavy cast base 12, to be built-up as a bench unitassembly 1, that can be actually completely tested, adjusted and subsequently put into a surrounding circuit-breaker tank 41.

The insulating half-shields 79 are fabricated of a glass-wound epoxy material, for example, having embedded mounting studs therein at the upper and lower ends. The gas flow is, consequently, directed into regions within the circuit-breaker tank 41, where it encounters relatively cool unionized gas.

The upper metallic electrostatic shield 96 is the main shield for all of the top bolts 94 and connectors of the stationary contact assembly 13, and relieves the voltage gradient around the sharp corners of the hardware items 94. Accordingly, the present arrangement provides an easy assembly and disassembly feature, whereby the upper metallic electrostatic shield 96 may be secured, as by a metallic clipping arrangement, by the use of three evenly-spaced resilient metallic mounting clips 98, for example, so as to removably hold the upper metallic electrostatic shield 96 in place.

We have used, for example, three evenlyspaced resilient clips 98, which are just a bent-up piece of spring steel, which results in a resilient holding of the metallic shield 96.

In other words, all one must do is to take hold of the upper-disposed electrostatic shield 96, push it down over these three resilient metal clips 98, and the clips 98 are distorted somewhat, and then one hears an audible click, and the electrostatic shield 96 is thus pushed into a region, where it is mechanically trapped by these three spaced resilient clips 98. They are preferably evenly spaced around a circle, so that when one pushes the electrostatic shield 96 on, and it clicks into the end configuration of the three clips 98, one cannot move it either up or down.

To remove the metallic electrostatic shield 96 requires no special tools. One merely reaches in and puts one's thumb under one of the resilient clips 98, pulls it back, and the upper-disposed electrostatic shield 96 will come up. One can accordingly get it off and removed with just two hands and no required tools.

With regard to the shunting capacitor tubes 37. they are mounted with respective end fittings 62, 63 one on each end, which are required because it is not mechanicaly strong enough by itself to be directly mounted to anything. The lower end-fitting 63 has a stud 38 sticking out of the lower end of the capacitor-tube 37, resembling a straight pin; and there is a drilled hole 39 in the central, relatively-heavy mounting plate 32. One just drops this stud 38, at the end of the capacitortube 37, into the provided recess 39, and there is no bolting at the lower end of the capacitor-tube 37 whatsoever. Also, at the bottom end of the capacitor-tube 37 there is a little spring clip 43 (Fig. 22), which makes an electrical connection to the support plate 32.

When the stud 38 is dropped out into the hole 39, this causes contact 43 to automatically make electrical contact with the central, relatively-heavy mounting casting plate 32 and the bottom of the capacitor-tube 37.

Then all one needs to do is swing the capacitor-tube 37 over a few degrees, and an assembly man inserts one mounting bolt 50 (Fig. 23) at the top connection of the capacitor-tube 37. and it bolts into the lower metallic electrostatic shield 97 of the upper stationary contact assembly 13 by an accommodating mounting hole.

The interrupting assembly I provides a unit. which is completely made up of modular pieces. roughly three in number, that make up the entire interrupter 53, and allowing for adjustments and inspection to be done on a bench-assembly basis. that is in an environment where it is very easy to work in.

The modules 2 can then be assembled into the breaker through the man-hole 70 of the breaker tank 41. or assembled onto the lower base-plate 12. onto which the component parts mount; and subsequently inserted into the breaker tank 41.

This design permits several men to be inside of the breaker tank 41 at one time for any adjustment or inspection purposes. and additionally allows for a very quick removal of any parts. which may have deteriorated during the operational life of the circuithreaker 53. All parts. which are possibly subject to wear. can be immediately replaced without difficulty. This can be done easily through the man-hole 70 (Fig. 1). Inspection ot parts additionally, may be made through the man-hole 70. There is nothing to block the vision of this inspection, and maintenance is facilitated.

A feature of the tank design 41 is the geometry and entrance flanges 55, 56 (Fig. 2).

The hollow insulating support tube 40 is constructed of cast epoxy with suitably shaped metallic inserts used for attaching the tube to the lower support 12 and the central support plate 32. Use of the cast epoxy allows a very compact overall breaker design because a relatively high electrical stress can be allowed in this material. This allows a very short length of tube to be used, reducing the diameter of the tube because a shorter tube will have less mechanical moment (from shipping and operating loads) impressed upon it. This then allows the central support plate 32 to be relatively smaller and the tank 48 to be shorter and of a smaller diameter than it would be if some other material was used for the hollow support tube 40.

WHAT WE CLAIM IS: 1. A circuit-interrupter including contact means separable to establish an arc, said contact means including a stationary contact and a cooperable movable contact, a first substantially cylindrically-shaped metallic electrostatic shield encompassing the stationary contact and ensuring a low-gradient electrostatic field between the separated contacts in the fully open-circuit position of the circuit-interrupter, and an upper-disposed, second, cylindrically-shaped metallic electrostatic shield for encompassing line-terminal connecting means of said stationary contact means and in which a plurality of resilient metallic clips are provided whereby to enable a ready mounting and dismounting of the second metallic electrostatic shield.

2. A circuit-interrupter as claimed in claim 1, including a pair of laterally-disposed modular-type puffer interrupting units, each puffer interrupting unit comprising a relatively-stationary contact structure and a separable movable contact structure, a sideinsulating baffle-plate for each puffer-type interrupting unit for fixedly supporting the stationary and movable contact structures in a predetermined vertically. spaced-apart relationship, a relatively-heavy lower metallic supporting plate, means securing each of said side insulating baffle-plates to said relativelystationary lower-disposed metallic supporting plate, a relatively-stationary piston structure for each puffer unit, each respective relatively-stationary piston structure being upstandingly supported by said lower-disposed relatively-heavy metallic supporting plate, each puffer interrupting unit including a movable operating cylinder carrying said movable contact structure and sliding over said relatively-stationary piston structure whereby to compress gas therebetween, lineterminal connection means, means for electrically connecting the relatively-stationary contact structure to said line-terminal con

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (18)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   96 requires no special tools. One merely reaches in and puts one's thumb under one of the resilient clips 98, pulls it back, and the upper-disposed electrostatic shield 96 will come up. One can accordingly get it off and removed with just two hands and no required tools.

   With regard to the shunting capacitor tubes 37. they are mounted with respective end fittings 62, 63 one on each end, which are required because it is not mechanicaly strong enough by itself to be directly mounted to anything. The lower end-fitting 63 has a stud 38 sticking out of the lower end of the capacitor-tube 37, resembling a straight pin; and there is a drilled hole 39 in the central, relatively-heavy mounting plate 32. One just drops this stud 38, at the end of the capacitortube 37, into the provided recess 39, and there is no bolting at the lower end of the capacitor-tube 37 whatsoever. Also, at the bottom end of the capacitor-tube 37 there is a little spring clip 43 (Fig. 22), which makes an electrical connection to the support plate 32.

   When the stud 38 is dropped out into the hole 39, this causes contact 43 to automatically make electrical contact with the central, relatively-heavy mounting casting plate 32 and the bottom of the capacitor-tube 37.

   Then all one needs to do is swing the capacitor-tube 37 over a few degrees, and an assembly man inserts one mounting bolt 50 (Fig. 23) at the top connection of the capacitor-tube 37. and it bolts into the lower metallic electrostatic shield 97 of the upper stationary contact assembly 13 by an accommodating mounting hole.

   The interrupting assembly I provides a unit. which is completely made up of modular pieces. roughly three in number, that make up the entire interrupter 53, and allowing for adjustments and inspection to be done on a bench-assembly basis. that is in an environment where it is very easy to work in.

   The modules 2 can then be assembled into the breaker through the man-hole 70 of the breaker tank 41. or assembled onto the lower base-plate 12. onto which the component parts mount; and subsequently inserted into the breaker tank 41.

   This design permits several men to be inside of the breaker tank 41 at one time for any adjustment or inspection purposes. and additionally allows for a very quick removal of any parts. which may have deteriorated during the operational life of the circuithreaker 53. All parts. which are possibly subject to wear. can be immediately replaced without difficulty. This can be done easily through the man-hole 70 (Fig. 1). Inspection ot parts additionally, may be made through the man-hole 70. There is nothing to block the vision of this inspection, and maintenance is facilitated.

   A feature of the tank design 41 is the geometry and entrance flanges 55, 56 (Fig. 2).

   The hollow insulating support tube 40 is constructed of cast epoxy with suitably shaped metallic inserts used for attaching the tube to the lower support 12 and the central support plate 32. Use of the cast epoxy allows a very compact overall breaker design because a relatively high electrical stress can be allowed in this material. This allows a very short length of tube to be used, reducing the diameter of the tube because a shorter tube will have less mechanical moment (from shipping and operating loads) impressed upon it. This then allows the central support plate 32 to be relatively smaller and the tank 48 to be shorter and of a smaller diameter than it would be if some other material was used for the hollow support tube 40.

   WHAT WE CLAIM IS: 1. A circuit-interrupter including contact means separable to establish an arc, said contact means including a stationary contact and a cooperable movable contact, a first substantially cylindrically-shaped metallic electrostatic shield encompassing the stationary contact and ensuring a low-gradient electrostatic field between the separated contacts in the fully open-circuit position of the circuit-interrupter, and an upper-disposed, second, cylindrically-shaped metallic electrostatic shield for encompassing line-terminal connecting means of said stationary contact means and in which a plurality of resilient metallic clips are provided whereby to enable a ready mounting and dismounting of the second metallic electrostatic shield.
2. 2. A circuit-interrupter as claimed in claim 1, including a pair of laterally-disposed modular-type puffer interrupting units, each puffer interrupting unit comprising a relatively-stationary contact structure and a separable movable contact structure, a sideinsulating baffle-plate for each puffer-type interrupting unit for fixedly supporting the stationary and movable contact structures in a predetermined vertically. spaced-apart relationship, a relatively-heavy lower metallic supporting plate, means securing each of said side insulating baffle-plates to said relativelystationary lower-disposed metallic supporting plate, a relatively-stationary piston structure for each puffer unit, each respective relatively-stationary piston structure being upstandingly supported by said lower-disposed relatively-heavy metallic supporting plate, each puffer interrupting unit including a movable operating cylinder carrying said movable contact structure and sliding over said relatively-stationary piston structure whereby to compress gas therebetween, lineterminal connection means, means for electrically connecting the relatively-stationary contact structure to said line-terminal con

   necting means for each puffer-type interrupting unit, a horizontally-extending cross-bar structure mechanically and electrically connecting the two movable operating cylinders, a vertically-movable insulating operating rod pivotally connected by a partially spherical bearing to said horizontally-extending crossbar structure, so as to compensate for manufacturing inaccuracies and to provide proper alignment of vertical motion of the two laterally-spaced operating cylinders.
3. 3. A circuit-interrupter as claimed in claim 2, wherein each puffer-type interrupting unit has a vertical metallic guide-stem rod associated with its respective movable contact structure, and each respective metallic guide-stem rod being guided by said relatively-stationary piston structure.
4. 4. A circuit-interrupter as claimed in claim 3, wherein the lower-disposed relatively-heavy metallic supporting plate has a downwardly-extending flange or rib portion to electrostatically shield the guide-stem rod in its fully-open-circuit position.
5. 5. A circuit-interrupter as claimed in any one of claims 2 to 4, wherein each puffertype interrupting unit has a respective capacitor-tube, and the respective capacitor-tube is provided with a lower-disposed mounting stud, which may readily be placed in a recess portion provided in the horizontally-disposed relatively-heavy metallic supporting plate.
6. 6. A circuit-interrupter as claimed in claim 5. wherein the upper end of the capacitor-tube may be detachably bolted to the upper stationary contact structure of the circuit-interrupter.
7. 7. A circuit-interrupter as claimed in claim 2. wherein a vertically-disposed hollow insulating support tube is provided surrounding the vertically-arranged operating rod and additionally supporting said relatively-heavy metallic supporting plate upwardly away from grounded, lower-disposed housing structure.
8. 8. A circuit-interrupter as claimed in claim 7 wherein the support tube is a cast epoxy tube with shaped metallic inserts cast in each end to serve as mounting points.
9. 9. A circuit-interrupter as claimed in any one of claims 2 to 8. wherein a plurality of generally U-shaped tubular metallic memhers are positioned around said relativelyheavy metallic supporting plate for grading the electrostatic field between the relativelyheavy metallic supporting plate and the lower-disposed grounded housing structure.
10. 10. A circuit-interrupter as claimed in claim 9, wherein the horizontally-disposed cross-bar structure is formed as a metallic electrostatic shielding structure having a generally U-shaped configuration.
11. l l The circuit-interrupter as claimed in claim 10. wherein an additional lower-disposed metallic electrostatic shield supporting structure is fixedly secured to the lower ends of the operating cylinders.
12. 12. A circuit-interrupter as claimed in claim 3, wherein the metallic guide-stem rods have two vertically-spaced guide-supports associated with the relatively-stationary piston structure.
13. 13. A circuit-interrupter as claimed in any one of claims 5 to 12, wherein a cluster of relatively-stationary flexible main contact fingers are disposed interiorly of the lowerdisposed, first, electrostatic shield, and the movable contact structure comprises a movable operating puffer-cylinder having an annular movable main contacting portion, which makes contacting engagement in the closed-circuit position with said cluster of relatively-stationary contact fingers.
14. 14. A circuit-interrupter as claimed in any one of claims 1 to 13 including an upstanding metallic grounded tank structure, a pair of laterally-spaced terminal-bushings extending downwardly interiorly within said grounded metallic tank structure each carrying a line-conductor thereinto, a pair of laterally-spaced puffer-type circuit interrupting units interconnected to a respective lineconductor carried by a respective terminalbushing, common operating means including a conducting cross-bar mechanically interconnected whereby vertical opening and closing movements of said operating-rod structure cause simultaneous opening and closing movements of the corresponding two movable contact structures, a hollow insulating supporting member surrounding said operating rod, said hollow cylindrical insulating support member resting upon the lower portion of the grounded metallic tank structure, whereby the weight of the two puffer interrupting units is substantially carried wholly by said lower portion of the grounded metallic tank structure.
15. 15. A circuit-interrupter as claimed in claim 14, wherein an operating mechanism is located externally of the grounded metallic tank structure, and linkage means mechanically interconnects said operating mechanism with said vertically-extending operating-rod structure.
16. 16. A circuit-interrupter as claimed in claim 15. wherein a bell-crank pivotal linkage structure is disposed below said upstanding hollow cylindrical insulating support member and interrelates vertical opening and closing movements of said operating rod with said externally-located operating mechanism.
17. 17. A circuit-interrupter as claimed in any one of claims 14 to 16, wherein the upstanding hollow insulating supporting cylindrical member is fabricated from a glasswound epoxy material.
18. 18. A circuit-interrupter. constructed and adapted for use, substantially as hereinbefore described and illustrated with reference to the accompanying drawings.