US2924690A - Circuit interrupters - Google Patents

Description

Feb. 9, 1960 T. E. BRowNE, JR., ErAL 2,924,690

CIRCUIT INTERRUPTERS 8 Sheets-Sheet l Filed Dec. 24, 1 954 Fig. I.

INVENTORS Thomas E. Browne,Jr. 8f /5 Alber? P. Strom. A{(BY l/TTORNEY 7 .2 m l2.; Y

Feb. 9, 1960 T. E. BROWNE, JR., ETAL CIRCUIT INTERRUPTERS 8 Sheets-Sheet 2 Fig.4.

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CIRCUIT INTERRUPTERS 8 Sheets-Sheet 6 File@ Deo. 24. 1954 Fig. IO.

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Feb. 9, 1960 T. E. BRowNE, JR., ETAL 2,924,690

CIRCUIT INTERRUPTERS Filed Dec. 24, 1954 8 Sheets-Sheet 8 United States Patent O CIRCUIT INTERRUPTERS Thomas E. Browne, Jr., and Albert P. Strom, Forest Hills, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application December 24, 1954, Serial No. 477,466

19 Claims. (Cl. 20G-148) This invention relates to circuit interrupters in general, and, more particularly, to arc-extinguishing structures therefor.

United States patent application Serial No. 686,775,

tiled September 27. 1957, is a division of the present application. A general object of our invention is to provide an improved and highly effective circuit interrupter, which will interrupt the circuit therethrough more effectively than have circuit interrupters heretofore.

' A more specific object of our invention is to provide an improved circuit interrupter, particularly one of the gas-blast type, in which advantage is taken of the grounded metallic tank structure generally employed in the highvoltage, oil-circuit-interrupter tank art.

Another object of our invention is to take advantage of the unusual and phenomenal dielectric properties, and arc-extinguishing characteristics, of sulfur hexafluoride or selenium hexauoride, particularly when these gases are utilized in conjunction with a grounded metallic tank structure.

Still a further object of our invention is to provide an improved compressed-gas circuit interrupter, in which contact operation and/ or fluid ow is obtained by utilizing the compressed state of the gas.

Still a further object of our invention is to provide an improved circuit interrupter including a housing containing gas under pressure, in which fluid motion is obtained by exhausting from the tank cooled fluid, as distinguished from arc-heated fluid, to bring about improved performance.

An ancillary object of our invention is to adapt sulfur hexafluoride or selenium hexauoride gas to tank-type, grounded, metallic structures, in which preferably the gas is maintained at atmospheric, or higher pressures, within the tank to take advantage of its dielectric strength.

Further objects and advantages will readily become apparent when reading the following specification, taken in conjunction with the drawings, in which:

Figurel is a side elevational view, partially in vertical section, of a tank-type circuit interrupter embodying the principles of our invention, and shown in the closedcircuit position;

Fig. 2 is a fragmentary, enlarged, vertical sectional view through one of the arc-extinguishing units of the circuit interrupter of Fig. 1, the contact structure being shown in the closed-circuit position;

Fig. 3 is an enlarged, vertical sectional view through a modified type of arc-extinguishing unit, which may be substituted for the units illustrated in Figs. 1 and 2, the contact structure being shown in the closed-circuit position;

Fig. 4 is another modified type of arc-extinguishing unit, which may be substituted for the units of Figs. 2 and 3, the contact structure shown at an intermediate point in the opening operation;

Fig. 5 is a substantially vertical sectional view through a modified type of circuit interrupter, with the arc-ex- ICC tinguishing units being illustrated in side elevation, and the contact structure being shown in the closed-circuit position;

Fig. 6 is a fragmentary, enlarged, vertical sectional view through the left-hand arc-extinguishing unit of the circuit interrupter illustrated in Fig. 5;

Fig, 7 illustrates a modified type of exhaust valve operating arrangement, which may be utilized in conjunction with the arc-extinguishing unit illustrated in Fig. 6;

Fig. 8 is an enlarged, fragmentary, vertical sectional view through a modified type of exhaust-valve operating arrangement, which is directly .connected to the valve operating rod, and which may be substituted for the exhaust-valve operating arrangements of Figs. 6 and 7;

Fig. 9 is a fragmentary, enlarged, vertical sectional view through a modified type of arc-extinguishing unit, which may be substituted for the arc-extinguishing units, illustrated in Figs.v 5 and 6, the contact structure being shown in the partially open-circuit position;

Fig. l0 is a fragmentary, vertical sectional view through yet another modified type of arc-extinguishing unit, which may be substituted for the unit illustrated in Fig. 9 of the drawings; and, f

Fig. 1l is a fragmentary, vertical sectional view through still another modified type of arc-extinguishing unit, the contact structure being illustrated in the partially open-circuit position.

In U.S. patent application filed July 19, 1951, Serial No 237,502, now United States Patent 2,757,261, issued July 31, 1956, to Harry J. Lingal, Thomas E. Browne, Ir., and Albert P. Strom, and assigned to the assignee of the instant application, the remarkable arc-extinguishing characteristics of sulfur hexafluoride gas are described. It is known that this gas has a dielectric strength equal to that of insulating oil at slightly elevated pressure (2.5 to 3 atmospheres absolute) and so may be directly subsituted for oil as an insulating medium in circuit breakers, and the like, if it can be maintained at the elevated pressure. We have discovered the fact, demonstrated in experimental studies, that SP6 gas at moderate pressures may be employed in fluid-flow type circuit interrupting devices similar to those ordinarily filled with Oil with comparable effect. It has been shown particularly that in such devices, which cause -a definite volume of uid to flow through a channel surrounding the arcing contacts, effective interrupting performance can be obtained with total displaced volume of SF., gas no larger than the volumes of oil ordinarily displaced.

The use of SF, gas instead of oil in structures resembling those used with oil offers many advantages:

(1) The gas medium is non-inflammable, and hence eliminates the explosion and re hazard.

(2) Its lower density reduces the forces required to move it, and so can aid in achieving highest possible operating speeds.

(3) Compressibility of the gas serves to cushion the pressure shocks produced by the sudden drawing of highcurrent arcs in a confined fluid. The control of these explosive pressures in structures filled with nearly incompressible oil is a critical problem in the development of circuit breakers for the highest powers.

(4) The use of steel tanks fitted with high-voltage bushings, the common practice with oil circuit breakers, oers many practical advantages for a gas-filled breaker also. The use of SFB, under a few atmospheres pressure, promises to permit the retention of these practical advantages, especially (a) the availability of inexpensive bushing-type i current transformers as a part of the breaker, (b) the (5) If desired, the tanks for SF@ may be made smaller than for oil by using sufficiently elevated gas pressures to achieve dielectric strengths higher than that of oil.

(6) Energy for producing fiuid flow, contact motion, or both, can be stored in the contained gas by virtue of its compression, eliminating the necessity for large springs inthe breaker mechanism.

(7) Decomposition products caused by arcing do` not include carbon and are all good electricalA insulators. The chemicalr activity off the gaseous products, and the inertnessof the SP6, makes possible absorption of these gaseous products simply by providing some inert solid materials (e.g., activated alumina) within the enclosure in contact with the gas. This should make possible longer periods of use of the breaker before the necessity for replacing or reconditioning the interrupting medium, ork cleaning internal insulating surfaces.

(8) For the same amount of arcing, erosion ofthe contact surfaces should be less with gas than with liquid filling. This. is especially true for capacitor switching,

' where contact erosion under oil is a serious problem.

, To make most effective use ofthe gaseous medium, certainmodifications of interrupting structures generally used under oil are needed. We have found that contact between the arc and organic materials should be avoided, as pointed out in the aforesaid patent. Hence, such arc controlling parts as orifices, splitters and the inner walls of' arc boxes should be made of inorganicinsulating materials like polytetrafluoroethylene. For conducting parts, aluminum may be preferable to copper or brass. Because. of thehigh mobility or Wandering tendency exhibited by arcs in this gas, the arc space may need to be more, denitely restricted than is. necessary with oil filling.

Figures 1 through 11 illustrate interrupter designs, which embody the above principles, and so are particularly suited to use in metal-enclosed circuit'breakers, filled with SF@ or SeFs gas atv atmospheric, or higher pressures.

A relatively simple form of tank-enclosed SFS or SeF fiow interrupter is illustrated in Figs. 1 and 2 of the drawings. Referring to these figures, it will be observed that agrounded, metallic tank 1 is filled with sulfur hexafiuoride or selenium hexafluoride gas at atmospheric, or higher pressures, and has extending within it a pair of terminal bushings 2, 3 of the type generally used in the oil-circuit-breaker art.

Depending from the interior ends of the terminal bushings 2,-3 are a pair of serially connected arc-extinguishing units, generally designated by the reference numeral 4, and electrically interconnected by a conducting crossbar 5. The conducting cross-bar 5 may be vertically actuated, in the opening and closing movements, by an insulating lift rod 7, which may be operated by a suitable mechanism. As shown, the interrupting units 4 are mounted on the lower ends of bushings 2, 3 projecting into the enclosing tank 1, and the circuit is completed by the conducting cross-bar 5 movable by the. insulating lift rod 7 operated by a mechanism, exactly as is commonly done in oil-circuit breaker practice, except that the tank 1 must be sealed against gas leakage at the bushing and mechanism entry points. The gas sealed .within the tank 1 may be at atmospheric pressure, but preferably should erating cylinder 10, and have their lowerseats on a spring base- 15, threadedly securedA to the movable contact rod 16. v

The extremity 17 of the cross-bar 5 strikes the contact or piston rod 16, and moves it upwardly to the closedcircuit position as shown, against the opposition afforded by the battery of compression springs 13. During the opening operation, the lift rod 7 moves downwardly, as caused by the operating mechanism not shown, and permits the compression springs 13 to extend, driving the contact or piston rod 16 downwardly and carrying with it the movable, piston 9 and the orifice 8, compressing the gas within the region- 18 below the piston` 9 and causing it to flow upwardly through the orifice 19.

Vents 20 are provided at the upper end of the extinguishing unit 4 for permitting the heated gas to expand if necessary to the region within'the tank 1.

The interrupter 4 has been demonstrated in the laboratory to have remarkable interrupting performance. With an orifice diameter of only 5A; inch, it has successfully interrupted low-power-factor currents up to 3100 amperes at 90,000 volts single phase with SP5 gas pressure of 15 p.s.i. gauge. For application to acircuit breaker for the largest interruptingY ratings, the, orifice diameter 19 would be increased,l possibly to two inches, and the piston diameter to say l0 inches. It is apparent in Figs. l and 2 that the moving contact 11 is held closed by the cross-bar 5, and compression springs 13 serve to move the contact. 11 and piston 9 to. the open position when the cross bar is released. Further additional` motion of the cross-bar 5 beyond the limit of the piston stroke provides an additional isolating break, vas shown, by the dotted lines 22 inFig.A 1.

To yeffect the closing of -the interrupter, the interrupter mechanism moves the insulating lift rod 7 upwardly, compressing the` springs 13 and effecting contact engagement between the4 cooperating stationary and movable contacts 12, 11 respectively. To reduce the shock of the piston 9 at the end of its opening stroke, a cushion 214 may be provided, formed of any suitable resilient material.

Fig; 3, is an enlarged vertical section view taken through a modifiedy type of arc-extinguishing unit 23, which may be substituted for the unit, 4 of Figs. 1 and 2. It will be noted that4 the interrupting unit 23 is not provided with compression springs, as was the case with the` unit of Fig. 2,. Instead, as shown in Fig. 3, the contact-carrying piston 9 is pulled to the open position by the cross-bar 5 through latches 24, which are released by cams 25 at the end of the piston stroke, permitting the cross-bar 5 to move down farther and so to provide anisolating break..

The cams 25 are provided by downwardly extending insulating strips 26, which are fastened by screws 27 to the. bottomf14 of the insulating operating cylinder 10. `The latches 24 are biased apart by a compression spring 28 so that the rollers 29 will maintain engagement with the cam. surfaces 25.

During theclosing operation, the conducting crossbar 5 moves upwardly, as effected by the operating mechanism. rlhe noses 30 of the latches 24 reengage the notches 31 provided at the lower 'end of the contact rod 16a, and the cross-bar 5 forces the piston and contact assembly 9 upwardly effecting reengagement between the movable and stationary contacts 11, 12, as 'shown in Fig. 3. Again` a cushion 21 may be provided to limit any shock occurring at the extreme end of the -piston opening movement.

Fig. 4 shows an arrangement, which is generallyl similar to that illustrated in Fig. 3, but incorporates a compression spring 32, which serves to retrieve or retract the piston 9 following release of the latchs 24 by the cams "25. v 4

Fig. 4 illustrates the position of the several parts when the releasingaction has just taken place and prior to the return movement of the piston 9. Thus, the compression spring 32,v disposed within the insulatingl cylin- This would increase the isolating break distance for the same cross-bar stroke, and would cause iinal closure of the circuit to occur, upon closing the breaker, at the isolating break outside of the interrupting unit, generally designated by the reference numeral 33.

Fig. 5 illustrates a vertical sectional view through a modied tank structure, with the arc-extinguishing units 35 being shown in side elevation. It will be noted that each of the terminal bushings 36, 37 is provided with an exhaust passage 38 extending through the tubular conducting stud 39 passing interiorly within the terminal bushing 36, 37.

`A conducting cross-bar 40 electrically interconnects in series the two modied arc-extinguishing units 35, being actuated by an insulating lift rod 41. The upper end of the lift rod 41 is diagrammatically indicated as being actuated by an armature 42, associated with a closing solenoid 43. Thus, energization of the solenoid 43 will cause the armature 42 to move upwardly, and so cause closing motion of the conducting cross-bar 40. An opening spring 45 may be provided to effect opening motion of the cross-bar 40 following deenergization of the closing solenoid 43. However, our invention is not particularly concerned with the operating mechanism for the lift rod 41, and any suitable mechanism may be employed.

Fig. 6 more clearly illustrates the internal construction of the modiiied type of arc-extinguishing unit 35. With particular reference to this gure, it will be noted that there is a valve operating rod 44, which makes abutting relation with the cross-bar 40 near the end of the closing stroke. The valve operating rod 44 isbiased downwardly by a compression spring 46, which seats at its upper end against va laterally extending lug 47, which may be formed integrally with the metallic operating cylinder 48. The lower end of the compression spring 46 seats upon a flange member 49, secured to, and movable with, the valve operating rod 44. The upper end 50 of the valve operating rod 44 abuts against a cap 51, forming a lower seat for a second compression spring 52, the latter biasing a pilot exhaust valve 53 lin such a direction as to open an exhaust port 54, and

to close an inlet port 55. The pilot exhaust valve 53 includes a double-acting valve member 56, which is guided by a guide portion 57, constituting an integral part of a casting member 58.

The casting member 58 provides an exhaust passage 59, which communicates with the exhaust passage 38 extending through the terminal bushings 36, 37.

Associated with the casting member 58 is a main valve piston 60, which comprises a piston portion 61 and a main exhaust valve portion 62. A port 63, in the casting member 58, provides an entrance for high-pressure `gas from the region 64 within the tank 1 (Fig. 5) to the left-hand side of the piston member 61 at all times. As will become more apparent hereinafter depending upon the operation of the pilot exhaust valve 53, atmospheric pressure, or high-pressure gas will be present in the region 65 on the right-hand side of the piston member 61.

The main valve piston 60 has a valve stem 66 associated therewith of a reduced cross-section, as compared to the cross-section of the opening 67 through which it passes. Thus, high-pressure gas from the region 64 may pass through the port 63, and through the annular'area 68 about the restricted portion 69 of the valve stem 66, to enter into the region 70 on the top side of the operating piston 71. The operating piston 71 moves within the operating cylinder 48, and is spring-biased to its-lower position, as shown in Fig. 6, by a comprsion spring 72. The operating piston 7'1 effects upward travel of an orifice structure 73, including a piston 74 movable within an insulating operating cylinder 75'. Associated with the orice structure 73 is a movable contact 76, which makes engagement withl a second movable contact 77. The

movable contact 77 has a lost-motion connection 78 with the cross-bar 40. The lost-motion connection 78 includes a spring casing 79, xed to the extremity ofthe cross-bar 40 and enclosing a compression spring 80, which seats at its lower end against the cross-bar 40. The upper end of the compression spring 80 seats against a flange 81, secured to, and movable with, the movable contact 77.

-In the closed-circuit position of the modified type of arc-extinguishing unit 35, it will be obvious that the circuit therethrough includes the conducting stud 39, a conducting adaptor head 82, the casting member 58, a ex ible connector 83 to the movable contact 76. The circuit then extends 4through the second movable contact 77 and through the conducting cross-bar 40 to the righthand arc-extinguishing unit 35 (Fig. 5), through which the circuit extends in an identical manner to the righthand .terminal bushing 37.

To effect the opening'of the arc-extinguishing unit 35 it is necessary to effect downward opening travel of the insulating lift rod 41. This will cause corresponding downward movement of the cross-bar 40. The downward motion of the cross-bar 40 will permit the compression spring 46 to move the valve operating rod 44 downwardly, thereby permitting the compression spring 52 to close off the inlet port 55 and to open the exhaust port 54 associated with the pilot exhaust valve 53.

The opening of the exhaust port 54 will vent, or exhaust, the region 65 to the right of the piston portion 61 of main valve piston `60 to permit the high-pressure gas, constantly within the region 84, to move the rnain valve piston 60 toward the right, thereby opening the main exhaust valve 62. This will exhaust the region 70 above the operating piston 7'1 through the exhaust passage 59. Since the region 85, below the operating piston 71, is at high pressure, as afforded lby the ports 86 in the operating cylinder 48, the operating piston 71 will be forced upwardly by the high-pressure gas present within the region 85.

The upward movement of the main operating piston 71 will carry with it the orifice structure 73, including the piston 74, compressing the gas within the regionr 87 below the xed perforated plate 88, to cause the gas to ilow in the direction, as indicated by the arrows 89 in Fig. 6.

I-t will be obvious that following the take up of the lost-motion 78, during the initial downward movement of the cross-bar 40, the movable contact 77 will be carried therewith downwardly to the open-circuit position. Thus, the arc, which is established between the two movable contacts 76, 77. will be rapidly lengthened, and simultaneously subjected to a flow of gas forced out of the region 87, beneath the plate 88, by the upward movement of the piston 74.

It will be noted that the rightward movement of the main valve piston 60 will close ot the annular area 68 by the enlarged portion 90, which is dimensioned to just tit within the opening 67 of plate portion 91 of casting member 58. f

In the fully open-circuit position of the interrupter, not shown, the operating piston 71 remains in its upper position, and .the cross-bar 40 with the movable contact 77, is adjacent the lower end of the tank 1, establishing an adequate isolating gap between the contacts 76, 77.

To effect the closing operation, suitable mechanism, not shown, causes upward movement of the lift rod 41 and the cross-bar 40. The cross-bar 40, in striking the valve operating rod 44 and moving the same upwardly, compresses the spring 46, and actuates the pilot exhaust valve 53, causing the latter to close the exhaust port 54 and to open the inlet port 55. High-pressure gas, from the region 64 within the tank 1, flows through the inlet port 55 and acts against the right hand side of the piston 61. Since this gas pressure acts over the entire area of the piston portion 61, it quickly closes the main exhaust vvalve-"62. At the same time, the valve stem 66 moves the restricted portion .69 withinthe vopening .67', thereby permitting high-pressure gas to pass through the open port-63, throughthe annular area68', and into the region 70 on theltop side of rthe operating piston 71. It will -be :obvious that `the gas pressure will be equalized on both sides of the operating piston 71, and the .compress'ion spring 72'=will `then take over, andv drive the voperation piston 71 1and-"the orifice structure 73, together with the movable contact 76, downwardly to eiect engagement-between the contacts 76, 77. The .interrupter will then be intheclosed position.

IProviding the lost-'motion connection 78 permits the cross-bar 40 Ito pick up :speed before the inturned flange `portion 92 picks up the ilange 81 and drives the movable ycontact .77 downwardly.

Fig. 7 illustrates a modifiedatype of exhaust valve arrangement, which may be substituted for :the rvalve operating 'rod '44 and the pilot exhaust valve construction 53 .of fthe interrupting unit of Fig. 6. f

'Referring to Fig. 7, it will be observed that a terminal Abushing 94 has a magnet structure 95 'associated there- `with comprising a solenoid tripping coil 96, a stationary .armature97 and a movable .armature 98. The movable armature 98 is linked .by a rod 99 and a I.lever 100 to a pilotexhaust valve 101.

The pilot exhaust valve 101 operates similarly to the operation of the Ypilot exhaust valve 53 of Fig. 6. In other words, energization-of thev solenoid tripping .coil 96 will vreffect upward movement of the movable armature 98, effecting through the linkage 99, 100 closing of the inlet vport 102, and opening of the exhaust port 103. This will efectrightward movement ofthe main valve piston 104 -inthe manner previously described, the valve stem 105 lhaving" a plurality of bypassinggrooves 106, which function lin a Asimilar manner to the functioning of the -re- Kstricted portion 69 of the valve stem 66 in Fig. 6.

It will be noted that following extinction of the arcs ldrawn within the interrupters disposed within the tank 107 of Fig. 7, and deenergization of the tripping coil v96 the spring 108 will close the exhaust port 103 and open the inlet port V102. The high-pressure gas, 'which will now enter the region 65, will be assisted by the spring 109 to effect the leftward movement of'the valve piston` 104 and closing of the main exhaust port 110. The high-'pressure gas will then pass through the port 63, through 'the vgrooves 106 in valvestem 105, and `enter the region 70 above the operating piston 71 (Fig. 6). The spring v72 will then take over, and effect downward motion of theorifice structure 73 and hence downward movement of the movable Acontact '76.

During the closing operation,since the orifice structure 73 will already be at its lowermost position, as exp'lained--above,` the movable contact 77 will make engagement with the movable contact 76 prior to the time ofengagement of the contacts 76, 77 of the arrangement `shown in Fig. '6, where the valve operating rod 44 must be moved upwardly at the extreme end of the closing stroke.

The pilot valve exhaust arrangement 93 shown in Fig.

7,-operated by the trip coil 96,*serv'es to further increase the'spee'd of interruption, since tripping would begin immediately on closing of the trip circuit and would not require waiting' for motion of the ycross-arm `40.

A -still .further modified Vtype of exhaust valve arrangement is disclosed in Fig. 8 of the drawings. Here the valve operating rod 44a has a pin-and-slot connection 111 with the rexhaust valve stem 112. The lspring 46l (Fig. 6) effects downward movement of the valve operating yrod 44a upon lowering of the cross-bar 40 (Fig. 6)., The `spring 46 is of sufiicient strength, and the exhaust valve area isfof sufficiently small area, to cause downward movement of the exhaust -valve 113 of Fig. f8 against the spring `force exerted byl a lcompression spring 114 and the closing force exerted by lthe high gas yof directly actuated exhaust valve.

pressure.l The opening of the exhaust port .115 will effect Vopening of the nterrupter in the manner previously deposition.

From the foregoing it will be observed thatV Fig. 8 shows a directly operated exhaust valve arrangement, in which `the operating rod 44a may vhave an opportunity to pick up speed, before opening the Aexhaustvalve 113, because of kthe lost-motion afforded by the pin-andslot connection 111 between the valve operating rod 44a and the exhaust valve stem 112.

Fig. 9 illustrates a modiiied type of arc-extinguishing unit, .generally designated by the reference numeral 118.

.It will beobservedthat .in the extinguishing `units of Figs. v2, 3, 4 and 6 that the orifice structure was movable with the movable contact,r and Ihence possessed some inertia. To effect vvery high-speed motion of the main piston "causing yfluid ow, .the construction illustrated in Fig. 9

utilizes a stationary orifice structure 119. In other words, in thexunit 118 of Fig. 9, only the huid-driving piston 120 is caused 'to move bythe upward movementof .the operating piston 71.

The upward .movement .of the `piston 120 Vcompresses gas :Iwithin the region 121. A plurality .of inlet tubes `1-22 -slide with a relatively close -iit through the piston 120, so that upon upward movement of the 'main voperating piston 71, the piston 120 will force gas to iiow downwardlythrough the inlet tubes 122 in the manner indicated by the arrows 123. This gas will How into the orifice structure 119 comprising an orifice member 125 to eiect extinction of the arc 126, established between the `stationary contact 127 and the movable contact 128 carried by the extremity of the cross-bar 129.

-It will be 4noted that Fig. V9 illustrates a modified type -A valveV operating rodA 130 is spring-,biased downwardly by a spring l131, and is moved upwardly during the closing operation by the cross-bar 129. To eliminate the closingy force upon the exhaust valve 132 if the high-pressure gas acted upon itsentire lower area, we provide a bellows 133, which is `sealetlat its upper end to the exhaust valve 132, and which is sealed at its lower end to a lowerplate portion 134 of theupper casting member 58a. Thus, the spring 131 does not have -to exert a forcedownwardly suflicient to act against an-upward force, which would be equal to :theVgas .pressure times the total exhaust valvedarea. As noted, atmospheric pressure exists within the region 135 within the bellows 133, so that the high-pressure gas exerts an upward-closing force on the exhaust valve 132 only equal to the high-gas pressure times a differential area equal tothe area of the outlet port minus the area enclosed by the bellows, rather than on the whole valve area.

Hence, a much lighter spring 131 on thevalve operating krod 130 may be used, or with the same spring a much larger valve can be employed. A plurality, in this instance two, valve rods 136 mechanically interconnect the upper plate 137 of the valve operating rod 130 with lthe exhaust valve 132 itself. It vwill be -noted .that sealing sleeves 138 and ring gaskets 139 prevent .highpressure gas from passing along the rods 136 when the exhaust valve 132 is in its lower open position. As before, bypassing grooves 140 are provided to Vpermit highpressure gas from the region 64 within the tank 1 to pass along the grooves 140 into the region 70 when the exhaust valve 132 is in its upper closed position.

The operation of the modified extinguishing unit 118 will now be described. Lowering of vthe cross-bar 129 will serve to immediately establish an arc 126 and will at .the same time'permit .the compressionspring 131 .to'effect opening of vthe y.exhaust valve 132. This will .exhaust'th -9 terminal bushing, as previously explained, permitting the high-pressure gas within the region 85 to act upwardly on the operating piston 71. This will drive the piston 71 upwardly, carrying with it through the stern 141 the fluid driving piston 120. The uid driving piston 120 will compress the gas within the region 121 and force it downwardly through the inlet tubes 122 and into the orice structure 119, where arc extinction rapidly occurs. As long as the cross-bar 129 is in its lower position, the exhaust valve 132 remains open, and the pistons 120, 71 remain in their upper position.

During the closing operation the cross-bar 129 moves upwardly effecting engagement between the contacts 127, 128 and also causes upward movement of the valve operating rod 130 against the biasing action exerted by the compression spring 131. This will cause closing of the main exhaust valve 132, and high-pressure gas from the region 64 will then pass through the grooves 140, into the region 70 thereby enabling the compression spring 72 to take over and effect downward movement of both pistons 71 and 120. The interrupter is then in the fully closed position.

Fig. illustrates a construction in many respects similar to that previously described in connection with Fig. 9 of the drawings, except that a movable contact 142 is associated with the pistons 71 and 120. In other words, the piston rod 141a carries with it a tubular movable contact 142, having an inlet passage 143 associated therewith, through which gas from the region 121 may be forced. Consequently, upon upward movement of the pistons 71, 120, in a manner similar to that previously described in connection with Fig. 9 of the drawings, the tubular movable contact 142 moves upwardly at the same time that the movable contact 128 moves downwardly. The resulting arc 126 is thereby very rapidly established, and is subjected to gas flow not only passing downwardly through the orifice member 12S, but also downwardly through the inlet passage 143 associated with the movable contact 142. Spring-biased sliding finger contacts 144 press against the outer sides of the movable contact 142 to electrically interconnect the contact 142 with the metallic casting structure 145 and hence to the lower end of the terminal bushing 36.

It is believed Ithat the manner of operation is obvious, namely that upward movement of the pistons 71, 120 together with interconnecting piston rod 141a and tubular movable contact 142 subjects the resulting arc 126 to gas flow in the manner indicated by the arrows, the gas ow passing downwardly through the inlet tubes 122 and also downwardly through the interior 143 of the movable tubular contact 142. Arc extinction is rapid, it being noted that the arc 126 is initially established on the downstream side of the orifice 125.

Fig. 11 indicates a modified type of arc-extinguishing unit 147 in which the movement of the piston 120 is reversed to that previously shown in connection with Figs. 9 and 10 of the drawings. In other words, the operating piston 71 has the gas exhausted from the region 70 below it through the holes 70a and the exhaust valve v arrangement 148 which is identical to the exhaust valve arrangement 148 of Fig. 9. Consequently, the gas pres sure within the region 121 is raised, so that the gas flows downwardly through the orifice 125 and adjacent the established arc 149. This construction has'the advantage that the inlet ltubes 122 of Figs. 9 and 10 may be eliminated. Also, a retrieving or retracting tension spring 150 serves to raise the pistons 120, 71 following the admission of high pressure gas through the grooves 140 and into the region 70 when the exhaust valve 148 is closed This insures that at the start of any opening operation the pistons 71, 120 will be in their upper raised position.

From the foregoing description of several arc extinguishing units, it will be apparent that we have disclosed gas tlow interrupting-devices especially suitable for eecwww tive operation within a container filled with sulphur hexaiiuoride or selenium hexauoride gas at a moderately elevated pressure. In the forms illustrated in Figs. 1-4 of the drawings, the operation resulted in no loss of the gas, which .experience has shown may be used without replacement for a large number of interruptions. In other forms, such as the interrupters of Figs. 5, 6, 9, 10 and 1l, some gas is discharged through the tubular bushing studs during each operation, but only that amount contained within the operating cylinders 48, which would be very small, compared with the volume of the whole breaker tank. In addition, the discharge gas does not come directly from the arcing chamber and so is cold and relatively free from larc-produced decomposition products. The discharge through limited area ports of cold gas only eliminates the clogging difficulty, which limits the amount of hot gas which can be discharged and so may limit the currents which can be interrupted, when hot gas directly from 1the arc chamber must be vented through valves and ports.

The circuit interrupters of our invention are particularly adapted to use at least one gas selected from the group consisting of sulfur hexauoride and selenium hexauoride, or admixed with at least one of the group consis'ting of helium, carbon dioxide, air, nitrogen and argon.

The use of selenium hexafluoride as an arc-extinguishing medium is described and claimed in United States patent application filed September 14, 1954, Serial No. 455,976, now United States Patent 2,733,316, issued I anuary 31, 1956, to Thomas E. Browne Jr., Albert P. Strom and Harvey E. Spindle, and assigned to the assignee of the instant application.

Although we have described the interrupters as being particularly suitable for use with sulfur hexauoride gas or selenium hexauoride gas in a tank structure, it will be noted that certain features of the invention may well be applicable to interrupters operating with other gases than sulfur hexauoride gas or selenium hexauoride gas.

vFor example, the discharge of relatively cold gas, instead of hot ionized gas, may be applicable to interrupters utilizing compressed air, or other gases, such as nitrogen, hydrogen, etc. suitable for arc extinction. We do not, therefore, intend to limit our invention solely to the use of sulfur hexatluoride gas or selenium hexauoride gas or mixtures containing these gases, since other gases may be substituted therefor with advantage, and use may be made of certain features of the invention in connection therewith.

Although we have shown and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein, by those skilled in the art,without departing from the spirit and scope of the invention.

We claim as our invention:

1. A circuit interrupter including a tank having a pair of terminal bushings extending therein, an arc-extinguishing unit including separable contact means for establishing an arc disposed adjacent the interior end of each terminal bushing, an arc-extinguishing gas under pressure disposed within the tank, a cross-bar for electrically interconnecting the units, said separable contact means being constantly disposed in a gaseous region under pressure, a piston structure for effecting a circulating ow only of gas under pressure against the arc established between said separable contact means, said piston structure being associated with at least one of said arc-extin guishing units, said piston structure including an operating piston for effecting the motion thereof, the gas under pressure constantly acting upon one side of said operating piston, and valve means actuated by the opening motion of said crossbar for exhausting the gas pressure from the other side of said operating piston to eect thereby opening motion of the operating piston and consequent circulating flow of gas under pressure by ,saidY Aatea-4,1390

. 11 piston structure against the arc established within said one arc-extinguishing unit.

.2. A .gas-blast circuit interrupter including a tank lled with gas under pressure and having a hollow terminal bushing extending' therein, an arc-extinguishing unit disposed adjacent the inner end of the hollow terminal bushing, said arcextinguishing unit including apair of separable contacts constantly disposed in a gaseous region under pressure, said pair of separable contacts being separable to establish an arc during the opening operation of the circuit interrupter, piston structure including an operating piston for causing a circulating iiow only of gas under pressure against the arc, the gas under pressure constantly acting upon one side of the operating piston, and means for exhausting the gas on the other side of the operatingpiston through the hollow terminal bushing to eifect motion of the piston structure during the opening operation. n

3. A gas-blast circuit interrupter including a tank lled with gas under pressure and having a pair of terminal bushings extending therein, at least one of the terminal bushings being hollow, a pair of arc-extinguishing units disposed adjacent the interior ends of the terminal bushings, 'a conducting crossbar having a pair of movable contacts disposed at its outer ends and adapted to electrically connect the two units .in series in the closed circuit position, piston structure for causinga circulating How only including-an operating piston and a movable contact for at least one of the units, the last-mentioned movable contact cooperating with one of the contacts of said pair to vestablish an arc within a unit, said pair of arc-establishing contacts being constantly disposed in a gaseous region under pressure, said circulating piston structure servingto force a circulating flow of gas against the arc in said unit, means for exhausting the gas on one side ofthe operating piston through the hollow terminal bushing to effect motion of the piston structure during the opening operation, and the gas under pressure constantly acting on the other side of the operating piston.

4. A circuit interrupter including a tank filled with lgas under pressure and having a pair of terminal bushings extending therein, at least one of the terminal 'bushings beingy hollow, a pair of arc-extinguishing units disposed adjacent the interior ends of the terminal bushings, a conducting crossbar having a pair of movable contacts'disposed at its outer ends and adapted to electrically connect the two units in series in the closed circuit posi tion, piston structure including an operating piston for forcing gas .under pressure against the arc established within one unit, valve means Vfor exhausting the pressure backof the operating piston through said one hollow terminal bushing to cause .movement of said operating piston, a valve operating rod for effecting operation vof said valve means, and thecross-bar actuating the valve operating rod.

"5. A gasblast circuitinterrupter including a tank filled with gas under pressure and having a ,hollow terminal bushing extending therein, an arc-extinguishing unit disposed adjacent the inner end of the hollow terminal bushing, 'said arcwextinguishing unit including a pair of separable contacts constantly disposed in a gaseous region under pressure, said pair of separable contacts being separable tojestablish an are during the opening operation of the circuit interrupter, piston structure including an operating piston for causing a circulating iow only of gas underl pressure against the arc, the gas under pressure constantly acting upon one 'side of the operating piston, a main exhaust valve piston for exhausting .gas pressure from the other side of the operating piston through the hollow terminal bushing7 and a pilot exhaust valve to control operation of the main exhaust valve.

'6. A circuit iuterrupter including a tank filled with gas under pressure and having a pair of terminal bushings `extending therein, at least one of the terminal bushings 'being hollow, a pair of arc-extinguishing 'units disposed t v12 adjacent the interiorgends of the .terminal bushings, a conducting cross-bar having a pair of movable contacts -disposed at its outerl ends and adapted to electrically lconnect the two units in series in the closed circuit position, piston structure including an operating piston, a main exhaust valve piston for exhausting gas pressure from in back of the operating piston through the hollow terminal bushing, a pilot Vexhaust valve to control operation of the main exhaust valve, and means responsive to movement'of the cross-bar for actuating the pilot exhaust valve. Y

7. The combination in a compressed-gas circuit interrupter of a Atank 'filled with gas under pressure, a hollow terminal bushing leading into the tank, an arc-extinguishing unit ldisposed adjacent the interior end of the terminal bushing, means for establishing an arc within the unit, means for extinguishing the arc including a piston device, said piston device having an operating piston, a main exhaust valve piston for exhausting gas pressure from in back of 'the operating piston through the hollow terminal bushing, a pilot exhaust valve to control operation of the main exhaust valve, vand said pilot exhaust valve being of the two-way type to close the inlet valve from the tank and to open the exhaust valve leading out of the bushing in 'one position, and

to 'close the -exhaust valve vand open the inlet valve to the tank in the other position. n

8. The combination in a compressed-gas circuit interrupter of a tank filled with gas under pressure, a hollow terminal bushing leadinginto the tank, an arc-extinguishing unit disposed adjacent the interior end of the terminal bushing, said arc-extinguishing unit including a piston structure having an operating piston,the piston structure including va movable orifice and a movable Contact, a11 other movable contact, the two movable contacts being separable ina region which is constantly under gas pressure, said piston structure including the movable orifice being operable to force a circulating How only of gas under pressure against the arc which is established between the movable contacts, the gas under pressure constantly acting upon one side of said operating piston, vand exhaust-valve means for exhausting the gas pressure on the other side of said operating piston through the hollow terminal bushing.

9. The 'combination in a compressed-gas circuit interrupterv of a tank filled with gas under pressure, a hollow terminal bushing leading into the tank, an arc-extinguishing unit disposed adjacent the interior end of the terminal bushing, said arc-'extinguishing unit including a piston structure having an operating piston, the piston structure including va kmovable orice and a movable contact, another movable contact, the two movable contacts being separable in a region which is constantly under gas pressure, said piston structure including the movable orifice being operable to force a circulating flow only of gas under pressure against the -arc which is established between the movable contacts,the gas under pressure constantlyk acting upon 'one side ofsaid operating piston, exhaust-valve means for exhausting the gas pressure on the other side yof said operating piston through thehollow Vterminal lbushing, and a two-way 'acting pilot exhaust valve for operating'said exhaust-valvel means.

l0. A compressed gas circuit interrupter including a tank containing gas under pressure, 'a pair of hollow terminal bushings' extending into the tank and carrying larc-extinguishing units at `their interior ends, va conducting cross-bar Ielectrically interconnecting the pair of units in series, a movable contact at each end of the cross-bar, a cooperating movable ContactV associated with each unit, a gas driving piston device associated with each unit, yeach piston device including a movable orice member and also the cooperable movable contact for that particular unit all movable as a unit, each piston device also 'including 'an operating piston, exhaust valve means for Aexhausting ga's on 'one side of veach `operating piston 13 through the hollow terminall bushing for that particular unit, and means associated with movement of the crossbar for actuating the exhaust valve means.

11. A compressed gas circuit interrupter including a tank containing gas comprising as its essential constituent a gas selected from at least one of the group consisting of SF@ and SeF under pressure, a pair of hollow terminal bushings extending into the tank and carrying arc-extinguishing units at their-interior ends, a conducting crossbar electrically interconnecting the pair of units in series, a movable contact at each end of the cross-bar, a cooperating movable contact associated with each unit, a gas driving piston device associated with each unit, each pistondevice including a movable orifice member and also the cooperable movable contact for that particular unit all movable as a unit, each piston device also including an operating piston, exhaust valve means for exhausting gas on one side of each operating piston through the hollow kterminal bushing for that particular unit, and meansassociated with movement of the crossbar for actuating the exhaust valve means.

12. A compressed gas circuit interrupter including a tank containing gas under pressure, a pair of hollow terminal bushings extending into the tank and carrying arc-extinguishing units at their interior ends, a conducting cross-bar electrically interconnecting the pair of units in series, a movable contact at each end of the cross-bar, a cooperating movable contact associated with each unit, a gas driving piston device associated with each unit, each piston device including a movable orice member and also the cooperable movable contact for that particular unit all movable as a unit, each piston device also including an operating piston, a main exhaust valve for exhausting gas on one side of each operating piston through the hollow terminal bushing for that unit, and a two-way pilot exhaust valve controlling the main exhaust valve and responsive to movement of the crossbar.

13. A compressed-gas circuit interrupter including a tank constituting an enclosure and containing an arcextinguishing gas under pressure, a pair of hollow terminal bushings extending into the tank and carrying arcextinguishing units at their interior ends, each arc-extinguishing unit having separable contact means associated therewith for establishing an arc, a conducting cross-bar electrically interconnecting the pair of arc-extinguishing units in series, a movable contact disposed at each end of the cross-bar, piston structure associated with at least one of the arc-extinguishing units and operable to force said compressed arcextinguishing gas against an arc to effect arc extinction, an operating piston connected to said piston structure for effecting motion of the same, an operating cylinder within which said operating piston moves, the compressed gas wthin said tank acting at all times on one side of said operating piston, and exhaust valve means including a tripping solenoid for exhausting the compressed gas withinv said operating cylinder on the other side of said operating piston to the region externally of said tank through a hollow terminal bushing during the opening operation to eilect thereby opening movement of the operating piston.

14. A compressed-gas circuit interrupter including a tank constituting an enclosure and containing an arcextinguishing gas under pressure, a pair of hollow terminal bushings extending into the tank and carrying arcextinguishing units at their interior ends, each arc-extinguishing unit having separable contact means associated therewith for establishing an arc, a conducting cross-bar electrically interconnecting the pair of arc-extinguishing units in series, a movable contact disposed at each end of the cross-bar, piston structure associated with at least one of the arc-extinguishing units and operable to force said compressed arc-extinguishing gas against an arc to elect arc extinction, said one arc-extinguishing unit including a relatively stationary orifice structure and a relatively stationary Contact which 'constitutes a part of said separable contact means, an operating piston connected to said piston structure for effecting motion of the same, an operating cylinder within which said operating piston moves, the compressed gas within said enclosure acting at all times on one side of said operating piston, and means exhausting the compressed `gas within said operating cylinder on the other side of said operating piston to the region fexternally of said enclosure during the opening operation to effect thereby opening movement of said operating piston.

15. A compressed-gas circuit interrupter including a tank constituting an enclosure and containing an arcextinguishing gas under pressure, a pair of hollow terminal bushings extending into the tank and carrying arcextinguishing units at their interior ends, each arc-extinguishing unit'having separable contact means associated therewith for establishing an arc, a conducting cross-bar electrically interconnecting the pair of arc-extinguishing units in series, a movable contact disposed at each end of the cross-bar, piston structure associated with at least one of the arc-extinguishing units and operable to force said compressed arc-extinguishing gas against an arc to effect arc extinction, said one arc-extinguishing unit including a relatively stationary orifice structure, said piston structure including a cooperable movable contact which is separable from one of the aforesaid movable contacts, an operating piston connected to said piston structure for effecting motion of the same, an operating cylinder within which said operating piston moves, the compressed gas within said enclosure acting at all times on one side of said operating piston, and means exhaustthe compressed gas within said operating cylinder on the other side of said operating piston to the region externally of said enclosure during the opening operation to effect thereby opening movement of said operating piston.

16. A compressed-gas circuit interrupter including a tank constituting an enclosure and containing an arcextinguishing gas under pressure, a pair of hollow terminal bushings extending into the tank and carrying arcextinguishing units at their interior ends, each arc-extinguishing unit having separable contact means associated therewith for establishing an arc, a conducting cross-bar electrically interconnecting the pair of arc-extinguishing units in series, a movable contact disposed at each end of the cross-bar, piston structure associated with at least one of the arc-extinguishing units and operable to force said compressed arc-extinguishing gas against an arc to effect arc` extinction, said one arc-extinguishing unit including a relatively stationary orice structure, said piston structure including a cooperable movable tubular contact which is separable from one of vthe aforesaid movable contacts, an operating piston connected to said piston structure for effecting motion of the same, an operating cylinder within which said operating piston moves, the compressed gas within said enclosure acting at all times on one side of said operating piston, and means exhausting ing the compressed gas within said operating cylinder on the other side of said operating piston to the region externally of said enclosure during the opening operation to effect thereby opening movement of said operating piston.

17. A gasblast circuit interrupter including means detining an enclosure containing an arc-extinguishing gas under pressure, an arc-extinguishing unit disposed interiorly within said enclosure and having separable contact means for establishing an arc, the region about said separable contact means being constantly under pressure, piston structure associated with said arc-extinguishing unit operable to force said compressed arc-extinguishing gas in a circulating flow only against said arc to effect arc extinction, and means employing the compressed gas within said enclosure to move said piston structure.

18. A gas-blast circuit interrupter including means delining an enclosure containing an arc-extinguishing gas 'under pressure, 'an arc-extinguishing `unit disposed interiorly within said `enclosure land lhaving separable contact means for establishing an arc, the region about said separable contact means being 'constantly under pressure, piston structure associated with said arc-extinguishing unit operable to lforce said compressed arc-extinguishing Vgas in =a circulating low only against said arc to eect arc extinction, an -operating piston connected to said piston structure for etecting motion of the same, and means employing the compressed gas within saidenclosure to drive said operating piston and so eTect opening movement-of said piston structure.

19. -A circuit interrupter including means deningan enclosure containing an arc-extinguishing gas under pressure, an arc-extinguishing lunit disposed inter-iorly Within said lenclosure and having separable Contact means for establishing an arc, piston structure associated with said arc-extinguishing unit operable to forcesaid-compressed ,arc-extinguishinggas-against Said-arc to effect arc extinction, an operating piston `connected to said piston structure for eiecting motion ofthe same, an operating cylinder within 'which said operating piston move's, the cornpressed gas within -said `enclosure, acting-at all times ou one side of lsaid operating piston, and means exhausting 'the .compressed gas within said 4operating cylin'der on `the other side 'of said koperatirrgpiston tothe region externally of said enclosure during the openingoperation to eiect thereby opening movement of said operating piston.

Referenc'esCited inthe file of this patent UNITED STATES PATENTS 2,095,441 Howe oct. 12, 1937 10 2,108,560 Kesselring Feb. 15, 1938 2,221,670 Cooper Nov. 12, 1940 2,221,671 Cooper Nov. 12, 1940 2,281,385 Saint-Germain et al..- Apr. 28, 1942 2,364,981 Journeaux Dec. 12, 1944 15 2,442,010 -Leedset al. May 25,` 1948 2,445,529 Leeds JulyZO, 1948 2,459,612 Baker i Jan. 18, 1949 2,507,210 Ludwig et al, May 9, 18950 2,581,571 'Baker etzal. f Jan. 8, 1952 20 2,660,647 Rawlins Nov. 24, 1953 FOREIGN PATENTS n' 106,334 Australia :Ian."6, 1939 512,921 1952 Belgium Aug. 14,

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