US3889083A

US3889083A - Gas circuit breaker insulating tube support and high pressure vessel

Info

Publication number: US3889083A
Application number: US398858A
Authority: US
Inventors: Giovanni Paolo Guaglione; James R Mccloud; Hansruedi Aumayer
Original assignee: ITE Imperial Corp
Current assignee: ABB Inc USA
Priority date: 1973-09-19
Filing date: 1973-09-19
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10

Abstract

A two-pressure dead tank high voltage circuit breaker contains a plurality of series-connected circuit interrupters mounted within a grounded tank filled with sulfur hexafluoride at relatively low pressure. The interrupters are supported from the bottom of the tank by hollow insulation support tubes which are terminated with a blast valve assembly which in turn supports the interrupters. The insulation tubes serve the function of a pressure vessel to store relatively high pressure gas to eliminate the need for a separate pressure vessel and as a support for the blast valve assembly and also provide the necessary insulation between the interrupters and ground.

Description

United States Patent n 1 Guaglione et a1.

GAS CIRCUIT BREAKER INSULATING TUBE SUPPORT AND HIGH PRESSURE VESSEL Inventors: Giovanni Paolo Guaglione, Irvine;

James R. McCloud, Burbank, both of Calif.; Hansruedi Aumayer, l-larleysville, Pa.

Assignee: I-T-E Imperial Corporation, Spring House, Pa.

Filed: Sept. 19, 1973 Appl. No.: 398,858

US. Cl. 200/148 B; 220/145 R; 200/148 R Int. Cl. H0lh 33/42 Field of Search 200/148 R, 148 B, 148 J,

200/148 BV, 145 R References Cited UNITED STATES PATENTS 8/1961 Smith et a1. 200/148 B June 10, 1975 McKeough 200/148 R Golota 200/148 BV [57] ABSTRACT A two-pressure dead tank high voltage circuit breaker contains a plurality of series-connected circuit interrupters mounted within a grounded tank filled with sulfur hexafluoride at relatively low pressure. The interrupters are supported from the bottom of the tank by hollow insulation support tubes which are terminated with a blast valve assembly which in turn supports the interrupters. The insulation tubes serve the function of a pressure vessel to store relatively high pressure gas to eliminate the need for a separate pressure vessel and as a support for the blast valve assembly and also provide the necessary insulation between the interrupters and ground.

10 Claims, 2 Drawing Figures v a la 52 i 3 g a l .l f 1 I l I J72 e ee-Hi 5/ l J04 J00 r J C 503 24 u 57 25 .4

22 7a a 0'4 a! Y I) r: /Z a n GAS CIRCUIT BREAKER INSULATING TUBE SUPPORT AND HIGH PRESSURE VESSEL RELATED APPLICATIONS This application is related to copending application Ser. Nos. 398,871 filed Sept. l9, I973, entitled CONTACT STRUCTURE FOR HIGH VOLTAGE GAS BLAST CIRCUIT INTERRUPTER, in the name of H. Aumayer; 398,870, filed Sept. 19, 1973 entitled CONTACT FOR HIGH VOLTAGE GAS BLAST CIR- CUIT BREAKER WITH TIME-DELAYED OPEN- ING, in the name of L. J. Kucharski; 398,869, filed Sept. 19, I973, entitled MECHANICAL SUPPORT OF TRANSIENT RECOVERY VOLTAGE CAPACI- TOR WITHIN CIRCUIT BREAKER LOW PRES- SURE TANK, in the name of L. D. McConnell, all of which are assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates to high voltage gas circuit breakers, and more specifically relates to a novel insulation tube for supporting circuit interrupters within a low pressure grounded tank, which tube also serves as the major high pressure reservoir for a two-pressure circuit breaker.

Two pressure sulfur hexafluoride circuit breakers of the dead tank variety are well known to those skilled in the art and are shown, for example, in U.S. Pat. No. 3,526,734, issued Sept. 1, I970, entitled DEAD TANK GAS BLAST CIRCUIT BREAKER WITH INTER RUPTER STRUCTURE IMMERSED IN LOW PRES- SURE OF DEAD TANK, in the name of D. H. McKeough, and assigned to the assignee of the present invention.

In the prior art type breaker, a hollow insulation column of porcelain mounted on a plate in the bottom of the flattened circular housing supports a conductive pressure vessel of relatively large volume, which conductive vessel serves as the main high pressure reservoir for the two-pressure breaker. A blast valve assembly is then mounted on the pressure vessel with a part of the blast valve being inside the pressure vessel. Two interrupting breaker assemblies are then mounted on each blast valve assembly. High pressure gas is then supplied through the hollow porcelain insulator column to the conductive pressure vessel, where the high pressure gas is stored for breaker operation.

Upon the operation of the circuit breaker, the blast valve opens for a short time, admitting some of the stored gas from the high pressure vessel to the interrupters. The pressure in the main vessel is then replenished by gas flowing through the hollow insulator column.

BRIEF SUMMARY OF THE INVENTION In accordance with the present invention, the interrupter units are supported within the low pressure grounded tank by a novel insulating support tube which may be of fiber glass reinforced with epoxy and with metal end flanges. The insulation support tube has a relatively large diameter, for example, about 16 inches so that it can store a relatively large amount of high pressure gas at a pressure of about l5 atmospheres to serve as the main high pressure reservoir for the twopressure breaker operation. The same tube is then used as the main support for the blast valve and its associated interrupters and also serves to support these members which are at relatively high potential with respect to the grounded tank. This novel design then eliminates the need for a separate expensive pressure vessel mounted atop an expensive hollow porcelain column.

As a further feature of the invention, the blast valve structure associated with each insulation support column is mounted on a top metal flange of the support tube with the valve intake being inside the tube to provide an unrestricted flow of gas from the interior tube volume to the valve. After each operation of the blast valve, the pressure in the support tube will be replenished through an appropriate opening in a metal bottom flange of the tube without any further restriction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view of a circuit breaker which employs the novel contacts of the present invention where a portion of the grounded support tank of the circuit breaker has been removed to expose the various components therein.

FIG. 2 is a cross-sectional view through one of the interrupters of the circuit breaker of FIG. 1 and illustrates the novel contact structure of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIG. 1, there is shown, in partial section, one phase of a high voltage circuit breaker which incorporates the present invention, as will be later described. The circuit breaker of FIG. 1 can, for example, be rated at 230,000 volts and at 63,000 amperes. Conventionally, the breaker will be a threephase breaker and two other and identical phases to the one shown in FIG. 1 will also be provided.

In general, the circuit breaker phase of FIG. 1 is contained within a generally flattened spherical metallic tank 10 which is supported on metallic frame angle members 11 and 12. Angles 11 and 12 are suitably reinforced and extend rearwardly and support additional tanks to tank 10, which are spaced from the tank 10 and disposed generally parallel to tank 10 and constitute the other phases of the circuit breaker. The metallic tank 10 is a grounded housing and the circuit breaker shown herein for purposes of illustrating the invention is shown in a dead tank" configuration.

The terminal bushings for the breaker may be of any standard type and are shown for illustration herein as including the bushings l3 and 14 which extend through cylindrical shrouds l5 and 16, respectively, which are appropriately welded or otherwise secured to the tank 10 and are sealed relative to the interior of the tank. Gas barriers l7 and 18, respectively, are provided to prevent the leakage of gas from tank 10. Thus, tank 10 is filled with sulfur hexafluoride gas (or a gas mixture which includes sulfur hexafluoride) at a pressure of about 3 atmospheres. For purposes of the invention, any dielectric gas at any appropriate pressure could be used. For the embodiment described herein, the gas pressure within tank 10 will be designated a relatively low pressure.

Each of the bushings 13 and I4 is further associated with current transformers l9 and 20, respectively, which may also be of any desired construction.

A grounded flat support platform 21 is contained within the tank 10 and is supported from the bottom of tank 10 by welded support members, such as bolts 22 and 23 and others not shown. Platform 21 sits on leveling nuts, such as nuts 24 and 25, respectively, of the support bolts. The platform 21 then serves as a level mount for the circuit interrupter equipment to be contained within tank 10. In the case of the breaker shown in FIG. 1, four interrupters are to be connected in series with one another to define the circuit breaker voltage rating of 230 KV. Platform 21 supports two spaced hollow tubular insulation support members 26 and 27, respectively, which further serve the purpose of high pressure gas reservoirs.

Each of the insulation support members 26 and 27 support, at their tops, respective blast valve housings 28 and 29 which, in turn, support series-connected interrupter units 30-31 and 32-33, respectively. Each of the interrupter units contains a pair of interrupter contacts which are simultaneously opened in the presence of a blast of gas which assists in extinguishing the arc. It is to be noted that the tubes 26 and 27, blast valve housings 28 and 29, and interrupters 30 to 33 are mechanically supported solely from the platform 21 and that none of these components are supported from the bushings 13 and 14 or intermediate supports for the interrupters 31 and 32.

The top of interrupter 30 is electrically connected to the stud 35 of terminal bushing 13 through a flexible connection, which will be later described. The connection between the top of interrupter 30 and stud 35 is then covered by a corona shield 36.

The bottom of interrupter 30 is then connected through housing 28 to the bottom of interrupter 31. The top of interrupter 31 is connected through flexible shunts 36 to the top interrupter 32 with the tops of interrupters 31 and 32 and flexible connectors covered by corona shields 37 and 38, respectively.

The bottom of interrupter 32 is then connected through the blast valve housing 29 to the bottom of interrupter 33. The top of interrupter 33 is in turn connected to the stud 39 of bushing 14 by flexible connectors, such as flexible connectors 40 and 41. The connection previously referred to between interrupter 30 and stud 35 incorporates flexible connectors, such as the connectors 40 and 41. The connection to stud 39 is then covered by the corona shield 42.

FIG. I also shows voltage distributing impedances 43 and 44 connected across interrupters 30 and 33, respectivelyv Note that any suitable arrangement of parallel-connected capacitors or resistors could be used across the various interrupters 30 to 33 in order to assure appropriate distribution of steady state and transient voltages across the series-connected breaks.

FIG. 1 illustrates the provision of transient recovery voltage capacitors 50 and 51 which are to be connected from either of the line sides of the breaker to ground. It will be noted that the flattened elliptical shape of tank makes available free space in the outer central regions of the tank so that these capacitors can be mounted within this space without interference with the operation of the breaker or without interference with the dielectric integrity of the breaker. The mount ing of these capacitors is the subject of copending application Ser. No. 398,869.

It will be noted from FIG. 1 that the upper terminals of each of capacitors 50 and 51 are connected by relatively rigid conductors 52 and 53 to the tops of interrupters 30 and 33, respectively, and are directly and solidly connected to the bushing studs 35 and 39, re

spectively. The bottoms of capacitors 50 and 51 are then mechanically and electrically connected to the tank wall 10 by the support and grounding brackets 54 and 55, respectively.

The transient recovery voltage across the breaker is then controlled by the capacitors 50 and 51 in the manner generally set forth in US. Pat. No. 3,383.5]9, it being noted that each of capacitors 50 and 51 may have a value of approximately 0.0025 microfarads or any other desired value selected by the circuit designer.

The interior of the insulation reservoirs 26 and 27, which communicate with the blast valve housings 28 and 29 and thence to the interrupters 30 to 33 is at a relatively high pressure, such as 15 atmospheres of the same dielectric gas which fills tank 10.

The major pressure source for the breaker is an elongated cylinder which is filled with gas at high pressure and which may be covered with a heater blanket 61 to ensure that the gas temperature will always be sufficiently high to maintain it in a gaseous state. A protective shroud 62 covers the cylinder 60 (which may extend the full length of all of the phases of the breaker), with portholes such as porthole 63 being available to permit maintenance of the cylinder 60 and the blanket 61. A suitable gas control system, which need not be described to understand the present invention, provides suitable gas conduits and gas controls to conduct gas from the cylinder 60 through the conduit 64 which passes through a sealing plug 65 in tube 66 which is secured to tank 10.

The high pressure conduit 64 then extends through a T-shaped member and into conduits 67 and 68 as generally outlined by the arrows, in FIG. 1, such that high pressure gas is admitted to the interior of insulation reservoirs 26 and 27. As will be later described, this gas is normally sealed at the blast valve housings 28 and 29 and high pressure gas is released through the interrupters 30 and 33 and into low pressure tank 10 only when the contacts of the interrupters are operated.

A suitable mechanical operating mechanism (not shown herein) is provided to mechanically actuate crank arms, such as crank arm 70 associated with tube 26, which drive operating rods which extend through the center of support tubes 26 and 27 and upwardly to blast valve housings 28 and 29. Similar crank arms will be associated with each of the other interrupters of each phase of the breaker. Any conventional operating mechanism, such as a spring operated mechanism or hydraulically operated mechanism is then connected to each of the crank arms so that all blast valves and contacts can be simultaneously operated to either open or close all interrupter contacts.

The specific details of one interrupter structure, such as the interrupter 30 of FIG. 1 and a portion of the blast valve housing 28, are shown in FIG. 2. Referring now to FIG. 2, the interrupter and blast valve are shown in cross-section and at the top of FIG. 2. As will be later described, interrupters 30 to 33 are subassembled units which can be easily installed when the breaker is as sembled. Thus, FIG. 2 shows two flexible shunts and 81 which have

upper connectors

82 and 83 which are appropriately bolted to the stud 35 of bushing 13, while the other ends of shunts 80 and 81 are bolted to an upper conductive adapter member 84 of the interrupter 30. Note that the stud 35 does not serve as a mechanical support for the interrupter components.

The upper adapter 84 is bolted to a second adapter portion 85 with the two

components

84 and 85 defining a volume 86 which leads to discharge ports such as the discharge port 87 which is positioned adjacent a similar port 88 in the shield 36. Note the position of port 88 in FIG. 1.

Additional ports are distributed around the periphery of shield 36 which lead to similar openings defined between

adapter members

84 and 85. Two further ports of this general type are shown in FIG. 1 for shield 42 as the ports 89 and 9t).

The adapter member 84$ further serves to threadably receive a tubular arcing terminal 91. Note that arcing terminal 91 has an opening 910 therethrough which extends upwardly so that some are venting can be directly vertically upward along the axis of the opening in arcing terminal 91..

The use of flexible shunts to make the connection from the top of interrupter 30 to the terminal bushing stud 35 is made possible since the entire mass of interrupter structure 30 is supported on top of the blast valve housing 28. tn prior art arrangements, such as the arrangement shown in US. Pat. No. 3,526,734, the stationary Contact structure of the interrupter is rigidly fastened to and carried by the end of the terminal bushing. This structure required careful alignment. of the interrupter components during assembly of the breaker and during its operation. The structure shown in FIG. 2 eliminates the need for alignment during assembly of the circuit breaker and simple flexible shunt members 30 and 81 are used to connect the top of the preassembled interrupter 30 to the terminal bushing stud 35. Similar advantages apply to the connection between the top of interrupter 33 of FIG. 1 and the terminal bushing stud 39.

As previously described in connection with FIG. 1 the tops of interrupters 31 and 32 are connected in series by the flexible shunt 36a. This is to be contrasted to the prior art arrangement of US. Pat. No. 3,526,734 which required a separate support insulator extending from the top of the housing which would physically carry the stationary contacts for interrupters 31 and 32. by supporting interrupters 31 and 32 from the blast valve housings and 29, the separate support insulator and the alignment problems which were caused by the separate mounting of the stationary contacts of these interrupter-s are eliminated.

The interrupt r 313 of HQ. 2 contains an elongated, generally tubular stationary contact member 100 which has an nppcr solid ring-shaped end 101 and slots which form scgntcn tn-tract fingers, such as fingers 102 and 03 in its othe end. it will be further noted that the ends ofthe g ns .tcd ct'mtaci's such as segmented fincontar. ii" 1 3? terminate with arcing contact inserts which may have been formed as an insert ring which was brand to the tubular contact member be was slotted to form the reg fore the tubular member mcntctl finger.

The boi s hit b pass through the openings in flange 161 of stationar; P niaci it?!) are threaded into a coni 'Hthh clamps the end side of flange ltll against adaptor member 85. Ring 110 serves as an upper support tor the insulation tube 11] which is the interrupter i"? wing tube. Tube ill may be made of any (itBSST L' tutorial, surh as an epoxy reinforced glass tube or the iii-1: The upper end of tube 111 is suitably secured to and sealed with respect to ring as by the securing key 112 and sealing ring 113.

A set of bolt openings is formed in the inner diameter of ring 110 and these bolt openings receive bolts, such as bolt 120, which threadably engage ring member 121 and hold it in position. The exterior lower portion of ring 121 is threaded and threadably receives the insulation baffle 122 which may be of a suitable arc-resistant material such as Teflon, and serves as a guide for blast gases during the opening operation of the interrupter, and as a means to protect or shield tube 111 from the hot gases created during arc interruption. Baffle 122 also contains a plurality of thin, axially directed and circumferentially spaced fins, such as fin 123. These fins then prevent the formation of a vortex in the gas blast which is guided by baffle 122.

The lower end ofinsulation tube 111 is fixed in a conductive support ring and is fixed therein and sealed thereto as by the key 131 and sealing ring 132. The ring 130 is, in turn, secured to a spider plate 133 as by bolts, such as bolt 134, where the spider plate is formed of a conductive disk 1340 having radially extending web sections such as

sections

135 and 136 which are joined to a centrally extending hollow conductive shaft 137. The shaft 137 then slidably receives the segmented movable contact 138 which is slidably engaged with the outer surface of shaft 137.

The movable contact 138 consists of a generally tubularly shaped member having a solid ring-shaped end 139 which with a solid arcing ring 140, wiith the lower end of Contact 138 being segmented to form separate contact fingers, such as

fingers

141 and 142.

The

segmented finger elements

138 and 142 along with other similar fingers are flexed outwardly from their normal relaxed position, and are therefor biased inwardly and into sliding engagement with the outer surface of shaft 137. The solid upper end 139 of movable contact 138 is movable into and out of engagement with the segmented fingers, such as fingers 102 and 103 of stationary contact 100. When the segmented fingers 102 and 103 engage the contact 100, they are elastically flexed outwardly to inherently provide contact pressure to form a good low resistance contact.

It will be noted, during contact operation, that the baffle 122 will lead high pressure gas up from the annular volume which surrounds movable contact 138 and into the baffle 122 and then between the separating

contacts

138 and 100. The gas will also flow in two di rections through the are, both through the center of stationary contact 100 and the opening in arc terminal 91, and through the central opening in contact 138 shown as opening 151.

The movable contact 138 is connected to an operat ing shaft 152 (which contains the opening 151] and the upper end of shaft 152 is provided with a flange 153. The flange 153 is engageable with the rear surface 154 of the movable Contact 138 and also receives a compression spring 155. The compression spring 155 is seated at its bottom on a ledge 156 of a spring retaining cylinder 157 which is threadably secured within the upper end of contact 138. The bottom of cylinder 157 slides within the interior of conductive tube 137 and slides on a seal 158 within the shaft 137. The operation of the interrupter contacts described above will be later described after the blast valve arrangement and support of the interrupter from the blast valve housing 28 is described.

As is shown in FIG. 1, the blast valve housing 28 supports both interrupters 30 and 31. One lateral half of the blast valve housing 28 is shown in FIG. 2 insofar as it relates to the support of interrupter 30. it will be noted, however, that the blast valve housing 28 is symmetric so that the same structure shown in connection with interrupter 30 is provided on the opposite side of the center line 200 in FIG. 2 for the support and operation of interrupter 31.

The insulation support member 26 of FIG. 1 is partly shown in FIG. 2 and it is seen that a metal end cap 201 is fitted over and sealed to the top of insulation tube 26. The metal cap 201 then serves as the support for the conductive support casting 202 of the blast valve housing 26. Casting 202 is provided with a slot 203 therein for passing an arm 204 which is appropriately connected to the operating shaft 152 by the adapter fitting 205.

Cap 201 further serves to support ring 210 and circumferentially distributed posts such as posts 211 which are welded to ring 210. The posts 211 are then welded to a valve seat plate 212 which carries the cutoff valve ring 213 of the blast valve as will be later described. The valve ring 213 is then held in position by a clamp 214 which is clamped into engagement with ring 213 by bolts such as bolt 215.

The main operating rod 220, which extends from the crank of FIG. 1 then extends through plate 212 and clamping member 214 (in sealed relation therewith) and is connected to radiating arms, such as arm 221 of the blast valve sleeve 222. Note that sleeve 222 also carries the operating arm 204.

The upper end of blast valve sleeve 222 is engageable with upper blast valve seal 230 which is clamped in position by the clamping plate 231a. The ring-shaped valve seal 230 is carried on plate 231 which is generally supported by a ring 232 which is an integral portion of the casting 202.

The main blast valve sleeve 222 extends downwardly and is threadably secured to ring-shaped member 240 which has an outwardly projecting flange 241. Flange 241 is engageable with a shoulder 242 on an auxiliary sliding sleeve 243. Note that suitable sliding

seals

244 and 245 seal these sliding surfaces against pressure loss of high pressure gas which is in the interior of cap 201.

It is not possible generally to describe the operation of the interrupter and blast valve of FIG. 2. With the components in the position shown, the interrupter is closed and a current path is formed from terminal bushing stud 35 through the flange shunts and 81 and into the

adapter members

84 and 85 and the stationary contact 100. The current then transfers from stationary contact into the movable contact 138 and the

contact fingers

141 and 142 and into the conductive tube 137. From the conductive shaft 137 the current passes through casting 202 and then to interrupter 31 which is also supported on the blast valve housing 28. The current then proceeds through the interrupters 31, 32 and 33 in the same manner and exits at bushing 14.

While the breaker is closed, the high pressure gas from within the insulating support tube 26 fills the volume defined by the annular open gap between the bot tom seal 213 and sleeve 243 and upwardly within sleeve 222 and up to the valve seat 230. The interior of interrupter 30 is at the relatively low pressure of the interior of tank 10, as contrasted to the high pressure which is held at the valve seat 230.

In order to open the circuit breaker, the circuit 5 breaker operating mechanism (not shown) is actuated to cause all of the operating rods, such as operating rod 220 to move simultaneously. The downward movement of rod 220 causes the sleeve 222 to move downwardly thereby to open the seal between the upper end of 10 sleeve 222 and the valve seat 230. This permits the high pressure gas within sleeve 222 to move into the chamber which contains spider members and 136 and upwardly through the annular channel 150 within the insulation tube 111. Thus, the pressure within the annular volume 150 begins immediately to increase.

At the same time, the downward movement of sleeve 222 causes the shaft 152 to move downwardly and, initially, the upper flanged end 153 of shaft 152 will cause the spring 155 to begin to compress. This introduces an increasing downward force on the seal sleeve 157 and thus on the movable contact 138 which is connected to sleeve 157. Initially, however, the contact 138 does not move since the frictional forces between the segmented fingers, such as

fingers

141 and 142 of the movable contact against the outer surface of shaft 137 and the frictional force between upper contact end 139 and the segmented contacts of the stationary contact 100 are sufficiently high to prevent contact motion. Ultimately, 30 however, the spring force becomes sufficiently high as to drive the movable contact 138 downwardly, thereby causing the separation of the contact 138 from the segmented fingers of the stationary Contact 100 with a snap action. Note that eventually the flange 153 will 3 pick up shoulder 260 of sleeve 157 if the movable contact does not begin to move under the force of the compression spring 155 alone.

As the contact tip separates from the arcing contact finger portions of the segmented stationary 40 contact 100, an arc is drawn between them. Substantial gas pressure has already been established within chamber and high pressure gas may begin to flow between the separating contacts even prior to inception of the arc as when the contact separation is somewhat 45 delayed by the lost motion connection between shaft 152 and the movable contact 138.

As the

contacts

100 and 138 separate, sulfur hexafluoride or a similar interrupting gas passes rapidly through the annular region of contact separation with 50 a portion of the gas flowing into channel 151 and another portion of the gas flowing upwardly and through the central opening in arc terminal 91. The majority of the gas. however, is blasted into the interior of tank 10 through openings in the shield 36 such as the port 88 55 in FIG. 2.

As the contacts separate, the upper arc root will seat on the arc terminal 91 and the lower arc root will extend from the arcing tip 140. The are is quickly extin guished under the influence of the rapidly moving sulfur hexafluoride gas.

At the time the arc is extinguished. the sleeve 222 has moved sufficiently downward so that the shoulder 261 in the outside of the sleeve 262 has picked up the lower sleeve 243 so that the sleeve 243 is moved downwardly and into engagement with valve seat 213. This operation then cuts off the further flow of high pressure gas from the interior of cap 201 toward the interrupter,

thereby to conserve the high pressure gas in the reservoir.

In order to reclose the breaker. the operating rod 220 is moved upwardly so that the contact operating rod 152 moves upwardly to reclose the contacts. Little or no gas blast is necessary during the closing operation. Therefore. there is a time delay in the re-opening of the blast valve. Thus, the sleeve 243 remains sealed against seal 213 until sleeve 222 and its outwardly facing extension 241 move to a sufficiently high position that extension 241 engages the shoulder 242 of sleeve 243. At this point, the lower valve seat 213 is opened so that gas can flow for the very short time until the upper end of sleeve 222 seats against seal 230.

An important advantage of the contact structure described above is that the contact structure has few parts and no separate contact biasing springs. Thus, the contact arrangement is inexpensive and reliable. Moreover, it has been found that by arranging the contacts so that the segmented contact fingers extend from solid tubular ends for both contact 100 and contact 138, a shock wave is not transmitted through the moving

contact fingers

138 and 142 at the time of contact separation. Therefore, there is no bouncing of the

segmented contact fingers

138 and 142 on the outer surface of conductive shaft 137 so that there is no burning at this surface which burning would cause a high contact resistance.

A further advantage of the structure of FIG. 2 is that a time delay structure is easily built into the movable contact of the segmented contact configuration to ensure that gas blast action has started before the contacts separate.

A further advantage of the contact configuration shown is that. when the contacts open, the nozzle area for allowing rapid flow of gas from annular region 150 is snapped open with the opening of the contacts, thereby allowing an extremely large passage for the flow of high pressure gas immediately after contact separation.

The present invention makes novel use of the relatively large diameter support tubes 26 and 27 of FIG. 1 which serve the three functions of providing supports for the blast valve assemblies atop them such as blast valve assemblies 28 and 29, respectively; to provide in sulation between the blast valve assemblies 28 and 29 to the grounded tank; and to serve as pressure vessels to store high pressure gas which is needed for the high pressure blast operation during the operation of the blast valves and of the interrupter contacts.

The insulation support tubes 26 and 27 may be of any desired type and good results have been obtained when using a fiber glass tube reinforced with epoxy where the tube diameter is approximately 16 inches while the wall thickness of the tube could. for example, be A inch.

Each of tubes 26 and 27 is provided with metallic end caps 201-501 and S02503, respectively. Each of the metallic end caps 201, 501, 502 and 503 has the construction generally shown in connection with metallic end cap 201 and are rigidly secured to and sealed against the end of their respective insulation tubes 26 and 27. It will be further noted in FIG. I that the facing ends of the conductive caps 201, 501, 502 and 503 may be covered with conductive corona rings 504 to 507. The corona ring 504 has been removed in FIG. 2.

As best shown in FIG. 2, the blast valve housing 28 is mounted on the top cap 201 with the intake of the valve being within the tube 26 so that unrestricted flow of gas can flow from the interior of the tube 26 through the opened valve sleeves when the blast valve is operated.

The bottom caps 501 and 503 are provided with suitable bolt mounting means to enable the direct bolt mounting of the tubes 26 and 27 on the support platform 21.

The insulating support tubes 26 and 27 are described herein as being the main high pressure chambers for the two-pressure breaker. That is to say. these form the chambers from which high pressure gas will flow during an interruption operation. A further high pressure reservoir is provided outside of the breaker such as the tank 60 which is at extremely high pressure and serves to replenish the gas of chambers 26 and 27 after each gas blast operation of the breaker.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

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

l. A dead tank circuit breaker comprising, in combination:

a generally flattened spherical metallic tank filled with a dielectric gas at relatively low pressure;

a pair of terminal bushings entering the top of said tank and extending into the interior of said tank;

a plurality of gas blast circuit interrupters supported within said tank and insulated from said tank and electrically connected in series with one another, and electrically connected between said pair of terminal bushings;

a support platform secured to the bottom of said tank;

a relatively high pressure supply means disposed ex ternally of said tank;

and an interrupter support; said interrupter support comprising a hollow uniform cylindrical insulation tube of relatively thin wall thickness, and first and second spaced end caps connected to the opposite ends of said insulation tube;

said insulation tube being disposed within said tank with its axis extending in a vertical direction;

said first end cap being mechanically connected to said plurality of interrupters; said second end cap being connected to said support platform, whereby said interrupters are mechanically supported from said platform. and are electrically insulated from said tank;

and means connecting the interior of said insulation tube to said high pressure supply, whereby said insulation tube is at a relatively high pressure; the interior volume of said insulation tube being sufficiently large to store relatively high pressure gas in sufficient amount for at least one gas blast operation of said plurality of interrupters.

2. The circuit breaker of claim 1 which further includes blast valve means for controlling the release of relatively high pressure gas from said insulation tube, and through said interrupters and into the interior of said tank during the operation of said plurality of interrupters; said blast valve means being mounted on said first end cap means and communicating with the interior of said insulation tube; said plurality of interrupters being mounted on said blast valve means.

3. The circuit breaker of claim 1 wherein said insulation tube is of fiber glass construction and has a diameter of about 16 inches.

4. The circuit breaker of claim I wherein said first and second end caps are of metal.

5. The circuit breaker of claim 3 wherein said first and second end caps are of metal and wherein said end caps have cylindrical walls which extend over the ends and outer surfaces of said insulation tube; and first and second corona rings surrounding the ends of said cylindrical walls of said first and second end caps respectively.

6. The circuit breaker of claim 5 which further includes blast valve means for controlling the release of relatively high pressure gas from said insulation tube, and through said interrupters and into the interior of said tank during the operation of said plurality of interrupters; said blast valve means being mounted on said first end cap means and communicating with the interior of said insulation tube; said plurality ofinterrupters being mounted on said blast valve means.

7. The circuit breaker of claim 2 which further in cludes a second interrupter support. a second blast valve and a second plurality of interrupters disposed within said tank and being laterally spaced from and parallel to said first mentioned interrupter support. blast valve and plurality of interrupters and being identically constructed thereto. said plurality of interrupters. and said second plurality of interrupters being series-connected between said pair of terminal bushings.

8. The circuit breaker of claim 7 wherein said insulation tube is of fiber glass construction and has a diameter of about 16 inches.

9. The circuit breaker of claim 8 wherein said first and second end caps are of metal.

10. The circuit breaker of claim 8 wherein said first and second end caps are of metal and wherein said end caps have cylindrical walls which extend over the ends and outer surface of said insulation tube; and first and second corona rings surrounding the ends of said cylindrical walls of said first and second end caps respec

Claims

1. A dead tank circuit breaker comprising, in combination: a generally flattened spherical metallic tank filled with a dielectric gas at relatively low pressure; a pair of terminal bushings entering the top of said tank and extending into the interior of said tank; a plurality of gas blast circuit interrupters supported within said tank and insulated from said tank and electrically connected in series with one another, and electrically connected between said pair of terminal bushings; a support platform secured to the bottom of said tank; a relatively high pressure supply means disposed externally of said tank; and an interrupter support; said interrupter support comprising a hollow uniform cylindrical insulation tube of relatively thin wall thickness, and first and second spaced end caps connected to the opposite ends of said insulation tube; said insulation tube being disposed within said tank with its axis extending in a vertical direction; said first end cap being mechanically connected to said plurality of interrupters; said second end cap being connected to said support platform, whereby said interrupters are mechanically supported from said platform, and are electrically insulated from said tank; and means connecting the interior of said insulation tube to said high pressure supply, whereby said insulation tube is at a relatively high pressure; the interior volume of said insulation tube being sufficiently large to store relatively high pressure gas in sufficient amount for at least one gas blast operation of said plurality of interrupters.

4. The circuit breaker of claim 1 wherein said first and second end caps are of metal.

6. The circuit breaker of claim 5 which further includes blast valve means for controlling the release of relatively high pressure gas from said insulation tube, and through said interrupters and into the interior of said tank during the operation of said plurality of interrupters; said blast valve means being mounted on said first end cap means and communicating with the interior of said insulation tube; said plurality of interrupters being mounted on said blast valve means.

7. The circuit breaker of claim 2 which further includes a second interrupter support, a second blast valve and a second plurality of interrupters disposed within said tank and being laterally spaced from and parallel to said first mentioned interrupter support, blast valve and plurality of interrupters and being identically constructed thereto, said plurality of interrupters, and said second plurality of interrupters being series-connected between said pair of terminal bushings.

10. The circuit breaker of claim 8 wherein said first and second end caps are of metal and wherein said end caps have cylindrical walls which extend over the ends and outer surface of said insulation tube; and first and second corona rings surrounding the ends of said cylindrical walls of said first and second end caps respectively.