US3836741A

US3836741A - Adjustable contact nozzle and retractable arcing chamber for gas blast circuit breakers

Info

Publication number: US3836741A
Authority: US
Inventors: J Golota
Original assignee: ITE Imperial Corp
Current assignee: ABB Inc USA
Priority date: 1967-11-06
Filing date: 1967-11-06
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17
Also published as: CH493926A; CH498481A; GB1235204A; FR1588921A; CH504773A; SE356159B; JPS5130664B1; GB1235202A; DE1790174B1; DK136679C; GB1235203A; DK136679B; US3557331A; US3495057A

Abstract

A high voltage gas blast circuit breaker has a stationary contact with a central opening and an axially projecting neck. A movable contact, mechanically connected to the same operating rod that temporarily opens a blast valve, moves axially with respect to the stationary contact. A cylindrical baffle surrounds the stationary contact and is pressed against the stationary contact during gas blast conditions to form a gas blast channel which extends through the center of the stationary contact. Biasing springs bias the baffle axially away from the stationary contact.

Description

[ ADJUSTABLE CONTACT NOZZLE. AND

RETRACTABLE ARCING CHAMBER FOR Sept. 17, 1974 FOREIGN PATENTS OR APPLICATIONS 524,983 8/1940 Great Britain 200/148 GAS BLAST CIRCUIT BREAKERS 1,358,550 3/1964 France 200/148 [75] Inventor: John H. Golota, Los Angeles, Calif. 73 Assignee: I-T-E Imperial Corporation, Prim? Examiner-Robert Philadelphia Attorney, Agent, or FirmOstro1enk, Faber, Gerb and Soffen [22] Filed: Nov. 6, 1967 21 Appl. No.: 680,778 I 57 ABSTRACT A high voltage gas blast circuit breaker has a station- [52] US. C1. 200/148 R, ZOO/148 BV a y Contact with a central opening and an axially pro- [51] Int. Cl. H0111 33/82 je ting neck, A movable contact, mechanically con- [58] Field of Search 200/148, 148.2, 160; nected to the same operating rod that temporarily 151/5 opens a blast valve, moves axially with respect to the stationary contact. A cylindrical baffle surrounds the [56] References Cited stationary Contact and is pressed against the stationary UNITED STATES PATENTS Contact during gas blast conditions to form a gas blast 3,214,545 /1965 Cromer 200/148 channel which F f throPgh h center of 1116,5121" 3,218,421 11 1965 Latour 200 148 tlonary Contact Blfdsmg Sprmgs blas the baffle aXlally 3,339,046 8/1967 Giammona et 200/148 ay from the stationary contact. 3,436,505 4/1969 MCKeough ZOO/148 3,441,692 4 1969 Cromer et a1 200 148 x 3 Clams 33 Drawmg F'gures l2 1 1 :73 154 3; f/ 43 J 1\ 3 1 44 15 d (1J0! /Z7 j,

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PATENTEB 71974 3.836.741 saw me or 12 ADJUSTABLE CONTACT NOZZLE AND RETRACTABLE ARCING CHAMBER FOR GAS BLAST CIRCUIT BREAKERS This invention relates to high voltage gas blast circuit breakers, and more particularly relates to a retractable arcing. chamber for gas blast circuit breakers.

This application is related to copending applications Ser. No. 680,777, filed Nov. 6, 1967, in the name of John H. Golota, entitled Axially Vented Contact and Interrupter Structure for Gas Blast Circuit Breakers; Ser. No. 547,621, filed May 4, 1966, in the name of Daniel H. McKeough, entitled Slide Valve for Gas Blast Breakers, now US. Pat. No. 3,436,505; and Ser. No. 680,849, filed Nov. 6, 1967, in the name of Daniel H. McKeough, entitled Dead Tank Gas Blast Circuit Breaker, and are all assinged to the assignee of the present invention.

In accordance with, the present invention, there is provided an arcing chamber contact nozzle arrangement in an axial flow gas blast circuit breaker which employs a movable arcing chamber held in place by differential, gas. pressure during interruption. This chamber is retracted or moved relative to' the stationary contact nozzle to provide a complete break or gap with decay of chamber gas pressure following interruption and blast valve cutoff.

The invention provides a stationary nozzle contact assemblyand an arcing chamber free to engage the contact nozzle areola with increasing chamber gas pressure. Engaging or mating surfaces are shaped to conform closely so as to effectively seal the juncture and direct all gasflow out through the throat of the nozzle contact. Gasket sealsmay be used on either mating surface if desired. In addition, the stationary contact assembly absorbs all end thrust from the arcing chamber to effectively eliminate all axial tensile forces on the arcing chamber walls. The remainder of the stationary contact assembly allows for radial, axial and angular alignment of the nozzle with the arcing chamber and moving contact.

Accordingly, a primary object of this invention is to improve the interruption ability of a high voltage gas blast circuit breaker.

Another object of this invention is to provide a novel retractable arc chamber for gas blast interrupters which provides good control of the gas pressure during operation.

Another object of this invention is to provide a novel contact arrangement for gas blast interrupters which simplifies mounting thereof and provides improved operation.

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

FIG. 1 is a side view, partially in section, showing an entire assembly of the interrupters and operating mechanism of a circuit breaker made in accordance with the presentinvention. A

FIG. 2 is a cross-sectional view of one of the inter,- rupter assemblies of FIG. 1.

*FIG. 3 is a top view of the upper adaptor of FIGS. 1 and 2.

FIG. 4 is a cross-section of FIG. 3 taken across the section line 4 4 in FIG. 3.

FIG. 5 is a top view of the lower adaptor of FIGS. 1 and 2 which is located below the upper adaptor of FIGS. 3 and 4.

FIG. 6 is a cross-sectional view of FIG. 5 taken acrossthe section line 6 6 in FIG. 5.

FIG. 7 is a top view of the stationary contact of the interrupter of FIG. 2.

FIG. 8 is a cross-section view of the contact of FIG. 7 taken across the section line 8 8 in FIG. 7.

FIG. 9 is a top view of the movable contact assembly of FIGS. 1 and 2. i

FIG. 10 is a cross-section of FIG. 9 taken across the section line 10 10 in FIG. 9.

FIG. 11 is a top view of the locking disk of FIG. 10.

FIG. 12 is a cross-section view of FIG. 11 taken across section line 12 12 in FIG. 11.

FIG. 13 is a front view of one of the contact fingers of FIG. 10.

FIG. 14 is a top view of the contact finger retainer of FIG. 10.

FIG. 15 is a cross-section view of FIG. 14 taken across the section line 15 15 in FIG. 14.

FIG. 16 is a top view of the interrupter support.

FIG. 17 is a cross-section of FIG. 16 taken across the section line 17 17 in FIG. 16.

FIG. 18 shows a top view of the interrupter tube flange.

FIG. 19 is a cross-section of FIG. 18 taken across section line 19 19 in FIG. 18.

FIG. 20 is a plan view, partially in section, of the movable interrupter tube assembly.

FIG. 21 is a plan view of the retainer of FIG. 20.

FIG. 22 is a side view of FIG. 21.

FIG. 23 is a top view of the cylindrical air control valve.

FIG. 24 is a cross-section view of FIG. 23 taken across section line 24 24 of FIG. 23.

FIG. 25 is a top plan view of a three-pole dead tank circuit breaker arrangement using the interrupters of FIGS. 1 and 2 for each respective pole.

FIG. 26 is a side plan view of FIG. 25.

FIG. 27 is an end plan view of FIG. 25.

FIG. 28 shows a partial cross-sectional end view of one pole of FIGS. 25 to 27.

FIG. 29 shows a partial cross-sectional side view of one pole of FIGS. 25 to 27.

FIG. 30 is a partial cross-sectional view of one of the terminal bushings of FIGS. 25 to 29.

FIG. 31 is a top, partial cross-sectional view of FIGS. 28 and 29.

FIG. 32 is a front plan view of a portion of the operating mechanism of FIGS. 28 and 29.

FIG. 33 is a cross-sectional view of FIG. 32 taken across section line 33 33 in FIG. 32.

FIG. 1 shows the assembly of the novel interrupter assembly of the invention, and illustrates two series connected interrupters l0 and 11.

Interrupters

10 and 11 are identical and will be described in detail hereinafter. The interrupters l0 and l l are controlled by an operating mechanism, generally indicated by numeral 12, which is supported on a tank housing 13. Tank housing 13 is, in turn, carried on an elongated insulation pedestal 14 which may be carried on a high pressure gas supply at ground potential, as will be'later'described in FIGS. 25 to 29'.

Each'of interrupters l0 and 11 areconnected at their tops to insulator bushings, to be later described, which are connected in series with the circuit to beprotected. The connection surrounding the tops of interrupters I0 nate through openings 25 to 30. The upper surface of adaptor 18 then has a conical surface 31 which engages the conical lower surface 32 of insulator 17 to permit angular adjustment of insulator 17, as shown by arrow 17a in FIG. 2. A series of bolts, such as bolt 33 having washer 34, then extend through openings, such as through-opening 28, to secure upper adaptor 18 to insulator 17.

A lower adaptor 35 is then provided, as shown in FIGS. and 6, which has a plurality of extending ears containing through-openings 36 to 41 extending from acentral web 42. An annular groove 43 is cut through the web 42 so that it is held by the material of the extending ears. A plurality of through-holes and aligned tapped openings 44 to 49 are then formed in the web 42, and the interior web surface is threaded by thread 50. The through-openings 36 to 41 in lower adaptor 35 are then aligned with tapped openings m in upper adaptor 18 (FIG. 3), and suitable bolts and washers, such as bolt 51 and washer 52, shown in FIG. 1, secure shield 15 and adaptor plates 18 and together.

The interior thread of web 42 of lower adaptor 35 receives the stationary contact 53 of the interrupter. Contact 53 is "shown in FIGS. 7 and 8 and comprises a main body 54 having a central opening 55 which tapers outwardly to define a blast orifice. The outer diameter of body 54 is threaded with a thread 56, and an arcresistant insert 57. Thread 56 of contact 53 is then threaded into thread 50 of lower adaptor 35 and is secured therein by tightening a plurality of bolts, such as bolt 57a, shown in FIG. 2,v which pass through the through-openings in the lower part of web 42 and into the threaded opening 44. As these bolts are tightened, the upper and lower interior portions of web 42 tighten on thread 56 to hold contact 53 securely. Note that the axial contact position is easily controlled by threading contact 53 more or less into thread 50, as shown by arrow 58 in FIG. 2. Moreover, by providing clearance between the outer diameter of the bolts, such as bolt 51, which secure lower adaptor 35 to upper adaptor 18 and the corresponding through-openings, such as opening 36, lateral adjustment can be obtained for contact 53, as shown by arrow 59 in FIG. 2.

The movable contact assembly of FIGS. 1 and 2 is best shown in detail in FIGS. 9 to 15.

The movable contact assembly is composed of a circular cluster of contact fingers 60 to 71, each having generally rectangular shape, shown in FIG. 13 for contact 60. Each of the contact fingers have arcresistant inserts secured thereto, such as

inserts

72 and 73, secured to

contacts

60 and 66, respectively. Each of the contact fingers have two projections, such as

projections

74 and 75, for finger 60 in FIGS. 10 and 13, which receive biasing leaf springs, shown as'leaf springs 76 and 77 for

contacts

60 and 66 which bear on

insulation buttons

78 and 79, respectively.

The contacts 60 to 71 are laid on the outer notches v in contact retainer 80, shown in FIGS. 14 and 15, and are held on the retainer 80 by a spring retainer 81 which encircles the central exterior portions of the 4:: contacts. A spring 82, shown in FIG. 10, extends around the bottom interior of the contacts. A locking disk 83, shown in FIGS. 11 and 12, havin a central opening 84, is inserted into'retainer 80 .and into engagement with shoulder 80a of retainer 80. A

movable arcing contact is then secured to locking disk 83, as by pins. extending from disk 83 to arcing contact 85. It will be noted that arcing contact 85has a bottom flange 85a which has an outer diameter that engages the arcing contact tips of the arcing Contact fingers to limit their inward collapse and to provide commutation of the arc from insert 72 to contact 85 during opening. The interior of arcing contact 85 is threaded and threadably receives the end of operating shaft 86 and is secured thereon by locking nut 76, best shown in FIG. 10.

FIGS. 16 and 17 show the interrupter support 88 for slidably holding the movable contact assembly of FIG. 10. Support 88 contains a central stationary contact portion 89, the outer end of which slidably receives the lower

endsof contact fingers

60 and 71 in slidable engagement. Central portion 89 is connected to base portion 90 by four

streamlined webs

91, 92, 93 and 94 (FIG. 16). Base 90 has two sets of four throughopenings 95 to 98 and 99 to 102 in the corners thereof, and a set of through-openings 103 to 106, respectively, in the corners thereof. Two rings 107 and 108 of insulating material, shown in FIG. 2, are contained in

internal grooves

109 and 110, respectively, in the central opening 111 of central portion 89, shown in FIGS. 15 and 16, to seal around the operating rod 86, and to provide electrical insulation between rod 86 and base 90 as shown in FIG. 2. Support 88 is then fastened to support casting sections 112 and 113 (which areparts of a common casting) of FIGS. 1 and 2, as by bolts which pass through openings 95 to 102 into appropriate tapped

openings incasting sections

112 and 113, partly shown in FIG. 1 by bolts 1 14 and 115'. Note that theoperating rod 86 passes through a suitable opening, which may be sealed, in casting section 112.

An interrupter tube assembly, arranged above the I support 88 and enclosing the contact area is carried on a flange 116, shown in FIGS. 18 and 19. Flange 116 comprises an extending cylindrical portion 117 and four through-openings 118 to 121 in the comers thereof. Flange 116 is secured to support 88 beneath it by the four bolts (not shown) extending through openings 118 to 121.in flange 116 and respective openings 95 to 98 in support 88 (FIG. 16), which bolts are threaded into the

castings

112 and 113. V

An interrupter tube 122 is then secured to extension 117 in any suitable manner, where tube 122 is of glass fiber, or the like. Tube 122 then slidably receives the movable interrupter tube portion 123, which is movable in the direction of arrow 124,. with a gasket between the surfaces of tube 122 and sliding portion 123.

The sliding interrupter tube portion 123is best understood by reference 'to FIGS. 20, 21 and 22. Referring to FIG. 20, the movable interrupter tube comprises an outer insulation cylinder 125 and an-inner lining cylinder 126 which secure, between them, an insulation lining disk 127 and baffle ring 128. The bottom of the cylinders are secured by ring 129 which has a Iowerlip extending below liner 126 and a plurality of pins, such as pin 130, which extend into cylinder 125.

Four pins, three of which are shown as

pins

131, 132 and 133 in FIG. 20, then extend into openings in ring 129 and are locked therein by suitable locking pins, such as locking pin 134 for pin 133.

Pins

131 and 133 are seen in FIG. 2 with the four pins disposed from one another. Each of the pins have enlarged heads such as head 135 of pin 133, shown in FIG. 20, which are captured in housings, such as

housings

136, 137 and 138 for pins 131 to 133, respectively. A split retainer spring disk 139, shown in FIGS. 21 and 22, which is split at portion 140, has four openings 141 to 144 for receiving the four spring housings, including

housings

131, 132 and 133, as shown in FIG. 20. Internal springs, such as spring 145 of housing 138, then bias the housings 136 to 138 toward the ring 129 and

external springs

146, 147 and 148 bias plate 139 toward the ring 129.

In assembling the movable interrupter tube, it will be noted in FIG. 2 that the periphery of plate 139 is captured between adaptor 116 and support 88, with ring 129 beneath shoulder 150 in stationary tube portion 122. Also, it is seen that the baffle ring lies just adjacent the lower tapered surface of contact 53.

The operating mechanism for moving operating rod 86 is best shown in FIG. 1 where it is seen that the casting

sections

112 and 113 have a downwardly extending portion 151. Portion 151 has two slots for passing

ears

152 and 153 of cylindrical valve 154. The

ears

152 and 153 are then connected to links 154a and 155, respectively, which are, in turn, pivotally connected to operdisk 187 by bolt means, such as bolt 188. Sealing rings 189 and 190 prevent leakage between

rings

185 and 186. Ring 186 carries a main valve seat 191 which cooperates with the bottom of cylinder 158. Note that a sliding seal 192 is formed between disk 186 and shaft 177, and that a buffer 193 is connected to the top of disk 187 to receive the bottom of hub 159 when valve 158 moves down.

ating rods 86 for

interrupters

10 and 11 through

suitable couplings

156 and 157, respectively.

A blast valve is best shown in FIGS. 23 and 24 as comprising a cylindrical body 158 connected to a central hub 159 by streamlined arms 160 to 163. The ends of cylindrical body 158 are formed with valve

disk engaging sections

164 and 165. The interior opening in hub 159 is provided with a thread 166. The two

ears

152 and 153, shown above, then extend outward from cylindrical body 158.

Cylindrical valve body 158 then moves between an upper and lower valve seat. The upper valve seat is composed of an upper disk 167 which is secured to casting section 113 and a lower disk 168 which is bolted to disk 167 as by bolts such as bolt 169. Disk 168 is sealed with respect to casting section 113 by seal ring 170 and carries a main valve seat ring 171 which cooperates with the upper end of cylindrical valve body 158. A valve retaining disk 172 is bolted to disk 168 as by bolt 173 and securely holds ring 171 in position. Disk 172 also has a buffer disk 174 bolted thereto as by bolt 175 which engages nut 176 when the valve 154 is :moved upwardly.

Hub 159 is threaded on operating shaft 177 and is locked in place by nut 176 which is also threaded on ring 182 having a sealing ring 183 engaging ring 182 is provided with a sliding seal ring 184 which surrounds the lower portion of cylinder 158.

- The bottom of members 181 carries a ring 185. Ring 185 is connected to valve disk 186 and valve retainer The ring is welded to high pressure tank 13 which is composed of welded upper and lower halves 200 and 201, respectively. High pressure gas, such as air and preferably sulfur hexafluoride, is then supplied to the interior of tank 13 from the central channel through insulator 14 which is appropriately connected at its bottom to a high pressure gas source, as will be later described.

An elongated operating shaft 203, which extends coaxially with insulator 14, can be moved up and down by operating means, to be later described, which may be carried at ground, and is connected to shaft 177 by a shock-absorbing coupling.

FIG. 1 further shows a small tubular member extending downwardly and into the annular space between pedestal l4 and rod 203, and arranged so that any gas which condenses on the surface of housing 13 will flow downwardly and freely through the annular space without impinging on the insulating surfaces of

members

14 and 203.

The coupling as shown in FIG. 1 is comprised of a spring 204 captured between

rings

205 and 206 at its top and bottom, and an outer cylinder 207 on its outer periphery. Ring 205 is captured beneath a shoulder in shaft 177 as shown, while ring 206 is held by

nuts

208 and 209 which are threaded on the threaded bottom of shaft 177. Outer shells 210 and 211 each have threaded interiors, threaded on the outer threaded surface of cylinder 207 with extension 212 of shell 210 bearing on ring 205, while ring 206 seats under the interior shoulder in cylinder 207. Operating shaft 203 is then connected to shell 21 1 by connection ring 213. When shaft 203 moves down, it will be seen that downward force I is exerted through shells 211, 210, ring 205, and spring 204 on ring 206. Similarly, upward movement of shaft 203 is transmitted through cylinder 207, ring 206, spring 204, and ring 205. Thus, both upward and downward movement of shaft 203 is transmitted to shaft 177 through shock-absorbing spring 204. This also makes the mechanism relatively insensitive to small dimensional changes such as produced by misalignment and temperature changes.

FIGS. 25, 26 and 27 show plan views showing a three-pole dead tank circuit breaker, each pole using the interrupters of FIGS. 1 and 2. Referring to FIGS. 25, 26 and 27, the breaker is made up of three identical

single pole units

300, 301 and 302, each of which have bushings 303-304, 305-306 and 307-308, respectively. A control cabinet 309 is secured with the poles and contains a suitable gas compressor and gas control equipment for supplying the individual pole units with gas such as sulfur hexafluoride at the proper pressure, temperature and required conditions for cleanliness. Two high pressure

gas storage tanks

310 and 311 are located at the bottom of the breaker and receive the individual poles and cabinet 309 as shown. Suitable heaters (not shown) and suitable thermal insulation may be provided for

tanks

310 and 311, controlled from controls in cabinet 309 to maintain the gas in

tanks

310 and 311 at a high enough temperature to prevent excessive condensation.

FIGS. 28 and 29 show sectional views of pole 300 with the tank cut away. As shown in those figures, two interrupters eah identical to the interrupters of FIGS. 1 and 2 are contained within the flattened steel tank 312 of each pole to form four series connected breakers for each pole whereby the breaker can be used at operating voltages of 242KV maximum line-to-line voltage on three-phase power systems. Similar arrangements may be used for lower and higher voltages, e.g., 121 to 362 KV. The tanks are formed by joining together, as by welding, two sections whose axes of revolution are the horizontal center lines of each tank assembly in such a way'that approximately equal clearance to ground is achieved between all live parts and the tank surface. In this way, a minimum volume of gas is used for a particular operating voltage.

The interrupting assemblies are supported on columns 14 which are fastened and supported by the pole unit mechanism 313 in such a way that the high pressure gas may be used to fill the support columns 14 up to the blast valve 154 of FIGS. 1 and 2.

The

terminal bushings

303 and 304 extend down from the top of tank 312 and support the stationary contacts of the outer interrupters (contact 53 of FIG. 2).

Bushings

303 and 304 may be insulated internally by compressed gas, or may be of the solid core design.

An insulating column 314 (FIGS. 28 and 29) is supported at the top of the tank 312 and extends downwardly to support the stationary contacts of the two interior interrupters. Insulation operating rods, corresponding to operating rod 203 of FIG. 1, extend down through the support columns 14 of each of the interrupters and are connected to operating rod 315 through a crank mechanism 316 to operating rod 317. Rod 317 is connected to a bell crank assembly 318 which extends into control cabinet 309 (FIG. 29). Rod 317 is sealed by a flexible bellows 319, so that no sliding seals are used between the operating mechanism and the moving partswithin each of the pole units. All the moving parts of each of the pole units are connected by rigid metal rods which pass through piping 320 which may be metallic and welded to the individual tanks. Thus, all moving contacts are, in effect, connected to one operating mechanism in the control cabinet, using only the single flexible bellows 319. This minimizes the hazard of leakage of gas from the tanks or into the tanks.

Referring to FIG. 28, the

bushings

303 and 304 enter tank 312 through

conductive cylinders

330 and 331, respectively, which have end rings 332 and 333, respectively, fastened to their bottoms.

Cylinders

330 and 331 are formed in such'a manner that a relatively uniform electrostatic field distribution is obtained along the lower surface of the

housing

303 and 304 and between the outside of

shields

15 and 16 and the wall of tank 312. This is obtained by the symmetry shown and proper proportioning of the lower bushing termination and the inside surface of

cylinders

330 and 331.

FIG. 30 shows a detailed view, partly in cross-section of a gas filled bushing which can be used for bushing 303 and cylinder 330 which is bolted to insulation column 340 as by bolts such as bolt 341. The main conductor 342 is fastened to a lower thrust plate 343'and an upper thrust plate and spring assembly 344 as by threading, to connect upper and lower insulation portions 345 and 346 together by compressive forces. The lower end of the bushing is surrounded by shield 15 of FIGS. 1, 2 and 28. The lower end of cylinder 330 is terminated by the ring 332 which is in a plane normal to the axis of the bushing to provide a relativelyv uniform field between bushing 340 and tank 312, even though the bushing 303 passes through the tank wall at an oblique angle which. otherwise would result in anonuniform three-dimensional field. Thus, in FIG. 28, it is seen that it would be highly advantageous to. arrange the bushings, tanks and bushing cylinders in this way to maintain adequate electrical clearance between the top ends of the bushings in atmospheric air, and, atthe same time, achieve the required electrical clearance inside the tanks between live parts across the breaks; between live parts and ground parts; and at the same time achievinga minimum diameter and volume for tank 300.

FIG. 30 schematically shows a grading ring 350 disposed around the lower end of insulator portion 345 which is electrically connected to cylinder 330 which may be used to modify the electrostatic flux distribution around the top of the connecting flange 351 of insulator portion 345 and the flange 351 when mounted on the tank 312.

FIG. 30 also shows the equipotential lines of electrostatic flux in 10 increments when conductor 342 is energized and tank 312 is grounded. It will be seen that a nearly uniform tangential stress distribution is achieved along the surfaces of insulator portion 346, and a uniform radial stress is obtained between shield 15 and tank 312 and ring 332. Note that the relatively simple ring 332 is very effective in reducing the high local stresses at the junction between tank 312 and cylinder 330 which are inherent in the usual commercial joining operation.

Referring to FIGS. 28 and 29, suitable

current transformers

360 and 361 are disposed around the exterior portions of

bushings

303 and 304. Toroidal shaped grading rings 362 and 3 63, respectively, are disposed above

current transformers

360 and 361, respectively, and serve the same functions as ring 350 of FIG. 30. The leads of the various

current transformers

360 and 361 are connected within weatherproof junction boxes 364 and pass through

conduits

365, 366 and 367 to be interconnected to one another and to the control housing 309.

Conduits

364, 365 and 366 are rigid pipes which further serve to brace the top ends of the

pole units

300, 301 and 302.

The connection of high and low pressure gas to the various parts of the system is best shown in FIG. 31. Thus, two

conduits

370 and 371 extend from control cabinet 309 to

tanks

310 and 311 to a high pressure. The

tanks

310 and 31 1 are then connected by

conduits

372 and 373 to the bottom, and interior of support insulators 14, FIGS. 28 and 29. Thus,

high pressure tanks

310 and 311, support insulators 14 and interrupter tanks 13 are charged with high pressure sulfur hexafluoride gas at about 250 p.s.i.g. The interior of the large main tank 312 is maintained at a relatively low gas pressure such as 45 p.s.i.g., through conduit 375 which connects the tank 312 closest to cabinet 309 to the low pressure controls of cabinet 309. The remaining tanks of

poles

301 and 302 are maintained at this same relatively low pressure by conduits 376 which communicate between the various tanks.

FIGS. 32 and 33 show details of portions of the operating mechanism shown in FIGS. 28 and 29. In FIGS. 32 and 33, there is provided a mounting plate 380 which carries a plurality of bearings 381 for rotating shaft and lever assembly 315 (see FlGS. 28 and 29 and lever 316). The bearings 381 are fastened to plate 380 and guide the shaft assembly 315 and permit rotational movement around the center line of shaft assembly 315.

Link or crank 316 is pivotally connected to link 317, while its other end is connected to shaft 203 (FIGS. 1 and 2). Link 317 extends through the bearing and gland assembly 319 which is suitably bolted to plate 380 and sealed thereto by seal 382. A gas seal 383 is maintained under fixed axial load by spring 384. A bearing 385 which may be of a suitable low friction self-lubricating material guides the lower end of link 317, and may be of Teflon. A similar material may be used for all other bearings and guides inside the breaker, e.g.,

components

170, 184, 192, 107, 108 and 125. This eliminates the need for bearing lubrication and minimizes the abrasive effect of any particles produced by a power are such as metallic fluorides which may be produced when sulfur hexafluoride is exposed to a power arc.

FIGS. 29 and 31 show an accelerating spring assembly 390 located in each tank assembly which biases the linkage assembly including link 317 toward the breaker open position. Accelerating spring assembly 390 includes suitable compressive springs with suitable resilient over-travel stops to minimize decelerating forces at the end of the closing operation. This balances the accelerating forces between individual pole units and locates the stored energy in the springs close to the moving contacts without requiring transmission of high closing forces through the insulated operating rod 203.

When closing, the forces are transmitted from the operating mechanism in cabinet 309 through the metallic operating rods such as rod 317 into the accelerating opening springs 390. The insulated rod 203 need only transmit the relatively low compressive force required to accelerate the interrupter parts on closing and to overcome frictional and gas-pressure forces.

During opening, the accelerating forces are transmitted from mechanism 313 to the shaft assembly 315 and the insulating rod 203 transmits only the tension force required to accelerate the interrupter parts and overcome frictional and gas-pressure forces.

An additional compression accelerating spring 395 (FIG. 29) is located inside control cabinet 309 which also pushes the contacts toward their open position. Spring 309 is adjustable and permits minor adjustments of opening speeds of all moving contacts without requiring access to pressurized parts of the breaker. A dashpot 396, shown in FIG. 29, is suitably located to reduce acceleration forces produced at the end of the opening stroke.

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 inventionbe 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:

1. A movable arcing chamber for a high voltage gas blast circuit breaker; said circuit breaker comprising: a stationary contact having a central opening therethrough, a main annular body and an axially extending neck section having an outside diameter smaller than the outside diameter of said main annular body, and a radially directed shoulder joining said outside diameter of said main annular body and said outside diameter of said extending neck section; an elongated movable contact including a plurality of contact fingers arranged coaxially with the axis of said central opening in said stationary contact and moving axially into and out of engagement with said outside diameter of said stationary contact neck section; first support means for supporting said stationary contact; second support means for slidably supporting said movable contact; and operating means connected to said movable contact for axially moving said movable contact into and out of engagement with said stationary contact; said movable arcing chamber comprising an insulation cylinder slidably mounted on said second support means and concentrically surrounding said movable contact; means for releasably coupling said movable contact and said movable arcing chamber when said movable contact moves toward engagement with said stationary contact; one end of said movable arcing chamber engaging and sealing against said shoulder of said stationary contact when said movable contact engages said stationary contact, thereby to form a sealed chamber interiorly of said movable arcing chamber; biasing means normally biasing said movable arcing chamber away from said stationary contact; and a blast valve and a source of high pressure gas; said source of high pressure gas connected to said sealed chamber through said blast valve; said blast valve movable from a closed to an open position; said blast valve connected to said operating means for operating said blast valve between its said open and closed positions; said blast valve mechanically connected to said movable contact.

2. The device as set forth in claim 1, wherein said movable contact includes an elongated hollow conductive tube for mounting said plurality of contact fingers; the end of said tube adjacent said contact fingers communicating with saidcentral opening in said stationary contact and being external of said sealed chamber.

3. The device as set forth in claim 1, wherein said movable arcing chamber includes an inwardly projecting section on the end surface thereof exposed to the high pressure in the interior of said arcing chamber, thereby to hold said arcing chamber sealed to said stationary contact after said movable contact separates from said stationary contact, and subsequently moving away from said stationary contact due to said housing biasing means only after the pressure in said chamber decreases below a predetermined value.

Claims

2. The device as set forth in claim 1, wherein said movable contact includes an elongated hollow conductive tube for mounting said plurality of contact fingers; the end of said tube adjacent said contact fingers communicating with said central opening in said stationary contact and being external of said sealed chamber.