US3889084A

US3889084A - Contact for high voltage gas blast circuit breaker with time-delayed opening

Info

Publication number: US3889084A
Application number: US398870A
Authority: US
Inventors: Leonard J Kucharski
Original assignee: I T E 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 pair of contacts for use in a high voltage gas blast circuit interrupter each consists of tubular members having one solid end, with the opposite end of the contacts being segmented to define contact fingers. One contact is fixed and the end of its segmented fingers receive the solid end of the movable contact. The operating shaft for moving the movable contact to the open position is then connected to the movable contact through a spring member to cause a time delay between the initial opening operation of the operating shift and the opening of a blast valve also operated by the operating shaft before the movable contact is snapped to an open position with respect to the stationary contact.

Description

United States Patent mi Kueharski i 1 CONTACT FOR HIGH VOLTAGE GAS BLAST CIRCUIT BREAKER WITH TIME-DELAYED OPENING [75] Inventor: Leonard J. Kucharski. Harleysville.

[73] Assignee: I-T-E Corporation. Spring House.

[22] Filed: Sept. I9, 1973 [Zl] Appl, No.: 398,870

[ June 10, 1975 FOREIGN PATENTS OR APPLICATIONS 6|3.844 l2/l948 United Kingdom 200/!48 R Primary ExaminerRobert S. Macon Attorney, Agent or Firm0strolenk, Faber Gerb & Soffen l l ABSTRACT A pair of contacts for use in a high voltage gas blast circuit interrupter each consists of tubular members having one solid end, with the opposite end of the contacts being segmented to define contact fingers. One contact is fixed and the end of its segmented fingers receive the solid end of the movable contact. The operating shaft for moving the movable contact to the open position is then connected to the movable contact through a spring member to cause a time delay between the initial opening operation of the operating shift and the opening ofa blast valve also operated by the operating shaft before the movable Contact is snapped to an open position with respect to the stationary contact.

8 Claims, 4 Drawing Figures PATENTEDJUN 10 1915 men.

SHEET I CONTACT FOR HIGH VOLTAGE GAS BLAST CIRCUIT BREAKER WITH TIME-DELAYED OPENING 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; 398,869, filed Sept. l9, I973, entitled MECHANICAL SUPPORT OF TRANSIENT RE- COVERY VOLTAGE CAPACITOR WITHIN CIR- CUIT BREAKER LOW PRESSURE TANK, in the name of L. D. McConnell, and 398,868, filed Sept. 19, I973, entitled GAS CIRCUIT BREAKER INSULAT- ING TUBE SUPPORT AND HIGH PRESSURE VES- SEL, in the name of G. P. Guaglione et al., all of which are assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates to a novel contact structure for gas blast circuit interrupters, and more specifically relates to a novel contact structure which is easy to manufacture and which provides a time delay following the opening of a blast valve and the opening of the circuit breaker contacts to ensure the presence and flow of interrupting gas before the contacts open.

Circuit breakers are well known in the art in which a pair of contacts are open in the presence of a blast of gas such as sulfur hexafluoride which assists in extinguishing the arc drawn between the contacts. Devices of this type are shown, for example, in U.S. Pat. No. 3,526,734, issued Sept. 1, 1970, 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 in copending application Ser. No. 175,507, filed Aug. 27, 1971, now U.S. Pat. No. 3,823,289, entitled INTERRUPTER STRUCTURE FOR CIRCUIT BREAKER WITH INDIVIDUAL BLAST VALVES AND TIME-DELAYED UP- STREAM CUTOFF VALVE, in the name of L. D. Mc Connell et 211., both of which are assigned to the assignee of the present invention. In these devices, as well as in the device of the present invention, the movable contact operating shaft and the blast valve which admits high pressure gas such as SP into the arcing area when the valve opens are operated from the same oper ating shaft.

It is known that it is desirable to open the blast valve slightly before the contacts are opened so that a gas blast is established before the contacts initially open so that gas is present at the time of initial contact arcing. Prior mechanisms to accomplish this initial gas blast have, however, been very complex and required the use of numerous parts.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, a relatively simple lost-motion mechanical device is connected between the movable contact and the operating shaft which is also connected to the blast valve. This then creates a delay or dead time" in the separation of the arcing contacts to allow time to build up pressure of arc extinguishing gas in the contact region before the contacts separate. This dead time is obtained through the use of a reset spring which is compressed with the initial opening movement of the operating shaft, whereby the blast valve opens but the arcing contacts remain closed for some fixed time. The spring then reaches a point where it exerts sufficient force on the movable contact to overcome the friction between a segmented movable contact and a stationary support so that the contacts will snap open to initiate the arcing process. At the same time, the opening movement of the Contact also opens a relatively large passage to permit the high pressure gas to move downstream and ex tinguish the arc. The opening movement of the arcing contact also operates to reset the spring biasing mechanism and operating rod so that it is in condition for the breaker to be reclosed and ready for a new operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 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.

FIG. 2a is a top plan view of the stationary contact of FIG. 2.

FIG. 2b is a side plan view of the movable contact of FIG. 2.

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 I2. Angles I1 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 l3 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 It) and is supported from the bottom of tank by welded support members. such as

bolts

22 and 23 and others not shown. Platform 21 sits on le\el ing 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 volt age 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 as is more fully described in copending application Ser. No. 398.868, referred to above.

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 36a to the top of 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 con nected 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. 1 also shows

voltage distributing impedances

43 and 44 connected across the

interrupters

30 and 33, respectively. 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 voltage across the series-connected breaks.

FIG. 1 illustrates the provision of transient recovery voltage capacitors 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 10 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 mounting of these capacitors is the subject of copending application Ser. No. 398.869.

It will be noted from FIG. 1 that the upper terminals ofeach 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. respectively. 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. 3,383.5l9. 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 and 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 60 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 conduit 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

insula tion 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 assembled. Thus, FlG. 2 shows two flexible shunts S0 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 40. 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 90.

The adapter member 84 further serves to threadably receive a tubular arcing terminal 91. Note that arcing terminal 91 has an opening 911! 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 inter rupter structure 30 is supported on top of the blast valve housing 28. In prior art arrangements, such as the arrangement shown in U.S. 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 in terrupter 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 80 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 360. 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

28 and 29. the separate support insulator and the alignment problems which were caused by the separate mounting of the stationary contacts of these interrupters are eliminated.

The interrupter 30 of FIG. 2 contains an elongated, generally tubular stationary contact member 100 which has an upper solid ring-shaped end 101 and slots which form segmented contact fingers, such as

fingers

102 and 103 in its other end. The segmented fingers of contact 100 are also shown in FIG. 2a which is a top end view of the contact 100. It will be further noted that the ends of the segmented contacts. such as

segmented finger contacts

102 and 103 terminate with arcing contact inserts which may have been formed as an insert ring which was brazed to the tubular contact member before the tubular member was slotted to form the segmented finger.

FIG. 20 further illustrates openings such as opening 104 in the solid flange 101 which accepts the bolts. such as bolt 105 which secures the stationary contact to adapter member 85. The bolts which pass through the openings in flange 10] of stationary contact 100 are threaded into a conductive ring which clamps the end side of flange 101 against adapter member 85. Ring 110 serves as an upper support for the insulation tube 111 which is the interrupter housing tube. Tube lll may be made of any desired material. such as an epoxy reinforced glass tube or the like. The upper end of tube 111 is suitably secured to and sealed with respect to ring 110 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 ofa 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 11] from the hot gases created during arc interruption. Baffle 122 also contains a plurality ofthin, 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 134a 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 receives a solid arcing ring [40, with the lower end of contact 138 being segmented to form separate contact fingers, such as

fingers

141 and 142.

FIG. 2b show a side plan view of the movable contact 138. 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 directions 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 15!.

The movable contact 138 is connected to an operating 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 I38 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 hous ing 26. Casting 202 is provided with a slot 203 therein for passing an arm 204 which is appropriately con nected 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 70 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 po sition by the clamping plate 2310. 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 20].

it is now 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 80 and 81 and into the

adapter members

84 and 85 and the stationary contact 100. The current then transfers from stationary contact 100 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 interfi rupter 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 It) from within the insulating support tube 26 fills the volume defined by the annular open gap between the bottom 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 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 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

135 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, 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 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 140 separates from the arcing contact finger portions of the segmented stationary contact 100, an arc is drawn between them. Substantial gas pressure has already been established within chamber 150 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 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 a portion of the gas flowing onto 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 in FIG. 2.

As the contact 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 arc is quickly cxtinguished 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 26] 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 reclosc 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 scaled against seal 213 until sleeve 222 and its outwardly facing extension 24] mm c to a sufficiently high position that extension 24] 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 inexpensi c 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 I38 and H2 at the time ofcontact 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.

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 oftbc invention be limited not by the specific disclosure herein. but only by the appended claims.

lhc embodiment of the invention in which an exclusive property or privilege is claimed are defined as fol lows:

I. In a circuit interrupter.

a generally tubular stationary contact. one end of said generally tubular contact being segmented in an axial direction to define a generally circular Clllslcl of contact fingers.

(ill

a generally tubular movable contact movable into and out of engagement with said stationary contact. one end of said generally tubular movable contact being segmented in an axial direction to define a generally circular cluster of contact fingers. the opposite end of said movable contact being a generally solid ring;

said tubular stationary and movable contacts being coaxial; said solid ring end of said movable contact being movable into engagement with surfaces of said circular cluster of contact fingers of said stationary contact and having a diameter different than the diameter defined by said surfaces of said cluster of stationary contact fingers when they are unflexed. thereby to create a given contact pressure when said movable and stationary contacts are in engagement;

and a generally stationary conductive tube supported in insulated relation with respect to said stationary contact.

said tubular movable contact being coaxial with respect to said stationary conductive tube and being in sliding contact engagement therewith: said segmented movable contact fingers engaging a surface of said conductive tube; said conductive tube having a diameter different than the diameter defined by the engaging surfaces of said movable contact fingers when they are unflexcd. thereby to create a given contact pressure when said movable contact slides relative to said conductive tube;

a longitudinally movable o erating shaft connected to said tubular movable contact and being movable along the axis of said tubular movable contact to move said movable contact into and out ofengagement with said stationary contact:

a lost-motion connection means for connecting said operating shaft to said movable contact:

and gas blast means operatively connected to said operating shaft and operable for producing a blast of gas between said stationary and movable contacts during their movement to a disengaged position;

and wherein said lost-motion connection means delays the time at which said movable contact moves to said disengaged position until after said gas blast means produces a blast of gas whereby increased gas pressure is established in the region of engagement of said movable and stationary contacts before said contacts are opened.

2. In the circuit interrupter ofclaim I wherein the interior of said stationary contact and of said movable contact are permanently connected to a relatively low pressure region. whereby gas flows from the exterior of said stationary and movable contacts through the interiors thereof to said low pressure region during the op eration of said movable contact to a disengaged position relative to said stationary contact.

3. In the circuit interrupter of claim I wherein said lost-motion connection means includes spring means which is flexed to a biased condition in response to opening movement of said operating shaft. thereby to apply an increasing opening biasing force on said movable contact which eventually snaps said movable contact to its said disengaged position.

4. In the circuit interrupter of claim 3 which further includes a tubular spring retainer means which concentrically surrounds said operating shaft and which is slidably mounted on said conductive tube: one end of said retainer means being fixed to said movable contact; said spring means having one end thereof connected to said operating shaft and its other end connected to said spring retainer means 5. In the circuit interrupter of claim 4 wherein said spring retainer means is disposed concentrically with and between said operating shaft and said conductive tube.

6. in a circuit interrupter:

a generally tubular stationary contact;

a generally tubular movable contact movable into and out of engagement with said stationary Contact;

said tubular stationary and movable contacts being coaxial;

and a generally stationary conductive tube supported in insulated relation with respect to said stationary contact;

said tubular movable contact being coaxial with re spect to said stationary conductive tube and being in sliding contact engagement therewith;

a longitudinally movable operating shaft connected to said tubular movable contact and being movable along the axis of said tubular movable contact to move said movable contact into and out of engagement with said stationary Contact.

gas blast valve means connected to said longitudil2 nally movable operating shaft and operable to produce a blast of gas through said stationary and movable contacts in response to the movement of said operating shaft to move said movable contact out of engagement with said stationary contact; and a lost-motion connetion means for connecting said operating shaft to said movable Contact. whereby said lost-motion connection means delays the time at which said movable contact moves to said disengaged position until after said gas blast means produces a blast of gas. whereby increased gas pressure is established in the region of engagement of said movable and stationary contacts before said contacts are opened. 7. In the circuit interrupter of claim 6 which further includes a tubular spring retainer means which concentrically surrounds said operating shaft and which is slidably mounted on said conductive tube; one end of said retainer means being fixed to said movable contact; said spring means having one end thereof connected to said operating shaft and its other end connected to said spring retainer means.

8. In the circuit interrupter of claim 7 wherein said spring retainer means is disposed concentrically with and between said operating shaft and said conductive tube.

Claims

1. In a circuit interrupter; a generally tubular stationary contact, one end of said generally tubular contact being segmented in an axial direction to define a generally circular cluster of contact fingers; a generally tubular movable contact movable into and out of engagement with said stationary contact, one end of said generally tubular movable contact being segmented in an axial direction to define a generally circular cluster of contact fingers, the opposite end of said movable contact Being a generally solid ring; said tubular stationary and movable contacts being coaxial; said solid ring end of said movable contact being movable into engagement with surfaces of said circular cluster of contact fingers of said stationary contact and having a diameter different than the diameter defined by said surfaces of said cluster of stationary contact fingers when they are unflexed, thereby to create a given contact pressure when said movable and stationary contacts are in engagement; and a generally stationary conductive tube supported in insulated relation with respect to said stationary contact; said tubular movable contact being coaxial with respect to said stationary conductive tube and being in sliding contact engagement therewith; said segmented movable contact fingers engaging a surface of said conductive tube; said conductive tube having a diameter different than the diameter defined by the engaging surfaces of said movable contact fingers when they are unflexed, thereby to create a given contact pressure when said movable contact slides relative to said conductive tube; a longitudinally movable operating shaft connected to said tubular movable contact and being movable along the axis of said tubular movable contact to move said movable contact into and out of engagement with said stationary contact; a lost-motion connection means for connecting said operating shaft to said movable contact; and gas blast means operatively connected to said operating shaft and operable for producing a blast of gas between said stationary and movable contacts during their movement to a disengaged position; and wherein said lost-motion connection means delays the time at which said movable contact moves to said disengaged position until after said gas blast means produces a blast of gas whereby increased gas pressure is established in the region of engagement of said movable and stationary contacts before said contacts are opened.

2. In the circuit interrupter of claim 1 wherein the interior of said stationary contact and of said movable contact are permanently connected to a relatively low pressure region, whereby gas flows from the exterior of said stationary and movable contacts through the interiors thereof to said low pressure region during the operation of said movable contact to a disengaged position relative to said stationary contact.

3. In the circuit interrupter of claim 1 wherein said lost-motion connection means includes spring means which is flexed to a biased condition in response to opening movement of said operating shaft, thereby to apply an increasing opening biasing force on said movable contact which eventually snaps said movable contact to its said disengaged position.

4. In the circuit interrupter of claim 3 which further includes a tubular spring retainer means which concentrically surrounds said operating shaft and which is slidably mounted on said conductive tube; one end of said retainer means being fixed to said movable contact; said spring means having one end thereof connected to said operating shaft and its other end connected to said spring retainer means.

5. In the circuit interrupter of claim 4 wherein said spring retainer means is disposed concentrically with and between said operating shaft and said conductive tube.

6. In a circuit interrupter: a generally tubular stationary contact; a generally tubular movable contact movable into and out of engagement with said stationary contact; said tubular stationary and movable contacts being coaxial; and a generally stationary conductive tube supported in insulated relation with respect to said stationary contact; said tubular movable contact being coaxial with respect to said stationary conductive tube and being in sliding contact engagement therewith; a longitudinally movable operating shaft connected to said tubular movable contact and being movable along the axis of said tubular movable contact to move said movaBle contact into and out of engagement with said stationary contact; gas blast valve means connected to said longitudinally movable operating shaft and operable to produce a blast of gas through said stationary and movable contacts in response to the movement of said operating shaft to move said movable contact out of engagement with said stationary contact; and a lost-motion connetion means for connecting said operating shaft to said movable contact, whereby said lost-motion connection means delays the time at which said movable contact moves to said disengaged position until after said gas blast means produces a blast of gas, whereby increased gas pressure is established in the region of engagement of said movable and stationary contacts before said contacts are opened.

7. In the circuit interrupter of claim 6 which further includes a tubular spring retainer means which concentrically surrounds said operating shaft and which is slidably mounted on said conductive tube; one end of said retainer means being fixed to said movable contact; said spring means having one end thereof connected to said operating shaft and its other end connected to said spring retainer means.