US3920307A

US3920307A - Arc-out shut off valve assembly for a high voltage bushing

Info

Publication number: US3920307A
Application number: US499325A
Authority: US
Inventors: Clarence B Burns
Original assignee: RTE Corp
Current assignee: Cooper Power Systems LLC
Priority date: 1974-08-21
Filing date: 1974-08-21
Publication date: 1975-11-18
Anticipated expiration: 1992-11-18
Also published as: CA1026441A

Abstract

A high voltage cable termination bushing for terminating a high voltage cable and including a housing having an axial passage, an electrically conductive receptacle within the passage and supported intermediate the ends thereof, the passage being closed at the inner end, and a gas trap valve provided between the inner end of the passage and the receptacle, the valve being biased into engagement with the receptacle that traps gases within the passage. The gas trap valve is opened by the arc-extinguishing rod provided on the conductive probe of the cable connector and having a length sufficient to allow the valve to close at the anticipated position of the probe, with respect to the receptacle where the arc will be extinguished.

Description

United States Patent [191 I FOR A-HIGH VOLTAGE BUSHING lnventorz Clarence B. Burns, Oconomowoc,

Wis.

Assignee: RTE Corporation, Waukesha, Wis. Filed: Aug. 21, 1974 Appl. No.: 499,325

References Cited UNITED STATES PATENTS 5/1968 Phillips 339/111 [111 3,920,307 Burns Nov. 18, 1975 ARC-OUT SHUT OFF VALVE ASSEMBLY Primary Examiner-Roy Lake Assistant Examiner-DeWalden W. Jones Attorney, Agent, or Firm-Ronald E. Barry [57] ABSTRACT A high voltage cable termination bushing for terminating a high voltage cable and including a housing having an axial passage, an electrically conductive receptacle within the passage and supported intermediate the ends thereof, the passage being closed at the inner end, and a gas trap valve provided between the inner end of the passage and the receptacle, the valve being biased into engagement with the receptacle that traps gases within the passage. The gas trap valve is opened by the arc-extinguishing rod provided on the conductive probe of the cable connector and having a length sufficient to allow the valve to close at the anticipated position of the probe, with respect to the receptacle where the arc will be extinguished.

l2 Claim, 3 [Moving Figures probe has HIGH VOLTAGEBUSHING BACKGROUND O THE INVENTION a bushing which is used totra'p gases after a load break operation has been completed and as the probe is withdrawn from the entrance of the'bushing. The valve preventsionized gases 'from being'expelled from the bushing into "the atmosphere on separation; Prevention of theexp ulsion of the gases reduces the possibility of restrikeeither internally or externally from the probe to the' female contact or to the ground shield after the been completely withdrawn from the bush- SUMMARY. OF THE INVENTION In the present invention the valve is located internally of the arc chamber sothat the valve does not utilize arc extinguishing space. With the internal valve the arc has no chance of playing on the surface of the gas sealing surfaces, thus giving a more reliable seal.

. DRAWINGS The bushing'10 of the present invention is used to electricallyiconnect the conductive probe or contact 12 of an electrical connector'14 to an electrical apparatus mounted within a housing 16. A high voltage electrical connector ofthis type is shown in US. Pat. No. 3,474,386 of Edwin A. Link entitled Electrical Connector and issued on Oct. 21,1969. In this type of an electrical connector, a gas evolving, arc-quenching ex-' tension or rod 18 is provided on theend of the probe 12. The probe 12 and rod 18 are supported within a housing 20 that is designed to matingly engage the bushing 10. The bushing is provided with an electrically conductive receptacle 22 which is designed to electrically engage the probe 12 and an arc-quenching sleeve 24 which cooperates with the rod 18 to produce an arc-quenching gas on close-in or interruption. The

arc-quenching materials can be any of the well-known materials used for this purpose such as hard vulcanized fiber, the acrylics or polytetrafluoroethylene.

In a high voltage terminator of this type, the gas evolving materials respond to the heat of the arc to produce large volumes of gas that operate to quickly snuff the arc. It is generally agreed that the arc snuffing materials produce the intended result. However, as a re- .sult of the confinement of these gases within the bushing, the large volumes of hot ionized gases will be expelled from the bushing on withdrawal of the rod from the bushing forming a low resistance electrical path between '-the ground 'shieldand one of the energized contacts, of the separated electrically conductive members.-lThis condition can be extremely dangerous under fault current conditions increasing the risk of injury to 5 the operator and creating a destructive condition.

. In accordance with the-invention, the bushing 10 is provided with a gas trap valve assembly 26 which is located in a position to minimize the amount of gases expelled on withdrawal of the probe from the bushing. More particularly, the bushing 10 includes a housing 28 formed or molded from a dielectric material and having an axially extending passage 30. The housing 28 is adapted to be mounted in an opening 32 in the enclosure or housing 16 to provide an electrical connection between a high voltage cable andelectrical apparatus within the housing.

The electrically conductive receptacle 22 is supported within the passage 30 intermediate the ends thereof by means of a hollow tube or conductive member 34. In this re regard, the conductive member 34 is closed at the inner end by means of an electrically conductive plug 36 having a threaded member 38 extending into the housing 16 for connection to the electrical apparatus. A reduced diameter threaded section 40 is provided intermediate the ends of the member 34 for threadedly receiving the threaded ductive receptacle 22.

The entrance to the passage 30 is lined by-means of end 42 of the conthe arc-extinguishing sleeve 24 and extends inwardly into the tubular member 34 far enough to engage theend of the conductive receptacle 22. The sleeve 24 is supportedwithin the tubular member 34 by means of a threaded section 44 provided on the sleeve 24 which is threadedly received on the threaded end 46 of the tubular member 34.

Means are provided at the end of the sleeve 24 for sealingly engaging the probe -12,and rodl8. Such means is in the form of an O-ring seal 54 provided in a groove at the end of the sleeve-24.

The gas produced by the arc on interruption is trapped within the tube or member 34v by means of the valve assembly 26. The valve assembly 26 includes a,

valve member or element 48 which is biased by means of a spring 50 into engagement with a valve seat 52 provided on the end of the conductive receptacle 22. It should be noted that the valve assembly 26 is located approximately midway between the ends of the passage 30 so that any gas under pressure trapped between the valve means 26 and the end plug 36 will be prevented from being expelled from the bushing on withdrawal of the connector from the bushing. J

In operation, and referring to FIG. 1, the connector 14 is shown mounted on the bushing 10 with the con-.1 ductive probe 12 in electrical engagement with the conductive receptacle 22. The rod 18 extends through the receptacle 22 forcing the valve member 48 into the tubular member 34'and against the bias of the spring 50. The tubular member 34 will then be open throughout its full length. v

On withdrawal of the connector 14 from the bushing 10, as seen in FIG. 2, the probe 12 and rod 18 will be pulled outwardly from the receptacle 22; In the position shown'in FIG. 2, the arc length'between the probe 12 and the receptacle 22 will be at approximately the length at which the arc will be extinguished by the gases produced by the heat of the arc. It should also be noted that at this point, the valve member 48 will be simultaneously seated on the valve seat 52 trapping the gases within the member 34. At the instant just prio'rto seating the valve member 48 on the valve seat 52,g'aspre ssure within the tubular member 34: will 'be equ'al throughout the length of thebushingOn arc interrupatthe end of the sleeve 24 and the gas trap valve 26. The majority of the high pressure gases are therefore trapped within the sleeve 34 by the valve 26. This reduction in the volume of gases expelled from the bushcontacts on circuit disconnectiom FIG. 3 The valve'member or element 60 shown in FIG. 3

provides a means'for delaying closing of the tube 34 for different voltage ratings. in this regard, it should be noted that as the arc length or distance increases at higher voltages, the time for closing of the tube 34 is delayed in order to trapa greater amount of the gases [in the tube 34. Such means is in the form of the valve member which is normally biased by the spring 50 into engagement with the valve seat 52 to close the tube 34. The valve member 60 is provided with an extension 62 that is axially aligned with the rod 18. The combined length of the extension 62 and the length of the rod 18 are selectedto correspond to the arc distance for each voltage rating in accordance with the arcing distance. If the lengths are properly selected, the valve member will close,,the passage 34 at arc-out.

I claim: t t

l. A high voltage cable termination bushing for connecting an electrical apparatus to an electrically conductive probe having an arc extinguishing rod on the end, said bushing comprising: a housing formed from an insulating material and having a passage, said housing being adapted to be mounted in the entrance to a housing for an electrical apparatus, an electrically conductive member supported within said passage intering reduces the-danger of strike over between the liver mediate the ends thereof, electrically conductive means closing one end of said passage, said conductive means being electrically connected to said conductive member for connecting said bushing to the apparatus within the housing, valve means positioned within said passage between said conductive member and said conductive means for trapping gases between said member and said conductive means, said valve means being normally in a closed position and opened by the arc exting'uishing rod on the end of the probe on cable termination, on withdrawal of the probe the valve means will close to prevent the escape of gases trapped in the passage.

2. The bushing according to claim 1 wherein said valve means includes a valve member and a spring positioned to bias said valve member into engagement with said conductive member to close the passage.

3. The bushing according to claim 2 wherein said valve member includes an extension positioned to engage the rod, said extension and rod having a combined length established by the voltage rating for the bushing to close the passage at arc-out.

4 I 4. The bushing according to claim 1 including an arc extinguishing sleeve positioned at-the open end of said passage and an O-ring seal in the sleeve to sealingly en- I gage the probe.

5. The combination of an electrical connector having an electrically conductive probeand an arc extinguishing rod on the end of said probe and a high voltage cable termination bushing having a housing fonned from an insulating material and a passage extending through the length of the housing, said passage being closed at one end, an electrically conductive receptacle mounted in said passage intermediate to the ends thereof and being adapted to be electrically connected to an electrical apparatus, said receptacle includinga valve seat at the inner end, valve means positioned within said passage between the receptacle and said closed end of said passage for movement into engagement with said valve seat to trap gases within said passage, said rod having a length sufficient to provide for the extinction of the arc produced on withdrawal of the probe from the receptacle and to substantially simultaneously closesaid valve means at arc out.

6. The combination according to claim 5 wherein I said valve means includes a valve member positioned for movement into engagement with said valve seat and a spring biasing said valve member into engagement with said valve seat. 3

7. The combination according to claim 5 including means at the other end of said passage forsealingly engaging said probe and rod. v

8. The combination according to claim 5 including means on said valve member for' delaying closing of the pa 9. A high voltage cable termination bushing for connecting an electrical apparatus to an electrically conductive probe having an arc extinguishing rod .on the end, said bushing comprising: a housing formed from a dielectric insulating material and adapted to be mounted in the opening of an enclosure for an electrical apparatus, a passage in said housing, a hollow cylindrical electrically conductive tube in said passage, a

' conductive plug closing one end of said tube and being.

adapted to be connected to an electrical device apparatus within the enclosure, an electrically conductive receptacle supported in said tube intermediate the ends of said housing, normally closed valve means mounted in said tube for movement into engagement with said receptacle to define a gas trap chamber in said tube, said valve means being opened by the rod on said probe on cable termination, the rod being of sufficient length to allow the valve means to close onwithdrawal of the probe from the receptacle a sufficient distance to extinguish the arc.

10. The bushing according to claim 9 including an arc extinguishing sleeve supported at the entrance to said tube and means at the entrance to said sleeve for sealingly engaging said probe and rod.

11. The bushing according to claim 9 wherein said valve means includes a valve element and a spring positioned in said tube to bias said element into engagement with said receptacle. 6

12. The bushing according to claim 1 wherein said valve means includes means for delaying the closing of said valve means to correspond with arc out.

Claims

1. A high voltage cable termination bushing for connecting an electrical apparatus to an electrically conductive probe having an arc extinguishing rod on the end, said bushing comprising: a housing formed from an insulating material and having a passage, said housing being adapted to be mounted in the entrance to a housing for an electrical apparatus, an electrically conductive member supported within said passage intermediate the ends thereof, electrically conductive means closing one end of said passage, said conductive means being electrically connected to said conductive member for connecting said bushing to the apparatus within the housing, valve means positioned within said passage between said conductive member and said conductive means for trapping gases between said member and said conductive means, said valve means being normally in a closed position and opened by the arc extinguishing rod on the end of the probe on cable termination, on withdrawal of the probe the valve means will close to prevent the escape of gases trapped in the passage.

4. The bushing according to claim 1 including an arc extinguishing sleeve positioned at the open end of said passage and an O-ring seal in the sleeve to sealingly engage the probe.

5. The combination of an electrical connector having an electrically conductive probe and an arc extinguishing rod on the end of said probe and a high voltage cable termination bushing having a housing formed from an insulating material and a passage extending through the length of the housing, said passage being closed at one end, an electrically conductive receptacle mounted in said passage intermediate to the ends thereof and being adapted to be electrically connected to an electrical apparatus, said receptacle including a valve seat at the inner end, valve means positioned within said passage between the receptacle and said closed end of said passage for movement into engagement with said valve seat to trap gases within said passage, said rod having a length sufficient to provide for the extinction of the arc produced on withdrawal of the probe from the receptacle and to substantially simultaneously close said valve means at arc out.

6. The combination according to claim 5 wherein said valve means includes a valve member positioned for movement into engagement with said valve seat and a spring biasing said valve member into engagement with said valve seat.

7. The combination according to claim 5 including means at the other end of said passage for sealingly engaging said probe and rod.

8. The combination according to claim 5 including means on said valve member for delaying closing of the passage.

9. A high voltage cable termination bushing for connecting an electrical apparatus to an electrically conductive probe having an arc extinguishing rod on the end, said bushing comprising: a housing formed from a dielectric insulating material and adapted to be mounted in the opening of an enclosure for an electrical apparatus, a passage in said housing, a hollow cylindrical electrically conductive tube in said passage, a conductive plug closing one end of said tube and being adapted to be connected to an electrical device apparatus within the enclosure, an electrically conductive receptacle supported in said tube intermediate the ends of said housing, normally closed valve means mounted in said tube for movement into engagement with said receptacle to define a gas trap chamber in said tube, said valve means being opened by the rod on said probe on cable termination, the rod being of sufficient length to allow the valve means to close on withdrawal of the probe from the receptacle a sufficient distance to extinguish the arc.

11. The bushing according to claim 9 wherein said valve means includes a valve element and a spring positioned in said tube to bias said element into engagement with said receptacle.