SE464948B

SE464948B - High-voltage circuit breaker

Info

Publication number: SE464948B
Application number: SE8903701A
Authority: SE
Inventors: D Andersson
Original assignee: Asea Brown Boveri
Priority date: 1989-11-06
Filing date: 1989-11-06
Publication date: 1991-07-01
Also published as: SE8903701L; SE8903701D0

Abstract

The invention concerns an outdoor circuit breaker which has a contact system enclosed in a casing 1 which is filled with gas, e.g. SF6, at a certain positive pressure. The casing consists of a jacket insulator 10 of porcelain with two flanges 11, 12. A rupture disc 9 prevents the jacket insulator from bursting in the event of an abnormally great increase in pressure in the circuit breaker. If a flash-over takes place in such a way that the arc cannot be extinguished, e.g. across an open pole and a low current (less than approx. 1 kA) thereafter flows for several seconds, there is a danger that the pressure will not rise sufficiently to release the rupture disc 9 while on the other hand the porcelain 10 which in addition is subjected to strong thermal stresses on account of the arc, can break even at the filling pressure. In this case the pressure can be reduced by placing a suitably shaped seal 14 of an alloy with a suitable melting point at the end of a pipe 13 entering from outside which ends in the vicinity of the breaking position. The design and melting point are selected so that the device does not operate in the event of normal breaking. If required this device can be integrated with the fixed contact 4 of the breaker. Alternatively the rupture disc 9 can be supplemented by a device which makes a hole in the disc in the event of too great an exchange of heat between the contacts 4, 5. <IMAGE>

Description

464 948 Ändamålet med föreliggande uppfinning är att vid en brytare av ovannämnda slag åstadkomma en anordning som kan släppa ut gasen i sådana fall då trycket ej är tillräckligt för att utlösa sprängblecket, men mantelisola- torn riskerar att sprängas på grund av den termiska påfrestningen. Detta uppnås enligt uppfinningen genom en brytare som uppvisar de i känneteck- nande delen av patentkrav 1 angivna särdragen. The object of the present invention is to provide in the case of a switch of the above-mentioned type a device which can release the gas in such cases when the pressure is not sufficient to trigger the explosive plate, but the jacket insulator risks being blown due to the thermal stress. This is achieved according to the invention by means of a switch which has the features stated in the characterizing part of claim 1.

Principen för uppfinningen är att man släpper ut gasen ur brytaren när en ljusbåge har brunnit en viss tid oberoende av tryckstegringen. Anordningen dimensioneras så att den ej utlöses vid normala brytningar.The principle of the invention is that the gas is released from the switch when an arc has burned for a certain time, independent of the pressure rise. The device is dimensioned so that it is not triggered during normal refractions.

Uppfinningen skall förklaras närmare genom beskrivning av ett antal utför- ingsexempel under hänvisning till bifogade ritning, i vilken fig 1 visar schematiskt i axialsnitt en första utföringsform av en en- ligt uppfinningen utförd brytare, fig 2 och 3 visar i axialsnitt den fasta kontakten i en andra resp tredje utföringsform av en sådan brytare, och fig 4 visar schematiskt de för uppfinningen väsentligaste delarna i en fjärde utföringsform av en uppfinningsenlig brytare.The invention will be explained in more detail by describing a number of exemplary embodiments with reference to the accompanying drawing, in which Fig. 1 shows schematically in axial section a first embodiment of a switch according to the invention, Figs. 2 and 3 show in axial section the fixed contact in a second and third embodiments of such a switch, and Fig. 4 schematically shows the most essential parts of the invention in a fourth embodiment of a switch according to the invention.

Den i fig 1 schematiskt visade brytaren har ett gastätt hölje 1 bestående av en mantelisolator 10 av porslin med två metalliska flänsar 11, 12 som tjänstgör som anslutningar. Höljet är fyllt med gas, t ex svavelhexa- fluorid, av några atmosfärers övertryck.The switch schematically shown in Fig. 1 has a gas-tight housing 1 consisting of a mantle insulator 10 of porcelain with two metallic flanges 11, 12 which serve as connections. The casing is filled with gas, such as sulfur hexafluoride, overpressure of some atmospheres.

Höljet innehåller ett huvudkontaktställe med en fast och en rörlig huvud- kontakt 2 resp 3 samt ett ljusbågskontaktställe med en fast och en rörlig ljusbågskontakt 4 resp 5. De fasta kontakterna 2, 4 är förbundna med den övre flänsen 12. I det visade exemplet är denna förbindelse utförd via en rörformig metallskärm 6. De rörliga kontakterna 3, 5 är mekaniskt kopplade till ett ej visat manöverdon via en axiellt förskjutbar dragstång 7, som med lämplig tätning är förd genom den nedre flânsen 11. Den elektriska förbindningen mellan de rörliga kontakterna 3, 5 och flänsen 11 åstadkom- mes genom glidkontakter (ej visade). En blåsdysa 8 som är utförd i isole- rande material är fixerad vid de rörliga kontakterna och rör sig tillsam- mans med dessa.The housing contains a main contact point with a fixed and a movable main contact 2 and 3, respectively, and an arc contact point with a fixed and a movable arc contact 4 and 5, respectively. The fixed contacts 2, 4 are connected to the upper flange 12. In the example shown, this connection made via a tubular metal screen 6. The movable contacts 3, 5 are mechanically coupled to an actuator (not shown) via an axially displaceable drawbar 7, which with a suitable seal is passed through the lower flange 11. The electrical connection between the movable contacts 3, 5 and the flange 11 are provided by sliding contacts (not shown). A blow nozzle 8 made of insulating material is fixed to the movable contacts and moves together with them.

Claims

464 948 In order to prevent the jacket insulator 10 from bursting in the event of an abnormally large pressure increase in the housing, a bursting plate 9 is arranged in the upper flange 12. Furthermore, the switch is provided with a thermal safety valve in the form of a pipe 13 which enters through the upper flange 12 and to the breaking point where the pipe is terminated with a closure 14 of relatively easily digestible material. If an arc burns for a longer time than normal, the closure 14 melts and the gas flows out through the tube 13. The location of the closure and the amount of material and its melting point are chosen so that the device is not triggered during a normal break. The thermal safety valve can also be integrated with the switch's fixed arc contact. Figs. 2 and 3 thus show examples of embodiments where a hollow plug contact 4 is used as an outflow pipe. In the embodiment according to Fig. 2, the nelt seal is made of the contact's own material, whereby the contact may be made with one or more weakenings 18 distributed around the contact. the material in the socket. The function is the same as in the embodiment according to Fig. 1. Fig. 4 shows an example of an embodiment where an ordinary explosive plate 9 has been supplemented with a device which punches holes in the plate in the event of excessive heat generation between the contacts. In the example, this is done by an anchor 15 melting and releasing a percussion pin 16 which is thrown by a tensioned spring 17 against the explosive plate. However, the device can be designed in a number of other ways. The energy for driving the percussion pin can also come from an exothermic chemical reaction that is triggered in, for example, a powder kit when the temperature rises. IN PATENT CLAIMS

High-voltage switchgear with a housing (1) made at least partially of insulating material and filled with gaseous extinguishing agent containing a switching point with two cooperating contacts (4, 5), at least one of which is movable, characterized in that the switch is provided with a thermal safety valve (13, 14) comprising a release means (14) located near the breaking point, which is arranged to be triggered by the heat generation of an arc and thereby expose a pressure relief opening in the housing. 7,464,948

Switch according to claim 1, characterized in that the safety valve comprises a pipe coming in from outside (13) whose inner end is in the vicinity of the breaking point, and that said release means is constituted by a closure (14) of a relatively easily digestible material arranged. at the said end of the tube. »

Switch according to claim 1, characterized in that the second (fixed) contact (4) is hollow and that the axial hole of the contact at one end opens into the air outside the switch and at its other end, located at the contact point, is sealed by means of said release means.

A switch according to claim 3, characterized in that the release means consists of at least a part of the end portion of the hollow contact (Ä) located closest to the breaking point.

Switch according to claim 3, characterized in that the release means consists of an insert (14) arranged in the hollow contact of a material which has a lower melting point than the material in the contact (4).

Switch according to claim 1, characterized in that the safety valve comprises an explosion plate (9) and a percussion pin (16) arranged for puncturing the explosion plate.

Switch according to claim 6, characterized in that the trigger means is arranged to, if the heat generation of the arc exceeds a certain value, release a prestressed spring (17) for driving the striker pin (16) in the direction of the bursting plate (9).

Switch according to Claim 6, characterized in that the striking pin is under the influence of a spring (17) acting in the direction of the explosive plate (9), and in that the release means consists of an anchorage (15) arranged for the striking pin. , which is arranged to melt if the heat generation of the arc exceeds a certain value. tea

A switch according to claim 6, characterized in that the percussion pin (16) is arranged to be activated by a substance in which an exothermic chemical reaction is triggered by a rise in temperature.