US3339046A

US3339046A - Blast valve arrangement for compressed gas operated circuit breakers

Info

Publication number: US3339046A
Application number: US447015A
Authority: US
Inventors: Giammona Salvatore; Utku Ruhi
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1964-05-25
Filing date: 1965-04-09
Publication date: 1967-08-29
Anticipated expiration: 1984-08-29
Also published as: SE301515B; GB1046577A; DE1207991B; CH410108A

Description

g- 29, 1967 s. GIAMMONA ETAL 3,339,046

BLAST VALVE ARRANGEMENT FOR COMPRESSED GAS OPERATED CIRCUIT BREAKERS Filed April 9, 1965 @QLM IN VEN TOR.

Soluafore GI ammano; Rubi Ufiku BY United States Patent 3,339,046 BLAST VALVE ARRANGEMENT FOR COM- PRESSED GAS OPERATED C I R C U I T BREAKERS Salvatore Giammona, Nussbaumen, and Ruhi Utku, Baden, Switzerland, assignors to Aktiengesellschaft Brown, Boveri & Cie., Baden, Switzerland, a joint-stock company Filed Apr. 9, 1965, Ser. No. 447,015 Claims priority, application Switzerland, May 25, 1964, 6,812/ 64 3 Claims. (Cl. 200-148) The present invention relates in general to electrical circuit breakers of the type in which the contact members are blasted with a compressed gas as they separate in order to facilitate extinction of the are drawn between the contacts, and is more particularly directed to an improved arrangement for the valving by which the compressed gas is introduced to the zone where the contact members are separated. The blast valve structure includes a tubular valve member which is directly connected with the movable contact member of the circuit breaker and this tubular valve member cooperates with an annular stationary valve seat, the interior of the tubular valvemember, when the latter is in closed position, being at a lower pressure than that which prevails in the zone surrounding the exterior of the valve member.

In prior known constructions of compressed gas circuit breakers or switches, it has been the practice to arrange the blast valve in the immediate vicinity of the contact members in order to initiate the blasting action on the contacts with the least possible delay. For this purpose, the movable tubular member of the valve is directly connectedwith the movable contact member and both are actuated by a common drive device. In such case it has proved to be very advantageous to make the movable contact member in the form of a tulip configured structure consisting of a circular basket-like array of contact fingers'and which is arranged'within the tubular valve member in such manner as to establish a bridging contact for connecting or disconnecting, respectively two axially aligned stationary tubular nozzle-like contact members of the circuit breaker. The known arrangement is such that the blast valve and contact structure are located within a switch chamber which is always filled with a compressed gas, and that in the closed position of the contact member, i.e., in the current-carrying condition of the circuit breaker, the interior of the tubular valve member as well as the interiors of the two stationary tubular contact members are subjected to a gas pressure which is lower than that prevailing within the switch chamber. For example, the interiors of the valve member and switch members can be in communication with the open air externally of the circuit breaker casing.

In the known construction, the valve seat which cooperates with the movable tubular valve member is established by a stationary annular plate-like valve member which is rigidly secured, for example, to one of the stationary tubular contact members of the breaker. The

movable valve member has included a drive piston one side of which communicates with the open air, the other side of the drive piston being subjected to the gas pressure within the switch chamber to effect its movement in the valve opening direction. Such an arrangement, however, still has the disadvantage in that during the starting phase of a breaker opening operation only a relatively small effective piston driving area is available and hence, only a comparatively small piston driving force is applied to the movable valve member.

With more modern compressed gas operated circuit breakers, higher contact opening speeds are desirable and hence, it is desirable to have the movable contact member attain as high a speed as possible at the moment ofcontact separation. This desired objective can be fulfilled in a comparatively simple manner in accordance with the present invention which is characterized by'the fact that the plate-like valve member which formsthe seat for the movable valve member, is also arranged for displacement in the same direction in which the valve member moves towards its open position, the valve seat member including a first piston operative in a closed position of the circuit breaker contact members and which serves as a starting piston during a partial stroke of the opening movement for obtaining additional acceleration of the movable valve member, and the valve seat member also including a second piston which functions to bring about a return movement of the valve seat member to its initial position after the blast valve has been opened. The end result is a much shorter opening time for the circuit breaker contacts and a further advantage is that the valve seat itself is protected from any harmful eifects that would otherwise be produced from the arc itself.

The foregoing and.other objects and advantages in herent in the invention will become more apparent from the following detailed description of one suitable embodiment and from the accompanying drawings, the single figure of which shows the improved circuit breaker blast valving structure in a vertical central section. In order to simplify the drawings, the remainder of the switch contact structure and the housing which provides a chamber for the contacts and blast valve structure have not been included since they are not believed to be essential to an understanding of the invention as defined in the appended claims.

With reference now to the drawing, the interior of the switch chamber, not illustrated, and which contains the compressed gas, is designated simply by numeral 11. The two main contact members of the circuit breaker which are stationary are designated 1, 2 and these 'are seen to be in the form of tubular members axially aligned and with the gas entrance ends thereto arranged in spaced confronting relation and configured as nozzles to facilitate passage of the switching gases. concentrically surrounding the tubular nozzle contact member 1 and radially spaced therefrom is a cylindrical guide member 3 which is also stationary. The annular space between guide member 3 and contact member 1 serves as a cylinder and accommodates the tubular movable valve member 4 of the blast valve structure, its drive piston part 4a being slidingly guided by the wall surfaces of contact member 1 and guide member 3. A helical compression spring 5 is accommodated within an annular bore 40 within the movable valve member 4, this bore being open at the upper end of the valve member and being terminated at the piston part 4a which establishes one abutment for spring 5. The other end of spring 5 also bears against an abutment, not shown, located above the valve member and the force of spring 5 serves to bias the valve member 4 in the downward, valve closing position. The zone 6 within the cylindrical guide member 3 serves as a control zone, which, in a manner already known, can be filled with compressed gas through a control valve, not shown, for closing the blast valve, and emptied for opening. A circular, basket-like array of contact fingers 7 held together by means of upper and lower garter springs 8 are disposed with the movable valve member 4 and are secured to the latter by means of upper and lower projections 7a. In the closed position of valve 4 the contact fingers 7 bridge the gap between and engage the confronting nozzle ends of the

stationary contact members

1 and 2.

The lower end 4b of valve member 4 provides a rounded annular portion which is adapted to engage a valve seat in the form of an annular packing ring 10 accommodated in an annular recess in the lower tubular valve member 9. The latter includes a first piston portion 9a which is arranged for a sliding movement on the exterior cylindrical surface of the stationary contact member 2, and also includes a second piston portion 9b which is accommodated for sliding movement within a cylindrical recess 24, the limits of sliding movement in the recess 2a being determined by the upper and lower end walls defining this recess. The underside of piston portion 9b communicates with the open air through channel 2b located within the stationary contact member 2.

The improved blast valve structure operates in the following manner. In the position depicted in the drawing, the

blast valve

4, 9 is closed, the valve part 4b being pressed against seat 10. This is due to the fact that by. the gas pressure prevailing within zone 6, valve member 4 is pushed downward, the annular-shaped area limited by the two diameters d and d determining the active surface since the annular area enclosed between the diameters d and d which is loaded by the gas pressure prevailing in the surrouunding space 11 establishes a smaller force component acting upwardly upon valve member 4. To simplify matters, it has been assumed that the gas pressures in zones 6 and 11 are equal, and that the interior of valve member 4, as well as the interior of the

tubular contact members

1, 2 are under atmospheric pressure, for example. In an analogous manner, there is exerted on the other valve member 9 a force directed upward which results from the pressure within zone 11 and the ring-shaped surface of piston portion 9a located between the diameters d and d In the selected example, d =d so that the blast valve system consisting of the

parts

4 and 9 is in equilibrium to the outside. The

parts

4 and 9 are held by spring 5 in the lower limit position which is determined by the abutment of the lower face of piston portion 9b against lower end face of recess 2a.

In order to open the blast valve, zone 6 is opened to the atmosphere. When this occurs, the blast valve system consisting of

theparts

4 and 9 is set in motion very rapidly because already, after a relatively slight drop in pressure in zone 6 there is sufficient excess of force upward which results from the pressure difference in zones 6 and 11 multiplied by the large ring surface enclosed between diameters-d and d' (=d In the initial phase of movement, therefore, valve member 9 functions, due to its piston 9a, as a startingaid for the acceleration upward of the movable valve member 4 and hence, of the movable contact basket 7. This occurs during a partial stroke, which is limited by the fact that during its upward movement, the upper end face of piston portion 9b then strikes against the upper end face of recess 2a. In the further course of movement, the seating part 412 lifts from the seating ring 10, thus opening the valve and permitting compressed gas within the switch chamber zone 11 to enter in a radially inward direction. Simultaneously the compressed gas reaches the upper face of piston portion 9b and functions to push the valve member 9 back to its lower limit position since the underside of this piston communicates with the free air by way of channel 2b. This quick return of valve member 9 has the advantage that the packing ring forming the valve seat is quickly isolated from the zone in which it would otherwise be possibly damaged by the action of the arc, metal splashes and the like which arise when the circuit breaker contacts disengage. A further advantage arises from the fact that the lead-through cross section available for supply of the quenching gas to the switching area is additionally increased in a very desirable manner.

We claim:

1. In an electrical circuit breaker of the gas blast type, the combination comprising first and second stationary tubular contact members arranged coaxially and with the ends thereof located in spaced confronting relation to establish flow of an arc extinguishing gas therethrough, a basket-like arrangement of contact fingers surrounding the confronting end portions of said stationary contact members in bridging relation thereto, a blast valve structure surrounding said stationary contact members, said blast valve structure comprising a first tubular valve member mounted for sliding movement back and forth upon said first stationary contact member and to which said contact fingers are secured for movement therewith to connect and disconnect the bridge between said first and second stationary contact members, the interior of said first valve member being at a lower gas pressure than the Zone surrounding said blast valve structure when the latter occupies its closed position, and a second tubular valve member mounted for back and forth sliding movement upon said second stationary contact member between limit positions, said second tubular valve member including an annular seat adapted to receive a ring-shaped seating portion provided on said first movable valve member as well as first and second piston portions, said first piston portion being operative when said blastvalve occupies its closed position as a starting piston during a partial stroke of the opening movement of the blast valve to .obtain additional acceleration for said first tubular valve member and contact fingers, and said second piston portion being operative subsequent to the opening of said blast valve to return said second tubular valve member to its initial position, and spring means biasing said first tubular valve member into engagement with said second tubular valve member and effecting a bridging relationship as between said contact fingers and said stationary contact members.

2. An electrical circuit breaker as defined in claim 1 wherein said second tubular valve member has its second piston portion slidable in a circular recess in said second stationary contact member, and channel means extending from said recess to the open air so as to place the side of said second piston portion away from said first movable valve member in communication with the open air.

3. An electrical circuit breaker as defined in claim 2 wherein the opposite ends of said recess in said second stationary contact member serve as abutments for said second piston portion thus establishing the limits of movement thereof in both directions.

References Cited UNITED STATES PATENTS 3,185,802 5/1965 Amalric ZOO-448.2 3,240,910 3/1966 Floessel 200--l48 3,286,066 11/ 1966 Floessel 200-148 ROBERT s. MACON, Primary Examiner,

Claims

1. IN AN ELECTRICAL CIRCUIT BREAKER OF THE GAS BLAST TYPE, THE COMBINATION COMPRISING FIRST AND SECOND STATIONARY TUBULAR CONTACT MEMBERS ARRANGED COAXIALLY AND WITH THE ENDS THEREOF LOCATED IN SPACED CONFRONTING RELATION TO ESTABLISH FLOW OF AN ARC EXTINGUISHING GAS THERETHROUGH, A BASKET-LIKE ARRANGEMENT OF CONTACT FINGERS SURROUNDING THE CONFRONTING END PORTIONS OF SAID STATIONARY CONTACT MEMBERS IN BRIDGING RELATION THERETO, A BLAST VALVE STRUCTURE SURROUNDING SAID STATIONARY CONTACT MEMBERS, SAID BLAST VALVE STRUCTURE COMPRISING A FIRST TUBULAR VALVE MEMBER MOUNTED FOR SLIDING MOVEMENT BACK AND FORTH UPON SAID FIRST STATIONARY CONTACT MEMBER AND TO WHICH SAID CONTACT FINGERS ARE SECURED FOR MOVEMENT THEREWITH TO CONNECT AND DISCONNECT THE BRIDGE BETWEEN SAID FIRST AND SECOND STATIONARY CONTACT MEMBERS, THE INTERIOR OF SAID FIRST VALVE MEMBER BEING AT A LOWER GAS PRESSURE THAN THE ZONE SURROUNDING SAID BLAST VALVE STRUCTURE WHEN THE LATTER OCCUPIES ITS CLOSED POSITION, AND A SECOND TUBULAR VALVE MEMBER MOUNTED FOR BACK AND FORTH SLIDING MOVEMENT UPON SAID SECOND STATIONARY CONTACT MEMBER BETWEEN LIMIT POSITIONS, SAID SECOND TUBULAR VALVE MEMBER INCLUDING AN ANNULAR SEAT ADAPTED TO RECEIVE A RING-SHAPED SEATING PORTION PROVIDED ON SAID FIRST MOVABLE VALVE MEMBER AS WELL AS FIRST AND SECOND PISTON PORTIONS, SAID FIRST PISTON PORTION BEING OPERATIVE WHEN SAID BLAST VALVE OCCUPIES ITS CLOSED POSITION AS A STARTING PISTON DRUING A PARTIAL STROKE OF THE OPENING MOVEMENT OF THE BLAST VALVE TO OBTAIN ADDITIONAL ACCELERATION FOR SAID FIRST TUBULAR VALVE MEMBER AND CONTACT FINGERS, AND SAID SECOND PISTON PORTION BEING OPERATIVE SUBSEQUENT TO THE OPEINING OF SAID BLAST VALVE TO RETURN SAID SECOND TUBULAR VALVE MEMBER TO ITS INITIAL POSITION, AND SPRING MEANS BIASING SAID FIRST TUBULAR VALVE MEMBER INTO ENGAGEMENT WITH SAID SECOND TUBULAR VALVE MEMBER AND EFFECTING A BRIDGING RELATIONSHIP AS BETWEEN SAID CONTACT FINGERS AND SAID STATIONARY CONTACT MEMBERS.