US3286066A

US3286066A - Gas blast circuit breaker with spring mounted hollow contact member and associated exhaust valve controlled thereby

Info

Publication number: US3286066A
Application number: US396093A
Authority: US
Inventors: Floessel Carl Dieter
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1963-10-17
Filing date: 1964-09-14
Publication date: 1966-11-15
Anticipated expiration: 1983-11-15
Also published as: AT258397B; CH403011A; GB1049497A

Description

Nov. 15, 1966 c. D. FLOESSEL 3,286,066

GAS BLAST CIRCUIT BREAKER WITH SPRING MOUNTED HOLLOW CONTACT MEMBER AND ASSOCIATED EXHAUST VALVE CONTROLLED THEREBY Filed Sept. 14, 1964 2 Sheets-Sheet 1 INVENTOR Curl, Diefer Floessel 1am, 1 2) PM ATTOR NFV-S 3,286,066 w CONTACT N 15. 19 c. o. FLOESSEL GAS BLAST CIRCUIT BREAKE R WITH SPRING MOUNTED HOLLO MEMBER AND ASSOCIATED EXHAUST VALVE CONTROLLED THEREBY 2 Sheets-Sheet 2 Filed Sept.

j m 4 W n M J m 5 a T a 7 a D P w 5 Z, w g Q fiA/A, A A7 2 g w J 5 L m, a 4 a A A7 M H fi J 2 MM w a -controlled through an insulating pipe.

United States Patent 3,286,066 GAS BLAST CIRCUIT BREAKER WITH SPRING MOUNTED HOLLOW CONTACT MEMBER AND ASSOCIATED EXHAUST VALVE CONTROLLED THEREBY Carl Dieter Floessel, Fislisbach, Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cie, Baden, Switzerland, a joint-stock company Filed Sept. 14, 1964, Ser. No. 396,093 Claims priority, application Switzerland, Oct. 17, 1963, 12,750/ 63 7 Claims. (Cl. 200-148) The present invention relates to an arrangement for operating the gas exhaust valves in gas blast circuit breakers in which the arcing chambers are permanently filled with gas under pressure and contain nozzle-shaped contact pairs, each contact being associated with a gas exhaust valve and one of said contacts of each pair being directly actuated, whereas the other is spring loaded and yieldingly mounted in relation thereto to permit its participation in part of the breaking motion of the movable contact before the two contacts actually separate.

Gas blast circuit breakers are known in which the rupturing means have the form of a twin break contact device. The nozzle-shaped contacts are located inside a chamber which is kept continuously under gas pressure. When the circuit is broken, contact separation is achieved by either one or both contacts being actuated and the resultant arc is quenched by a gas blast. To this end each nozzle-shaped contact is associated with a gas exhaust valve at its exhausting end, said valve being closed when the circuit breaker is closed and briefly opened when the contacts break, permitting the pressurized gas in the arcing chamber to escape through the interior of the nozzle-shaped contacts to the outside and thereby to extinguish the arc by the blast of gas entering the nozzle.

The gas exhaust valves are controlled pneumatically or hydraulically in such a way that one gas exhaust valve is operated by a device kept at ground potential, whereas the other gas exhaust valve is pneumatically or hydraulically When the circuitbreaker is in rupturing position the insulating pipe is at high potential and this gives rise to the familiar problem of current creep. This is particularly difiicult to control if the circuit breaker is of .a kind in which the voltage ruptured by each break is relatively high, say 110 kv.

or more. It has also been proposed to control the indirectly operated gas exhaust valve through the intermediary of an insulated transmission member which, during operation, is only briefly in contact with the valve and which is separated therefrom in rupturing position by a gas-filled isolating gap, so that a permanent path for a creep current cannot form on the transmission member which bridges the separated circuit breaker contacts. In air circuit breakers it has finally been proposed to load the normally stationary contact by a spring and to mount it yieldingly in relation to the movable contact so that it can participate in part of the breaking motion of the movable contact.

The invention concerns an arrangement in which one of the contacts is likewise thus yieldingly mounted. The object contemplated by the invention is to provide a solution of the problem of operating the gas exhaust valve without the use of an insulating transmission member. To this end the invention proposes to construct the movable valve member of the gas exhaust valve associated.

with the yieldingly mounted contact in the form of a differential piston and also to provide a servo valve operable both by the movable gas exhaust valve member and by the yielding contact in such a way that the exhaust gas valve is operable by the contacts to open when the breaking motion begins and by the servo valve to close when the contacts have been separated for a predeterminable time.

The novel concept which underlies the invention will be more particularly described by reference to the accompanying drawings which illustratively show an embodiment of the invention.

In the drawings:

FIG. 1 is a sectional elevation of an arrangement in which the exhaust gas valve associated with one of the breaking contacts and its control means are shown partly in section, whereas in FIG. 2 the same arrangement is shown in an intermediate position during separation of the breaking contacts.

FIG. 3 is the same arrangement in interrupting position.

In FIG. 1 the movable nozzle-shaped breaking contact is indicated at 1. 2 is the usually stationary, likewise nozzle-shaped breaking contact firmly attached to an intermediate member 3 which is slidably mounted between a movable exhaust valve member 4 and the cover 5 of the valve casing 6. A thimble-shaped sliding bushing 7 which is bolted to cover 5 by screws 8 supplies current to contact 2. Supported by webs 9 a valve seat 10 is contained in valve casing 6, the seat together with valve member 4 forming the gas exhaust valve. A sealing ring 4a is countersunk in the flared lip 4b of valve member 4. The valve casing 6 further contains an insertion 11 formed at its lower end with ribs 11a for supporting the insertion inside valve casing 6. Between the two

components

6 and 11 is an annular channel 12 which communicates on the one hand with the exhaust 6a of valve casing 6 and on the other hand through a channel 14a in a partition 14 with a chamber 13. The partition 14 contains another channel 14b through which two

chambers

15 and 16 communicate. Moreover, a sealing ring 17 is inserted into the partition. An annular valve seat 18 is firmly let into insertion 11 and carries a sealing ring 19. A movable valve member 20 which has the shape of an annulus is slidably contained between part 4 and part 14 and in cooperation with sealing rings 17 and 19 forms a servo valve. The two chambers 13 and 21 communicate through an opening 200 in valve 20. A spring 22 is interposed between partition 14 and intermediate member 3, whereas, a further spring 23 is located between partition 14 and a damping piston 24. The top of intermediate member 3 has an inner recess and embraces a circular clip 25 inserted into a groove in valve member 4. Cover 5 is firmly attached to valve casing 6 by screws 26. Through an opening 5a in cover 5 chamber 16 is in permanent communication with the interior 27 of the arc chamber which in the drawing is not specially indicated. In FIGS. 2 and 3 parts also shown in FIG. 1 are identified by the same reference numbers.

The described arrangement functions as follows:

In FIG. 1 the two breaking

contacts

1 and 2 are shown in contacting position. Apart from chamber 27, the two

chambers

15 and 16 as well as the interiors of the breaking

contacts

1 and 2 contain a pressurized gas at a given normal pressure. The pressure in chambers 13 and 21 is atmospheric because they are in communication with the ambient atmosphere through channel 14a, channel 12 and the gas exhaust 6a. For rupturing the current, breaking contact 1 is raised by actuating means not shown in the drawing. Urged by spring 22 the other breaking contact 2 first participates in this movement, spring 22 thrusting the intermediate member 3 and contact 2 which is firmly connected thereto upwards so that the two

contacts

1 and 2 do not at first break. The movable valve member 4 of the gas exhaust valve is likewise arranged to participate in this movement. Valve member 4 functions in the manner of a differential piston. In closing position an upward pneumatic thrust acts on an inner section of the valve member of diameter d This is only partly balanced by a downward pneumatic thrust acting on an outer cross section of diameter d The difference between the two thrusts therefore pushes valve member 4 upwards, sealing ring 4a being lifted off valve seat 10 and thereby permitting the gas in the interior of the breaking

contacts

1 and 2 to exhaust through 611 to the outside. Since the inside of the movable breaking contact 1 is likewise associated with a conventional exhaust valve (not shown) which is opened by the initiation of the breaking movement, the interior of the two contacts is simultaneously exhausted upwards through contact 1. As illustrated in FIG. 2 the upper limit of displacement of valve member 4 and of contact 2 is reached when a shoulder 40 on valve member 4 has' lifted the movable valve member 20 of the servo valve against sealing ring 17 and shoulder 3a of the intermediate member 3 bears against the circular clip 25. However, contact 1 continues to rise, FIG. 2, until an arc extinction gap a has opened between the two breaking

contacts

1 and 2. A gas blast is produced across the arc between the two contacts, said gas blast being due to gas streaming from chamber 27, as indicated by arrows, through the interior of the breaking contacts and valve member 4 out into the atmosphere from exhaust 6a. At the end of a period (blowing time) which is sufiicient for ensuring that the arc will be quenched, the exhaust valve' 4, 10 must reclose. This is accomplished by pressurized gas from chamber 15 now entering chamber 21, as indicated by arrows, and building up pressure therein. At the end of a predetermined period of time which can be controlled by suitably designing the section of channel 14b, the pressure in chamber 21 reaches a level which is sufficiently high for the resultant thrust on piston 4b to push valve member 4 and, by the cooperation of the circular clip 25 and the intermediate member, contact 2 into the position shown in FIG. 3. From a comparison of FIGS. 2 and 3 it will be readily seen that the distance b between

contacts

1 and 2 is now wider than it was in FIG. 2 (where this distance is only a). Distance b is the break when the circuit breaker is in rupturing position. This gap is very conveniently established by valve member 4 of the exhaust valve and the yielding contact 2 being coupled by

parts

25 and 3 in such a way that the closing valve member 4 can entrain contact 2. For returning the circuit breaker to its make position, the movable contact 1 is lowered by its associated actuating means. When this contact has closed gap b contact 2 is entrained by contact 1 and depressed, intermediate member 3 and the movable valve member 20 of the servo valve participating in this yielding downward motion until the position illustrated in FIG. 1 has been reestablished. During the descent of valve member 20 chamber 21 exhausts to the outside through opening 20a, chamber 13, channel 14a, channel 12 and exhaust opening 6a.

In order to prevent rebound when the circuit breaker is closed, it is desirable to provide means for damping the moving contact 2. In the illustrated embodiment this is conveniently done by slidably mounting a damping piston 24 in cover 5, the damping piston being carried downwards by intermediate member 3 during the yielding descent of contact 2. This generates a temporary pressure drop in chamber 28 (FIG. 1) (suction damping) because the pressure in this chamber can only build up again through the small clearance between the sliding contact faces of parts and 24. The damping piston 24 is therefore braked by the full counterpressure existing in chamber 16.

In order to provide a compact design it is preferred to construct valve member 20 of the servo valve in the form of an annular member which concentrically surrounds the movable valve member 4 of the gas exhaust valve.

Exhaust valve, servo valve and the yielding breaking contact can thus be conveniently assembled to form one structural unit which can be easily held in position from one end of the arcing chamber, for instance by the cupshaped part forming exhaust 6a.

Apart from completely eliminating the need for insulating transmission members for operating the exhaust Valve associated with the stationary contact, the novel arrangement has the further advantage of permitting the break between the contacts to be opened in a desirable manner in two stages, although the rupturing movement of the movable contact is quite continuous. The actuating means associated with the latter can therefore be of simple and inexpensive construction.

I claim:

1. A gas blast circuit breaker comprising a chamber having a continuous filling of pressurized gas, first and second nozzle type contact members disposed within said chamber, said first contact member being actuatable towards and away from said second contact member to effect engagement and disengagement respectively of said contact members, said second contact member including spring means establishing a yieldable mounting therefor enabling said second contact member to follow said first contact member for a predetermined distance without separating therefrom during an initial opening phase of the circuit breaker, a gas exhaust valve correlated to the interior of said second contact member and which serves when open to discharge to atmosphere the pressurized gas flowing through said second contact member from said chamber when said contact members become disengaged, said exhaust valve including a valve seat and a movable valve member constituted as a pressure differential piston, said exhaust valve member being held against its seat by said second contact member when said contact members are engaged, and a servo valve including first and second seats and a valve member actuatable in one direction to engage said first seat by movement of said exhaust valve member to the open position and actuatable in the opposite direction to engage said second seat by movement of said second contact member during a contact engaging operation of the circuit breaker, said se'rvo valve member when engaged with said second seat establishing a differential force on said exhaust valve member derived from atmospheric pressure and in such direction as to ready said exhaust valve member to follow the movement of said second contact member during said initial opening phase of the circuit breaker and effect opening of said exhaust valve, and said servo valve member whenengaged with said first seat establishing a time delayed force on said exhaust valve member derived from said pressurized gas within said chamber and in such direction as to cause said exhaust valve member to reengage its seat and hence shut off flow of pressurized gas through said second contact member.

2. A gas blast circuit breaker as defined in claim 1 and which further includes means coupling said second contact member to said movable exhaust valve member to effect a wider separation of said second contact member from said first contact member upon movement of said exhaust valve member in such direction as to reengage its seat.

3. A gas blast circuit breaker as defined in claim 1 and which further includes damping means cooperative with said second contact member for damping movement thereof in a closing movement of said contact members.

4. A gas blast circuit breaker as defined in claim 1 wherein said movable exhaust valve member is tubular and said movable servo valve member has an annular configuration and surrounds said movable exhaust valve member concentrically.

5. A gas blast circuit breaker comprising a chamber having a continuous filling of pressurized gas, first and second nozzle type contact members disposed within said chamber, said first contact member being actuatable towards and away from said second contact member to effect 5. engagement and disengagement respectively of said contact members, said second contact member including spring means establishing a yieldable mounting therefor enabling said second contact member to follow said first contact member for a predetermined distance without separating therefrom during an initial opening phase of the circuit breaker, a gas exhaust valve correlated to the interior of said second contact member and which serves when opened to discharge to atmosphere the pressurized gas flowing through said second contact member from said chamber when said contact members become disengaged, said exhaust valve including a valve seat and a movable valve member constituted as a pressure differential piston, said exhaust valve member being held against its seat by pressure exerted on said second contact member by said first contact member when said contact members are engaged, and a servo valve for said exhaust valve actuatable in one direction to a first position by yielding movement of said second contact member during a contact engaging operation of said circuit breaker as a result of pressure exerted by said first contact member and being actuatable in the opposite direction to a second position by movement of said exhaust valve member towards its open position, said servo valve when in said first position establishing a pressure differential on said exhaust valve member acting in the opening direction thereof, and said servo valve when in said second position establishing a pressure differential on said exhaust valve member acting in the closing direction thereof to effect a time-delayed reclosure thereof.

6. A gas blast circuit breaker as defined in claim 5 and which further includes means coupling said second contact member to said movable exhaust valve member to effect a wider separation of said second contact member from said first contact member upon movement of said exhaust valve member in the closing direction thereof.

7. A gas blast circuit breaker as defined in claim 5 wherein said exhaust valve member is tubular and said servo valve has an annular configuration and surrounds said exhaust valve member concentrically.

References Cited by the Examiner UNITED STATES PATENTS Re. 25,631 8/1964 ForWal-d 200l48 ROBERT K. SCHAEFER, Primary Examiner.

ROBERT S. MACON, Examiner.

Claims

1. A GAS BLAST CIRCUIT BREAKER COMPRISING A CHAMBER HAVING A CONTINUOUS FILLING OF PRESSURIZED GAS, FIRST AND SECOND NOZZLE TYPE CONTACT MEMBERS DISPOSED WITHIN SAID CHAMBER, SAID FIRST CONTACT MEMBER BEING ACTUATABLE TOWARDS AND AWAY FROM SAID SECOND CONTACT MEMBER TO EFFECT ENGAGEMENT AND DISENGAGEMENT RESPECTIVELY OF SAID CONTACT MEMBERS, SAID SECOND CONTACT MEMBER INCLUDING SPRING MEANS ESTABLISHING A YIELDABLE MOUNTING THEREFOR ENABLING SAID SECOND CONTACT MEMBER TO FOLLOW SAID FIRST CONTACT MEMBER FOR A PREDETERMINED DISTANCE WITHOUT SEPARATING THEREFROM DURING AN INITIAL OPENING PHASE OF THE CIRCUIT BREAKER, A GAS EXHAUST VALVE CORRELATED TO THE INTERIOR OF SAID SECOND CONTACT MEMBER AND WHICH SERVES WHEN OPEN TO DISCHARGE TO ATMOSPHERE THE PRESSURIZED GAS FLOWING THROUGH SAID SECOND CONTACT MEMBER FROM SAID CHAMBER WHEN SAID CONTACT MEMBERS BECOME DISENGAGED, SAID EXHAUST VALVE INCLUDING A VALVE SEAT AND A MOVABLE VALVE MEMBER CONSTITUTED AS A PRESSURE DIFFERENTIAL PISTON, SAID EXHAUST VALVE MEMBER BEING HELD AGAINST ITS SEAT BY SAID SECOND CONTACT MEMBER WHEN SAID CONTACT MEMBERS ARE ENGAGED, AND A SERVO VALVE INCLUDING FIRST AND SECOND SEATS AND A VALVE MEMBER ACTUATABLE IN ONE DIRECTON TO ENGAGE SAID FIRST SEAT BY MOVEMENT OF SAID EXHAUST VALVE MEMBER TO THE OPEN POSITION AND ACTUATABLE IN THE OPPOSITE DIRECTION TO ENGAGE SAID SECOND SEAT BY MOVEMENT OF SAID SECOND CONTACT MEMBER DURING A CONTACT ENGAGING OPERATION OF THE CIRCUIT BREAKER, SAID SERVO VALVE MEMBER WHEN ENGAGED WITH SAID SECOND SEAT ESTABLISHING A DIFFERENTIAL FORCE ON SAID EXHAUST VALVE MEMBER DERIVED FROM ATMOSPHERIC PRESSURE AND IN SUCH DIRECTION AS TO READY SAID EXHAUST VALVE MEMBER TO FOLLOW THE MOVEMENT OF SAID SECOND CONTACT MEMBER DURING SAID INITIAL OPENING PHASE OF THE CIRCUIT BREAKER AND EFFECT OPENING OF SAID EXHAUST VALVE, AND SAID SERVO VALVE MEMBER WHEN ENGAGED WITH SAID FIRST SEAT ESTABLISHING A TIME DELAYED FORCE ON SAID EXHAUST VALVE MEMBER DERIVED FROM SAID PRESSURIZED GAS WITHIN SAID CHAMBER AND IN SUCH DIRECTIONS AS TO CAUSE SAID EXHAUST VALVE MEMBERR TO REENGAGE ITS SEAT AND HENCE SHUT OFF FLOW OF PRESSURIZED GAS THROUGH SAID SECOND CONTACT MEMBER.