US2280321A - Gas blast circuit breaker - Google Patents

Description

April 21, 1942. H. THOMMEN l 2,280,321

GAS BLAST -CIRCUIT BREAKER l Filed Feb. 8, 1940 iatented Apr. 2l, 1942 GAS BLAST CIRCUIT BREAKER Hans Thommen, Baden, Switzerland, assigner to Aktiengesellschaft Brown, Boverl & Cie., Baden,

Switzerland Application February 8, 1940, Serial No. 317,949 In Germany November 17, 1938 (Cl. 20o-148) 8 Claims.

In order to check and diminish the frequency of the interruptions caused in networks by arc short circuits the conductors are quickly interrupted and switched in again by means of circuit breakers. The reclosing process should be performed so quickly that the power stations connected to the network conductors do not fall out of synchronism. For this reason the conductors should remain without voltage for only a fraction of a second. More recently this reclosing process has preferably been undertaken by means of switching devices having arcing contacts for interrupting current iiow and asecond set of contacts for the voltage isolation, a gas blast circuit breaker being used for interrupting the power, this ensuring a sumciently short operating time. Such ,circuit breaker arrangements can operate advantageously in such a manner that for a normal interruption both sets of contacts are opened in dependence on each other and one after the other, whilst when a disturbance occurs the arclng contacts are reclosed at least once during which time the voltage disconnecting contacts remain closed, but if the disturbance prevails the conductor is automatically switched out due to both sets of contacts being opened. In all known circuit breaker arrangements of this kind separate contact places are provided for interrupting the power and disconnecting or isolating the voltage.

The present invention deals with a gas blast circuit breaker having a single set of relatively y movable contacts that serve as an arcing gap subjected to an air blast for interrupting the tion and the isolation of the volt-age is main- Several constructional examples are illustrated diagrammatically in the accompanying drawing, Figures 1 to 3 showing a sectional view of the pressure chamber, all parts which are not essential for an understanding of the invention having been omitted from the drawing. Figs. 4a, 4b and 4c are curves illustrating the relationship between the contact separation and time for three different characteristic interruption conditions.

In Figs. 1-3, a represents a pressure chamber which for instance is made of insulating material and contains the contacts b, c. Gas under pressure is supplied to the pressure chamber a through a main control valve from a pressure gas reservoir A and when switching out, this gas flows through the Contact gap formed by the contacts b, c to the atmosphere, after having first spread over and de-ionised the opening arc and if desired, also passing through a silencer or, cooler. On the outflow side of the pressure chamber a is located a stop valve d that responds'to a gas blast through the contact gap to interrupt the blast.

In the constructional example shown in Fig. 1 the contact b is a nozzle contact on the exhaust side of the pressure chamber a and the countercontact c is a pin contact; both contacts are arranged to move in opposite directionsI in the pressure chamber. The nozzle contact b is carried by a piston i in a cylinder having ports m, m at its' opposite ends for the admission of pressure gas from chamber a and from a conduit lc, respectively. A spring e moves the piston i downwardly to engage the contacts b, c when the opposite sides of the piston i are subjected to the same gas pressure, and the piston moves upwardly to separate the contacts when pressure gas is admitted to the cylinder through port m but not through the upper port m. The countercontact c is for instance opened and closed by an electro-pneumatic control which is separate from the main control valve. In the example shown in Fig. 1 the power is interrupted due to the nozzle contact b moving relative to the stationary pin contact c, whilst for isolating the voltage the pin contact is moved a further distance from the elevated nozzle contact. The lengths of travel of contacts b, c therefore vary according to the various kinds of switching operation performed. The stroke of the nozzle contact b is smaller than that of the pin contact c because the former requires only to be moved such a distance that a gap is obtained which is suitable for extinguishing the arc by means of the gas blast, Whilst the pin contact c must be moved so arthat the required voltage isolation is achieved.

For a normal disconnection which can either be undertaken by hand or by remote control, the nozzle contact b is brought into the open position and the opening arc is extinguished by the gas blast, the nozzle contact returns to the closed position, and thereupon the voltage is isolated by moving the pin contact c into its open posiopens into the cylinder of piston j' valve d is closed by the action of the outilowing pressure gas which passes through the valve bore to the rear side of the piston f and acts on this latter against the spring g. The conduit lc opens into the cylinder below the piston f to admit pressure gas when the valve d is to be held in open position. After the voltage has been isolated the main valve can be closed.

The opening and the closing of the switch system may be controlled by the usual relay circuits and electrically operated valves but, for simplicity of illustration, are shown diagrammatically in Fig. l as manually operable valves. The main valve V for initiating the opening of the switch system is located in the pipe or conduit n that connects the pressure storage tank A to the interior of the arcing chamber a. The flow of pressure gas through conduit Ic is controlled by a valve v; and the now of pressure gas to the cylinder B, for displacing the piston C to lower the pin contact c for voltage isolation, is controlled by the valve v in the conduit ic'.

When a fault occurs, a protective relay responds automatically to open the main valve, corresponding to valve V of the diagrammatically illustrated control system of Fig. l, thereby to admit pressure gas to the chamber a and to the lower face of the piston i through the port m, to initiate the opening movement of the nozzle contact b for interrupting the power, so that the arc can be extinguished. Pressure gas is not admitted to the conduit k at this step in the circuit opening operation. The separation of contacts b, c establishes an arc-extinguishing blast across the contact gap, and pressure gas passes to the upper face of the piston f through the hollow piston rod and thereby moves the piston f downwardly to interrupt the blast by closing the outlet for the pressure gas. The valve d may be opened and the arcing contacts b, c again closed, the main control valve V being still open, by admitting gas under pressure through the pipe k to the upper side of the piston i of the nozzle contact b and also below the piston f of the valve d. Thereupon thernozzle contact b returns to its closed position, the valve d opens and the contact place b, c is subjected to a second gas blast upon the subsequent closing of valve v in pipe k. When reclosing, care must be taken that the valve d opens only after the contacts b, c are closed. that is to say the pressure in the pressure chamber must be maintained during the reclosing operation. The reclosing operation can if necessary be repeated by means of a suitable arrangement ofthe protective relays and the electro-pneumatic control, before the final disconnection is effected by moving the pin contact c relative to the stationary contact d.

In the constructional example illustrated in Fig. 2 lar contact through which the pressure gas lcan ow to the atmosphere. This construction necessitates the provision of an additional stop valve d1, similar to valve d, and carried by the hollow rod of a piston f' that is normally held in retracted position by a spring g'.4 The pipe k at the side the control elementsl the pin contact c is constructed as a tubulla -contact in opposite directions.

adjacent the valve d'. The method of operation ot this arrangement corresponds to that shown in Fig. 1.

Fig. 3 shows an arrangement in which a xed nozzle contact b1 is arranged in the pressure chamber, the movable pin contact c being electropneumatically controlled in such a manner that it makes the required movements for interrupting the power` and isolating the voltage one after the other. A stop valve d, such as described with reference to Fig. 1, is provided above the fixed nozzle contact b1 to seal oi the pressure chamber a after the gas blast has extinguished 'the arc drawn between contacts brand c by the initial movement of the pin contact c. In a normal circuit opening operation, as indicated by the curve of Fig. 4a, the pin contact c is initially moved a short distance into a favorable arc-extinguishing position and, after the extinction of the arc, is moved into the end position corresponding to voltage isolation. When the relay system effects a reclosure of the contacts b1, c before the voltage-isolation displacement of the pin contact c, the reclosing operation is effected in accordance with the characteristic curve of Fig. 4b. If the fault is still on the Aline after this reclosure of the contacts, the pinl contact c is again displaced a short distance for arc extinction, and is thus displaced further for voltage isolation, as shown by the curve of Fig. 4c.

The pin contact can in this case be constructed as a tubular contact, as shown in Fig. 2, so that the pressure gas can escape from the place of After the ilrst partial travel stroke for interrupting the power has been accomplished, the movable contact can be temporarily stopped by any known means. It is also possible for instance to compensate the movement of the contact by means of pressure gas so that the pin contact has an oscillating movement during the rst contact stroke.

Although several embodiments of the present invention have been illustrated and described,.it

will be apparent to those skilled in the art that various changes and modications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

l. In a gas blast circuit breaker, a pressure chamber, a nozzle contact extending through a wall of said chamber, a piston slidable in a cylinder and carrying said nozzle contact, ports at the opposite ends of said cylinder and opening into said pressure chamber and and a conduit respectively, spring means urging said nozzle contact into circuit closing position, a cooperating contact within said chamber for closing the bore of said nozzle contact when said contacts are engaged, and valve means at the exterior of said chamber and responsive to the flow of pressure gas through said nozzle contact to terminate the escape of pressure gas through said nozzle contact upon a separation of said contacts.

2. In a gas blast circuit breaker, a pressure chamber, anozzle contact extending through a wall of said chamber, a piston carrying said nozzle contact and slidable in a cylinder open to said chamber, a cooperating contact within said chamber, spring means in said cylinder urging said nozzle contact into engagement with said cooperating contact; a valve at the exterior of said chamber for closing the bore through said nozzle contact, a piston and hollow piston rod carrying said valve, spring means urging said valve towards open position, said hollow piston stein being alined with said nozzle contact to pass pressure gas to the rear of the associated piston to close said valve, and means for admitting pressure gas to said pistons to move the first piston into contact-closing position and to move the 'second piston into valve-opening position.

3. In a gas blast circuit breaker, a pressure chamber, a nozzle kcontact in said chamber and having a bore opening to the exterior thereof, a cooperating contact in" said chamber, means for moving one of said contacts away from the other to separate said contacts for the interruption of current ow, means for supplying pressure gas to said chamber to establish an arc-extinguishing blast through the gap between the separated contacts, means responsive to the blast through the bore of said nozzle contact to close said bore, and means for moving said cooperating contact away from said nozzle contact for voltage isolation.

4. In a gas blast circuit breaker, a pressure chamber, a nozzle contact in said chamber and having a bore opening to the exterior thereof, a

cooperating contact in said chamber, means supporting said nozzle contact for movement away from said cooperating contact for the interruption of current ilow, means for supplying pressure gas to said chamber to establish an arcextinguishing blast through the gap between the separated contacts, means responsive to the blast through the bore of said nozzle contact to close said bore, and means for moving said cooperating contact away from said nozzle contact for voltage isolation.

5. An electric circuit breaker comprising an arcing chamber having an outlet, a pair of co- I\perating contacts arranged in said chamber,

means for separating said contacts, means for producing a uid blast across said contacts for extinguishing an arc drawn therebetween upon separation thereof, valve means for controlling the escape of pressure iluidlfrom said outlet upon a separation of said contacts, a iluid pressure motor operable in one direction by pressure iluid escaping from said outlet to move said valve means into closed position to terminate the escape of pressure fluid from said outlet, and means for admitting pressure iluid to said motor to operate the same in the opposite direction to open said valve means.

6. An electric circuit breaker as claimed in claim 5, wherein said means for separating said contacts comprises means for initially separating said contacts to draw an arc between the same, and means for effecting a further separation of said contacts for voltage isolation.

7. An electric circuit breaker comprising an arcing chamber, a pair of cooperating contacts within said chamber, each contact being hollow and having a bore opening to the exterior of the arcing chamber, means for separating said contacts, means for admitting a pressure gas to said arcing chamber to produce a blast across said contacts `for extinguishing an arc drawn therebetween upon separation thereof, the pressure gas escaping from said arcing chamber through the bores of said contacts, and means responsive to the escape of pressure gas through said bores for closing the same.

8. An electric circuit breaker as claimed in claim 7, wherein said means for separating said contacts includes means operable individually to move the respective contacts away from each other.

HANS THOMMEN.

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