EP1580783B1 - Control device for the coordinated actuation of at least two switching devices, of which one is a vacuum switch - Google Patents

Description

DESCRIPTION

The invention relates to a control device for the coordinated actuation of at least two switching devices electrically connected in series to constitute a switching assembly of which a first switching device in the vacuum comprises a pair of separable contacts for the switching between a closed position and an open position. The control device comprises a main operating shaft for operating a second switching device immersed in a gaseous insulating fluid contained in a certain volume at a predetermined pressure, and further comprises an auxiliary shaft adapted to be displaced by coupling means for allow the operation of a moving contact of the first switching device during a displacement of the main shaft, the movable contact being held in abutment against the other contact in the closed position of the first device by a force intended to produce a contact pressure greater than a determined value. It is well known that a certain contact pressure is generally necessary when a vacuum interrupter is closed, in order to prevent the contacts from separating under the effect of the electrodynamic repulsion forces. particularly if a short-circuit current flows through the switch.

A device of this kind is known in particular from the patent document WO9708723 . The control device for operating a hybrid high voltage circuit breaker comprises a main operating shaft for operating a dielectric insulating gas switch such as SF ₆ . This hybrid circuit breaker is insulating in the air, since the gas switch breaking chamber is contained in an insulating casing which has fins on its outer surface. The main operating shaft is contained in a compartment delimited by a housing, which communicates with another compartment delimited by the insulating envelope of the gas switch to allow the main shaft to be connected to the moving contact of the switch. . This housing is sized to contain a vacuum switch whose fixed contact is connected to one of its walls. The housing is therefore a pole of the hybrid high voltage circuit breaker.

A connection terminal of this pole of the hybrid circuit breaker is fixed to the housing being interposed between the two compartments, so that the permanent current in the circuit breaker does not pass through the vacuum switch whose function is to support the transient voltage recovery during a power interruption. The movable contact of the vacuum interrupter is electrically connected to the moving contact of the gas interrupter by a connecting braid, and is actuated by an auxiliary shaft which comprises spring means for producing a sufficient contact pressure when the vacuum interrupter is closed. This auxiliary shaft is perpendicular to the main shaft and is coupled by a bracket-shaped lever which pivots about an axis fixed to the housing, which allows a movement return substantially 90 °.

The vacuum interrupter is subjected to the pressure of the dielectric insulating gas which fills the two compartments. Since a virtually zero pressure prevails in the sealed chamber of the vacuum interrupter, also known as the vacuum interrupter, this chamber must be designed to withstand the external gas pressure forces which may be particularly intense, particularly on the insulating cylindrical wall. as well as the metal bellows of the vacuum bulb. If the pressure of the insulating gas must be relatively high, generally greater than five bars when using a gas mixture with a proportion of nitrogen greater than 80% as known from the state of the art, or using pure nitrogen, it is possible to use a vacuum bulb whose structure of the sealed chamber is designed to resist this pressure, but this type of vacuum switch is still rare and particularly expensive. It is also possible to provide a protective reinforcement around the vacuum switch, as known from the Japanese patent document. JP 20003045300 which describes the realization of a resin molding around a vacuum ampoule intended to be immersed in a pure nitrogen medium under a pressure of several bars. This solution is still expensive to implement, and it remains difficult to avoid a too high pressure of insulating gas is applied in particular on the metal bellows of the bulb at the risk of deforming or breaking.

It is also known from the patent application in Europe EP 1,310,970 another device of this type, which uses different coupling means to allow the operation of the movable contact of the vacuum switch by an auxiliary shaft coupled to the main shaft. In addition, the two switching devices (not shown in this patent document) are electrically connected in series via, in particular, a casing which encloses the coupling means and which communicates with the interrupting chamber of the switch. gas. As a result, the permanent current in the hybrid circuit breaker passes through the vacuum interrupter. The auxiliary shaft comprises resilient means such as, for example, an arrangement of disc springs or Belleville washers to produce a sufficient contact pressure when the vacuum interrupter is closed. These elastic means are housed inside an abutment member having substantially the shape of a socket whose bottom is pierced to be traversed by the auxiliary shaft. This abutment member is firmly inserted inside a flange which is connected to the housing and which participates in the electrical connection in series of the two switching devices. During an opening of the vacuum switch, the elastic means deform being maintained between the bottom of the sleeve and a collar secured to a shaft of the auxiliary shaft. The free distance between this collar and a shoulder of the bushing determines the remaining travel for the moving contact of the vacuum interrupter until the switch is fully open.

The vacuum switch is located in a compartment adjacent to the compartment defined by the housing. The two adjacent compartments communicate through the interior space of the abutment member, even though the passage for the insulating gas through the aforementioned spring arrangement is relatively narrow. Therefore, if the pressure of the insulating gas in the gas switch break chamber is to be relatively high, the vacuum switch compartment will inevitably be subjected to the same or nearly equal pressure. The problem of resistance to pressure for the sealed chamber of the vacuum interrupter can therefore also arise with such a hybrid circuit breaker device.

On the other hand, elastic means such as washers for producing the contact pressure in the vacuum switch do not allow to obtain a significant stroke for the movable contact of the switch. Typically, elastic washers allow a maximum stroke of the order of a centimeter. However, hybrid high-voltage circuit breakers will be required to respond to increasingly higher voltage ranges, which will require adopting vacuum switches with a spread of contacts increasingly important, typically greater than two centimeters. It seems in this case difficult to be able continue to use disk washers or springs in the control device of a vacuum interrupter, since the maximum spacing of the contacts of this switch would then be limited by the characteristics of these elastic contact pressure means independently of the intrinsic characteristics of the switch. It may be recalled in this regard that the maximum intrinsically permissible stroke for the moving contact of a vacuum interrupter generally depends on the elastic limits of the metal bellows sealing switch.

The adoption of conventional coil springs can achieve the desired travel for the movable contact of the vacuum switch. But because the contact pressure is conventionally provided integrally by a mechanical spring, the dimensions and the moving mass of the spring contact pressure device must inevitably increase with the maximum intensity of short circuit allowed by the switch.

The object of the invention is to remedy these drawbacks. A first object of the invention is to make it possible to increase the insulating gas pressure in a gas switch of a switching assembly, and in particular of a hybrid cut-off switching assembly, without this necessitating increasing the protection of the vacuum interrupter against the pressure of the gas surrounding its sealed chamber, in particular at the level of the metal sealing bellows. A second object of the invention is to propose a control device for a switching assembly comprising a vacuum interrupter, which allows to possibly do without a mechanical elastic arrangement to produce the contact pressure in the switch or that allows at least such an elastic arrangement does not have to produce alone the essential of the contact pressure required for the switch to pass a short-circuit current. Finally, an ancillary purpose is to allow the movable contact of the vacuum interrupter to be operated over the entire stroke intrinsically allowed for the switch.

For this purpose, the subject of the invention is a control device as defined above, characterized in that the auxiliary shaft passes through a wall which separates the volume of gaseous insulating fluid from another volume of fluid at a pressure. lower, the difference of the respective pressures of the two fluids providing a certain force which is applied to the auxiliary shaft and which participates in the contact pressure force.

According to a first advantageous embodiment, a portion of the auxiliary shaft is constituted by a piston able to be displaced inside a bore formed by a part which is sealingly mounted on an opening of the wall, insulating gas sealing means being arranged between the piston and the bore. Preferably, the wall and the bore constitute a conductive assembly electrically connected to a pole of the second switching device, the piston comprises at least one electrically conductive portion connected to the moving contact of the first switching device, and sliding contacts are arranged between bore and the conductive portion of the piston. The wall may be constituted by a face of a housing which encloses at least a portion of the gaseous insulating fluid volume and in which are arranged the coupling means.

If the switching assembly is intended to be used as an air-insulated switchgear, the housing is preferably open on one side which is sealingly connected to one end of an insulating jacket providing insulation in the housing. air between the two poles of the second switching device. The casing is then placed directly in the air, and has a role of sealing between the insulating gas of the second apparatus and the outside air.

If on the other hand the switching assembly is intended to be used as a shielded type of equipment in a metal enclosure, the housing then has a role of mechanical support and no longer sealing since the metal casing of the equipment is necessarily sealed between the volume of gaseous insulating fluid and the outside air.

According to a second embodiment, the wall is sealed to a conductive plate electrically connected to a pole of the second switching device and has a flexible zone in the center of which is provided an opening which is traversed with sealing by the auxiliary shaft. The flexible zone of the wall then constitutes a sealing bellows which has a mechanical role of producing a differential pressure force. Preferably, the auxiliary shaft comprises a portion in the form of a guide piston adapted to be moved with electrical contact inside a bore electrically connected to the conductive plate.

In the two aforementioned embodiments, the coupling means may comprise mechanical elastic compression means capable of exerting a resultant force on the auxiliary shaft to participate in the contact pressure force in addition to the force provided by the difference of the respective pressures of the two insulating fluids

The invention, its characteristics and its advantages, are specified in the description which follows, with reference to the appended drawings which illustrate certain embodiments thereof by way of non-limiting examples.

The figure 1 schematically represents a control device according to the invention, applied to a cutoff and disconnection assembly known per se and shown in the closed position of current flow.

The figure 2 schematically represents the control device of the figure 1 in the open position of interruption of the current by the switching assembly.

The figure 3 schematically represents a control device according to the invention, applied to a hybrid switching switching assembly in which the vacuum switching apparatus is disposed substantially perpendicular to the main axis of the switching apparatus in the gas .

The figure 4 schematically represents the control device of the figure 3 in the open position of the switching assembly.

The figure 5 schematically represents a control device similar to that of the figure 3 , in which is provided the possibility of a reclosing of the switchgear in the vacuum after the end of the circuit breaker function provided by the switchgear in the gas.

The figure 6 schematically represents a control device similar to that of the figure 5 , in an application for a shielded switching assembly.

The figure 7 schematically represents another control device according to the invention, wherein the coupling means between the main shaft and the auxiliary shaft allow a similar result to that provided by the control device of the figure 3 and in which a safety evacuation is provided in case of leakage at the gaseous insulating fluid sealing means.

The Figures 7a and 7b very schematically represent the operating principle of the mobile contact of the switching device in the vacuum through the rotating cam coupling means shown on the figure 7 .

The figure 8 schematically represents the control device of the figure 3 to which are added resilient means for increasing the contact pressure in the closed position of passage of the current in the switching assembly.

The figure 9 schematically represents an improvement of the mechanism for actuating the moving contact of the switching apparatus in such a vacuum that represented on the figure 3 , to increase the contact pressure in this device without increasing the maneuvering energy required for a control device according to the invention.

The figure 9a is an enlargement of the improved actuation mechanism that is shown on the figure 9 in the closed position of the switching assembly.

The figure 9b schematically represents the actuating mechanism of the figure 9a in the open position of the switching assembly.

The Figure 9c schematically represents another mechanism for improved actuation of the moving contact of the switching apparatus in a vacuum, allowing a result similar to that provided by the actuating mechanism of the figure 9 .

The figure 9d schematically represents another improved actuation mechanism of the moving contact of the switching apparatus in a vacuum.

The figure 10 schematically represents an alternative embodiment of the gaseous insulating fluid sealing means whose pressure is used for the operation of a control device according to the invention.

The figure 11 schematically represents an alternative embodiment of the control device shown in FIG. figure 10 , which comprises a safety space at atmospheric pressure operating on the safety principle used in the control device of the figure 7 .

The control device according to the invention which is schematically represented on the figure 1 is applied to a switching assembly, and more specifically a cutoff and disconnection assembly, as known in particular from the patent document WO 0074095 A1 . This document describes an operating mechanism for the combined actuation of two switching devices electrically connected in series, with a first switchgear device in a vacuum and a second switching device consisting of a switchgear disconnector arranged in air to provide a disconnect function after the power cut by the first device. The operating rod of the movable contact of the vacuum switch can be actuated in translation by means of a pivoting cam adapted to press against a shoulder secured to the rod at its end. The mechanism for providing contact pressure is not described in this document, but a conventional spring mechanism and / or electromagnetic drive may be used. The connecting rod of the pivoting knife is articulated on a lever integral in rotation with the cam, just as the main operating shaft is articulated on another lever to drive the cam in rotation.

Thus, a movement of the main operating shaft makes it possible to actuate the two switching devices in a coordinated manner, which allows the respective movable contacts of these devices to have movements which follow a determined temporal sequence. The profile of the cam allows here to quickly separate the contacts of the vacuum switch before that the rotation of the cam is sufficient to separate the pivoting knife from the fixed contact of the disconnector, which corresponds to a normal sequence for such a cutoff and disconnect assembly.

The cutoff and disconnect assembly shown on the figure 1 is similar on many points with that described in the patent WO 0074095 A1 . The first modification according to the invention for this state of the art consists in providing an enclosure filled with a gaseous insulating fluid G ₂ under a pressure P ₂ and in the volume V ₂ of which the disconnecting apparatus 10 is housed and a much of the control device. This enclosure comprises a metal casing 7 which is electrically connected to the pivoting knife 15 of the disconnector 10 and which is open on the side of the disconnector 10 to be assembled in a sealed manner with an end of an insulating casing 18. The fact of having the disconnector disposed in a pressurized gaseous medium which has better dielectric insulation properties than the ambient air makes it possible to increase the dielectric strength of the disconnector in the open position, or to reduce the dimensions of the disconnector without reducing its dielectric strength.

The casing 7 constitutes one of the two poles of the disconnector, and the insulating casing 18 ensures the insulation in the air between the casing and the other pole which supports the fixed contact 16 of the disconnector. It is placed directly in the air, and has a sealing role between the insulating gas G ₂ and the air. The tree main 2 maneuver comprises a translationally movable portion through the housing tightly to be connected to a not shown control mechanism. As in the device of WO 0074095 , coupling means 3 comprise a pivoting cam 14 integral with a lever on which is articulated a connecting rod 12 for actuating the pivoting knife 15. These means 3 allow to couple the respective movements of the main shaft 2 and the shaft auxiliary 4 which serves as operating rod of the movable contact 5 of the vacuum switch 1. This contact 5 is shown in the closed position of current flow, and bears against the fixed contact 6 of the vacuum switch to ensure the necessary contact pressure.

The auxiliary shaft 4 here comprises a piston 4A which passes through a sealed wall 7A of the casing 7 and which is able to be moved inside a bore 8 formed by a part which is sealingly mounted on an opening of said wall 7A. Sealing means 17 to the insulating gas G2, produced by an O-ring, are arranged between the piston and the bore 8. The piston 4A comprises at least one electrically conductive portion 4A2 which is assembled in electrical contact with the movable contact 5 of the vacuum switch. During the displacement of the piston 4A, the portion 4A2 of the piston also remains in electrical contact with the bore 8 by means of sliding contacts such as, for example, spring-loaded toric contacts known per se.

The bore 8 opens out of the casing 7 on a volume V ₁ filled with a fluid G ₁ maintained at a pressure P ₁ less than the pressure P ₂ of the gaseous insulating fluid G ₂ in the housing. The fluid G ₁ may be an insulating gas, of the same nature or different from G ₂ , or a liquid or a dielectric gel, or a small volume of air or other gas at the pressure P ₁ without dielectric properties and provided adjacent a volume of solid or dielectric gel that surrounds the sealed chamber of the vacuum interrupter to provide dielectric isolation between the two poles of the switch. On the figure 1 , the fluid G ₁ represented is an insulating gas contained in a rigid insulating envelope 11 fixed sealingly against the housing 7 around its bore 8.

The difference between the pressure P ₂ of the gas G ₂ inside the casing 7 and the pressure P ₁ of the gas G ₁ inside the sealed envelope 11 applies to the piston 4A a differential pressure force Fp which is the product of the value P ₂ -P ₁ and the section of the piston in the bore 8. Depending on these parameters, the differential pressure force Fp can be provided to ensure the contact pressure force necessary to maintain the contacts 5 and 6 of the vacuum switch 1 rest against each other even if a short-circuit current flows through the switch. It should further be noted that the total differential pressure force which is exerted on the movable contact 5 of the vacuum interrupter 1 is actually the sum of the the differential pressure force Fp defined above and the gas pressure force G ₁ exerted on the metal bellows 19 of the vacuum interrupter, because this bellows makes a mobile separation between the vacuum in the sealed chamber of the switch and the gas G ₁ around this chamber. In the following, the contact pressure force F _c is defined as the force to be exerted on the moving contact 5 of the vacuum interrupter in addition to the gas pressure force G ₁ exerted on the bellows d sealing the switch, in order to keep the contacts of the switch pressed against each other under specified current conditions.

On the figure 2 , the control device of the figure 1 is schematically shown in the open position of interruption of the current by the switching assembly. The part of the pivoting knife disconnector is not shown, but it will be understood from the position of the connecting rod 12 of operation of the pivoting knife of the disconnector that the knife is open. The movement of the main shaft 2 towards the bottom of the figure, driven by a not shown control device, causes the rotation of the pivoting cam 14, the profile of which is intended to press against the shoulder 4B of the auxiliary shaft 4 from the beginning of the rotation. The bearing force of the cam 14 against the shoulder 4B is provided sufficient to exceed the differential pressure force Fp which remains substantially constant over the entire stroke of the piston 4A. At the end of the piston stroke, as shown in the figure, the contacts 5 and 6 of the vacuum switch are separated with a spacing provided to not exceed the elastic limits of the metal bellows 19 of this switch.

On the figure 3 a control device according to the invention is shown schematically in an application for a switching assembly called hybrid breaker or hybrid circuit breaker, which associates the switchgear in a vacuum to a switchgear device in a gas . In what follows, these two switching devices are called respectively vacuum switch and gas switch. The gas switch 10, not shown on the left of the figure, typically has a moving contact assembly comprising a movable arc contact able to be operated in translation by the main shaft 2 for operating the hybrid circuit breaker. This main shaft is connected in conventional manner by an insulating rod to a control mechanism not shown to the right of the figure. The position of the shaft 2 corresponds here to the closed state of the hybrid circuit breaker, that is to say the state of passage of a permanent current in the circuit breaker. The vacuum switch 1 and the translation axis of the auxiliary shaft 4 are arranged in the same direction Y substantially perpendicular to the direction of the translation axis X of the main shaft 2, but it is conceivable to provide an angle different from 90 ° between these two directions.

The vacuum switch 1, the bore part 8, the piston 4A and the sealing means 17 are of the same type as the corresponding elements on the figure 1 . Preferably, the O-ring which constitutes the sealing means 17 is not in contact with the electrically conductive portion 4A2 in the form of a sleeve of the piston 4A, and is arranged in a housing of the part which forms the bore 8 so as to to be in permanent support against an annular element 27 mounted with seal on this part 4A2. The annular element 27 is not necessarily electrically conductive, and is provided to be able to be moved in abutment against the O-ring without significantly affecting the quality of the seal. The leakage rate of the gaseous insulating fluid G ₂ to the volume V ₁ of gaseous insulating fluid G ₁ can thus be maintained at a very low level over a year of operation of the hybrid circuit breaker.

Ideally, it will be sought for the amount of gas G ₂ fleeing to the volume V ₁ a mean value in time substantially equal to the loss of the gas G ₁ from the volume V ₁ to the outside of the insulating envelope 11. From in this way, if the gases G ₁ and G ₂ are of the same nature or have similar dielectric properties, the pressure P ₁ of gas in the envelope 11 can be maintained within a range of permissible extreme values [P _1min , P _1max ] to maintain the dielectric strength between the two poles of the vacuum interrupter 1 while not exceeding a maximum critical value for the mechanical structure of the switch. For safety, a device for measuring the pressure P ₁ may be provided in particular to control that this pressure remains above the low limit P _1min and prevent the tripping of the hybrid circuit breaker if P ₁ falls below this limit. Conversely, if the critical maximum value P _{1max is exceeded} , a safety device consisting of, for example, a prestressed spring valve 23 may be provided. Such a valve, which can be installed for example in an opening of the metal disk 22 which carries the fixed contact 6 of the vacuum interrupter 1 and which closes the envelope 11, is designed to open slightly in order to allow a clearance towards the atmosphere of a small amount of the gas G ₁ in overpressure relative to the maximum critical value. Of course, this solution assumes that the gas G ₁ does not present a danger to the atmosphere, and it is in this case advantageous to use pure nitrogen.

The difference of the respective pressures P ₂ and P ₁ of the two gaseous insulating fluids G ₂ and G ₁ gives a certain force F p which is applied to the auxiliary shaft 4 and which here by itself provides all the contact pressure force F _c , in the same way as for the device of the figure 1 . This force Fp is proportional to the square of the diameter D of the piston.

In a similar way to the switching assembly shown in the figure 1 , the metal casing 7 is open on the side of the gas switch 10 to be assembled in a sealed manner with an end of a insulating casing (not shown) which encloses the cut-off chamber of the gas switch. The casing 7 is one of the two poles of the gas switch 10 being electrically connected to the movable contact assembly, not shown, of this switch. The conductive portion 4A2 of the piston 4A remains in electrical contact with the bore 8 through sliding contacts 9. The hybrid circuit breaker thus formed is of the air-insulating type as well as the device of the figure 1 .

The coupling means 3 between the main shaft 2 and the auxiliary shaft 4 comprise a cam 30 which is integral in translation with the main shaft 2 and which can be formed by a section 2A of this shaft 2 as shown in FIG. . The surface of the cam 30 is arranged to allow the guiding of a rolling element or roller 31 which is integral in motion with the auxiliary shaft 4. The axis of this roller is mounted on a bearing carried by a cradle 4A3 which constitutes a part of the auxiliary shaft 4. This cradle is fixed on a part 4A1 inserted in the electrically conductive part 4A2 of the piston 4A, this part 4A1 not being necessarily conductive since the electrical conduction between the bore 8 and the contact mobile 5 of the vacuum switch is provided by the part 4A2. An end portion 4B of the cradle 4A3 of the auxiliary shaft 4 is slidable in translation in a guide element 13 which is fixed on a face 7B of the casing 7, this face being opposite to the face which constitutes the wall 7A crossed by the piston 4A of the auxiliary shaft.

Thus, during a tripping of the hybrid circuit breaker to interrupt the current, the translational drive of the main shaft 2 along the X axis allows, after a determined dead travel, to translate the auxiliary shaft 4 in translation. the Y axis until the complete separation of the contacts 5 and 6 of the vacuum switch as shown in FIG. figure 4 . The dead stroke of the main shaft 2 is defined here as the distance to be traveled by the shaft, and therefore also to be traversed by the moving arc contact of the gas switch, so that the cam 30 comes into contact with the wheel 31 from the closed state of the circuit breaker. It is well known that such a dead travel is generally necessary in a hybrid circuit breaker, so that the arc contacts of the gas interrupter separate with a certain relative speed substantially at the moment when the separation of the contacts of the vacuum switch. The dead stroke is also sometimes referred to as the relative speed setting distance of the gas switch arcing contacts, and typically corresponds to the mutual overlap distance of the two arcing contacts of the switch in a contact configuration. called tulip.

The cam and wheel coupling used here between the main shaft 2 and the auxiliary shaft 4 implements a well-known principle in the field of motion return mechanisms. Such coupling has also been used for a long time for coordinated control systems of several electrical switches including a vacuum switch. In particular, the patent document EP0132083 shows a device for actuating a vacuum switch and a disconnector from an operating shaft of the movable contact of the disconnector moved in translation by a single command. A cam integral in translation with this shaft is coupled to a caster integral in translation with the movable contact of the vacuum interrupter, this switch being arranged perpendicularly to the shaft. A contact pressure spring permanently applies a thrust on the moving contact of the vacuum switch, to obtain the necessary contact pressure in the switch in the closed position.

The coupling means 3 used in the present control device are therefore similar to those described in EP0132083 . It may be noted that the invention makes it possible advantageously to dispense with the indispensable contact pressure spring in a conventional control device, or in any case allows the force to be exerted by a mechanical spring device to be reduced, as shown later in the drawings. comments from figures 8 and 9 . Preferably, in the present control device according to the invention, the wheel 31 and the main shaft 2 are arranged so that a small clearance exists between these two elements in the closed state of the hybrid circuit breaker shown in FIG. figure 3 , and also during the course of the dead race by the main shaft during a tripping of the circuit breaker. Indeed, during the operation of the hybrid circuit breaker, it is known that the contacts of the vacuum interrupter can erode under the action of arcing during their separation and cause and over time a slight approximation of the movable contact to the fixed contact in the closed state of the switch. The low clearance mentioned above is intended to allow this slight approximation, which also allows that no stress caused by the contact pressure force on the auxiliary shaft 4 is applied to the main shaft 2 in the state closed circuit breaker hybrid.

The height of the cam 30 in the direction of the Y axis of translation of the auxiliary shaft 4 is provided as a function of the spacing e desired for the contacts 5 and 6 of the vacuum switch, as shown in FIG. figure 4 .

On the figure 4 , the control device of the figure 3 is shown schematically in the open position of the switching assembly. For the sake of simplification, the optional device for safety against the gas overpressure in the insulating envelope of the vacuum interrupter 1 is not shown in this figure. From the closed state of the hybrid circuit breaker shown on the figure 3 , the tripping of the circuit breaker is effected by a translation of the main shaft 2 along the X axis to the right of the figure to separate the arcing contacts from the gas switch 10. After the course of the dead travel by the main shaft 2, the main part 30A which corresponds to the so-called opening slope of the cam 30 comes into contact with the wheel 31 to translate the auxiliary shaft 4 in translation along the Y axis downwards from the FIG. . The movable contact 5 of the vacuum switch thus adopts a motion profile predetermined by the shape of the main portion 30A. The translation of the auxiliary shaft 4 is completed when the path of the wheel 31 leaves the main part 30A of the cam, that is to say when the surface of the cam on which the wheel is supported becomes parallel to the direction of the cam. X axis. It is thus possible to continue the mutual separation of the arcing contacts of the gas interrupter after the contacts 5 and 6 of the vacuum interrupter 1 are completely separated with the desired distance e, until 'at the end of the breaker function shown on the figure 4 . It may be noted that during the opening of the vacuum switch 1, the O-ring which constitutes the sealing means 17 remains in permanent abutment against the annular element 27 with which it seals the piston 4A with gas.

In the end position of the breaker function shown on the figure 4 , the wheel 31 is in abutment against the cam 30 by exerting thereon a force equal to the force Fp provided by the difference of the respective pressures of the two gases on either side of the piston 4A. The main shaft 2 and its cam 30 thus provide a locking function of the movable contact 5 of the vacuum switch in its open position.

On the figure 5 is schematically represented a control device similar to that of the figure 3 , in which the vacuum interrupter is closed again after the end of the circuit breaker function provided by the gas switch. The extra race performed here by the main shaft 2 after the end of the circuit breaker function can allow the switching assembly to provide a disconnector function in addition to the circuit breaker function, because the arc contacts of the switch to gas can be sufficiently far apart to provide a disconnection distance in the gaseous insulating fluid G ₂ of the switch. The section 2A of the main shaft 2 on which the cam 30 is formed is elongated with respect to the design of the cam of the device. figures 3 and 4 to allow to provide on the cam a secondary portion 30B with a so-called reclosure slope. This reclosing slope is inclined in the opposite direction to the opening slope of the main part 30A of the cam.

During the additional travel performed by the main shaft 2, the slope profile of the abutment 30B allows the wheel 31 and thus the auxiliary shaft 4 to approach the fixed contact of the vacuum switch so that the mobile contact come press this fixed contact with an instantaneous speed almost zero at the moment of impact. The same contact pressure force as that corresponding to the closed state of the hybrid circuit breaker is applied to the moving contact of the vacuum interrupter after its reclosing. Reclosing prevents the electrically connected parts of the movable contact of the vacuum interrupter from being at a floating potential when the hybrid switch-breaker is in the disconnection position, because such a floating potential could damage the switch. empty in certain configurations of the line that is sectioned by the switching set.

On the figure 6 is schematically represented a control device similar to that of the figure 5 , in an application for a shielded switching assembly. It may be noted that in this type of application, the casing 7 which is at the potential of the high voltage in operation must be electrically insulated from the sealed metal casing 42 which constitutes the shielded vessel of the switching assembly. Because this sealed tank encloses the gaseous insulating fluid G ₂ of the gas circuit breaker at a certain pressure P ₂ , it is not essential that the casing 7 is also gas-tight, except for providing, for example, a gas pressure. higher in the crankcase than in the space remaining between this crankcase and the tank. In the present application, the housing 7 is open, and has the same role of electrical conductor and mechanical support in the control devices according to the invention shown above for air-insulated switchgear assemblies.

The main shaft 2 and its cam 30 are provided to allow the switching assembly to provide a disconnector function in addition to the circuit breaker function. Optionally, a conductive portion of the main shaft 2 is electrically connected to the casing 7 by sliding contacts and is provided at its outer end to the housing of a stud 2B on which is articulated an insulating rod which forms a portion 2C of the shaft 2 and which crosses with sealing the tank 42 of the shielded assembly to be connected to a control mechanism not shown. The pad 2B is arranged to come into electrical contact with a terminal 43 fixed to the tank 42 and through which the insulating rod 2C of the shaft 2 passes, thanks to an additional stroke of the shaft 2 after the end of the disconnecting function. The casing 7 is thus potential-ground to the tank 42, via the conductive part of the main shaft 2. This makes it possible to ground the shielded line which is connected to the fixed contact of the vacuum switch, since this switch was closed at the end of the circuit breaker function and therefore its fixed contact is electrically connected to the housing 7. The central conductor 50 of the shielded line is here immersed in the gas G ₁ surrounding the sealed chamber of the vacuum switch and whose pressure P ₁ is lower than the pressure P ₂ of the gas G ₂ surrounding the gas switch. The switching assembly thus produced is a shielded hybrid switch-breaker which can provide an additional grounding function on one side of the line.

The figure 7 schematically represents another control device according to the invention, shown in the closed state of the switching assembly. The auxiliary shaft 4 is identical to that of the control device of the figure 3 . It similarly carries a roller 31 intended to be displaced by a cam, and is likewise able to slide in translation in a guide element 13 fixed to the casing 7. The coupling means between the main shaft 2 and the 'tree auxiliary 4 here use a rotary cam 14 'to act on the wheel 31. The rotation shaft 48 of the cam 14 'is mounted on bearings fixed to the casing 7, and is integral in rotation with a wheel 32 which comprises a circular toothing meshing with a rack 21 carried by the main shaft 2. Thus , a translation of the main shaft causes the rotation of the cam 14 'whose profile is intended to act on the wheel 31 after a certain dead stroke of the main shaft, in a coordinated manner with the separation of the contacts of the switch gas.

The dielectric medium around the sealed chamber of the vacuum interrupter is constituted here by a dielectric material 28 molded around this chamber and contained in an insulating envelope 11. In known manner, the insulating envelope 11 could as well be constituted by the dielectric material 28 overmolded if this material has sufficient mechanical rigidity and weather resistance. Only a small volume V ₁ of gaseous fluid G ₁ is adjacent to the sealed chamber of the vacuum interrupter, between the flange of the chamber traversed by the moving contact of the switch and the bore part 8 in which can slide the piston 4A of the auxiliary shaft 4. The gas G ₁ is not necessarily insulating, since it has no role of dielectric insulation to ensure between the poles of the vacuum switch, and it It is not necessary to control the pressure of this gas since a possible leak would not have any consequences on the dielectric insulation between the poles.

Sealing means 26 are provided here to prevent any communication between the volume V ₁ and the outside atmosphere, and the gas G ₁ is filled at a pressure higher than the atmospheric pressure so that a possible leakage of the volume V _{1 is} carried out in one direction towards the outside atmosphere. This provision aims to maintain a volume V ₁ free of moisture and dust of the outside atmosphere. Preferably, the gas G ₁ is filled at the factory, during assembly of the switching assembly, at a pressure for example of the order of twice the atmospheric pressure and which corresponds to the temporary filling pressure of the gas G ₂ in the casing 7 for the safe transport of the switching assembly before final on-site filling for operation. It is therefore not necessary to fill and control the volume V ₁ after the switching assembly is out of the factory, which is significant for the operator. It may be noted that the sealing means 26 are not essential, since it would be acceptable for the volume V _{1 to} be filled with air in communication with the outside atmosphere if the flange which is traversed by the moving contact of the switch vacuum is provided to operate in such a configuration.

The bore part 8 comprises a radial orifice 24, which communicates the external atmosphere with an interstitial space between the piston 4A and the bore 8 and which opens into this interstitial space between the sealing means 17 and the switch empty, of so that a possible gas leak G ₂ of the volume V ₂ of the casing 7 through the sealing means 17 is discharged to the outside atmosphere. Thus, such a leakage of the gas G _{2 would} not cause an increase in the gas pressure in the volume V ₁ , and it is therefore unnecessary to install between this volume and the external atmosphere a safety device such as a valve. overpressure evacuation as the valve 23 of the device of the figure 3 . The radial orifice 24 constitutes in itself a safety evacuation in the event of leakage of the gas G ₂ through the sealing means 17.

The Figures 7a and 7b very schematically represent the principle of operation of the movable contact of the vacuum switch through the rotating cam 14 '. The figure 7a reproduces the configuration of the figure 7 in which the contacts of the vacuum interrupter 1 are closed. In practice, it may be noted that a small clearance is required between the rolling surface of the wheel 31 and the surface of the arcuate portion of the cam 14 'which corresponds to the path of the idle stroke.

The figure 7b corresponds to the configuration of the figure 7 after tripping of the hybrid circuit breaker and at the moment when the contacts of the vacuum interrupter are completely separated with the desired distance e. The cam has made a rotation of almost 180 ° here, which can be continued while maintaining the spacing e. It may be noted that the profile of the cam would allow a reclosing of the vacuum switch by an additional stroke of the main shaft 2 and provided of course that the rack 21 has a sufficient length.

The coupling by a rotary cam allows a result similar to that obtained by a coupling using a cam in translation as in the control device of the figure 3 . The control device of the figure 7 may have as advantages on the one hand to be able to reduce the relative speed of impact between the respective surfaces of the cam 14 'and the wheel 31 at the end of the dead stroke, and on the other hand to greatly reduce the transverse forces exerted on the main shaft 2, which allows in particular to limit the wear of the longitudinal guide elements of the shaft. However, such a coupling is more expensive to achieve than a coupling using a cam in translation.

The control device shown schematically on the figure 8 constitutes an improvement of the control device of the figure 3 . Mechanical means of elastic compression are in fact added to reinforce the contact pressure in the closed position of passage of the current in the switching assembly. These resilient compression means comprise a spring 35 which is mounted prestressed on the auxiliary shaft 4 in the direction of the axis Y of the shaft. This spring 35 has one end which bears against a pusher element 34 housed in an abutment member 34 'fixed to the cradle 4A3 of the shaft 4, and has another end which bears against the piston 4A of the shaft . This pusher element 34 is able to be brought closer to the other end of the spring 35, by detaching from its stop position held by the member 34 ', when a low amplitude compression of the spring 35 is performed under the action of a finger 33 which is fixed to the main shaft 2 and which is here provided to slide against the push member 34.

Such compression of the spring 35 makes it possible to apply to the auxiliary shaft 4 a force which is added to the differential pressure force Fp provided by the difference in the respective pressures of the two gaseous insulating fluids, and which reinforces the pressure force. contact F _c in the closed position of the switching assembly, that is to say the closing position of the switching device in the gas. Such a configuration can be advantageous if the force Fp proves insufficient to ensure by itself the contact pressure force F _c necessary to withstand the electrodynamic forces tending to move the contacts of the vacuum switch in the case of a short circuit current. This configuration may indeed be preferred to the alternative which would be to increase the diameter of the piston 4A to increase the differential pressure force, because it allows to maintain a minimum value of contact pressure force even in case of significant gas leakage from the volume of the gas switch. Such a minimum value of contact pressure force provided by a mechanical spring would make it possible to maintain operating the switching assembly in its closed position to pass a nominal current, even in the unlikely event that the volume of the gas switch would be reduced to atmospheric pressure following a very significant gas leak . There would thus be no repulsion (with separation) of the contacts of the vacuum interrupter and arcing of arcs between the contacts, provided that said minimum value of contact pressure force exceeds the minimum value required for a rated current specified.

Thus, the addition of a mechanical spring system to reinforce the contact pressure in a control device according to the invention can constitute an appreciable security in terms of safety and continuity of operation of the switching assembly provided with the control device. Other configurations than that of the device of the figure 8 for such additional systems with mechanical springs can be envisaged, and the mechanical energy of the spring or springs can be used to participate in the work of complete separation of the contacts of the vacuum switch, as shown in the following.

A complementary system with mechanical springs is shown schematically on the figure 9 , allowing an improvement of the actuating mechanism of the moving contact of the switching apparatus in the vacuum as shown in FIG. figure 3 . This complementary system has mechanical means of elastic compression which comprise two springs 36 and 37 each acting on a pivoting arm whose one end comprises a wheel arranged to press against a profiled rolling surface on the cradle 4A3 of the auxiliary shaft 4, on the side of the end 4B of the shaft 4 which can slide in translation in a guide member 13 'fixed to the housing.

This complementary system with springs is shown in enlargement on the figure 9a . The two pivoting arms 38 and 39 each carry a wheel 40 and 41 respectively. The two profiled rolling surfaces on the cradle 4A3 are here symmetrical, as are the provisions of the springs 36 and 37 and the pivoting arms. In the closed position of the switching assembly, the resulting force F _r exerted by the spring system is directed along the Y axis of the auxiliary shaft 4, due to the symmetry of the arrangement of the system with respect to this axis. The profile of the rolling surfaces on the cradle 4A3 is provided so that the resulting force F _r is directed in the same direction as the differential pressure force F _p , thus participating in the contact pressure force F _c which is equal to the sum Fp + F _r . This profile is also designed so that the force F _r changes direction along the Y axis, during a displacement of the auxiliary shaft 4 consecutive to a maneuver of the main shaft 2 for opening or closing the switching assembly.

The change of direction of the force F _r is visible on the figure 9b which represents the actuating mechanism in the open position of the switching assembly at the end of the circuit breaker function. Each rolling surface has a profile with a lateral boss, so that the projected component on the Y axis of the force exerted by a spring 36 or 37 on the auxiliary shaft 4 vanishes to change direction when the contact between a wheel 40 or 41 and the running surface passes the top of the lateral boss. The top of such a boss is defined as the zone of the boss furthest from the Y axis. Thus, when the roller 31 carried by the auxiliary shaft 4 passes through the main part 30A of the cam 30 causing the displacement of the shaft, during an opening or closing of the switching assembly, the force F _r decreases in absolute value to cancel and change direction.

During the opening of the switching assembly, the force F _r changes direction to oppose the differential pressure force Fp. It may be noted that such a change of direction makes it possible to reduce somewhat the work to be performed by the control mechanism of the main shaft 2 for complete opening. It is understood that the energies of the springs as well as the profiles of the lateral bosses are provided so that the force F _r remains lower than Fp in absolute value, so that the auxiliary shaft 4 is always subjected to a resultant force equal to the sum of the mechanical and pneumatic forces which is directed towards the vacuum interrupter to allow a closing (or reclosing) of the contacts of the switch.

On the Figure 9c is schematically shown another mechanism for improved operation of the moving contact of the switching apparatus in the vacuum. The result is similar to that provided by the actuating mechanism of the figure 9 , and allows to a lesser extent to increase the contact pressure in this device without increasing the maneuvering energy required for the control device. The two identical springs 36 and 37, arranged symmetrically with respect to the Y axis, each have a first end articulated in rotation on a fixed support, and a second end articulated in rotation on the auxiliary shaft. The change of direction of the force F _{r is} effected when the two springs are simultaneously oriented in the same direction perpendicular to the axis Y of the auxiliary shaft, which occurs in practice when the tree has traveled most of the stroke e for the desired spacing of the contacts of the vacuum switch.

On the figure 9d is schematically shown another improved actuation mechanism of the movable contact of the switching apparatus in the vacuum, which advantageously combines the two previous solutions. The cradle 4A3 of the auxiliary shaft 4 comprises a single profiled running surface on which is supported a wheel mounted at one end of a pivoting arm. As for the solution described with reference to figures 9 , 9a and 9b , one end of a spring 37 acts on this pivoting arm, and the profile of the rolling surface has a lateral boss provided so that the projected component on the Y axis of the force exerted by the spring 37 on the auxiliary shaft 4 can be canceled to change direction. The cradle 4A3 also has a pivoting hinge attached to one end of another spring 36 as in the solution described with reference to the Figure 9c . The spring 36 has a lower energy than the spring 37, and the resulting force F _r exerted by the two springs on the shaft 4 has a component F _r X which is oriented towards the gas switch, along the axis of X translation of the main shaft 2.

This orientation of the component F _r X makes it possible to reduce the instantaneous forces at the contact surface 13'A between the end 4B of the shaft 4 and the guide element 13 'fixed to the casing 7. These instantaneous forces are indeed relatively important when the cam 30 comes into contact with the wheel 31 during an opening operation of the switching assembly, due to the instantaneous speed of several meters per second for the translation of the main shaft 2, and a fortiori if the opening slope of the main portion 30A of the cam 30 is relatively pronounced. It may be noted that the presence of the pivoting spring 36 is not essential, and its main role is to reinforce if necessary the component F _r Y of the resultant force F _r along the Y axis while decreasing the component F _r X.

On the figure 10 is schematically represented an alternative embodiment of the gaseous insulating fluid sealing means G ₂ of the gas switch and whose pressure P ₂ is used for the operation of a control device according to the invention. There is no provision for gas sealing means in the interstitial space 49 between the piston 4A 'and the bore part 8' which carries the sliding contacts 9. The piston essentially has a role of mechanical guiding of the auxiliary shaft 4 and electrical conduction between the movable contact of the vacuum switch and a conductive plate 20 electrically connected to a pole of the gas switch, this plate 20 may constitute a face of a metal housing as referenced 7 in the previous achievements. The vacuum switch is surrounded by a gas G ₁ which is distributed on both sides of the piston 4A 'with substantially the same pressure P ₁ . The piston 4A 'may comprise a passage formed by a small channel 25, but such a channel is not normally necessary because even a relatively slow equalization of the pressure of the gas G ₁ between the two sides of the piston is effected by the interstitial space 49 not gas tight. Preferably, a device 45 for measuring the pressure P ₁ is provided in particular to control that this pressure remains above the low limit P _1min .

The wall 7 'which separates the two gaseous insulating fluids G ₁ and G ₂ is sealingly sealed to the conductive plate 20, and has a flexible zone in the center of which is provided an opening which is traversed with sealing by the auxiliary shaft 4 This wall 7 'is in the form of a sealing bellows, and may be made from a metal intended to provide a flexibility and sufficient mechanical strength. It preferably has the shape of a disk open at its center for the passage of the shaft 4. Its diameter may be much greater than the diameter of the piston 4A ', the latter can also be decreased as the electric conduction section by the sliding contacts 9 remains in adequacy with the current to be passed through the switching assembly. By increasing the diameter of the wall 7 ', it is possible to obtain a differential pressure force Fp greater than that which would be obtained by a sealed piston control device as represented for example on the figure 3 , this comparison meaning for substantially equal moving masses between the two control devices. In addition, since in a bellows-type solution, there is no movable surface relative to a seal, it is possible to obtain a very good seal at the sealed connection between the bellows and a movable assembly as constituted here by the auxiliary shaft 4.

The leakage rate of the gas G ₂ at the pressure P ₂ to the volume V ₁ of the gas G ₁ at the pressure P ₁ is normally negligible, and the quantity of gas G ₂ passing in this volume V ₁ will normally always be lower than the quantity of gas G ₁ can leak from this volume to the outside of the insulating envelope 11. There is therefore in principle no risk that the pressure P ₁ increases until exceeding the maximum value P _1max critical for the mechanical structure of the vacuum interrupter, and it it is not necessary to provide a safety device such as a valve for evacuating gas G ₁ under pressure. However, for absolute safety, it can be provided between the volume V ₁ and the outside atmosphere an economic gas evacuation device, consisting of a rupture disk 46 also sometimes called frangible disk and intended to break when the difference gas pressure between the two sides of the disc exceeds a determined breaking value. This rupture disk 46 is mounted here on a metal annular piece 44 which electrically connects the bore piece 8 'to the conductive plate 20, and which also contributes to the seal between the volume V ₁ and the external atmosphere.

An alternative embodiment of the preceding control device of the figure 10 is schematically represented on the figure 11 . This variant comprises a safety space at atmospheric pressure which operates on the safety principle used in the control device of the figure 7 . Indeed, in the case where the wall 7 ', which has a particular role of sealing bellows with respect to gas G ₂ of the gas switch, would not provide a perfect seal, any gas leak G ₂ through this bellows would be discharged to the outside atmosphere via a channel 24. The volume V ₁ which is between the wall 7 'and the piston 4A of the auxiliary shaft communicates with the outside atmosphere through the channel 24, and the G ₁ gas contained in this volume V ₁ is here atmospheric air.

As for the switching assembly of the figure 7 a dielectric material 28 is overmolded around the sealed chamber of the vacuum interrupter. The gas G ₀ of the volume V ₀ between the material 28 and the piston 4A is similar to the gas G ₁ used for the device of the figure 7 and what has been said previously with respect to this gas remains valid for the present configuration. The piston 4A has no role here to generate the necessary contact pressure force in the vacuum interrupter. On the contrary, since the gas G ₀ is at a pressure preferably greater than atmospheric pressure, the differential pressure between the two sides of the piston generates a force which tends to oppose (while still much lower) the differential pressure force generated by the gas G ₂ on the flexible wall 7 '. Preferably, the diameter of the piston 4A will be provided as small as possible, provided that the electrical conduction section through the sliding contacts 9 remains sufficient. It may be noted that the sealing means 26 and the annular sealing element 27 are not necessarily indispensable and that the gas G ₀ could then be atmospheric air, as explained above in connection with the device of the figure 7 .

The control devices which have been described in the foregoing have been shown in applications to switching assemblies having in each case a vacuum interrupter associated with a gas switch. However, it is understood that control device according to the invention can be applied to a switching assembly of which a first and / or a second switching device consists of several switches arranged electrically in series or in parallel. For example, it is known that a switching assembly may comprise a vacuum switching apparatus consisting of a plurality of vacuum interrupters connected in parallel with their moving movable contacts in movement while being connected to the same auxiliary shaft displaceable in translation.

Claims (16)

1. A control device for actuating at least two items of switchgear in co-ordinated manner, which items are electrically connected together in series to constitute a switchgear assembly in which a vacuum first item of switchgear (1) that performs interruption in a vacuum includes a pair of contacts (5, 6) that can be separated to switch from a closed position to an open position, the control device including a main drive shaft (2) for actuating a second item of switchgear (10) immersed in a gaseous insulating fluid (G₂) contained in a certain volume (V₂) at a determined pressure (P₂), the control device further including an auxiliary shaft (4) suitable for being moved by coupling means (3) to enable a moving contact (5) of the first item of switchgear (1) to be driven when said main shaft (2) is moved, said moving contact (5) being held pressed against the other contact (6) of said first item of switchgear (1), when said first item of switchgear is in the closed position, by a force (F_c) chosen to generate a contact pressure higher than a determined value, said control device being characterized in that said auxiliary shaft (4) passes in leaktight manner through a wall (7A, 7') which separates said volume (V₂) of gaseous insulating fluid (G₂) from another volume (V₁) of fluid (G₁) at a lower pressure (P₁), the difference between the respective pressures (P₂, P₁) of the two fluids (G₁, G₁) procuring a certain force (Fp) which is applied to said auxiliary shaft (4) and which participates in said contact pressure force (F_c).
2. A control device according to claim 1, in which a portion of said auxiliary shaft (4) is constituted by a piston (4A) suitable for being moved inside a bore (8) formed by a part which is mounted in leaktight manner in an opening in said wall (7A), sealing means (17) for sealing relative to said gaseous insulating fluid (G₂) being arranged between said piston (4A) and said bore (8).
3. A control device according to claim 2, in which said wall (7A) and said bore (8) constitute an electrically conductive assembly connected to a pole of the second item of switchgear (10), said piston (4A) includes at least one electrically conductive portion (4A2) connected to the moving contact (5) of the first item of switchgear (1), and sliding contacts (9) are disposed between said bore (8) and said conductive portion (4A2) of the piston.
4. A control device according to any one of claims 1 to 3, in which said wall (7A) is constituted by one face of a casing (7) which encloses at least a portion of said volume (V₂) of gaseous insulating fluid (G₂) and in which said coupling means (3) are disposed.
5. A control device according to claim 4, in which the auxiliary shaft (4) has an end portion (4B) suitable for sliding in translation in a guide element (13, 13') that is fixed to a face (7B) of the casing (7) that is opposite the face constituting said wall (7A).
6. A control device according to any one of claims 1 to 5, in which the main shaft (2) has a segment (2A) that has one side provided with a surface arranged to form a cam (30) for guiding a rolling element (31) which is constrained to move with the auxiliary shaft (A).
7. A control device according to any one of claims 1 to 6, in which said coupling means (3) comprise resilient compression mechanical means suitable for exerting a force on said auxiliary shaft (4) for participating in said contact pressure force (F_c) in addition to the force (Fp) procured by the difference in the respective pressures (P₂, P₁) of the two fluids (G₂, G₁).
8. A control device according to claim 7, in which said resilient compression means comprise a spring (35) which is mounted on the auxiliary shaft (4) and which has one end pressing against a pusher element (34) suitable for being compressed under the action of a finger (33), said finger being fixed to said main shaft (2) and arranged to press against said pusher element (34) when the second item of switchgear (10) is in the closed position.
9. A control device according to claim 7, in which said resilient compression means comprise at least one spring (36, 37), the resultant force (F_r) exerted by said compression means on said auxiliary shaft (4) being organized to change direction along the axis (Y) along which said shaft moves in translation while said shaft is moving to open the first item of switchgear (1), while remaining lower than the force (F_p) procured by the difference in the respective pressures (P₂, P₁) of the two fluids (G₂, G₁).
10. A control device according to claim 9, in which said spring (36, 37) acts on a pivotally mounted arm (38, 39) having one end provided with a wheel (40, 41) arranged to press against a shaped-profile rolling surface on said auxiliary shaft (4).
11. A control device according to claim 9 or 10, in which said resultant force (F_r) has a component (F_rX) which is oriented continuously towards the second item of switchgear (10) along the axis (X) along which the main drive shaft (2) moves in translation.
12. A control device according to claim 2, in which said bore (8) has a radial orifice (24) that puts the outside atmosphere into communication with a gap between the piston (4A) and the bore (8), said radial orifice (24) opening out into said gap between said sealing means (17) and the first item of switchgear (1), so that any leakage of gas (G₂) through the sealing means (17) is discharged to the outside atmosphere.
13. A control device according to claim 1, in which said wall (7') is bonded to a conductive plate (20) electrically connected to a pole of the second item of switchgear (10) and has a flexible zone in the center of which an opening is provided through which said auxiliary shaft (4) passes in leaktight manner.
14. A control device according to claim 13, in which said auxiliary shaft (4) is provided with a piston (4A, 4A') suitable for being moved inside a bore (8, 8') electrically connected to said conductive plate (20), and in which sliding contacts (9) are arranged between said piston and said bore.
15. A control device according to claim 14, in which sealing means (26) are arranged between said piston (4A) and said bore (8), and in which said other volume (V₁) is provided between said piston (4A) and said wall (7'), the volume (V₁) being in communication with the outside atmosphere so as to be filled with air substantially at atmospheric pressure.
16. A control device according to any one of claims 1 to 11, and 13 to 15, in which said fluid (G₁) of said other volume (V₁) is a gas, and in which a safety device constituted by a valve (23) or by a breakable disk (46) makes it possible to discharge the gas (G₁) towards the outside atmosphere in the event that the pressure (P₁) of said gas exceeds a critical value.

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