SWITCHING SYSTEM OF AN ELECTRICAL DEVICE

A switching system for switching an electrical device that includes a vacuum breaker. The vacuum breaker includes a fixed electrode, and a mobile electrode, able to move between a first position, referred to as a closed position, and a second position, referred to as an open position. The electrical device also includes a driving plate connected to the mobile electrode, and a main switch able to move between a first position allowing electrical current to pass in a main electric circuit of the electrical device and a second position preventing electrical current from passing in the main electric circuit, the main switch being configured to drive the driving plate during the transition from the first position to the second position, so as to cause the mobile electrode to make the transition from the closed position to the open position. The electrical device further includes a contact-maintaining element configured to maintain mechanical and electrical contact between the driving plate and the main switch while the driving plate is being driven by the main switch.

TECHNICAL FIELD

The present invention relates to the field of medium-voltage vacuum breaker switching devices, which comprise components known as vacuum breakers or vacuum interrupters. Vacuum breakers are used for example in medium-voltage, which is to say from 1 to 52 kV, electrical distribution devices. The vacuum breakers are notably associated with actuators to cut off the current in part of an electric circuit.

PRIOR ART

Arranging a vacuum breaker in a branch parallel to a main branch containing a main switch for one phase of an electrical device is known, notably from patent EP2182536. In such an architecture, no current passes in the vacuum breaker during normal operation, which is to say when the main switch is closed so as to cause the current to circulate through the main branch. During the operation of opening of the main switch, a part of the main switch closes the parallel branch containing the vacuum breaker before the current in the main branch is interrupted. The current is then interrupted in the main branch, so that all of the current then passes through the vacuum breaker. As it continues its opening travel, the main switch drives the plate connected to a mobile electrode of the vacuum breaker, and this opens the contact of the vacuum breaker. The electric current is thus cut off. This then avoids the creation of an electrical arc in the main switch, because the electrical current is passing only in the vacuum breaker at the moment at which the current is cut off. Because the vacuum breaker has electrical current passing through it only during transient phases of cutting off the current, this breaker can be simplified and smaller in size in comparison with the vacuum breakers generally intended to be placed in series with the main switch.

In order to guarantee effective cutting-off of the current, the main circuit must be opened (broken) in under around 30 milliseconds. The relative speed between the switch and the driving plate of the vacuum breaker, at the moment at which the two components come into contact with one another is high enough to create an impact shock. This impact shock is liable to cause the plate to bounce relative to the switch, which is to say that the mechanical contact between the two components is temporarily no longer assured. A parasitic electrical arc may thus be created between the driving plate and the switch, in addition to the controlled electrical arc that is created within the vacuum breaker. There are various reasons why this parasitic electrical arc is to be avoided. On the one hand, the parasitic electrical arc has a tendency to erode the plate, which is to say that it wears away the surface for contact between the plate and the switch, thereby impairing long-term reliability. In addition, the parasitic electrical arc encourages re-arcing of the electric circuit after the current has been cut off, and this may damage the devices connected to the circuit. Also, the electrical arc may potentially be created between two distinct phases of the device, with the risk of severely damaging the device.

It is therefore desirable to have a solution for avoiding the creation of a parasitic electrical arc during the phase of opening of the main switch.

SUMMARY

To this end, the invention proposes a switching system for switching an electrical device, comprising:a vacuum breaker comprising:a fixed electrode,a mobile electrode, configured to move between:first position, referred to as closed position, in which the fixed electrode and the mobile electrode are in contact with one another so as to allow electrical current to pass, anda second position, referred to as open position, in which the fixed electrode and the mobile electrode are separated from one another so as to prevent electrical current from passinga driving plate connected to the mobile electrode,a main switch able to move between a first position allowing electrical current to pass in a main electric circuit of the electrical device and a second position preventing electrical current from passing in the main electric circuit,the main switch being configured to drive the driving plate during the transition from the first position to the second position, so as to cause the mobile electrode to make the transition from the closed position to the open position,a contact-maintaining element configured to maintain mechanical and electrical contact between the driving plate and the main switch while the driving plate is being driven by the main switch.

The contact-maintaining element makes it possible to maintain mechanical contact between at least a portion of the main switch and a portion of the driving plate. Electrical contact between the driving plate and the main switch is thus maintained. As a result, the creation of a parasitic electrical arc between the driving plate and the main switch is avoided. Premature wearing of the switching system is avoided. Likewise, the risk of premature damage to the electrical device as a result of poor breaking of the current is eliminated. The life and the reliability of the switching system and of the electrical device are improved.

The features listed in the following paragraphs may be implemented independently of one another or in any technically possible combination:

According to one embodiment of the switching system, the contact-maintaining element comprises an electrically conducting elastically deformable element configured to be elastically stressed in response to the movement of the main switch from the first position to the second position. More specifically, the electrically conducting elastically deformable element is configured to be elastically stressed in response to the movement of the main switch from the first position to the second position when the distance between the driving plate and the main switch becomes less than a predetermined distance.

The elastically deformable element is configured to relax elastically in response to an increase in the distance between the driving plate and the main switch so as to maintain contact between the driving plate and the main switch.

If the distance between the driving plate and the main switch increases, as a result of the driving plate bouncing back off the main switch, the elastically deformable element relaxes and continues to ensure mechanical contact and, therefore, electrical contact, between the main switch and the driving plate.

The predetermined distance is comprised between 2 millimetres and 6 millimetres.

A natural frequency of the elastically deformable element is higher than 2000 Hz.

This range of natural frequencies allows the elastically deformable element to maintain contact with the driving plate if the latter moves away from the main switch as a result of the initial impact shock between these two components during the driving phase.

According to one exemplary embodiment of the switching system, the elastically deformable element is connected to the main switch.

The elastically deformable element comprises a projecting portion projecting from the main switch in the direction of travel of the main switch from the first position to the second position.

The elastically deformable element is a torsion spring.

The elastically deformable element is formed from metal wire.

The diameter of the metal wire is between 0.5 millimetres and 3 millimetres.

The torsion spring is made from a copper and beryllium alloy.

This alloy is able to provide good elastic properties and good thermal resistance so that the torsion spring is able to withstand the heating created by the transient passage of the electrical current upon each opening (breaking) of the circuit through movement of the main switch.

The main switch comprises a first bar and a second bar, the first bar and the second bar being distant from one another. The first bar and the second bar are parallel to one another. The first bar and the second bar are in contact with a fixed contact of the main circuit when the main switch is in the position in which the main circuit is closed. The first bar and the second bar are connected by a transverse connecting spindle. The connecting spindle passes through a coil of the torsion spring.

The connecting spindle connecting the first bar and the second bar comprises a groove to receive the coil of the torsion spring.

The torsion spring is thus held in place with respect to the connecting spindle without the addition of further components.

The torsion spring comprises a first strand and a second strand which are connected by a coil. An end portion of the first strand is placed in a cutout in the first bar and an end portion of the second strand is placed in the cutout of the first bar.

The retaining spring is thus retained relative to the first bar without the addition of further components. In addition, the choice of the size of the cutout makes it possible to regulate the amount of preload, or prestress, in the spring.

The axis of the coil is parallel to the end portion of the first strand and the end portion of the second strand.

This makes the placement of the coil of the retaining spring in the receiving groove of the connecting spindle and the placement of the ends of the retaining spring in the cutout in the first bar easier.

According to one exemplary embodiment, the cutout is oblong in shape.

As an alternative, the cutout is rectangular in shape.

The first strand comprises a substantially rectilinear portion adjacent to the coil and a bent portion, the bent portion being extended by a connecting portion connecting it to the end portion of the first strand.

The substantially rectilinear portion of the first strand and the bent portion extend in a plane substantially perpendicular to an axis of the coil.

The second strand comprises a substantially rectilinear portion adjacent to the coil and a connecting portion connecting it to the end portion of the second strand.

In the unconstrained state, the substantially rectilinear portion of the first strand and the rectilinear portion of the second strand form an angle of between 0° and 40°.

According to one exemplary embodiment, the torsion spring is preloaded.

The preloading of the torsion spring makes it possible to ensure good electrical contact with the driving plate if the driving plate bounces back off the main switch.

The preload in the torsion spring is between 15 newtons and 50 newtons, and notably around 25 newtons.

According to one exemplary embodiment of the switching system, the elastically deformable element is connected to the driving plate.

The elastically deformable element projects from the driving plate.

The elastically deformable element is an elastic strip configured to deform in bending.

The elastic strip has a first portion rigidly connected to the driving plate and a free second portion.

The free portion comprises a portion bent into a U-shape adjacent to the portion that is rigidly connected to the driving plate.

The free portion of the elastically deformable strip projects from the driving plate.

The elastic strip is screw fastened into the driving plate.

The elastic strip is made of steel.

The thickness of the elastic strip is comprised between 0.3 millimetres and 0.8 millimetres.

The length of the free portion of the elastic strip is comprised between 1 centimetre and 5 centimetres.

The width of the free portion of the elastic strip is comprised between 1 centimetre and 6 centimetres.

According to another embodiment of the switching system, the contact-maintaining element comprises a damping element configured to limit the acceleration of the driving plate while the driving plate is being driven by the main switch.

According to one embodiment of the switching system, the main switch and the driving plate are configured so that the main switch drives the plate via the contact-maintaining element.

More specifically, the main switch drives the driving plate via the contact-maintaining element during at least part of the travel of the main switch making the transition from the first position to the second position.

According to one embodiment, the contact-maintaining element is secured to the driving plate.

According to another embodiment of the switching system, the contact-maintaining element is secured to the main switch.

According to yet another embodiment of the switching system, the damping element is formed by the driving plate.

According to one embodiment, the contact-maintaining element comprises a block of elastomer.

For example, the contact-maintaining element comprises a damping element made of an elastomer based on EPDM or on polyurethane or on natural rubber or on thermoplastic.

According to one exemplary embodiment, the contact-maintaining element is covered with an electrically conducting layer. The contact-maintaining element may be covered with an electrically conducting strip. The electrically conducting strip may be made of metal, for example steel.

According to one embodiment, the contact-maintaining element comprises a block of elastomer fixed to the driving plate.

For example, the electrically conducting strip that covers the contact-maintaining element comprises a plate and a protrusion projecting from the plate, and the protrusion is placed in a receiving housing of the driving plate.

According to one exemplary embodiment, the protrusion comprises a plurality of studs spaced apart from one another.

The plate is of parallelepipedal shape.

The plate has a thickness comprised between 0.5 and 5 millimetres.

The studs have a thickness comprised between 0.1 and 2 millimetres.

In one exemplary embodiment, the contact-maintaining element is fixed to the driving plate by fixing screws. The fixing screws pass through the plate.

According to another exemplary embodiment, the contact-maintaining element is overmoulded onto the driving plate.

According to one embodiment of the switching system,the driving plate comprises a first surface, referred to as bearing surface,the main switch comprises a second surface, referred to as driving surface, configured to be in contact with the bearing surface while the main switch is making the transition from the first position to the second position, the main switch is able to rotate about an axis and comprises an end portion, opposite to the axis, and the driving surface is adjacent to the end portion.

According to one embodiment, the bearing surface is formed on an electrically conducting strip that covers the contact-maintaining element.

According to one embodiment, the contact-maintaining element comprises the bearing surface of the driving plate.

According to another embodiment, the switching system comprises a connecting element connecting the driving plate to the mobile electrode, and the contact-maintaining element is positioned between the connecting element and the driving plate. For example, a damping element is placed between the connecting element and the driving plate.

According to one embodiment, the switching system comprises a connecting element connecting the driving plate to the mobile electrode, the connecting element comprising a pivot and an end stop, and the driving plate is configured to bear against the end stop when the main switches is making the transition from the first position to the second position so that the main switch drives the connecting element.

According to one exemplary embodiment, the contact-maintaining element is placed on the driving plate and the contact-maintaining element is configured to bear against the end stop.

As an alternative, the end stop of the connecting element is formed by the contact-maintaining element.

According to one embodiment, the driving plate is configured to pivot about the pivot without driving the connecting element when the main switch is making the transition from the second position to the first position.

The driving plate comprises an electrically conducting zone configured to be in contact with the main switch when the main switch is making the transition from the first position that allows electrical current to pass in a main electric circuit, to the second position that prevents the passage of electrical current in the main electric circuit.

More specifically, the electrically conducting zone of the driving plate is in contact with the main switch during at least part of the travel of the main switch making the transition from the first position to the second position.

According to another embodiment of the switching system, the contact-maintaining element comprises a sliding-contact element configured to create a sliding electrical contact between the main switch and the driving plate while the driving plate is being driven by the main switch.

As a preference, the sliding-contact element is made of metal.

Thus, the sliding-contact element makes it possible to ensure electrical continuity between the main switch and the driving plate.

According to one embodiment, the sliding-contact element is secured to the driving plate.

According to one aspect of the invention, the main switch comprises a contact surface, and the sliding-contact element is configured to come into contact with the contact surface while the driving plate is being driven by the main switch.

Advantageously, the contact surface extends in a plane perpendicular to the axis of rotation of the main switch.

According to one embodiment, the main switch comprises an electrical-connection surface configured to be in contact with a fixed contact of the main circuit when the main switch is in the position in which the main circuit is closed, and the electrical-connection surface is adjacent to the contact surface.

The electrical-connection surface and the contact surface may partially overlap one another.

The electrical-connection surface and the contact surface may be coincident.

According to one aspect of the invention, the main switch comprises a first bar and a second bar, the first bar and the second bar being distant from one another and parallel to one another, the first bar and the second bar being in contact with a fixed contact of the main circuit when the main switch is in the position in which the main circuit is closed. The fixed contact of the main circuit is placed between the first bar and the second bar when the main switch is in the position in which the main circuit is closed,each of the first bar and second bar comprises a contact surface, and the sliding-contact element is configured to come into contact with each sliding-contact surface while the driving plate is being driven by the main switch.

Each bar of the main switch comprises an electrical-connection surface configured to be in contact with the fixed contact when the main switch is in the first position, and the contact surface is adjacent to the electrical-connection surface.

The contact surface of the second bar is placed facing the contact surface of the first bar.

As a preference, the first bar is planar. The second bar is planar.

The first bar and the second bar are made of metal.

The sliding-contact element comprises a flexible blade extending perpendicular to the driving plate, the flexible blade being configured to create a sliding contact with the main switch.

The sliding-contact element may comprise a first flexible blade and a second flexible blade, and the first flexible blade is configured to come into contact with a contact surface of the first bar and the second flexible blade is configured to come into contact with a contact surface of the second bar.

The first flexible blade comprises an inclined portion, the inclined portion facing towards the second flexible blade. The second flexible blade comprises an inclined portion, the inclined portion facing towards the first flexible blade.

The sliding-contact element has a U-shaped profile.

Each flexible blade the forms one branch of the U.

The first flexible blade and the second flexible blade are connected by a base perpendicular to the plane of the first flexible blade and of the second flexible blade.

The base of the U forms a fixing surface for fixing to the driving plate.

The base of the U comprises a through-holes for the passage of a fixing screw for fixing the sliding-contact element to the driving plate.

According to another embodiment of the switching system, the sliding-contact element comprises a rigid main rod extending perpendicular to the driving plate, the main rod is surrounded by a plurality of flexible rods extending transversely to the main rod, and the flexible rods are configured to create a sliding contact with the main switch.

The sliding-contact element comprises a plurality of rows of flexible rods extending axially along the main rod. The flexible rods are distributed at 360° all around the main rod.

The flexibility of the transverse rods allows the application of the friction force acting between the sliding-contact element and the main switch to be progressive.

According to yet another embodiment, the sliding-contact element comprises a rigid main rod extending perpendicular to the driving plate, the main rod is surrounded by a spring with angled coils, and the angled coils are configured to create sliding contact with the main switch.

Like with the preceding embodiment, the flexibility of the coils of the spring enable the establishment of the sliding contact between the sliding-contact element and the main switch to be progressive.

According to yet another embodiment, the sliding-contact element comprises a rigid rod extending perpendicular to the driving plate, and the rigid rod is configured to create sliding contact with the main switch.

According to one exemplary embodiment, the rigid rod has a rectangular cross section.

The rigid rod is chamfered.

According to an alternative form of embodiment, the rigid rod has a circular cross section.

The invention also relates to an electrical device comprising a switching system as described hereinabove, wherein the vacuum breaker is placed in parallel with the main switch.

DESCRIPTION OF THE EMBODIMENTS

To make the figures easier to read, the various elements are not necessarily drawn to scale. In these figures, elements that are identical bear the same references. Certain elements or parameters may be indexed, which is to say designated for example as first element or second element, or else first parameter and second parameter, etc. This indexing is intended to differentiate elements or parameters that are similar but not identical. This indexing does not imply that one element or parameter takes priority over another, and the denominations may be interchanged. Where it is specified that a subsystem comprises a given element, that does not exclude there being other elements present in that subsystem.

FIG.1schematically depicts an electrical device1comprising a switching system50. The switching system50comprises a vacuum breaker2. The vacuum breaker2is placed in parallel with the main switch20.

The electrical device1comprises a main circuit30in which an electrical current can circulate. The main circuit30corresponds example to one of the phases of the electrical device1. The switching system50makes it possible selectively to cut off the passage of current in the main circuit30, or to allow current to pass in the main circuit30. The switching system50comprises a main switch20. The main switch20is mobile in rotation.

The vacuum breaker2is provided for medium-voltage, which is to say a voltage of between 1 kV and 52 kV, electrical equipment. The vacuum breaker2comprises a housing forming a sealed vacuum chamber. What that means is that the pressure prevailing inside the chamber is below 10-4 millibars.

As illustrated inFIG.1, the main circuit30comprises a fixed contact35. The electrical device1here comprises an earthing contact40. The switch20is mobile in rotation between a nominal position for the circulation of electric current in the main circuit30, illustrated as A inFIG.1, and a position in which the switch20is connected to the earthing contact40, illustrated as F in that same figure. The main switch20can be rotated about an axis D. According to other exemplary embodiments which have not been depicted, it is possible for the earthing contact not to be present. The vacuum breaker2forms part of a branch tapped off from the main circuit30. This tapped-off branch is connected at a first end to the main circuit30and ends at its second end in a mobile part. The mobile part is mechanically connected to the mobile electrode4of the vacuum breaker2. The mobile part comprises a driving plate5.

FIG.1schematically describes the successive steps of an operation of cutting off the current in the main circuit30. Steps A to F are in chronological order. The broken lines ending in an arrow indicate the passage of the current. In B, the main switch20has initiated a rotational movement. As it rotates, the main switch20will come into contact with and drive the driving plate5which is connected to the mobile electrode4of the vacuum breaker2. The driving plate5, also referred to as contact element, is an element for driving of the mobile electrode4. The movement of the driving plate5thus makes it possible to open (break) the contact in the vacuum breaker2. The driving plate5comprises an electrically conducting element connected to the mobile electrode4. The main switch20comes into contact with the electrically conducting element during part of its travel. The driving plate5may pivot about an axis of rotation under the thrust of the main switch20. The control device that kinematically connects the driving plate5and the mobile electrode4is not detailed inFIG.1. In B, electrical contact between the switch20and the fixed contact35is still established, because of the width of the contacting zones. Electrical contact between the main switch20and the vacuum breaker2is also made. The main switch20is in contact with the driving plate5which is electrically conducting and electrically connected to the mobile electrode4. An electric current circulates simultaneously in the fixed contact35and, in parallel, into the vacuum breaker2. In other words, the electric current circulates both in the main circuit30and in the tapped-off branch. In C, the main switch20has continued its rotational movement and is no longer in contact with the fixed contact35. The main switch20has begun to move the driving plate5. The vacuum breaker is closed, which means to say that the fixed electrode3and the mobile electrode4are in contact. All of the current passes through the vacuum breaker2. The electric current no longer circulates in the main circuit30but does circulate in the tapped-off branch. In D, the main switch20has moved the driving plate5further, and this has triggered the opening of the vacuum breaker2. The mobile electrode4has thus begun to move away from the fixed electrode3. The switching system50that allows the vacuum breaker2to be opened will be described in detail in the paragraphs which follow. The current passes in the vacuum breaker2in the form of an electric arc when the contact opens. In E, the driving plate5has continued to be driven by the main switch20and the separation between the mobile electrode4and the fixed electrode3is at a maximum. Shortly after the phase current passes through zero, the current in the vacuum breaker2is cut off. The current in the main circuit30is thus cut off. In F, the main switch20has completed its rotational movement and is in contact with the earthing contact40.

The driving plate5comprises an electrically conducting zone15configured to be in contact with the main switch20when the main switch20is making the transition from the first position P1′ that allows electrical current to pass in a main electric circuit30, to the second position P2′ that prevents the passage of electrical current in the main electric circuit30. The electrically conducting zone15of the driving plate5is in contact with the main switch20during at least part of the travel of the main switch20making the transition from the first position P1′ to the second position P2′. The structure of the driving plate5is for example made of plastic.

FIGS.2to8detail a first embodiment of the invention. The switching system50for switching an electrical device1comprises:a vacuum breaker2comprising:a fixed electrode3,a mobile electrode4, configured to move between:a first position P1, referred to as closed position, in which the fixed electrode3and the mobile electrode4are in contact with one another so as to allow electrical current to pass, anda second position P2, referred to as open position, in which the fixed electrode3and the mobile electrode4are separated from one another so as to prevent electrical current from passinga driving plate5connected to the mobile electrode4,a main switch20able to move between a first position P1′ allowing electrical current to pass in a main electric circuit30of the electrical device1and a second position P2′ preventing electrical current from passing in the main electric circuit30, the main switch20being configured to drive the driving plate5during the transition from the first position P1′ to the second position P2′, so as to cause the mobile electrode4to make the transition from the closed position P1to the open position P2,a contact-maintaining element6configured to maintain mechanical and electrical contact between the driving plate5and the main switch20while the driving plate5is being driven by the main switch20.

The contact-maintaining element6is positioned at the second end of the tapped-off branch comprising the vacuum breaker2, or at the main switch20.

In this first embodiment of the switching system50, the contact-maintaining element6comprises a damping element13configured to limit the acceleration of the driving plate5while the driving plate5is being driven by the main switch20.

Thanks to the damping element13, the contact-maintaining element6makes it possible to reduce the impact shock between the main switch20and the driving plate5and thus able to avoid a phenomenon whereby the driving plate5bounces back off the main switch20. Because mechanical and electrical contact between the driving plate5and the main switch20is maintained, there is no parasitic electrical arcing between the driving plate5and the main switch20. Premature wearing of the switching system is thus avoided. Likewise, the current is cut off more reliably and the risk of premature damage to the electrical device is eliminated. The life and the reliability of the switching system and of the electrical device are improved. Contact-maintaining is to be understood as meaning that contact between the components is assured for a duration longer than the duration for which contact would exist in the absence of the contact-maintaining element. Residual bouncing between the components may occur in certain circumstances. In that case, the amplitude of the bouncing is less than 3 millimetres and the duration of the bouncing is less than 1 millisecond. In other words, any bouncing is of amplitude and duration that are low enough for it to be able to be considered that mechanical and electrical contact is maintained during the course of the operation of the main switch20.

The driving plate5is a driving element connected to the mobile electrode4of the vacuum breaker2. In other words, the contact-maintaining element6is configured to maintain mechanical and electrical contact between the main switch20and the driving plate5while the driving plate5is being driven by the main switch20. In particular, the contact-maintaining element6is configured to limit the acceleration of the driving plate5during an initial phase of the driving of the driving plate5by the main switch20. The contact-maintaining element6is configured to limit the acceleration of the driving plate5at least during the phase of mating of the main switch20with the driving plate5, which is to say the phase during which the main switch20comes into contact with the driving plate5and begins to drive same.

FIGS.2to6detail various steps in the travel of the switch20with a view to opening (breaking) the main circuit30. The fixed electrode3and the mobile electrode4form an electrical contact. An electric current may pass in the contact when the fixed electrode3and the mobile electrode4are pressed against one another, as illustrated inFIG.2and inFIG.3. InFIG.4, an electric arc is present between the two electrodes of the vacuum breaker, and precedes the cutting-off of the current. The current in the contact is interrupted when the mobile electrode4and the fixed electrode3are moved away from one another as illustrated inFIG.5. InFIG.6, the switch20has pivoted far enough to no longer be in contact with the driving plate5. InFIGS.2to6, broken lines indicate the passage of the electric current.

According to a first embodiment, illustrated inFIGS.2to8, the main switch20and the driving plate5are configured so that the main switch20drives the driving plate5via the contact-maintaining element6.

More specifically, the main switch20drives the driving plate5via the contact-maintaining element6during at least part of the travel of the main switch20making the transition from the first position P1′ to the second position P2′. Thus, the damping element13is interposed between the main switch20, the electrically conducting zone15, and the driving plate5during at least part of the travel of the main switch20making the transition from the first position P1′ to the second position P2′. The main switch20comes into contact with the driving plate5via the electrically-conducting zone15and the damping element13. In other words, the mating of the main switch20with the driving plate5is via the electrically-conducting zone15and the damping element13.

For that purpose, the contact-maintaining element6is covered with an electrically conducting strip15. The strip15is made of metal, for example steel. In other words, the electrically-conducting zone of the driving plate5is formed here by the strip15. The contact-maintaining element6may also be covered with an electrically conducting layer.

In the example illustrated, the contact-maintaining element6is secured to the driving plate5. In an embodiment variant which has not been depicted, the contact-maintaining element6may be secured to the main switch20. More specifically, the damping element13is then secured to the main switch20.

In the first embodiment, the contact-maintaining element6comprises a damping element13. The damping element13is a block of elastomer. The elastomer may be based on EPDM (a copolymer of ethylene-propylene-diene monomer) or on thermoplastic or on polyurethane or on natural rubber.

According to the first embodiment, illustrated inFIGS.2to8, the contact-maintaining element6comprises a block of elastomer fixed to the driving plate5.

FIG.7andFIG.8detail, in exploded view, one exemplary embodiment of a contact-maintaining element6comprising a damping element13made of elastomer.

The electrically-conducting strip15covers the contact-maintaining element6which, here, comprises the damping element13. The strip15comprises a plate7and a protrusion8projecting from the plate7, and the protrusion8is placed in a receiving housing9of the driving plate5. During the assembly phase, the protrusion8is able to slide in a receiving housing9of the driving plate5. The damping element13is inserted into the driving plate5and the protrusion8of the strip15slides in the receiving housing9until the strip15has come to bear against the damping element13. The strip15is connected to the driving plate5via the damping element13. The damping element13is pressed against the bottom of the receiving housing9. The desired damping properties are obtained through the choice of the dimensions and the material of the damping element.

As depicted inFIG.8, the protrusion8comprises a plurality of studs10,10′,10″ spaced apart from one another. The plate7is of parallelepipedal shape. The plate7has a thickness comprised between 0.5 and 5 millimetres. The studs10have a thickness comprised between 0.1 and 2 millimetres. The protrusion8here comprises two studs10,10′ of parallelepipedal shape, extending in a main direction D1. The protrusion8comprises a third stud10″, of parallelepipedal shape, extending in a transverse direction D2perpendicular to the direction D1.

The thickness of the damping element13, and the material used, make it possible to adjust the damping effect obtained so as to ensure that electrical and mechanical contact between the strip15, the driving plate5and the main switch20is maintained during the opening (breaking) travel of the vacuum breaker2. In the example depicted, the strip15is fixed to the driving plate5by fixing screws that allow the damping element13to be compressed. The fixing screws pass through the plate7. InFIG.7, the fixing screws have not been depicted, only the through-holes37for the fixing screws being visible.

Other forms of damping element13are also conceivable according to the invention. According to another exemplary embodiment, not depicted, the damping element13may for example be overmoulded onto the driving plate5.

As depicted notably inFIG.3,the driving plate5comprises a first surface11, referred to as bearing surface,the main switch20comprises a second surface12, referred to as driving surface, configured to be in contact with the bearing surface11while the main switch20is making the transition from the first position P1′ to the second position P2′, the main switch20is able to rotate about an axis D and comprises an end portion14, opposite to the axis D, and the driving surface12is adjacent to the end portion14.

The contact-maintaining element6comprises the bearing surface11of the driving plate5. The zone in which contact between the contact-maintaining element6and the main switch20occurs varies according to the angular position of the main switch20. The bearing surface11here forms part of the electrically conducting strip15.

The switching system50comprises a connecting element16connecting the driving plate5to the mobile electrode4. As depicted inFIG.2and detailed inFIG.7, the switching system50comprises a connecting element16connecting the driving plate5to the mobile electrode4, the connecting element16comprising a pivot17and an end stop18, and the driving plate5is configured to bear against the end stop18when the main switch20is making the transition from the first position P1′ to the second position P2′ so that the main switch20drives the connecting element16. A portion18′ of the driving plate5is in contact with the end stop18of the connecting element16. In other words, when, inFIGS.2to5, the main switch20pivots as indicated schematically by the curved arrow in dotted line, the driving plate5and the connecting element16are rigidly connected such that the movement of the main switch20is transmitted to the mobile electrode4of the vacuum breaker2.

According to one embodiment which has not been depicted, the contact-maintaining element6is placed between the connecting element16and the driving plate5. In other words, a damping element13is placed between the connecting element16and the driving plate5. Thus, the damping element13may be placed on the driving plate5, and the damping element13is configured to bear against the end stop18. The damping element13may thus be placed on the portion designated18′ inFIG.7. According to another embodiment which has not been depicted, the end stop18of the connecting element16may be formed by the damping element13. In other words, in this embodiment, contact between the main switch20and the driving plate5occurs without any damping element interposed between these two components. The damping element is interposed in the connection between the driving plate5and the connecting element16.

The driving plate5is configured to pivot about the pivot17without driving the connecting element16when the main switch20is making the transition from the second position P2′ to the first position P1′. Thus, the main switch20may resume its initial position after effecting a travel aimed at closing the main circuit30. In other words, the pivoting of the driving plate5with respect to the pivot17allows the switching device50to be reset.

According to another exemplary embodiment, not depicted, the damping element is formed by the driving plate5. The driving plate5in such a case is then made from a resilient material of the elastomer type.

The damping sought in this embodiment is achieved through the deformation of the driving plate5upon contact between the main switch20and the strip15. The elastomeric material is chosen so that the Shore A hardness is comprised between 50 and 90. To guide the rotation of the driving plate5about the axis of the pivot17, a rigid ring is interposed between the driving plate5and the axis of the pivot17of the connecting element16. The ring is secured to the driving plate5. The ring has not been depicted in the figures. The conducting strip15is fixed to the driving plate5and allows electrical contact with the main switch20.

FIGS.9to14describe a second embodiment of the switching system50. In this embodiment, the contact-maintaining element6comprises a sliding-contact element19configured to create a sliding electrical contact between the main switch20and the driving plate5while the driving plate5is being driven by the main switch20.FIGS.9to14are schematic views from above detailing the main switch20and the sliding-contact element19.

The electrical contact there is between the main switch20and the plate5by virtue of the sliding-contact element19makes it possible to maintain continuity of electrical contact during the movement of the main switch20. Thus, as in the first embodiment, the mechanical contact as well as the electrical contact between the main switch20and the driving plate5are maintained. Because the electrical continuity between the main switch20and the vacuum breaker2is maintained, the formation of a parasitic electric arc is avoided.

The sliding-contact element19here is made of metal. The sliding-contact element19thus makes it possible to ensure electrical continuity between the main switch20and the driving plate5.

In this second embodiment, the sliding-contact element19is secured to the driving plate5.

The main switch20comprises a contact surface21, and the sliding-contact element19is configured to come into contact with the contact surface21while the driving plate5is being driven by the main switch20.

The contact surface21extends in a plane perpendicular to the axis of rotation D of the main switch20. In other words, the contact surface21and the driving surface12providing the driving of the driving plate5are distinct and unconnected. The driving surface12of the switch20ensures the driving of the driving plate5by applying pressure to the driving plate5. The contact surface21ensures electrical contact with the sliding-contact element19.

The main switch20comprises an electrical-connection surface22configured to be in contact with a fixed contact35of the main circuit30when the main switch20is in the position P1′ in which the main circuit30is closed, and the electrical-connection surface22is adjacent to the contact surface21.

The electrical-connection surface22and the contact surface21may partially overlap one another. The electrical-connection surface22and the contact surface21may be coincident.

More specifically, the main switch20comprises a first bar23and a second bar24, the first bar23and the second bar24being distant from one another and parallel to one another, the first bar23and the second bar24being in contact with a fixed contact35of the main circuit30when the main switch20is in the position in which the main circuit30is closed. The fixed contact35of the main circuit30is placed between the first bar23and the second bar24when the main switch20is in the position in which the main circuit30is closed, and each of the first bar23and second bar24comprises a contact surface21,21′, and the sliding-contact element19is configured to come into contact with each sliding-contact surface21,21′ while the driving plate5is being driven by the main switch20. By definition, the position in which the main circuit30is closed is the position that allows current to pass in the main circuit30. This is therefore the position in which the main switch20and the fixed contact35are in contact. The first bar23here is planar. Likewise, the second bar24is planar. The first bar23and the second bar24are made of metal.

Each bar23,24of the main switch20comprises an electrical-connection surface25,25′ configured to be in contact with the fixed contact35when the main switch20is in the first position P1′, and the contact surface21,21′ is adjacent to the electrical-connection surface25,25′.

The contact surface21′ of the second bar24is placed facing the contact surface21of the first bar23. The direction in which the contact surface21and the contact surface21′ face one another is the direction of the axis of rotation D of the main switch20.

According to the second embodiment illustrated inFIGS.9to11, the sliding-contact element19comprises a flexible blade26extending perpendicular to the driving plate5, the flexible blade26being configured to create a sliding contact with the main switch20.

More specifically, and as indicated schematically inFIG.9, the sliding-contact element19comprises a first flexible blade26and a second flexible blade26′. The first flexible blade26is configured to come into contact with a contact surface21of the first bar23and the second flexible blade26′ is configured to come into contact with a contact surface21′ of the second bar24.

In other words, the sliding-contact element19is inserted between the two bars23,24of the main switch20. Each of the two flexible blades26,26′ respectively comes into contact with a bar23,24during the course of the travel of the main switch20, thereby creating the desired sliding contact.

As detailed inFIG.10, the first flexible blade26comprises an inclined portion27, the inclined portion27facing towards the second flexible blade26′. Likewise, the second flexible blade26′ comprises an inclined portion27′, the inclined portion27′ facing towards the first flexible blade26. The inclined portions27,27′ make it easier to insert the sliding-contact element19between the two bars23,24.

The sliding-contact element19in this example has a U-shaped profile. Each flexible blade26,26′ forms one branch of the U. The first flexible blade26and the second flexible blade26′ thus extend in parallel planes P1, P1′. The first flexible blade26and the second flexible blade26′ are connected by a base29perpendicular to the plane of the first flexible blade26and of the second flexible blade26′. The base29of the U forms a fixing surface28for fixing to the driving plate5. The base29of the U comprises a through-hole for the passage of a fixing screw for fixing the sliding-contact element19to the driving plate5.

According to a first variant of the second embodiment, depicted schematically inFIG.12, the sliding-contact element19comprises a rigid main rod31extending perpendicular to the driving plate5, the main rod31is surrounded by a plurality of flexible rods32extending transversely to the main rod31, and the flexible rods32are configured to create sliding contact with the main switch20.

The sliding-contact element19in this case comprises a plurality of rows of flexible rods32extending axially along the main rod31. The flexible rods are distributed at 360° all around the main rod31.

The flexibility of the transverse rods32makes it possible to obtain sliding electrical contact between the sliding-contact element19and the main switch20. In addition, the flexibility of the transverse rods allows for easy insertion of the sliding-contact element19between the bars23,24of the main switch20.

According a second variant of this second embodiment, indicated schematically in part B ofFIG.13, the sliding-contact element19comprises a rigid main rod31extending perpendicular to the driving plate5, the main rod31is surrounded by a spring33with angled coils34, and the angled coils34are configured to create sliding contact with the main switch20.

Like with the preceding variant, the flexibility of the coils34of the spring33enable the sliding contact between the sliding-contact element19and the main switch20to be progressive. The spring33with inclined coils34has the overall shape of a torus. The spring33is detailed in part A ofFIG.13.

According a third variant, indicated schematically inFIG.14, the sliding-contact element19comprises a rigid rod36extending perpendicular to the driving plate5, and the rigid rod36is configured to create sliding contact with the main switch20.

According to one exemplary embodiment, the rigid rod36has a rectangular cross section. The rigid rod36is chamfered. The chamfers eliminate the right angle at the corners of the rectangular section and make it easier to insert the rigid rod36between the bars23and24of the main switch20.

According to another exemplary embodiment, the rigid rod36has a circular, elliptical or oval cross section. The diameter of the rod is chosen to be slightly greater than the distance between the two bars23and24so as to create sliding contact when the rod is inserted between the two bars. The sliding-contact element19may also be a tube having the same external dimensions as the rigid rod36described.

FIGS.15to18describe a third embodiment of the switching system50.

In this embodiment of the switching system, the contact-maintaining element6comprises an electrically conducting elastically deformable element41configured to be elastically stressed in response to the movement of the main switch20from the first position P1′ to the second position P2′ when the distance d between the driving plate5and the main switch20becomes smaller than a predetermined distance S. The elastically deformable element is a contact element, which is to say an element ensuring mechanical and electrical contact with the main switch20.

The elastically deformable element is also configured to relax elastically in response to an increase in the distance d between the driving plate5and the main switch20so as to maintain contact between the driving plate5and the main switch20.

The elastically deformable element is interposed between the driving plate5and the main switch20. The elastically deformable element is electrically conducting. The predetermined distance S is comprised between 2 millimetres and 6 millimetres.

The natural frequency of the elastically deformable element41is higher than 2000 Hz.

This minimum value for the natural frequency allows the elastically deformable element41to maintain contact with the driving plate5if the latter moves away from the main switch20as a result of the initial impact shock between these two components during the driving phase. In other words, this value for the natural frequency allows the elastically deformable element to remain constantly in contact with the main switch20, even if a bounce phenomenon exists. Specifically, the natural frequency of the elastically deformable element is very much greater than the frequency of any bouncing there might be of the driving plate, for example by a factor comprised between 5 and 10.

According to one exemplary embodiment of the switching system50, illustrated inFIGS.15to18, the elastically deformable element41is connected to the main switch.

The elastically deformable element41comprises a projecting portion projecting from the main switch20in the direction of travel of the main switch20from the first position P1′ to the second position P2′. A portion of the elastically deformable element41thus protrudes beyond the edge of the bars23,24facing the driving plate5. InFIG.16, the symbol S schematically indicates the extent to which the elastically deformable element41protrudes beyond the edge of the main switch20. The arrow in broken line indicates the direction of rotation of the main switch20as it passes from the position P1′ allowing the passage of current in the main circuit30to the position P2′ preventing the passage of current.

The various views inFIG.15illustrate the way in which the elastically deformable element41acts. In this figure, views A to D indicate, in chronological order, the relative position of the main switch20and of the driving plate5. It will be noted that the direction of rotation of the main switch20, indicated schematically by a curved arrow in dotted line, is the opposite of that ofFIGS.3to6. The elastically deformable element41defines a zone of initial contact between the main switch20and the driving plate5as the main switch20makes the transition from the first position P1′ to the second position P2′. In part A ofFIG.15, the first bar23of the main switch20is still distant from the plate5when the elastically deformable element41comes into contact with the surface of the plate5. The distance d between the main switch20and the driving plate5at the instant corresponding to part A ofFIG.15is indicated by the sign d_A. Once the initial mechanical contact has been established, the remainder of the travel of the main switch20deforms the elastically deformable element41, stressing it. In part B ofFIG.15, the deformation of the elastically deformable element41is at its maximum and the edge of the first bar23of the main switch20comes into contact with the driving plate5. The distance between the first bar23and the driving plate5is therefore zero. The impact shock between the main switch20and the driving plate5may cause the driving plate5to bounce back off the main switch20causing the driving plate5to move away from the main switch20, which means that these two components cease being in contact and the distance between these two components becomes non-zero, as illustrated in part C. The symbol d_C schematically indicates the non-zero distance d between the main switch20and the driving plate5. The elastically deformable element41is relaxed and continues to be in contact with the driving plate5. During this phase, mechanical contact, and, therefore, electrical contact, between the main switch20and the driving plate5is maintained through the agency of the elastically deformable element41. In part D, the main switch20has caught up with the driving plate5and is once again in contact therewith. The elastically deformable element41is once again compressed to the maximum extent. Just a single bounce is illustrated here although the mechanism of action is the same when there are a number of successive bounces. The predetermined distance S is selected so that it is greater than the maximum amplitude of bounce-back of the driving plate5with respect to the main switch20. Thus, the elastically deformable element may remain in contact with the main switch thanks to the succession of compression and relaxation phases, and maintain electrical contact. The stiffness of the elastically deformable element is chosen to be low enough that it does not prevent the main switch20from touching the driving plate5. In other words, the stiffness of the elastically deformable element allows zero clearance between the main switch20and the driving plate5. When this clearance is zero, the deformation of the elastically deformable element is at its maximum.

The elastically deformable element41here is a torsion spring. The elastically deformable element41is formed from metal wire. The diameter of the metal wire is between 0.5 millimetres and 3 millimetres.

The torsion spring41is made from a copper and beryllium alloy. This alloy is able to provide good elastic properties and good thermal resistance so that the torsion spring is able to withstand the heating created by the transient passage of the electrical current upon each opening (breaking) of the main electric circuit30through movement of the main switch20.

FIG.17details the main switch20. The main switch20comprises a first bar23and a second bar24, the first bar23and the second bar24being distant from one another and parallel to one another. The first bar23and the second bar24are in contact with a fixed contact35of the main circuit30when the main switch20is in the position in which the main circuit30is closed. The first bar23and the second bar24are connected by a transverse connecting spindle51. The connecting spindle51passes through a coil42of the torsion spring41.

The first bar23and the second bar24are flat rectilinear elements. The first bar23and the second bar24extend in parallel planes and are placed facing one another in a direction transverse to the plane in which they extend.

The connecting shaft51passes transversely through the first bar23and the second bar24of the main switch20. The connecting shaft51is connected to the first bar23. A shoulder54of the connecting shaft51, detailed inFIG.18, bears against the lateral surface of the first bar23which is the opposite surface to the second bar24. A helical spring55ensures sufficient contact pressure between the two bars23,24and the fixed contact35to ensure the quality of the electrical connection between the mobile elements of the main switch20and the fixed contact35.

As detailed in part B ofFIG.18, the connecting spindle51connecting the first bar23and the second bar24comprises a groove52to receive the coil42of the torsion spring41. The coil42of the torsion spring41is received in the receiving groove52of the connecting spindle51that connects the first bar23and the second bar24. The torsion spring41is thus held in place with respect to the connecting spindle51without the addition of further components.

As illustrated notably inFIG.16, the torsion spring41comprises a first strand43and a second strand44which are connected by a coil42. An end portion45of the first strand43is placed in a cutout53in the first bar23and an end portion46of the second strand44is placed in the cutout53of the first bar23.

The torsion spring41is thus held in place with respect to the first bar23without the addition of further components. In addition, the choice of the size of the cutout makes it possible to regulate the amount of preload, or prestress, in the torsion spring41.

The end portion45of the first strand43and the end portion46of the second strand44extend in parallel directions. The end portion45of the first strand43and the end portion46of the second strand44are parallel to the connecting spindle51connecting the first bar23and the second bar24. The axis of the coil42is parallel to the end portion45of the first strand43and the end portion46of the second strand44.

This makes the placement of the coil42of the retaining spring41in the receiving groove52of the connecting spindle51and the placement of the ends of the torsion spring41in the cutout53in the first bar23easier. Specifically, the coil42of the torsion spring can be inserted into the groove52of the connecting spindle51, and the two end portions45and46of the torsion spring41are introduced simultaneously into the cutout53. The deformation of the torsion spring41while it is being fitted can be achieved using a tool or by hand.

The end portion45of the first strand43and the end portion46of the second strand44extend longitudinally on the one same side of the plane in which the first strand43and the second strand44extend. In other words, the two end portions45,46of the torsion spring41both point in the same direction.

The cutout53here is oblong in shape. As an alternative, the cutout53may be rectangular in shape.

As detailed in part A ofFIG.18, the first strand43comprises a substantially rectilinear portion47adjacent to the coil42and a bent portion49, the bent portion49being extended by a connecting portion49′ connecting it to the end portion45of the first strand43. The substantially rectilinear portion47of the first strand43and the bent portion48extend in a plane substantially perpendicular to an axis of the coil42. The second strand44comprises a substantially rectilinear portion48adjacent to the coil42and a connecting portion48′ connecting it to the end portion46of the second strand44. In the unconstrained state, the substantially rectilinear portion47of the first strand43and the rectilinear portion48of the second strand44form an angle T of between 0° and 40°.

The torsion spring41is preloaded here. In other words, a force greater than the preload force needs to be exerted in order to increase the elastic deformation of the torsion spring41. The preload in the torsion spring41is between 15 newtons and 50 newtons, and notably around 25 newtons. The preloading of the torsion spring41makes it possible to ensure good electrical contact with the driving plate5if the driving plate5bounces off the main switch20. The preload in the torsion spring41is between 5° and 30°. This corresponds to a closing-up of the angle T.

FIG.19andFIG.20illustrate a fourth embodiment of the switching system50. In this embodiment, the elastically deformable element is connected to the driving plate5. The elastically deformable element projects from the driving plate5. The elastically deformable element is an elastic strip61configured to deform in bending. As in the third embodiment, the elastically deformable element is therefore a contact element, which is to say an element ensuring mechanical and electrical contact with the main switch20.

The elastic strip61has a first portion62rigidly connected to the driving plate5and a free second portion63. The free portion63of the elastically deformable strip61projects from the driving plate5.

The free portion63comprises a portion64bent into a U-shape. The bent-over portion64is adjacent to the portion62that is rigidly connected to the driving plate5.

The elastic strip61here is screw fastened into the driving plate5. InFIG.20, the symbol65designates the through-hole for the fixing screw used to fix the elastic strip61to the driving plate5.FIG.21illustrates a variant in which the elastic strip61is fixed using three fixing screws66. The elastic strip61comprises three through-holes67through which the tightening tool can pass. According to another variant which has not been depicted, part of the elastic strip61is overmoulded with the material from which the driving plate5is formed. No fixing screw is then needed. For example, the part which, inFIG.19, receives the head of the fixing screw can be overmoulded.

The elastic strip61is made from a copper and beryllium alloy. The thickness of the elastic strip is comprised is between 0.3 millimetres and 0.8 millimetres. The length of the free portion of the elastic strip61is comprised between 1 centimetre and 5 centimetres. The width of the free portion of the elastic strip61is comprised between 1 centimetre and 6 centimetres.

When the main electric circuit30is opened (broken), the main switch20first of all comes into contact with the free portion63of the elastic strip61, which projects from the driving plate5, as indicated inFIG.19andFIG.20. In these figures, only the first bar23of the main switch20has been depicted, and the arrow indicated in dotted line indicates the direction of travel of the main switch20during opening (breaking) of the main circuit30. The operation is similar to that of the first embodiment variant. The main switch20deforms the elastic strip61until this strip comes into abutment with the driving plate5. Once the main switch20is driving the driving plate5, the free portion63of the elastic strip61maintains contact with the first bar23and the second bar24of the main switch20. Specifically, if the distance between the driving plate5and the bars23,24of the main switch20increases, on account of a bounce phenomenon associated with the impact shock between the components, the free portion63relaxes and remains in contact with the bars23,24of the main switch20. Mechanical and, therefore, electrical, contact is thus maintained. The protrusion S of the free portion63when unconstrained, the thickness of the elastic strip, and the length of the free portion63, enable the dynamic behaviour of the elastic strip61to be adapted so as to compensate for any bouncing of the driving plate5. The protrusion S in the unconstrained state is comprised between 1 millimetre and 5 millimetres, and is more particularly equal to 3 millimetres.

According to a variant of the fourth embodiment, the switching system comprises an additional damping element configured to limit the acceleration of the driving plate5while the driving plate5is being driven by the main switch20.

The contact-maintaining element therefore comprises the elastic strip61and the additional damping element which together ensure mechanical and electrical contact with the main switch20.

The damping element has, for example, the properties of that described in the first embodiment ofFIGS.2to8.

The damping element is interposed between the free portion63of the elastic strip61and the driving plate5. The damping element is also able to improve performance by being compressed when the main switch20applies force to the elastic strip61. When the plate5is being driven by the main switch20, the free portion63of the elastic strip61is deformed until such point as it comes into contact with the additional damping element, and then the additional damping element is compressed.

The damping element thus makes it possible to minimize still further the bounce phenomenon and thus improve the electrical and mechanical contact as the main switch20makes the transition from the first position P1′ to the second position P2′.

In this variant, the protrusion S of the free portion63in the unconstrained state is comprised between 1 millimetre and 5 millimetres, and is more particularly equal to 2 millimetres. The additional damping element is not depicted inFIG.20and is not visible inFIGS.19and21because it is hidden by the elastic strip61.