EP2573785A1 - Three-phase electrical short-circuiting device with pyrotechnic actuator - Google Patents

Abstract

This electric short-circuiter comprises: - several terminals (2-4), an isolation (22-24, 29) of these terminals between them, a pyrotechnic actuator (7) delimiting a chamber, several contacts (61-63) movable between an open waiting position and a closed short-circuit position, a device (50, 53) for driving these movable contacts (61-63) from the open waiting position to the closed short-circuit position, under a propulsive action of the pyrotechnic actuator (7), - Waiting spaces (92) for two of the movable contacts (61-63), each at a level located between two of the terminals (2, 3). When in their open waiting positions, two of the mobile contacts are each in one of the waiting spaces (92). Solid frangible dielectric partitions (90) isolate the phase terminals (2-4) from the movable contacts (61-63) in their open waiting positions. These are mobile contact retaining partitions (61-63) for storing energy in said chamber, firstly after a triggering of the pyrotechnic actuator (7), until rupture of the frangible partitions (90). ).

Description

Technical field of the invention

The present invention relates to a three-phase electric short-circuiter, of the type comprising at least first, second and third phase terminals, a dielectric insulation of these phase terminals therebetween, and a pyrotechnic actuator delimiting an expansion chamber of pyrotechnic actuation gases. The invention finds particular application in the protection of humans and equipment in the electrical field, particularly against the various hazards related to arcing, including internal arcs that occur in electrical cabinets or other confined spaces.

State of the art

In a pyrotechnic actuator, the energy caused by the pyrotechnic generation of gas is used to propel an actuator.

Known short-circuiters use pyrotechnic actuators to produce the maneuver leading to the desired short-circuit. An advantage of such actuators is to allow very short closing times to be obtained. This advantage is particularly interesting in the protection against electric arcs, in particular against the internal arcs, whose important effects which are both destructive for the equipment and dangerous for the personnel, sometimes with very high levels of severity of injury. as much attenuated as the arc is quickly interrupted. In this protection against electric arcs, the desired performances are therefore very high, especially in terms of speed of short-circuiting. In addition, an arc short-circuiter must generally have a large dielectric strength, in particular to withstand lightning strikes without deteriorating.

Examples of the use of pyrotechnics in short-circuiters are proposed in the US patent application US 2009/0120773 , as well as in European patent applications EP 2 073 229 and EP 2 073 235 .

In the international patent application WO 99/21255 , there is described a short-circuiter of the aforementioned type. This short-circuiter has the function of putting three phases shorted and grounded, following a command. The short circuits on the different phases occur successively, the time elapsing between the establishment of the first short circuit and the establishment of the last short circuit. The performance of the demand short-circuiter WO 99/21255 in terms of speed and / or efficiency of short-circuiting of the phases, may be considered insufficient or, at least, it seems legitimate to seek to obtain better ones.

Object of the invention

The object of the invention is at least to make it possible to improve the performance of a short-circuiter of the aforementioned type, at least in terms of speed and / or short-circuiting efficiency.

According to the invention, this object is achieved by means of a short-circuiter according to the appended claim 1.

The first and second movable contacts are respectively in the first and second waiting areas when in their open waiting positions.

During a transition to their closed short-circuit positions, each of the first and second mobile contacts connects very quickly to its destination terminal, without crossing before one or more other terminals. This makes it possible to obtain a very substantial improvement in the performance of a short-circuiter of the aforementioned type, at least in terms of speed and / or short-circuiting efficiency.

Achievement of improved performance, at least in terms of speed and / or short-circuiting efficiency, also results from the fact that the energy which, until the breaking of the first, second and third frangible partitions, s is stored in the expansion chamber causes the driving power released by this rupture is very high.

The short-circuiting device defined by claim 1 may incorporate one or more other advantageous features, alone or in combination, in particular among those defined below.

Advantageously, each of the first, second and third phase terminals comprises a receiving hole of the corresponding mobile contact. Preferably, each of the first, second and third movable contacts has the form of a conductive ring which comprises at least one slot so as to be elastically deformable inwards towards a contracted configuration in which the conductive ring is adapted to centrifugal clamping on the surface of the receiving hole of the movable contact defined by this conductive ring.

Advantageously, the pyrotechnic actuator comprises a piston and a body which defines a cylinder. Preferably, the piston and a side wall of the cylinder partially delimit said expansion chamber. Preferably, the mechanical coupling device comprises a movable bar for coupling to the piston. Preferably, this piston is slidably mounted in the cylinder so that the expansion chamber is delimited on one side of the piston, namely on the side of the movable bar, so that the movement of the piston under the action of the gases pyrotechnic actuation is performed in the direction of a pull on the movable bar, to the pyrotechnic actuator.

Advantageously, at least a portion of said insulation is made of a solid dielectric material.

Advantageously, the electric short-circuiter comprises a ring of electrical insulation gas which is confined at least by a solid dielectric material portion of the insulation so as to isolate the first movable contact in its open waiting position and the first phase terminal of each other, together with one of the frangible partitions.

Advantageously, said insulation comprises at least first and second insulating sections which are separate parts and succeed one another along a direction of actuation of the movable contacts between their open waiting and closed short-circuit positions. Preferably, the first insulating section comprises at least the first frangible partition which isolates the first phase terminal of the first movable contact in its open waiting position and which is frangible during a displacement of this first movable contact from its open position. waiting towards its closed position of short circuit. Preferably, the second insulating section comprises at least the second frangible partition which isolates the second phase terminal of the second movable contact, in its open waiting position, and which is frangible during a displacement of the second movable contact from its open waiting position to its closed short-circuit position.

Advantageously, at least one intermediate portion of the first insulating section is between said first and second phase terminals.

Advantageously, the short-circuiter comprises at least one annular isolation seal, which is located between the first and second insulating sections and which contributes to electrically isolating the second phase terminal of the first movable contact in its open waiting position.

Advantageously, the electric short-circuiter comprises a bar which carries the movable contacts.

Advantageously, said bar electrically connects the movable contacts to each other.

Advantageously, said bar passes through at least a portion of solid dielectric material of the insulation and retains at least laterally this portion.

Advantageously, at least one of the movable contacts is threaded onto said bar.

Advantageously, said bar carries a drive flange at least of the movable contact threaded from its open waiting position to its closed short-circuit position.

Advantageously, the insulation holds at least one of the movable contacts in an axial direction of the bar.

Advantageously, said bar passes at least through the first and second phase terminals.

Advantageously, the first and second insulating sections at least are threaded onto said bar.

Advantageously, said first and second phase terminals hold together the first insulating section, in an axial direction of the bar.

Advantageously, the electric short-circuiter comprises two elements for axial guidance of said sliding bar, these two guide elements axially retaining between them several members selected from the terminals, the movable contacts and at least a part of said insulation.

Advantageously, the two guide elements are flanged towards each other, on an element which is made of dielectric material and which at least partially surrounds several members chosen from the terminals, the movable contacts and at least a part of said insulation. .

Advantageously, the electric short-circuiter comprises a clamping subassembly forming a conductive loop which is closed on itself and which surrounds the phase terminals.

Advantageously, the electric short-circuiter comprises a fixed earth connection contact.

Advantageously, the short-circuiter comprises at least one conductive ring which defines one of the movable contacts and which comprises at least one slot so as to be elastically deformable towards the inside. Preferably, at least one of the terminals comprises a receiving hole and tightening of this conductive ring when this ring is in the closed position of short circuit.

Advantageously, the movable contacts are electrically connected to each other in the open waiting position.

Brief description of the drawings

• la figure 1 est une vue en perspective d'un court-circuiteur électrique conforme à l'invention et de trois barres électriques par l'intermédiaire desquelles ce court-circuiteur est connecté dans une installation électrique triphasée ;
• la figure 2 représente le même court-circuiteur triphasé que la figure 1, mais tel que vu sous un autre angle et dissocié des trois barres électriques visibles sur cette figure 1 ;
• la figure 3 est une vue éclatée, en perspective, qui représente un premier sous-ensemble d'éléments constitutifs du court-circuiteur des figures 1 et 2 ;
• la figure 4 est également une vue éclatée, en perspective, qui représente un deuxième sous-ensemble d'éléments constitutifs du court-circuiteur des figures 1 et 2 ;
• la figure 5 est une vue en perspective sur laquelle une partie fixe du court-circuiteur des figures 1 et 2 est représentée en coupe longitudinale et où un ensemble mobile de ce court-circuiteur est dans une première position, à savoir une position ouverte d'attente ;
• la figure 6 est une vue sur laquelle le court-circuiteur des figures 1 et 2 est représenté de la même manière qu'à la figure 5 et où l'ensemble mobile est dans une deuxième position, à savoir une position fermée de court-circuit ;
• la figure 7 est une vue en perspective du sous-ensemble de la figure 4 et en représente les constituants tels qu'assemblés en faisant artificiellement abstraction des éléments du sous-ensemble de la figure 3, dans un souci de clarté ;
• la figure 8 est une vue en coupe longitudinale et en perspective d'un actionneur pyrotechnique du court-circuiteur des figures 1 et 2 ;
• la figure 9 est un agrandissement d'un médaillon qui est sensiblement identique au médaillon IX de la figure 5 et qui représente une portion du court-circuiteur des figures 1 et 2 ;
• la figure 10 est un agrandissement d'un médaillon analogue au médaillon IX et représente un détail de réalisation selon une variante de réalisation de l'invention.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention given as non-restrictive examples and represented in the accompanying drawings, among which:

• the figure 1 is a perspective view of an electric short-circuiter according to the invention and three electrical bars through which this short-circuiter is connected in a three-phase electrical installation;
• the figure 2 represents the same three-phase short-circuit figure 1 but as seen from another angle and dissociated from the three electric bars visible on this figure 1 ;
• the figure 3 is an exploded view, in perspective, which represents a first subset of constituent elements of the short-circuiter of Figures 1 and 2 ;
• the figure 4 is also an exploded view, in perspective, which represents a second subset of constituent elements of the short-circuiter of the Figures 1 and 2 ;
• the figure 5 is a perspective view on which a fixed part of the short-circuiting Figures 1 and 2 is shown in longitudinal section and where a movable assembly of this short-circuiter is in a first position, namely an open waiting position;
• the figure 6 is a view on which the short-circuiter of Figures 1 and 2 is represented in the same way as at the figure 5 and wherein the moving assembly is in a second position, namely a closed short-circuit position;
• the figure 7 is a perspective view of the subset of the figure 4 and represents the constituents as assembled by artificially disregarding the elements of the subset of the figure 3 , for the sake of clarity;
• the figure 8 is a view in longitudinal section and in perspective of a pyrotechnic actuator of the short-circuiter of Figures 1 and 2 ;
• the figure 9 is an enlargement of a medallion which is substantially identical to the medallion IX of the figure 5 and which represents a portion of the short-circuiting Figures 1 and 2 ;
• the figure 10 is an enlargement of a medallion similar to the medallion IX and represents a detail of embodiment according to an alternative embodiment of the invention.

Description of a preferred embodiment of the invention

On the figure 1 , an electric short-circuiter 1 according to the invention is mounted on three electrical connection bars U, V and W, through which it is connected in a three-phase electrical installation.

It itself three-phase, the short-circuiter 1 comprises three terminals 2, 3 and 4 electrically isolated from each other, which are more precisely phase terminals. Among these terminals, that referenced 3 is an intermediate terminal directly bolted to the bar V. Two conductive tabs 5 are each bolted to one of the other two terminals 2 and 4, for example to the way represented in the figure 2 , and each connect this terminal 2 or 4 to one of the phases U and W.

The short-circuiter 1 comprises an electromechanical block 6 and a pyrotechnic actuator 7, which are assembled in the extension of one another in a compact assembly of small size, which is advantageous.

The pyrotechnic actuator 7 comprises a metal body 10 and an attached pyrotechnic cartridge 11 whose function is to provide actuating gases produced by means of a chemical reaction initiated by an electric discharge, in a manner known per se. Preferably, the powder at the origin of the pyrotechnic actuating gases is an explosive powder contained by the pyrotechnic cartridge 11. In fact, the generation of the actuation gases by chemical reaction of an explosion-proof powder or standard powder is preferred to the use of explosive explosive. As used herein, an explosive powder produces a subsonic wave (velocity of propagation between 10 m / s and 400 m / s) when it reacts chemically, whereas a wave generated by a detonating explosive progresses to a speed between 2000 and 3500 m / s.

Preferably, the fixing of the pyrotechnic cartridge 11 to the body 10 comprises crimping.

The crimping combination of the pyrotechnic cartridge 11 and the body 10 to one another and the use of an explosive powder, and not a detonating explosive, contribute to the fact that the short-circuiter 1 can be considered non-pyrotechnic equipment according to Directive 93/15 / EEC, which is advantageous.

The short-circuiter 1 consists of an assembly of parts, some of which are represented at figure 3 , while others are at the figure 4 , for the sake of clarity.

As can be seen at figure 3 , terminals 2 to 4 generally have the shape of flattened parallelepipeds, which are arranged substantially parallel to each other and perpendicular to a longitudinal axis XX 'of the short-circuiter 1. Each of these three terminals 2 to 4 is pierced of one of three through holes 20, in the extension of each other. More specifically, the cross section of each hole 20 is circular and centered on the axis X-X '. At least one of the two opposite openings of each hole 20, each of the three terminals 2 to 4 has an engagement chamfer 21.

Always on the figure 3 , references 22, 23 and 24 designate three distinct insulating sections, also called spacers, which follow each other along the longitudinal axis XX 'and which are identical hollow parts, which is advantageous in particular in terms of manufacturing and referencing costs. .

An axial hole 25 passes right through each spacer 22, 23 or 24, which has a stud 26 or mounting tail by interlocking in two consecutive axial holes, namely the hole 20 of one of the terminals 2 to 4 and the hole 25 of one of the other two spacers 22 and 23, except in the case of the pin 26 of the spacer 22. The stud 26 equips an insulating spacer portion 27, which is also traversed by the hole 25.

Opposite its tenon 26, each spacer 22, 23 or 24 has a countersink 28 formed in the intermediate portion 27, at an outlet of the axial hole 25 of this spacer, and adapted to receive an annular element of electrical insulation 29. Preferably, the latter form also a seal against dust and especially against any fine metal particles.

The spacers 22 to 24 are made of dielectric material, for example thermosetting polymer or thermoplastic polymer and, advantageously, polycarbonate loaded with glass fibers. Advantageously identical, the three seals 29 are made of an elastic dielectric material, for example ethylene-propylene-diene-monomer material also designated by the acronym EPDM.

On the figure 3 it is also possible to see an insulation element in the form of an envelope portion, and more precisely in the form of a stirrup 30, which delimits a housing 31 partially open, in particular laterally. This stirrup 30 comprises an end wall or base 32, from which extend two facing wings 33, on either side of the longitudinal axis X-X '.

The base 32 is pierced right through a circular hole 34 centered on the axis X-X '. Each wing 33 has an outer longitudinal groove 35 for receiving a clamping tie which is not shown in FIG. figure 3 and whose function will be explained later.

The stirrup 30 may be made of any suitable dielectric material, for example from bakelized fabric, such as that marketed under the name "CELORON", or polyimide, such as polyimide sold under the name "ULTEM".

On the figure 4 the body 10 and the cartridge 11 are dissociated from each other. The cartridge 11 comprises a male end 40 connecting to the entrance of a passage 41 in a conventional manner. In the example shown, the fixing of the cartridge 11 uses an alternative to crimping, namely a removable clamping member 43. Screwed into the passage 41, this removable clamping member 43 holds the cartridge 11 in place.

The body 10 is also pierced with an axial hole 42 for the passage of a movable support and traction bar 50, a head of which constitutes a piston 51 intended to be slidably mounted in the body 10 and provided, in the example shown, two annular seals 52 axially offset. Advantageously, the bar 50 and the piston 51 are coaxial. Each of them is one of two pieces of metal in one piece, screwed into one another and, for example, made of suitable steel.

At the opposite end of that provided with the piston 51, the movable bar 50 carries a nut 53 which defines a drive flange in the direction of traction towards the pyrotechnic actuator 7 and which is rigidly associated with the movable bar 50 , by screwing.

In the manner of an axial guide, the movable bar 50 carries four contacts which are slidably slid axially on it and which are more precisely a fixed ground contact 60 and three movable contacts 61, 62 and 63. The movable bar 50 is electrically conductive and electrically connects between them the fixed contact 60 and the three movable contacts 61 to 63.

Each of these three movable contacts 61 to 63 has the form of a direct contact electrical connection ring, several times slit so as to be elastically deformable inwards, to a contracted configuration in which this ring is able to exert a centrifugal clamping. Each of the movable contacts 61 to 63 is provided with a tubular pusher 66 which extends it by being rigidly associated with it.

Like the fixed contact 60, the assembly formed by the movable contact 61 and a pusher 66 is an integral piece made of an electrically conductive material, such as copper or a copper-based alloy. It is advantageously identical the assembly formed by the movable contact 62 and another pusher 66, as well as the assembly formed by the movable contact 63 and the last pusher 66.

The fixed contact 60 comprises a flange 67 bearing against the body 10, as well as an axial and tubular extension of electrical connection by direct contact 68, whose free end comprises an annular and external centering groove 69.

Always on the figure 4 , the components of a clamping subassembly comprise two opposite tie rods 70, each of which has the form of a stud in the example shown. A nut 71 and a washer 72 associated with this nut equip one end of each tie rod 70, the other end of which is also equipped with a washer and a nut, or screwed into the body 10 of the pyrotechnic actuator 7.

The clamping subassembly also comprises an axial clamping plate 73 and the body 10, which are arranged opposite one another, so as to retain between them, axially, the elements slipped on the bar of support 50, as can be seen at Figures 1 and 2 . The clamping plate 73 is pierced with a bearing 74 for axial guidance of one end of the moving assembly comprising the piston 51, the bar 50, the nut 53, the pushers 66 and the movable contacts 61 to 63.

In other words, the components of the short-circuiter 1 are held together by the movable support bar 50 and by an axial restraint. More specifically, the movable bar 50 passes through certain components and thus retains them laterally, as can be clearly seen in FIG. figure 5 . A retaining acts in a complementary manner, in the axial direction, that is to say in that defined by the longitudinal axis X-X '. It is the fact of the bridle subassembly, whose constituents are shown assembled to the figure 7 . On the latter, other constituents of the short-circuiter 1 are not represented for the sake of clarity. Each placed on one of the two sides of the stirrup 30, the tie rods 70 pull the body 10 and the clamping plate 73 towards one another and, in so doing, clamp them on this stirrup 30.

Figure 8 illustrates the arrangement of the piston 51 slidably mounted in a cylinder 80, which defines the body 10 of the pyrotechnic actuator 7. The annular seals 52 provide a double annular seal between the piston 51 and the wall of the cylinder 80.

The passage 41 of brought actuating gases opens into a chamber 81 of compression and expansion of these gases. The side wall and a bottom of the cylinder 80, as well as the piston 51, a part of the movable bar 50 and an annular seal 82 jointly delimit the compression chamber and then expansion chamber 81, on one side of the piston 51 , ie on the side of the movable bar 50 and the electromechanical block 6. In this way, the movement of the piston 51 under the action of the pyrotechnic gases is effected in the direction of a traction T on the movable bar 50, towards the pyrotechnic actuator 7, and not a thrust in the opposite direction. The longitudinal axis X-X 'is also the sliding axis of the moving assembly comprising the piston 51, the bar 50 and the nut 53, which the bar 50 couples to the piston 51.

The function of the seal 82 is to provide an annular seal between the movable bar 50 and a bearing 83 for axial guidance of this bar 50.

In contrast to the chamber 81, a removable safety stop 84 is screwed into the cylinder 80 and serves to prevent accidental ejection the piston 51 out of the body 10. Drilled a through axial passage 85, it can be traversed by an air flow to or from the outside, so as not to achieve a tight seal.

On the figure 5 , the short-circuiter 1 is open, in a waiting position or armed position where it does not establish a short circuit. As can be seen on this figure 5 the spacers 22 to 24 are subsequently arranged along the X-X 'axis, partially fitting into each other so as to form together an insulating assembly, which also comprises the seals 29 and which is made of a solid dielectric material.

The intermediate portion 27 of the spacer 22 isolates the two terminals 2 and 3 from each other. This spacer 22 also isolates the terminal 2 and the movable contact 61 between them. One of the seals 29 participates in the electrical insulation between this movable contact 61 and the terminal 3. The pin 26 of the spacer 22 axially holds the movable contact 61 away from the fixed contact 60 and the terminal 2.

The intermediate portion 27 of the spacer 23 isolates the two terminals 3 and 4 from each other. This spacer 23 also isolates the terminal 3 and the movable contact 62 between them. One of the seals 29 participates in the electrical insulation between this movable contact 62 and the terminal 4. The post 26 of the spacer 23 axially holds the movable contacts 61 and 62 away from the terminal 3.

The intermediate portion 27 of the spacer 24 isolates the terminal 4 and the clamping plate 73 from one another. This spacer 24 also isolates the terminal 4 and the movable contact 63 between them. One of the seals 29 participates in the electrical insulation between this movable contact 63 and the clamping plate 73. The pin 26 of the spacer 24 axially holds the movable contacts 62 and 63 away from the terminal 4.

The fixed contact 60 is immobilized axially by clamping its flange 67 between the body 10 of the pyrotechnic actuator 7 and the base 32 of the stirrup 30.

Each of the spacers 22 to 24 comprises a breakable or frangible partition 90, one of which is easily discernible to the figure 9 . On this figure 9 it can be seen that such a frangible partition 90 associates between them the post 26 and the intermediate portion 27 of each of the spacers 22 to 24, while isolating one of the terminals 2 to 4 of one of the movable contacts 61 to 63 Adjoining each frangible partition 90, a ring 91 of electrical insulation gas such as air is confined, being localized so as to complete the electrical insulation that makes this frangible partition 90 between one of the terminals 2 to 4 and one of the movable contacts 61 to 63.

It follows from the above that the short-circuiter 1 has a modular design, which is advantageous.

On the figure 5 , each of the movable contacts 61 to 63 is axially offset from each of terminals 2 to 4. The movable contact 61 is in a storage or waiting space 92 located between the two consecutive terminals 2 and 3. The movable contact 62 is located in another waiting space 92, which is located between the two consecutive terminals 3 and 4.

Each of the movable contacts 61 to 63 is further electrically isolated from the terminals 2 to 4, by the insulating assembly comprising the succession of spacers 22 to 24, the seals 29 and the gas rings 91. This insulating assembly also isolates the terminals 2 to 4 electrically fixed contact 60. The short-circuiter 1 is thus in an open waiting position, in which it establishes no short circuit.

The above-mentioned insulating assembly has the advantage of having a sufficiently high resistance to be able to withstand lightning strikes. In particular, it resists a pulse wave of 12 kV, without damage, and meets the requirements of IEC 60947-1.

When the short-circuiter 1 opened as at figure 5 is connected in a circuit under voltage, significant electric and magnetic fields are generated around the terminals 2 to 4. These fields could generate a risk of untimely fire of the pyrotechnic cartridge 11. In the short-circuiter 1, this risk is effectively thwarted by several features. On the one hand, the stirrup 30, in particular its base 32, provides effective insulation between the terminals 2 to 4 and the pyrotechnic actuator 7, and in particular its pyrotechnic cartridge 11. On the other hand, thanks to the relative provision of the compression and expansion chamber 81 and the piston 51 along the axis XX 'and by driving the movable coupling bar 50 in a traction movement T, none of the movable contacts 61 to 63 are is located between this actuator 7 and the terminal closest to it, that is to say the terminal 2. In addition, the clamping subassembly comprising the two opposite tie rods 70, the clamping plate 73 and the body 10 form a belt which constitutes a conductive loop closed on itself and which surrounds the terminals 2 to 4. It is believed that this conductive loop acts against the propagation of the electric and magnetic fields, according to the principle implemented in the so-called Faraday cages.

The short-circuiter 1 can be used in an arcing device, including the internal arcs. This device may be similar to that described in the application for European patent EP 2 073 229 above and include one or more sensors for detecting an arc, as well as a central decision and control. The latter is able to send a triggering order for the pyrotechnic cartridge 11 in the case where this unit has just received a signal addressed by at least one of the sensors and signaling the detection of an electric arc.

A triggering of the pyrotechnic cartridge 11 leads to the initiation of a chemical reaction generating very rapidly actuating gases. Through the passage 41, these gases proceed to the chamber 81, where they raise the pressure in an extremely short time. In a first step, this pressure increases without immediately causing actuation of the piston 51 and the movable assembly coupled to this piston. This results from the retention of this moving assembly by the spacers 22 to 24. When the pressure in the chamber 81 is sufficiently high, the frangible partitions 90 of these spacers break together, which suddenly releases the piston 51 and the coupled mobile assembly. 51. The energy stored in the compression chamber 81 until the rupture of these partitions makes the driving power released by this rupture is very high and propels the piston 51 at high speed into the piston. the direction indicated by the arrow T at the figure 5 . The frangible partitions 90 are calibrated to break when the pressure in the chamber 81 reaches a predetermined threshold.

It follows from the foregoing that the frangible partitions 90 serve several functions, which is advantageous, especially in terms of overall simplicity, cost and space. In particular, they perform an electrical isolation prior to the triggering of the pyrotechnic actuator 7, then they intervene directly in the operation of this actuator 7 once it is triggered.

In this respect, the rupture of the frangible partitions 90 at a given pressure, that is to say a predefined pressure, makes it possible to achieve very short closing times, in particular of less than 1 ms, including in cases where a powder explosion is used to generate the actuating gases in the pyrotechnic actuator 7.

The movable assembly coupled to the piston 51 is propelled as quickly as the piston 51 itself. It comprises the movable contacts, whose referenced 63 is driven with a pusher 66 pushed by the nut 53. Via one of the other pushers 66, the movable contact 63 in turn actuates the movable contact 62, which even pushes on the last pusher 66 and thus causes the movable contact 61 on the extension 68 of the fixed contact 60.

The short-circuiter 1 goes from the open configuration of the figure 5 to the short circuit configuration of the figure 6 in a very short time from the initiation of the pyrotechnic cartridge 11. In particular, it has been possible to achieve closing times of less than 1 ms from the initiation of the pyrotechnic cartridge 11.

In addition, the movable contacts 61 to 63 substantially reach at the same time the terminals 2 to 4. It follows that the short-circuiting of the different phases are practically simultaneous, instead of being successive. On the contrary, in the device shown in figure 5 of the international patent application WO 99/21255 aforementioned, the short-circuiting of the different phases are successive.

The moving assembly coupled to the piston 51 comprises a plurality of parts. Instead of being propelled in the opposite direction to the actuator 7, these parts are propelled towards the base 32 of the stirrup 30 and towards the body 10 of this actuator 7. There follows several advantages, one of which is a considerable reduction in the risk of projection of the part out of the short-circuiter 1 during its operation, which is very important in terms of safety. A second advantage of the propulsion of the moving assembly towards the base 32 and the body 10 is that the latter form a counter-thrust or stop mass which, acting in the manner of an anvil, reduces the importance of the shock transmitted to the permanent fixing elements of the short-circuiter 1 and echoed In this one.

On the figure 6 , each of the movable contacts 61 to 63 is compressed in a hole 20 of one of the terminals 2 to 4 and exerts a radial clamping on the surface of this hole 20. It follows a very effective electrical contact. This is not the case in the device shown in figure 5 of the international patent application WO 99/21255 supra. In this respect, it is even thought that the actual functioning of this device is questionable. Indeed, the single mobile part of short-circuit in the device of the application WO 99/21255 could enlarge the holes of the terminals, towards a flared global shape, during its projection through these terminals. This would result from a phenomenon that is well known in ballistics.

Always on the figure 6 , the movable contacts 61 to 63 are connected to each other, which achieves the short-circuit sought. These movable contacts 61 to 63 are further connected to the fixed contact 60, which is connected to the earth by a driver not shown for the sake of clarity. In summary, terminals 2 to 4 are short-circuited and connected to the ground at the figure 6 .

It follows from the foregoing that the short-circuiter 1 performs short-circuiting at the same time extremely fast, frank, and simultaneous or almost simultaneous.

Thanks in particular to the very effective electrical contacts between the terminals 2 to 4 and the mobile contacts 61 to 63 tablets in these terminals in the closed position of short circuit of the figure 6 , the short-circuiter 1 is also able to resist for periods of 100 to 500 ms to short circuits whose current has an intensity of between 10 kA and 150 kA rms. It follows that the short-circuiter 1 is particularly suitable for the protection of a high power electrical installation, although it may also be suitable for another installation, such as a medium power installation.

While, according to the inventors at the origin of the present invention, the short-circuiters of the prior art fail to short-circuit the phases of a three-phase installation in about 20 ms at best, the short-circuiter 1 has the advantage of being extremely faster, since it can short-circuit the phases of a polyphase installation in less than 1 ms.

On the figure 10 is represented an enlarged portion of a short-circuiter 101 according to an alternative embodiment of the invention. This short-circuiter 101 is generally identical to the short-circuiter 1. It comprises spacers identical to each other, which replace the spacers 22 to 24, fulfilling the same functions as these, and one of which is partially visible and referenced 123 to the figure 10 . This spacer 123 confines a gas ring 191, which fulfills the same function of electrical insulation as the gas ring 91 and which is distinguished by its position, particularly with respect to the corresponding frangible partition, referenced 190 in the short- circuitry 101 and equivalent to that referenced 90 in the short-circuiter 1.

The invention is not limited to the embodiment and variants described above. In particular, its implementation is not limited to the single case of three-phase. On the contrary, the invention finds application also in other electrical configurations, especially in single-phase configurations. In addition, the outer surface of the insulating spacer portion 27 may not be cylindrical. In particular, it may have a rectangular cross section and / or define fins or beads succeeding one another in the longitudinal direction.

Claims (17)

Three-phase electrical short circuit, comprising: first, second and third phase terminals (2-4), an insulation by dielectric material (22-24, 29, 91, 123, 191) of these first, second and third phase terminals between them, and a pyrotechnic actuator (7) delimiting a pyrotechnic gas expansion chamber (81) for actuation,
characterized in that it comprises: first, second and third contacts (61-63) movable between an open waiting position (FIG 5), wherein the insulation (22-24, 29, 91, 123, 191) electrically isolates at least the first, second and third phase terminals therebetween, and a closed short-circuit position (Fig.6), wherein each movable contact (61-63) is connected directly to one of the first, second and third terminals of phase and wherein the first, second and third movable contacts (61-63) are electrically connected to each other, - a device (50, 53) for mechanical coupling of the first, second and third movable contacts (61-63) to the pyrotechnic actuator (7) and for driving these first, second and third movable contacts (61-63 ) from the open waiting position to the closed short-circuit position, under a propulsive action of the pyrotechnic actuator (7), at least a first waiting space (92) for the first movable contact (61), at a level located between the first and second phase terminals (2, 3), so that the first movable contact (61) finds in this first waiting space (92) when the first movable contact (61) is in its open waiting position, at least a second waiting space (92) for the second movable contact (62), at a level located between the second and third phase terminals (3, 4), so that the second movable contact (62) finds in this second waiting space (92) when the second movable contact (62) is in its open waiting position,
said insulation (22-24, 29, 91; 123, 191) having first, second and third frangible solid dielectric partitions (90) each of which isolates one of the first, second and third phase terminals (2-4) of one of the first, second and third movable contacts (61-63) in their open waiting positions, these first, second and third frangible partitions (90; 190) being retaining partitions of the first, second and third movable contacts (61-63) and the mechanical coupling device (50, 53) for storing energy in said expansion chamber (81), firstly after a triggering of the pyrotechnic actuator (7), up to breaking the first, second and third breakable partitions (90; 190) and releasing said energy when driving the first, second and third movable contacts (61-63) from their open waiting positions to their closed positions short-circuit uit, said expansion chamber (81) being a chamber for compressing and then expanding the pyrotechnic actuating gases. Short-circuiting device according to Claim 1, characterized in that each of the first, second and third phase terminals (2-4) comprises a hole (20) for receiving the corresponding moving contact (61-63), each of the first, second and second and third movable contacts (61-63) having the shape of a conductive ring which has at least one slot so as to be elastically deformable inward towards a contracted configuration in which the conductive ring is able to exert a tightening centrifugally on the surface of the hole (20) for receiving the movable contact (61-63) defined by this conducting ring. Short-circuiting device according to one of the preceding claims, characterized in that the pyrotechnic actuator (7) comprises a piston (51) and a body (10) which defines a cylinder (80), the piston (51) and a side wall of the cylinder (80) partially delimiting said expansion chamber (81), the mechanical coupling device (50, 53) comprising a movable bar (50) for coupling to the piston (51), said piston (51) being slidably mounted in the cylinder (80) so that the expansion chamber (81) is delimited on one side of the piston (51), namely on the side of the movable bar (50), so that the movement of the piston (51) under the action of the pyrotechnic actuating gases is carried in the direction of traction (T) on the movable bar (50), to the pyrotechnic actuator (7). Short-circuiting device according to any one of the preceding claims, characterized in that it comprises a ring of electrical insulation gas (91; 191) which is confined at least by a portion of solid dielectric material (23; 123) of the insulation so as to isolate the first movable contact (61) in its open waiting position and the first phase terminal (2) from each other, together with one of the first, second and third partitions frangible (90). Short-circuiting device according to any one of the preceding claims, characterized in that said insulation comprises at least first and second insulating sections (22, 23) which are distinct pieces and which follow each other along a direction (X- X ') for actuating the first, second and third movable contacts (61-63) between their open waiting and closed short-circuit positions, the first insulating section (22) comprising at least the first frangible partition (90; 190) which isolates the first phase terminal (2) of the first movable contact (61) in its open waiting position and which is frangible upon a displacement of this first movable contact from its open waiting position to its position. closed from a short-circuit, the second insulating section (23) comprising at least the second frangible partition (90; 190) which isolates the second phase terminal (3) from the second movable contact (62) in its open waiting position, and which is frangible during a displacement of this second movable contact (62) from its open waiting position to its closed short-circuit position. Short-circuiting device according to Claim 5, characterized in that at least one intermediate portion (27) of the first insulating section (22) is located between said first and second phase terminals (2, 3). Short-circuiting device according to any one of claims 5 and 6, characterized in that it comprises at least one annular insulation seal (29), which is located between the first and second insulating sections (22, 23) and which contributes to electrically isolating the second phase terminal (3) of the first movable contact (61) in its open waiting position. Short-circuiting device according to any one of the preceding claims, characterized in that it comprises a bar (50) which carries the first, second and third movable contacts (61-63). Short-circuiting device according to claim 8, characterized in that said bar passes in at least a portion of solid dielectric material (22-24, 29; 123) of the insulation and retains at least laterally this portion. Short-circuiting device according to any one of claims 8 and 9, characterized in that at least one of the first, second and third movable contacts (61-63) is threaded onto said bar (50). Short-circuiting device according to claim 10, characterized in that the insulation (22-24) retains at least one of the first, second and third movable contacts (61-63) in an axial direction (X-X ') of the bar (50). Short-circuiting device according to one of claims 8 to 11, characterized in that said bar (50) passes at least through the first and second phase terminals (2, 3). Short-circuiting device according to any one of claims 5 to 7 and any one of claims 8 to 12, characterized in that the first and second insulating sections (22, 23) at least are threaded onto said bar (50). Short-circuiting device according to claim 13, characterized in that said first and second phase terminals (2, 3) hold together the first insulating section (22) in an axial direction (X-X ') of the bar (50). ). Short-circuiting device according to any one of claims 8 to 14, characterized in that it comprises two elements (10, 73) for axially guiding said sliding bar (50), these two guide elements (10, 73). axially holding together a plurality of members selected from the first, second and third phase terminals (2-4), the first, second and third movable contacts (61-63) and at least a portion of said insulation. Short-circuiting device according to Claim 15, characterized in that the two guide elements (10, 73) are flanged towards one another on an element (30) which is made of dielectric material and which at least partially surrounds a plurality of members selected from the first, second and third phase terminals (2-4), the first, second and third movable contacts (61-63) and at least a portion of said insulation (22-24, 29; 123). Short-circuiting device according to Claim 16, characterized in that it comprises a clamping subassembly (10, 70-73) forming a conductive loop which is closed on itself and which surrounds the first, second and third terminals of phase (2-4).

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