EP0146424A1 - Electrical switch with rotating arc - Google Patents

Abstract

1. Self blow-out electric circuit breaker with arc rotation depending on a magnetic field, comprising insides a sealed housing (10), filled with sulphur hexafluoride, an arc formation chamber, in which is arranged a pair of separating contacts (16, 18) and an arc extinguishing chamber in which is arranged a pair of ring-shaped electrodes situated face to face in order to constitute annular tracks (28, 32) for the migration of the arc to be extinguished, and a magnetic blow-out device (34, 56) by rotation of the arc on said annular tracks (28, 32), characterized in that the movable contact of said pair of contacts is extended without discontinuity by an arcing horn (24) extending between the arc formation chamber and the extinguishing chamber and joining with one (28) of said annular tracks, the other annular track (32) being associated with the stationary contact (16), a current supply conductor (23) constituting a blow-out loop of the arc in the direction of the annular tracks (28).

Description

The invention relates to an electric switch with self-blowing by rotation of the arc under the action of a magnetic field comprising inside a sealed enclosure filled with sulfur hexafluoride a chamber for forming arc, in which is housed a pair of separable contacts and an arc extinguishing chamber in which is housed a pair of annular electrodes arranged face to face to form circular tracks of migration of the arc to be extinguished and a magnetic blowing device for rotating the arc on said circular tracks.

An electric switch of the kind mentioned, for example described in the French patent? 2,494,493, has the advantage of an extremely reduced control energy, the energy necessary for blowing the arc being entirely derived from the current to be interrupted. This rotary arc switch or circuit breaker has an interesting architecture allowing the production of a compact and economical circuit breaker. The switching of the arc to the circular tracks of rotation takes a certain time and this delay affects the breaking performance of the circuit breaker and increases the erosion of the contacts of the circuit breaker.

The object of the present invention is to remedy this drawback and to improve the switching of the arc.

According to a first embodiment of the invention, the switch is characterized in that the movable contact of said pair of contacts is extended by an arcing horn extending between the formation chamber and the extinction and connecting to one of said circular tracks, the other circular track being associated with the fixed contact.

The arc horn avoids any discontinuity between the movable contact and the associated circular track, so as to allow rapid displacement of the arc root anchored on the movable contact towards the circular track. This rapid displacement is accompanied by an elongation of the arc and an increase in the arc voltage facilitating switching. The rapid displacement is favored by an appropriate supply of the bow horn, so as to impose on the current a loop trajectory blowing the arc in the direction of the circular track. The movable contact, arc horn and circular track assembly advantageously constitutes a monobloc piece pivotally mounted on a fixed axis perpendicular to the plane of movement of the movable contact. The pivot axis is arranged in the vicinity of the circular track on one side or the other of the latter or possibly in the center along a diameter of the circular track in order to compensate for the electrodynamic forces applied to the circular track. In the open position of the switch contacts, the planes containing the circular tracks are substantially parallel, so as to keep the length of the arc in rotation on the circular tracks.

According to a development of the invention, the magnetic blowing field in rotation of the arc is generated by a coil inserted between the fixed contact and the fixed circular track attached to one of the faces of the coil. The circular track and blowing coil assembly is arranged in a part of the enclosure of the switch constituting the arc extinguishing chamber juxtaposed with the arc forming chamber formed by the pair of separable contacts. The arc horn constitutes a connection without solution of continuity between the two chambers.

According to an alternative embodiment of the invention, the magnetic blowing field is generated by a permanent magnet attached to the fixed circular track, so as to generate a radial field in the migration migration area of the arc. In this embodiment, the circular track fixed can be connected to the fixed contact by a continuous fixed arcing horn extending opposite the movable arcing horn. The displacement of the arc towards the circular tracks is particularly rapid, any discontinuity in the migration paths of the arc roots being avoided. The reactance of the arc circuit comprising the circular tracks is close to that of the main circuit containing the contacts, which facilitates rapid switching of the arc by limiting the duration of stagnation of the arc on the contacts.

The configuration according to the invention makes it possible to eliminate the shunt contacts, and it is easy to add to the aforementioned contacts main contacts ensuring the passage of the nominal current.

According to a second embodiment of the invention, the switching of the arc is improved by limiting the increase in the reactance of the arc circuit during the path from the latter to the circular tracks of rotation.

The switch includes means for successively inserting the turns of the coil _j staggered along said tracking track in order to gradually insert the coil into the electrical circuit. The arc drawn between the contacts moves quickly towards the circular tracks without switching on the blowing coil during the initial phase of displacement. During its path, the arc successively encounters the means for inserting the turns of the coil and gradually turns the latter on. The progressive insertion of the coil delays the progression of the arc, but only in the final phase avoiding any stagnation or re-ignition of the arc on the contacts. The progressive excitation of the coil can be carried out in a particularly simple manner by using the edges of the turns of the coil to constitute the successive anchoring points of the arc.

The coil, of the radial type, is connected to the fixed contact by a fixed horn which extends parallel to the arcing horn of the movable contact. During the separation of the contacts the arc moves quickly on the fixed and movable arc horns to meet the edges of the successive turns and gradually insert the turns of the coil in the manner described above before reaching the circular tracks of rotation. Any discontinuity of the arc horns is thus avoided, the increase in the reactance of the arc circuit being gradual and effective at the end of the arc path in the direction of the circular tracks.

The circular tracks can be in the form of split rings constituting an additional arc blowing coil and it is possible to reduce the mass of the mobile part by using an articulated part of which only the contact part is mobile, the horn arc and the associated circular track remaining fixed.

• - la figure 1 est une vue schématique en coupe axiale d'un interrupteur selon l'invention, représenté en position fermé des contacts;
• - la figure 2 est une vue analogue à celle de la fig. 1, montrant l'interrupteur en position ouvert;
• - la figure 3 est une coupe suivant la ligne III-III de la fig. 2;
• - la figure 4 est une coupe suivant la ligne IV-IV de la fig. 2;
• - La figure 5 est une vue analogue à ceLLe de La fig. 1, illustrant une variante de réalisation à aimant permanent;
• - La figure 6 est une vue schématique en coupe axiale d'un interrupteur selon L'invention, doté d'une bobine dont Les spires sont insérées progressivement;
• - La figure 7 est une vue en coupe seLon La Ligne VII-VII. de La fig. 6.

Other advantages and characteristics will emerge more clearly from the description which follows of several embodiments of the invention, given by way of nonlimiting examples and represented in the appended drawings in which:

• - Figure 1 is a schematic view in axial section of a switch according to the invention, shown in the closed position of the contacts;
• - Figure 2 is a view similar to that of FIG. 1, showing the switch in the open position;
• - Figure 3 is a section along line III-III of FIG. 2;
• - Figure 4 is a section along line IV-IV of FIG. 2;
• - Figure 5 is a view similar to that of FIG. 1, illustrating an alternative embodiment with a permanent magnet;
• - Figure 6 is a schematic view in axial section of a switch according to the invention, provided with a coil whose turns are gradually inserted;
• - Figure 7 is a sectional view along Line VII-VII. of fig. 6.

In the figures, a pole of an electric circuit breaker comprises a sealed envelope 10 made of an insulating material filled with a gas with high dielectric strength, in particular sulfur hexafluoride under an appropriate pressure. Bushings 12, 14 shaped as current supply terminals pass through the wall of the casing 10, one of the bushings carrying a fixed contact 16 capable of cooperating with a movable contact 18 mounted on one of the ends of a contact carrier arm 20, the opposite end of which is articulated on a fixed axis 22. A braid 23 extending perpendicular to the contact carrier arm 20 in the direction of the bushing 14 connects the latter to the end carrying the movable contact 18 to impose a loop-shaped trajectory on the current. In the closed position of the switch, shown in fig. 1, the current entering, for example at a given time through the bushing 12, travels through the butted contacts 16, 18, the braid 23 to come out through the bushing 14, following inside the envelope 10 a substantially straight path. The contact-carrying arm 20 extends transversely to this rectilinear trajectory of the current and is capable of struggling in the plane of FIG. 1, to cause the separation of the contacts 16, 18. Between the end carrying the movable contact 18 and that articulated on the axis 22 the contact carrier arm 20 successively comprises an arc horn 24 and a ring 26, the front face of which constitutes a circular arc track 28. Opposite the circular track 28 is disposed a circular track 32 arranged on an annular electrode 30 attached to the front face a coil 34 fixed to a support 36 integral with the bushing 12. The coil 34 is electrically inserted between the bushing 12 and the annular electrode 30, so as to be excited as soon as the arc is switched on this electrode 30. The annular electrode 30 is juxtaposed with the fixed contact 16, extensions 38 of the fixed contact 16 and / or of the electrode 30 reducing the separation interval to facilitate switching of the arc from the fixed contact 16 to the electrode 30 It is easy to see that the enclosure confined by the envelope 10 has two parts, one which contains the contacts 16, 18 and in which the arc is formed, and a second comprising the arcing tracks 28, 32 where the arc is extinguished. These two by ties or chambers are juxtaposed and connected by the arc horn 24 guiding the arc in its path from the formation chamber to the extinguishing chamber. In the open position of the switch, shown in Figure 2, the contact carrier 20 is substantially parallel to the annular electrode 30, so that the two circular tracks 28, 32 are at a constant distance.

• En position fermé, représenté_eà la figure 1, les contacts 16, 18 sont fermés tandis que les pistes circulaires 28,32 sont espacées l'une de l'autre. Le courant parcourt le circuit contenant les contacts 16, 18 et la tresse 23, la bobine 34 étant désexcitée. Lors d'une commande d'ouverture, engendrée par un mécanisme quelconque, le bras porte-contacts 20 pivote vers le bas sur la figure 1, vers la position représentée à la figure 2, de séparation des contacts 16, 18. L'arc tiré entre les contacts 16, 18 s'étend dans la position initiale "a" entre les contacts 16, 18 en étant soumis à une force électrodynamique de soufflage engendrée par la trajectoire en boucle du courant parcourant la tresse 23. Sous l'effet de cette force de soufflage l'arc progresse vers les positions successives "b", "c" et "d" en direction des pistes circulaires 28, 32,la racine d'arc ancrée sur le bras porte-contacts 20 ne rencontrant aucune discontinuité sur sa trajectoire de cheminement. La racine d'arc ancrée sur le contact 16 commute sur l'électrode 30 en mettant en circuit la bobine de soufflage 34, qui engendre un champ magnétique radial dans l'intervalle de séparation des pistes circulaires 28, 32. L'arc ancré sur les pistes 28, 32 est entrainé en rotation par le champ magnétique de soufflage et s'éteint rapidement d'une manière bien connue des spécialistes. Le passage de l'arc de la chambre de formation vers la chambre d'extinction est extrêmement_.rapide ce qui limite l'érosion des contacts 16,18.

The switch according to FIGS. 1 to 4 operates as follows:

• In closed position, shown _e in Figure 1, the contacts 16, 18 are closed while the circular tracks 28,32 are spaced from each other. The current flows through the circuit containing the contacts 16, 18 and the braid 23, the coil 34 being de-energized. During an opening command, generated by any mechanism, the contact-carrying arm 20 pivots down in FIG. 1, towards the position shown in FIG. 2, for separating the contacts 16, 18. The arc pulled between the contacts 16, 18 extends in the initial position "a" between the contacts 16, 18 being subjected to an electrodynamic blowing force generated by the loop path of the current flowing through the braid 23. Under the effect of this blowing force the arc progresses towards the successive positions "b", "c" and "d" in the direction circular tracks 28, 32, the arc root anchored on the contact-carrying arm 20 not encountering any discontinuity on its path of travel. The arc root anchored on the contact 16 switches to the electrode 30 by switching on the blowing coil 34, which generates a radial magnetic field in the separation interval of the circular tracks 28, 32. The arc anchored on tracks 28, 32 is rotated by the magnetic blowing field and quickly goes out in a manner well known to specialists. The passage of the arc from the formation chamber to the quenching chamber is extremely _. rapid which limits the erosion of the contacts 16,18.

In the other figures, which represent different variant embodiments, the same reference numbers designate parts similar or identical to those shown in Figures 1 to 4.

The magnetic blowing field produced by a coil in the switch according to FIGS. 1 to 4, can obviously be generated by a permanent magnet 40 attached to the fixed circular track 32 in the manner shown in FIG. 5. The permanent magnet 40 , advantageously of annular shape, can be axially or radially magnetized and does not require any electrical supply, it is possible to connect the circular track 32 to the fixed contact 16 by an arc horn 42 extending parallel and facing the horn arcing 24 of the movable contact carrier 20. The arcing horns 24, 42 constitute the tracks of the arc roots from the formation chamber towards the extinguishing chamber, these tracks having no solution of continuity. The operation of the switch according to FIG. 5 is identical to that described above, the arc drawn between the contacts 16, 18 moving rapidly towards the tracks circulars 28, 32 where it goes out. In FIG. 5, the hinge axis 22 is shown passing through the center of the circular track 28, this arrangement making it possible to balance the electrodynamic forces of the currents flowing through the circular tracks 28, 32. It is clear that the axis 22 can be arranged as shown in FIG. 1, at the end of the contact-carrying arm 20 or possibly at another point, for example on the opposite side of the circular track 28, these different positions of the axis 22 being valid for the switch according to figure 1 or that according to figure 5. The operation remains of course identical.

Referring now to Figures 6 and 7, there is shown a coil 56 of the radial type produced by a spiral winding of a ribbon, the internal end of the ribbon being electrically connected to the circular track 32, while the external end is connected to the bushing 12 associated with the fixed contact 16. The lower edges 58 of the ribbon, arranged facing the circular track 28, are stripped and possibly in slight projection to allow the hooking of the arc. The moving part of the switch corresponds exactly to that illustrated in FIGS. 1 and 2, and we recognize the contact-carrying arm 20 articulated on the axis 22 and carrying the fixed contact 18, the circular track 28 and the horn. arcing 24. When the contacts 16, 18 are separated, the arc drawn between these contacts is blown out by the loop effect in the direction of the circular tracks 28, 32. The arc root anchored on the arm carries -contacts 20 does not encounter any discontinuity during its journey towards runway 28, which is extremely rapid. The arc root anchored on the fixed contact 16 moves in parallel and encounters during its progress The slices 58 of the successive turns of the coil 56 by gradually inserting these turns before reaching the circular track 32. A displacement is thus obtained rapid arc roots, both on the fixed contact side and on the movable contact, the assembly being particularly simple. Referring to Figure 7, we see that The circular track 28 is constituted by a split ring for adding a magnetic blowing coil, The circular track 32 can be of the same type to increase the intensity of the magnetic blowing field .

It should be noted that other architectures implementing the principles of the invention are conceivable and that it is possible to combine the rotational blowing of the arc with a pneumatic blowing, for example with self-expanding well known to specialists. . The constitution of the movable contact and the associated circular track in a single piece increases the mass of this piece and its inertia, this drawback being able to be avoided, if necessary, by providing an articulated contact of which only the bearing end The contact would be movable. . Other variants, in particular switches with main contacts traversed by the nominal current, can of course be produced, these contacts opening prior to the contact described above and associated with circular tracks 28, 32.

Claims (10)

1. Electric switch with self-blowing by rotation of the arc under the action of a magnetic field., Comprising inside a sealed enclosure (10) filled with sulfur hexafluoride a chamber for forming arc, in which is housed a pair of separable contacts (16,18) and an arc extinguishing chamber in which is housed a pair of annular electrodes arranged face to face to form circular tracks (28, 32) of migration of the arc to be extinguished and a device (34,56) for magnetic blowing in rotation of the arc on said circular tracks (28,32), characterized in that the movable contact of said pair of contacts is extended by an arc horn (24) extending between the formation chamber and the extinguishing chamber and connecting to one (28) of said circular tracks, the other (32) circular track being associated with the fixed contact ( 16). 2. Switch according to claim 1, characterized in that the movable contact (18), the arcing horn (24) and the associated circular track (28) constitute a single piece (20) pivotally mounted on a fixed axis ( 22) perpendicular to the plane of movement of the movable contact (18). 3. Electric switch according to claim 2, characterized in that said one-piece piece (20) of elongated shape carries in the vicinity of one of its ends the movable contact (18) and of the opposite end the circular track (28) , said pivot axis (22) being on the side of said opposite end. 4. Electric switch according to claim 3, characterized in that said pivot axis (22) extends along a diameter of the circular track (28) to balance the electrodynamic forces. 5. Electric switch according to claim 1, 2, 3 or 4, characterized in that the circular track (28, 32) has a continuity solution to form a blowing turn in rotation of the arc. 6. Electrical switch according to claim 3, 4 or 5, characterized in that the supply of current (23) to said piece (20) is carried out on the side of said one end so as to form a blowing loop of the arc anchored on said piece towards the circular track (28). 7. Electric switch according to any one of the preceding claims, characterized in that the blowing device consists of a coil (34) attached to said other circular track (32) associated with the fixed contact (16), said coil (34 ) being connected on the one hand to the fixed contact (16) and on the other hand to said other circular track (32) to be switched on when switching the arc of the fixed contact (16) on the associated annular track (32). 8. Electric switch according to any one of claims 1 to 4, characterized in that the blowing device consists of a permanent magnet (40) attached to said other circular track (32) associated with the fixed contact (16), a arcing horn (42) connecting the fixed contact (16) and the associated circular track (32) extending between the formation chamber and the extinguishing chamber opposite the arcing horn (24) of the contact mobile. 9. Electric switch according to one of claims 1 to 7, characterized in that the sections (58) of the successive turns of the coil (56) are arranged in attachment points of the root of the arc and staggered along of the tracking track so as to gradually insert the turns during the course of the arc towards the extinguishing chamber, the circular track (32) being arranged in the vicinity of the central turning being electrically connected to the latter. 10. Electric switch according to claim 9, characterized in that said coil (56) is juxtaposed laterally with the fixed contact (16), the successive sections (58) of the turns being arranged opposite the arc horn (24) of the contact carrier arm (20) carrying at one of its ends the movable contact (18) and at the opposite end the circular track (28).

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