EP3132460B1 - Rotating-arc circuit-breaker including a high-resistance field coil - Google Patents

Description

TECHNICAL AREA

The invention relates to a gas-insulated rotating arc high-voltage circuit breaker.

STATE OF THE PRIOR ART

The invention relates to a rotating arc circuit breaker comprising a fixed contact support and a movable contact support spaced from one another and carrying a fixed contact and a movable contact in translation, as well as an inductor located in a chamber. cutoff containing an insulating gas such as SF6.

The document US 4918268 discloses an electrical breaking device according to the preamble of claim 1. In such a circuit breaker known from the document US4918268 , the inductor is a winding shaped to be traversed by the current flowing through the circuit breaker at the time of its opening. If an electric arc is established between the contacts during the opening, the magnetic field generated by the inductor gives rise to Lorentz forces settling in the arc to rotate it around the axis of the circuit breaker so to promote its extinction.

In general, given the high current intensities that pass through such circuit breakers, the dimensioning and configuration of the inductor are generally problematic because it is necessary that the inductor generates a field at the same time. intense magnetic, but it does not heat up too much.

In this context, the inductor is configured to be traversed by current only when opening the contacts, and its winding is sized to enable it to withstand appropriate intensities.

In this context, the winding is often a so-called Bitter coil, which is a helical coil of sheet metal: it consists of a set of sheet metal parts, for example in the form of half-crowns whose ends are fixed to each other. others to form substantially plane turns superimposed on each other. An insulating band also helical is interposed between the turns so that they are isolated from each other.

Such a coil can thus have a high passage section and easily adjustable in terms of dimensioning, by varying the thickness of the sheet used for its manufacture.

Nevertheless, the manufacture of such a coil which necessarily comprises a relatively large number of sheet metal parts remains expensive. Moreover, the current density passing through such a coil is much larger at its inner periphery than at its outer periphery, which gives rise to much greater heating problems in the central part than in the periphery.

STATEMENT OF THE INVENTION

The invention relates to a rotating arc electric cut-off device such as a circuit breaker or a disconnector, according to claim 1. The device comprises a fixed contact and a movable contact, the movable contact being movable between a closed position in which it is in electrical contact with the fixed contact and an open position in which it is spaced from the fixed contact and at least one inductor including a coil for generating a magnetic field tending to rotate an electric arc appearing between the contacts during the opening of these contacts to promote the extinction of this arc, the inductor comprising a coil formed from a metal strip wound on itself in a spiral.

With this arrangement, the inductor comprises a coil capable of withstanding currents of high intensity while having a low manufacturing cost.

The invention also relates to a device as defined above, wherein the inductor comprises a metal hub around which the coil is wound, and a cylindrical metal ring enclosing the coil.

The invention also relates to a device as defined above, wherein the cylindrical ring comprises holes comprising points of soldering or brazing of the metal strip to the ring and / or wherein the hub comprises a slot through which a end of the band.

• l'inducteur est monté en extrémité d'un support du contact fixe en étant mobile entre une position rétractée et une position déployée, avec un ressort rappelant continuellement cet inducteur vers sa position déployée ;
• le contact mobile a une forme de piston comportant une jupe de même diamètre que la bague de l'inducteur et une calotte venant en appui sur l'inducteur à l'encontre du ressort pour le maintenir rétracté lorsque ce contact mobile est fermé, cette calotte étant écartée de l'inducteur pour qu'il occupe sa position déployée lorsque le contact mobile est ouvert ;
• le contact fixe est un contact glissant s'étendant dans le prolongement du support de contact fixe en ayant une extrémité libre qui est en appui radial sur la jupe du contact mobile lorsque ce contact mobile est fermé et en appui radial sur la bague de l'inducteur lorsque le contact mobile est ouvert.

The invention also relates to a device as defined above, in which:

• the inductor is mounted at the end of a support of the fixed contact being movable between a retracted position and an extended position, with a spring reminding continuously this inductor to its deployed position;
• the movable contact has a piston shape comprising a skirt of the same diameter as the ring of the inductor and a cap resting on the inductor against the spring to keep it retracted when the movable contact is closed, this cap being separated from the inductor so that it occupies its deployed position when the movable contact is open;
• the stationary contact is a sliding contact extending in the extension of the fixed contact support having a free end which is radially supported on the skirt of the movable contact when the movable contact is closed and bearing radially on the ring of the inductor when the moving contact is open.

The invention also relates to a device as defined above, in which the hub comprises a cylindrical portion on which the coil strip is wound, this cylindrical portion being extended by a circular plate perpendicular to the cylindrical portion, this plate being spaced apart. of the coil and electrically isolated from this coil.

The invention also relates to a device as defined above, in which the The hub's circular plate has an outer diameter corresponding to the outer diameter of the ring and the movable contact while being spaced and electrically isolated from the ring.

The invention also relates to a device as defined above, wherein the movable contact and the inductor each comprise a central opening for discharging insulating gas in the event of reheating resulting from an electric arc being established during 'opening.

The invention also relates to a device as defined above, wherein the hub comprises a portion of ferromagnetic material in its central region.

BRIEF DESCRIPTION OF THE DRAWINGS

• the figure 1 is a longitudinal sectional view of the circuit breaker according to the invention when it is closed;
• the figure 2 is a longitudinal sectional view of the movable contact of the circuit breaker according to the invention;
• the figure 3 is a longitudinal sectional view of the inductor of the circuit breaker according to the invention;
• the figure 4 is a cross-sectional view of the inductor of the circuit breaker according to the invention;
• the figure 5 is a longitudinal sectional view of the circuit breaker according to the invention at the beginning opening when a switching arc occurs;
• the figure 6 is a longitudinal sectional view of the circuit breaker according to the invention being opened after displacement of the switching arc;
• the figure 7 is a longitudinal sectional view of the circuit breaker according to the invention being opened when a cut-off arc is established between its contacts;
• the figure 8 is a longitudinal sectional view of the circuit breaker according to the invention once it is fully open and its arc cutoff has disappeared.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The idea behind the invention is a rotating arc cutting device architecture, the electromagnet of which is produced by the spiral winding of a copper strip, so as to constitute a coil capable of supporting high intensity currents while having a reasonable manufacturing cost.

In the example below, the invention is described for the case of a circuit breaker, but it can be applied to other types of electrical cut-off devices, such as for example a disconnector.

As visible in the figure 1 , the circuit breaker according to the invention, identified by 1, comprises an insulating jacket or insulator 2 having a shape of revolution extending along a longitudinal axis marked by AX. This envelope contains a support of fixed contact 3 and a movable contact support 4 which extend in the extension of one another, being spaced from one another along the longitudinal axis AX in the central part of the circuit-breaker where located the contact organs themselves.

These supports 3 and 4 are pieces of aluminum conductive revolution, of generally tubular shapes, and each support has its free end held in position in the insulator 2 by an insulating ring marked by 6 and 7, these rings being spaced apart. one another along the AX axis.

Each insulating ring 6, 7 surrounds the contact support that it carries being itself surrounded by the insulator 2 whose inner face is cylindrical.

Complementarily, a tubular spacer 8, of smaller thickness than the rings 6 and 7 extends from one ring to the other along the inner face of the insulator. The space that extends between the two insulating rings along the axis AX and which is delimited radially by the spacer 8 corresponds to the breaker chamber of the circuit breaker, which is marked by 9.

The generally tubular fixed contact support 3 carries a retractable assembly 11 housed in its free end.

This crew 11 comprises a slider 12 carrying an inductor 13 so as to constitute an assembly which is movable relative to the support 3 over a short length. Given this mobility in translation along the axis AX, the inductor 13 may protrude more or less from the free end of the support 3. A helical return spring 14 is interposed between the slider 12 and the fixed support 3 to continuously tend to recall the Crew 11 with its inductor 13 to its most output position relative to the end of this fixed support 3.

The movable contact, which is marked by 16 is carried by the support 4 being able to slide in the end of this support 4 along the longitudinal axis AX over a relatively large stroke. It is guided in longitudinal displacement by the support to be movable in a significantly greater stroke than that of the fixed contact.

This movable contact 16 is secured to an operating rod 17 extending along the axis AX being connected to an external actuating member not visible in the figures. The opening and closing of the circuit breaker are provided by the operating member which acts to move the rod 17 along the axis AX so as to move the moving contact 16 away from the fixed contact which extends in the extension of support 3.

This movable contact 16 has an outer piston shape, and it is continuously in electrical contact with the support 4 by means of a spring 18 forming a contactor. This spring 18 is a helical spring whose ends are joined, so that it has a global shape of ring crown. This spring 18 is mounted in an internal circular groove of the end of the support 4. This spring 18 is thus continuously in contact with the support 4 which carries it and with the cylindrical outer skirt 19 of the movable contact 16.

As visible more clearly in the figure 2 , the movable contact 16 which has a general piston shape having a cylindrical skirt 19 has a contact face corresponding to the cap of this piston which is flat. This cap 21 is supported on the fixed contact when the circuit breaker is closed and when it begins its opening. It has a central opening 22.

This central opening 22 makes it possible to put in communication the breaking chamber 9 and the internal space of the support 4 in the opening phase of the circuit-breaker so as to allow the gas heated in the breaking chamber 9 to escape from this chamber cut.

The inductor 13 carried by the crew 11 has a general shape of revolution and comprises, as visible more clearly in the figure 3 , a hub 23 surrounded by an inductor 24 and an outer cylindrical ring 26, and an electrical insulator 27.

The hub 23 which is conductive has a cylindrical central portion 28, one edge of which is extended radially outwards by a circular plate 29.

The cylindrical portion 28 extends along the axis AX, while the circular plate 29 extends perpendicularly to this axis. This plate 29 thus has a central opening 31 opening inside the cylinder 28. This opening 31 also allows, as in the case of the opening central 31 of the inductor, to evacuate out of the breaking chamber 9 of the heated dielectric gas by the formation of an electric arc in this chamber.

The inductor coil 24 surrounding the cylinder 28 is made from a strip of conductive material, such as a metal strip, which is wound around this cylinder 28 having for example its first end passed through a longitudinal slot provided for this purpose in the cylinder. The turns of this coil 24 are isolated from each other for example with a strip of insulating material having a width corresponding to that of the conductive strip and coiled together with the latter. It is also possible to directly use a metal strip having one or both of its faces previously covered with an insulating material.

Soldering or brazing points may be made at the end of the strip protruding from the inner side of the tube 28 to improve the electrical conduction between the strip and the tube 28.

Once the entire length of the conductive strip 24 has been wound, it is kept tight on itself to engage the outer ring 26 around it. Once the ring 26 is in position around the coil 24 held tight on itself, it is then released, so that its last turn, that is to say the most peripheral, then bears against the inner face of the ring 26, which is conductive, to be in contact with it.

This ring 26 is advantageously metallic, and it may be provided with several bores to achieve soldering points or brazing of the last peripheral coil to this ring so as to further improve the conductivity.

Thus, one of the ends of the coil 24 is electrically connected to the hub 23 and the other end of this coil is connected to the ring 26. As can be seen in particular in FIG. figure 3 the coil 24 surrounds the tubular portion 28 at a distance from the plate 29 so as not to have its edge in contact with this plate, and furthermore, the insulator 27 is interposed between the coil and the plate 29.

This insulator 27, which has a crown shape, can be put in place for example before winding the coil 24 by being engaged around the tube 28 and against the inner face of the plate 29. It can advantageously be a material of PTFE (polytetrafluoroethylene) type, designed to generate vapors favoring the extinction of a possible arc.

In addition to the insulator 27 and the strip of insulating material interposed between the turns of the coil 24, thermosetting insulating resin may be provided to cover the edge of the turns of the coil 24 which is opposite the insulator 27 along. AX axis.

In a more general manner, the assembly can be embedded in a thermosetting resin making it possible to improve the mechanical cohesion thereof, the electrical contact parts then remaining uncovered.

As visible in the figure 3 , the outer diameter of the plate 29 corresponds to the outer diameter of the ring 26, so that the circumferential edges 32 and 33 of these two elements face each other spaced apart from each other along the axis AX of a distance corresponding to the thickness of the insulation 27. The outer diameter of the plate can also be provided to be up to about twenty percent greater than the diameter of the ring.

These two edges 32 and 33 are each connected to one end of the coil 24 and the distance between them is chosen to allow the appearance of an electric arc to limit, if necessary, the intensity of the electric current flowing through the coil in the opening phase of the circuit breaker so as to reduce its heating by Joule effect.

If it is considered that the current flowing through this coil does not have to be limited, the distance separating the coil from the plate is chosen to be sufficient to hold the voltage generated by the passage of the current in the electromagnet. This distance can be increased by varying the spacing between the coil and the plate, and also by decreasing the diameter of this plate, which can, by order of magnitude, be reduced to two tenths of the diameter of the plate. the ring 26.

Referring back to figure 1 it can be seen that when the circuit breaker is closed, the movable contact 16 has its cap resting on the plate 29 of the inductor 13, against the return spring 14 on which is supported the slide 12 which is made of insulating material.

In this situation, that is to say when the circuit breaker is closed, the electrical contact between the support 3 of the fixed contact and the support 4 of the movable contact is established not by the support of the cap 21 on the plate 29 but by sliding contact fingers which extend the free end of the fixed support 3 to come radially bearing on the outer skirt 19 of the movable contact 16.

In other words, when the circuit breaker is closed, it is crossed by a current that does not flow through the inductor coil 24.

These slippery contact fingers that are spotted by 34 in the figure 1 constitute the fixed contact of the circuit-breaker. They extend approximately parallel to the axis AX, being regularly distributed around it, so as to surround the inductor 13 and the movable contact 16 whose outer diameters are the same.

Each finger 34 has at its end an electrical contact button biased radially towards the axis AX by the elasticity of the finger, so that it bears on the skirt 19 of the movable contact 16 when it is closed, that is to say when it is close to the free end of the support 3 as much as possible.

Thus, when the circuit breaker is closed, the current carried by the supports 3 and 4 does not cross the inductor coil 24 since this current passes directly from the support 3 to the movable contact 16 through the fixed contact formed by the fingers 34 carried by this support 3.

In the example of the figures, it is the fingers 34 which form the sliding contact, but it could equally well be constituted by a metal braid or any other device capable of providing a sliding electrical contact function.

The plate 29 of the inductor 13 and the cap 21 of the movable contact 16 constitute not contacts for the nominal current but contact areas on which are established the roots of an arc cutoff when opening the circuit breaker .

Starting from the situation of figure 1 where the circuit breaker is electrically closed, its opening consists in operating the rod 17 so as to move the movable contact 16 away from the fixed contact 34.

Firstly, the fingers 34 of the sliding contact leave the cylindrical outer skirt 19 of the movable contact 16 which moves away, before coming into radial abutment on the circular peripheral edge 33 of the plate 29. The current then passes successively through the support 3 , the fingers 34, the plate 29, then the cap 21 still resting on this plate, then the rest of the moving contact 16, then the circumferential spring 18 in order to reach the support 4.

When the opening movement continues, the fingers 34 leave the circumferential edge 33 of the plate 29 to bear on the outer ring 26 of the inductor, which corresponds to the situation of the figure 5 , in which the plate 29 and the face 21 are still supported one on the other. A switching arc C1 can then be established between the fingers 34 and the edge 33 of the plate 29.

At this stage, the electric current coming from the support 3 passes through the fingers 34 to pass via the ring 26 on which these fingers are resting, in the coil 24 to reach the hub 23 whose plate 29 bears on the cap 21, to reach the movable contact 16 and the support 3. In parallel with its passage in the coil 24, the current can also pass directly from the fingers 34 to the edge 32 so as to join the movable contact 16.

When the opening movement continues, the fingers 34 constituting the fixed contact continue to bear on the ring 26 while moving away from the edge of the plate 29 along the axis AX, which corresponds to the situation of the figure 6 . The switching arc C1 then has the possibility of being established between the edges 32 and 33, and no longer between the fingers and the edge 33, to continue to limit the intensity of the current flowing through the coil 24. This arrangement thus allows to limit premature wear of the fingers: they carry an arc root for a period that is small compared to the overall duration of the opening of the circuit breaker.

At this stage, the plate 29 is still resting on the cap 21, thanks to the longitudinal mobility of the crew 11 and the return spring 14.

When the opening movement is continued, the crew 11 reaches the end of its stroke, so that the inductor 13 exceeds a maximum value of the free end of the support 3, as its stroke is limited by mechanical stops.

The plate 29 is then no longer supported on the cap 21 of the movable contact 16 and a space now separates these two elements along the axis AX, which corresponds to the situation of the figure 7 .

At this stage, a cut-off arc C2 has formed between the plate 29 and the cap 21. This arc extends approximately parallel to the axis AX while being spaced radially from this axis AX. Moreover, the current flowing through the coil 24 generates a magnetic field.

Given the angle formed by the field line and the arc C2, this magnetic field gives rise to Lorentz forces, of orthoradial orientation with respect to the axis AX, which causes the rotation of the arc C2 around the axis AX, to promote its cut, that is to say its disappearance.

As indicated above, the expansion of the gas present in the interrupting chamber 9 due to the heat generated by the cut-off arc C2 is compensated by the evacuation of gas via the openings 22 and 31.

Thus, the arc C2 is forced to rotate about the axis AX so that its roots move on the surface of the plate 29 and the cap 21, and at the same time, these faces move away from one another. another to increase the length to be traversed by this arc. This leads to the cutting of this C2 arc, that is to say to its disappearance when the situation is reached. maximum opening corresponding to that of the figure 8 .

In the example of the figures, the magnetic field generated by the inductor is not channelized, but the system can be equipped with one or more ferromagnetic cores for channeling the field lines to improve the efficiency of the magnetic field on the field. the bow to extinguish. In this context, one possibility may be to provide a tubular element of ferromagnetic material mounted to the inner face of the hub 23 by hooping.

Moreover, in the example of the figures, the inductor and its return means and the sliding contact are carried by the fixed contact support, but it is possible to reverse the mounting. In other words, the inductor and its return spring and the contact slip can be carried by the moving contact of the circuit breaker.

Other arrangements can still be envisaged with regard to the components carrying the coil, the return spring as well as the sliding contact in the system.

Claims (5)

1. Rotating arc power outage device (1) such as a circuit breaker or a switch, comprising a stationary contact (34) and a mobile contact (16), the mobile contact (16) being movable between a closed position, wherein it is in electrical contact with the stationary contact (34) and an open position, wherein it is spaced from the stationary contact (34) as well as at least one inducer (13) including a coil (24) for generating a magnetic field extending to make an electric arc (C2) appearing between the contacts (11, 16) rotate, during the opening of these contacts to favour the extinction of this arc, the inducer (13) comprising a hub (23) comprising a cylindrical portion (28) on which is wound a metal strip to form a coil (24), a metal ring (26) clamping this coil (24), the cylindrical portion (28) of the hub (23) being extended by a circular plate (29) perpendicular to the cylindrical portion (28), this plate (29) being spaced from the coil (24) and insulated from this coil (24), the coil (24) having an end electrically connected to the plate (29) via the cylindrical portion (28) of the hub (23) and an end electrically connected to the metal ring (26) clamping the coil (24),
   characterised in that

   - the plate (29) is spaced and insulated from the coil (24) by an insulating material (27);

   - the inducer (13) is mounted at the end of a support of the stationary contact (3) by being mobile between a retracted position and a deployed position, with a spring (14), continually returning this inducer (13) to the deployed position thereof;

   - the mobile contact (16) has a piston shape comprising a sleeve (19) of the same diameter as the ring (26) of the inducer (13) and a cap (21) bearing on the inducer (13) against the spring (14) to keep it retracted when this mobile contact (16) is closed, this cap (21) being offset from the inducer (13), such that it occupies the deployed position thereof when the mobile contact (16) is open;

   - the stationary contact (34) is a sliding contact (34) extending in the extension of the stationary contact support (3) by having a free end which bears radially against the sleeve (19) of the mobile contact (16) when this mobile contact (16) is closed and bears radially against the ring (26) of the inducer when the mobile contact (16) is open, to make it possible for the establishment of an electric arc between the plate (29) and the ring (26) to limit the current passing through the coil (24) in case of need.
2. Device according to claim 1, wherein the cylindrical ring (26) has holes comprising points for welding or soldering the metal strip (24) to the ring (26) and/or wherein the hub (23) has a slot passed through by an end of the strip (24).
3. Device according to claim 1 or 2, wherein the circular plate (29) of the hub (23) has an outer diameter corresponding to the outer diameter of the ring (26) and of the mobile contact (16) while being spaced and electrically insulated from the ring (26).
4. Device according to any of the preceding claims, wherein the mobile contact (16) and the inducer (13) each comprise a central opening (22, 32) for releasing blanket gas in case of heating, resulting from an electric arc being established during opening.
5. Device according to one of the preceding claims, wherein the hub (23) has a portion made of ferromagnetic material in the central region thereof.

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