EP1191560A1 - Gas-blast device for electrical arc in an electrical modular apparatus - Google Patents

Abstract

The electrical arc gas extinguishing mechanism has a fixed contact (5) and a moving contact (4) held by a release mechanism. The release mechanism is activated by a thermal strip or magnetic drive. The unit is integrated in an isolated container with an extinction arc chamber and conductor arc sheet sides. The electrical arc generated on contact separation is preferentially passed to the arc extinguishing chamber by gas movements (19).

Description

The present invention relates to a gas blowing device electric arc, integrated in a modular electrical protection device line type circuit breaker.

These devices conventionally comprise a fixed contact and a contact mobile that establish an electrical connection when in contact with one on the other, and which cut it when they are separated, voluntarily using a joystick or automatically by tilting of a mechanical lock in the event of overcurrent or overload on the line.

When the fixed and mobile contacts move away from each other, an arc electric is created between them. We traditionally extinguish it by moving in at least one arc extinguishing chamber fitted the modular electrical appliance. The principle then used consists in lengthening or to divide the arc until the tension necessary for its maintenance is greater than that of the network in which the device is used, resulting in its extinction.

According to a first known solution, said voltage is increased by dividing the arc in a stack of deionization sheets. We increases the number of arc feet and, knowing the value of the voltage across each arc foot, a number of sheets allowing to achieve by addition to a total arc voltage greater than that of the network. A second classic solution consists in lengthening the arc to increase the tension.

In both cases, it is still necessary to move the arc so that it goes from the actual contact area in a place where there is enough lengthened or divided to meet the required criterion, namely to present a higher voltage than the network to be able to turn it off.

For this purpose, arc conduction sheets limiting on two sides opposite the arc extinguishing chambers, allied in particular to the effect of loop applying to the arc, direct it towards the terminal area of each room, where there is either a stack of sheets of deionization, that is to say a configuration achieving an elongation of the arc resulting in passing its voltage beyond that of the network.

However, the progression of the arc, even its extinction, are made more difficult by several factors sometimes caused by the arc itself, which influences its environment due to changes in certain physical parameters that it induces, which tend to keep it active. Thus, it causes for example an increase in temperature which as a corollary, increases the ionization of the plasma, which constitutes obviously a favorable condition for its existence.

Likewise, the gaseous medium changes and, in the vicinity of the arc, liquid and gaseous metallic particles from contacts may be present in ionized air. These particles increase the risk of rebooting.

Finally, the creation of the arc generates an overpressure, especially at its downstream, which tends to oppose its movement.

According to the present invention, these drawbacks are overcome by an improvement in the gaseous blowing of the arc, which leads to increasing the speed and efficiency of its movement towards the end of the extinguishing chambers where the extinguishing device (s) are located supra.

According to a main objective, this gas blowing is implemented via management of a set of pressures and flows applied to the plasma arc, generating forces causing it to move towards the extinguishing chambers without the addition of active consumer elements energy.

According to this objective, a gas circulation without external input energy is put in place so that the air is fresher, even regenerated and cooled is available at the contacts.

The circulation circuits are also provided to create a system depression / overpressure, respectively downstream and upstream of the arc, thus promoting its movement in the breaking chamber.

Finally, the device of the invention is configured to avoid plasma backflow to the contact area, which would consequence of increasing the risk of re-ignition on the contacts.

To fulfill these objectives, the invention, applying as mentioned to a modular electrical device of the circuit breaker type, provided with a contact fixed and a movable contact secured to a release lock actuated by either a thermal bimetal or by an actuator magnetic coil and magnetic circuit, these components being integrated in an insulating housing comprising at least one chamber arc extinguishing lined with arc conduction sheets, is characterized by what it involves means of creating gas displacements at the interior of the housing promoting the progression of at least one electric arc generated after separation of the contacts to at least one room corresponding arc extinction.

These means, closely linked to the architecture of the product, allow manage gas flows and pressures so that the arc or electric arcs are propelled towards their arc extinguishing chamber. This is achieved by configuring the interior of the case so that create gas flow circuits suitable for this purpose.

According to an additional possibility, the gas used is treated inside of the housing of the electrical appliance by means of pollution control making its characteristics unfavorable to the survival of the arc.

Thus, among the properties of the gas which favor the conservation of the arc, we find essentially ionization, the existence of particles and temperature. The purpose of gas treatment is therefore to cool the plasma to deionize it, to condense the vapors then clean it up by retaining the particles and droplets.

The management of flows and pressures and the depollution of gas are obviously treated simultaneously in the enclosure of the the electrical apparatus of the invention, since they proceed from geometry internal product.

The gas used is generally air, or more precisely essentially air-based, possibly modified by physico-chemical treatments due to the arc.

As part of the gas circulation management, the the invention includes means for injecting recycled air into the area contacts after their separation, said air being injected immediately upstream of the contacts, in order to push the arcs to the corresponding extinguishing chambers.

The goal is to provide not only air at temperatures below that which reigns at the level of the arc, if possible devoid of particles metal in order to degrade conditions as much as possible favorable to the perpetuation and reignition of said arc, but still generator of a favorable direction circulation to repel it.

In particular, said means for injecting recycled air comprise at minus a channel in which the recycled air circulates from downstream of the area contacts upstream of said area.

We are actually trying to use a maximum amount of fresh air contained in the product when the arc appears, hence the idea of a recycling in the longest possible channel relative to the volume possibilities of the housing.

According to one possibility, the recycled air passes through at least one room arc extinction, at the exit of which it is guided towards an area located upstream of the contacts in a flow which is oriented in the direction of these, creating an overpressure upstream.

This fresh air, repelled by the arc when it advances in the direction of its extinguishing chamber, is therefore led upstream of the arc. This is in made of a fluid circuit of which a large part of the gas is already present before the onset of the arc, and can therefore be described as contribution costs upstream of said arc.

In addition, to get rid of metallic particles, one at less of said channels includes a device for centrifuging solid and liquid metallic particles in the air after opening of contacts. Prior to centrifugation, the gas undergoes a sudden relaxation.

According to one possibility, this centrifugation device consists of a cylindrical wall chamber. The exit from the latter leads to a expansion conduit ending and opening on the contact area.

Air recycling notably increases the pressure by upstream of the arc. Downstream, the pressure is notably kept low by the existence of orifices which allow circulation towards the outside of the shell. It should be noted that the pressures upstream and downstream of the arc are also managed by the particular forms given to the zones involved in blowing, recycling, extinction etc ... and in particular to arc conduction sheets, recycling conduits etc ...

According to a possible variant, a fraction of the air located downstream of at least less an electric arc is entrained in a suction system creating a depression downstream of it.

In one of the envisaged configurations, this suction system comprises a duct disposed at the outlet of an arc extinguishing chamber, directing air to a portion using the Venturi effect located downstream of an evacuation opening made in a housing wall.

To create these zones, and in particular the channels or conduits of recycling, air intake and / or particle deposition areas metal, the modular device preferably comprises, between the shells forming the housing, a middle wall of parallel appearance to the long sides. The reliefs of this intermediate wall, cooperating with those which exist on the half shells of the case, form the configuration zones ensuring the management of gas circulation. In particular, the side facing the contacts has reliefs and orifices forming air circuits by combination with arc conduction sheets and ends of arc extinguishing chambers. The side of the side of the reel created by combination between its reliefs and those of the half-shell opposite conduits or channels. Depending on the case, the passage of air from one side to the other of said wall is made possible, in particular to lengthen fluid circulation channels.

In fact, the particular layout of this median wall, combined with components which adjoin or insert it on both sides, as well as orifices which are practiced there, allows the realization of all the channels, conduits and chambers performing the above functions.

In addition, in order to facilitate the establishment of an overpressure in upstream and a depression downstream of the arc in the zone forming zone contact, and to limit gas return, the distance between the walls of said contact zone and that between the conduction sheets arc at the output thereof are reduced to reduce the input section from the room.

It is important to prevent gas returns as much as possible likely to interfere with arc progression and decrease tension disruptive between open contacts, which would result in increase the risk of reboot.

In fact, the arc conduction sheets leave the zone of make contact with a loop form that develops towards each other, and walls of the contact area are provided with a raised tray bringing one closer to the other.

The resulting tightening, particularly at the outlet of said contact area, also allows the arch -also thanks to the shapes above mentioned - to easily switch during its journey towards the arc extinguishing chamber (s).

According to one possibility, the electric arc is then divided into two sections routed in opposition to two extinguishing chambers arc located in the same mean plane, facing each other, the two arc sections causing mutual gas blowing towards of their arc extinguishing chambers due to the creation of a overpressure between them.

The general dynamic of gas blowing is further strengthened by the existence of this overpressure between the two arcs progressing in opposition, that is to say substantially in the same direction but according to two opposite directions. This overpressure only exists when there are two extinguishing chambers obeying the above configuration.

To implement the features mentioned above, and in particular the various gas circuits, it is necessary to design, to inside the housing, suitable passage areas for gases.

For example, the centrifuge chamber, preferably arranged on the contact side, is supplied by a fraction of the outlet air an arc extinguishing chamber.

According to a possible alternative or complement, the centrifugation is arranged on the middle wall and it is located at the lateral end of each arc extinguishing chamber.

Likewise, a fraction of air leaving each extinguishing chamber arc is sent into a channel in the "coil" side of said median wall, then reinjected via at least one orifice into a conduit provided on the "contacts" side of said wall, upstream of the contact.

According to the arc extinguishing chamber concerned, and the orifice put in work, this second fraction can be directly recycled, then injected at the contacts, or stored in the product.

Another fraction of the air leaving each room arc extinction is sent via an orifice passing through the middle wall to a channel located on the other face of said wall, using the Venturi effect. The air can then be expelled from the housing.

Holes are drilled for this purpose in the shells forming the housing, at the side exits of the arc extinguishing chambers, also to allow a final fraction of air to be exhausted. They serve not only to evacuate the air contained in the housing, but still secondarily favor a depression in downstream of the arc.

Gas blowing naturally supports the measures traditional methods of extinguishing the arc, and in particular of the means used to lengthen it. Thus, according to an advantageous configuration, the walls of the apparatus of the invention bordering the arc extinguishing chambers are provided with reliefs offset from one wall to another, and interpenetrate without contact so as to stretch the electric arc forced to conform to the series of baffles thus created.

• la figure 1 est une vue en perspective d'un circuit électrique de disjoncteur, muni d'une bobine plane spiralée équipant un appareil électrique modulaire selon l'invention ;
• la figure 2 montre une vue perspective éclatée d'un disjoncteur selon l'invention ;
• la figure 3 montre le soufflage du contact par un gaz frais ;
• la figure 4 représente, au verso du conduit de la figure précédente, le canal d'accumulation de gaz frais ;
• la figure 5 montre la direction d'aspiration du gaz en aval de l'arc ;
• la figure 6 illustre la suite du système d'aspiration, au verso, avec l'effet venturi ;
• les figures 7 et 8 représentent deux circuits de recyclage par centrifugation ;
• la figure 9 est une vue globale d'un disjoncteur muni des deux circuits de recyclage des figures 7 et 8 ;
• la figure 10 montre les plateaux surélevés permettant une réduction de la distance entre les parois dans la chambre de contact ;
• la figure 11 représente les boucles réduisant l'ouverture entre les tôles de conduction d'arc en aval des contacts; et
• les figures 12a à 12e montrent la progression et la division de l'arc.

The invention will now be described in more detail, in particular with reference to the appended figures for which:

• Figure 1 is a perspective view of an electrical circuit breaker, provided with a flat spiral coil fitted to a modular electrical device according to the invention;
• Figure 2 shows an exploded perspective view of a circuit breaker according to the invention;
• Figure 3 shows the contact blowing with fresh gas;
• 4 shows, on the back of the conduit of the previous figure, the fresh gas accumulation channel;
• Figure 5 shows the direction of gas suction downstream of the arc;
• FIG. 6 illustrates the continuation of the suction system, on the back, with the venturi effect;
• Figures 7 and 8 show two recycling circuits by centrifugation;
• Figure 9 is an overall view of a circuit breaker provided with the two recycling circuits of Figures 7 and 8;
• FIG. 10 shows the raised plates allowing a reduction of the distance between the walls in the contact chamber;
• FIG. 11 represents the loops reducing the opening between the arc conduction sheets downstream of the contacts; and
• Figures 12a to 12e show the progression and division of the arc.

Referring to Figure 1, the electrical circuit chosen for this description, which is however only one possible example to which the invention applies, consists essentially of a coil induction (1), two connection terminals (2, 3), a fixed contact (4), a movable contact (5) and a bimetallic strip (6).

The electrical connections follow the following diagram: terminal (2) is connected to the bimetallic strip (6) via a flexible conductive braid (7). The coil (1) is also connected to said bimetallic strip (6) via a second flexible braid (8) arranged at one of its ends, the other end being connected to the fixed contact (4), which is extended by a sheet of arc conduction (9). The movable contact (5) is connected by means of another flexible conductive braid (10) to a sheet (11), the lower part of which (12) also serves as an arc conduction sheet, while the part upper is connected to the second terminal (3).

FIG. 2 shows a complete product, in this case a circuit breaker, including the housing composed of half-shells (32, 33) separated by a wall middle or intermediate (22), seen here from the "coil" side. Besides the elements already described, the circuit breaker comprises a handle (34) of control connected to a lock (35) to which the movable contact (5) is secured. This lock can flip in the event of an overcurrent (magnetic trip) overload (thermal trip) or manual opening via the handle (34).

The magnetic circuit is composed of a core referenced (13), extended by two branches (14,15), the whole forming a U whose the free end is provided with a movable pallet (16), which is the occurrence of a single piece with the thermal bimetallic strip (6). It is it is also possible, according to a variant, to separate these two parts.

The configuration shown includes two arc extinguishing chambers provided with sets of deionization plates (24, 25). These rooms are located in the same medium plane, and allow the extinction of two arc portions obtained after division of the main arc, which the spacing of the fixed (4) and mobile (5) contacts. Two shield sheets (17,18) equip the half-shells (32, 33) for magnetic purposes which do not contribute to the object of the present invention, and therefore do not the subject of a detailed description. It should be noted that the intermediate wall (22), located between the half-shells (32) and (33), is not shown here in detail, but only for illustrative purposes, in order to clarify its positioning in the product.

Figure 3 shows the assembled elements, seen from the side opposite the general orientation of the representation of FIG. 2. In this case, the components are assembled on the half-shell (33), and the wall intermediate (24) hides the spiral coil. The "contacts" side of said wall (22) therefore appears in this figure. It includes in particular a duct (19) which conveys fresh air (the flow of which is symbolized by arrows), said conduit (19) opening near and upstream of contacts (4, 5). This conduit (19) is delimited by reliefs which appear on the intermediate wall (22), which actually form the bottom and the two side walls, the upper part, designed to isolate and allow it to fulfill its function without gas exchanges or losses, being constituted by the half-shell (32).

Referring to Figure 4, showing the other side of the intermediate wall (22), the source of the air conveyed in said conduit (19) appears.

In this figure, the half-shells (32,33) are represented assembled, and the upper half-shell (33) is shown in transparency. The channel (20) is the one which supplies fresh air to the duct cited above (19). The air stored there is related, upstream, to the arc extinguishing chamber comprising the deionization plates (24). Downstream, this air passes through an orifice (21) formed in the intermediate wall (22), and opens into said channel (19). So the air stored in the channel (20) is pushed back towards the conduit (19) when an electric arc progresses towards the arc extinguishing chamber, i.e. after a tripping. The generated air flow supplies fresh air to the area upstream of the contacts (4,5), and consequently promotes the thrust of the electric arc created and plasma cooling by dilution.

The air which is forced back by the moving electric arc does not succeed only to move the gas masses in the channel (20) and in the conduit (19). Indeed, in addition to the passage located at the level of the sheets higher deionization (24), leading as seen in the channel (20), air can also be drawn in via an orifice (27), also practiced in the intermediate wall (22), and which appears in Figure 5. In reference to FIG. 6, the orifice (27) opens, on the other side of the wall intermediate (22), in a conduit (28), the high velocity of the cut from the deionization plates (25) created by effect Venturi a depression favoring the aspiration by the orifice (27).

It should be noted that the existence of this Venturi allows a suction effect thanks to the differential speed of the fluids in said Venturi. The air located downstream of the electric arc, and which enters the extinguishing chamber arc comprising the sheets (25) is drawn in via the orifice (27), said aspiration creating a depression favorable to the progression of the arc in the arc extinguishing chamber. It should be noted that the arc conduction sheet (12) (see Figure 5) does not have the same position as in Figure 3, because it must allow access to the orifice (27). It is therefore folded upwards to free access of this orifice (27) to a fraction of the air. We can also thus stretch the arc by raising it towards the orifice (27).

FIG. 7 shows only part of the circuit breaker of the invention, substantially centered on the core (13) of the magnetic circuit. This figure shows an air recycling circuit allowing its depollution. In the case shown, the arc extinguishing chamber does not have of deionization sheet, but a circular chamber whose operation will be explained below. In the upper part, just below the duct (19) carrying the fresh air, another room of circular appearance (28), followed by a conduit (29) terminating upstream of the contacts (4) and (5), allows the reinjection of clean air.

The gas located downstream of the electric arc is expanded, to condense metallic vapors at the entrance of the arc extinguishing chamber. Then, a circular flow occurs in the chamber (28). Because of the centrifugation, the massive particles are kept at the periphery, and the gas to be recycled is extracted from the side, and reaches the conduit (29). The inertia of massive particles forces them to stay in the flow facing the chamber (28). Therefore, clean air - because that devoid of these metallic particles- is reinjected upstream of the electric arc, allowing it to be driven back to the extinguishing chambers arc.

In general, the circulation of gases allows the cooling, in particular in contact with the air masses existing in the conduits, which leads to their deionization. The sudden relaxation of plasma also has the effect of cooling the gas, therefore ionize.

Referring to Figure 8, the same centrifugation process is produced in the chamber (30), with a yield which is theoretically better than in the chamber (28), because the dense particles are forced to stay on the outskirts, while the fresh air escapes through a orifice (31) central to said chamber (30).

It should be noted that in this configuration, there are no sheet metal deionization, and that the arc is drawn and laminated, in particular by the relief elements (36).

In this figure, only one of the walls of each chamber arc extinction appears, and the arc stretching mode using the elements (36) is not fully figured. It appears better in figure 9, showing relief elements (36, 36 ') located on the walls opposite chambers, the upper half-shell (33) being shown in transparency. The lower half-shell (32) is shown opaque. With the elements (36, 36 ') shown, the arc is laminated in zigzag, so as to lengthen it in all cases. The same configuration also appears in Figures 10 and 11.

The object of figure 10 is also to show that one proceeds to a narrowing of the distance between walls in the contact zone, at using the raised volumes (37, 38) which exceed on the one hand the intermediate wall (22) and on the other hand of the half-shell (32). It's about simply of prominent reliefs or plateaus at said level contact area.

Referring to Figure 11, the opening disposed at the outlet of said room is reduced by the particular configuration given to the sheets of arc conduction (9, 12). The fixed contact (4) is connected to a sheet of arc conduction (9), via a loop which advances towards a loop (26) of the same function arranged between the sheet (11) and the conduction sheet arch (12). It should be noted that the intermediate sheet (23) comprises also a summit part in this same region, whose interest will be explained with reference to the following figures.

The reduction in opening conferred by the above-mentioned loops, as well as the reduction in distance between the two walls due to the plates raised (37) and (38), limits gas return to the contact area, especially to maximize in one direction favorable the mutual gas blowing effect of the arcs after division, as will be seen in more detail below. In addition, by bringing together locally the sheets, we create a preferential reboot zone to protect the contacts. Finally, the loop on the arc sheet lower (23) being located on the natural trajectory of the arc, the switching is easy when dividing.

This is particularly what appears in Figures 12a to 12e. In the particular configuration of circuit breaker subject of the invention, there are two arc extinguishing chambers located in the same medium plane, in opposite each other. When the arc (39) is created, it moves towards said extinguishing chambers. Switching between mobile contact (5) and the loop (26) takes place naturally due to the shape thereof, as shown in Figure 12b. The arc continues to progress towards intermediate sheet (23), free of potential. The confluence of the three sheet loops allow natural switching at the time of division. It appears in Figure 12d, which shows the two sections of the arch in opposition. This opposite configuration is extremely favorable in terms of arc blowing because a overpressure is created between them, generating a gas flow in direction of the deionization plates (24, 25). One of the problems lies in the possibility of gas returns to the lock (35). The narrowing appearing in Figures 10 and 11 are intended to limit these gaseous returns. In addition, the gas flows from outlet openings of the channels (19) and (29), causing flows opposite to the gas return, also limit the latter.

Referring to Figure 12e, the arcs are cut in the sheets deionization, and gaseous fluids downstream of the arc portions may escape at the level of the lower deionization plates (see arrows). However, at the level of the deionization plates gases follow the circuits which have been explained previously. This figure 12e shows with arrows the circuits gaseous which are used in the configuration of the invention.

Figures 12a to 12e do not show the half-shells (32) and (33), but only the intermediate wall (22).

In the previous figures, several versions of circuit breakers comprising a gas blowing device according to the invention, such as a deionization device with overlapping sheets, a device with stretching and arc rolling and cylindrical recycling chamber, a device with suction pipe etc.

Of course, the invention is not limited to these configurations, but on the contrary encompasses all variants of form and configuration which are within the reach of ordinary skill in the art.

Claims (16)

Electric arc blowing device integrated into a modular electrical device of the circuit breaker type, the latter essentially comprising a fixed contact and a movable contact secured to a trip lock actuated by either a thermal bimetal strip or by a magnetic actuator with inductor coil and magnetic circuit, these components being integrated in an insulating housing with two half-shells comprising at least one arc extinguishing chamber bordered by arc conduction sheets, characterized in that it comprises means for creating displacements gaseous promoting the progression of at least one electric arc generated after separation of the contacts towards at least one corresponding arc extinguishing chamber. Electric arc blowing device according to the preceding claim, characterized in that the gas used for said gas displacements is treated inside the casing of the electrical appliance by pollution control means rendering its characteristics unfavorable to the survival of the arc. Electric arc blowing device according to one of the preceding claims, characterized in that it is provided with means for injecting recycled air into the contact area after their separation, said air being injected immediately upstream contacts, in order to push the arc (s) towards the corresponding extinguishing chamber (s), said means comprising at least one channel in which the recycled air circulates from downstream of the contact zone to its upstream . Electric arc blowing device according to the preceding claim, characterized in that the recycled air passes through at least one arc extinguishing chamber, at the outlet of which it is guided via at least one channel to an area located upstream of the contacts, according to a flow which is oriented in the direction of the latter, and capable of creating an overpressure there. Electric arc blowing device according to the preceding claim, characterized in that at least one of said channels comprises a device for centrifuging solid and liquid metallic particles contained in the air after switching off the contact, the gas having been previously suddenly relaxed. Electric arc blowing device according to the preceding claim, characterized in that the centrifugation device consists of a chamber with a cylindrical wall, the outlet of which opens onto an expansion duct terminating and opening upstream of the contacts. Electric arc blowing device according to any one of the preceding claims, characterized in that a fraction of the air located downstream of at least one electric arc is entrained in a suction system creating a vacuum in downstream of it. Electric arc blowing device according to the preceding claim, characterized in that the suction system comprises a duct disposed at the outlet of an arc extinguishing chamber, directing the air towards a portion of said duct using the 'venturi effect, arranged downstream of a discharge opening in a housing wall. Electric arc blowing device according to any one of the preceding claims, characterized in that in order to facilitate the establishment of an overpressure upstream and a depression downstream of the arc in the zone forming contact zone, and to limit the gas returns there, the distance between the walls of said contact chamber, and that between the arc conduction sheets at the outlet thereof, are reduced to reduce the entry section of bedroom. Electric arc blowing device according to the preceding claim, characterized in that the arc conduction sheets have a loop shape developing towards each other, at the outlet of the contact zone and at least l one of the walls thereof is provided with a raised plate. Electric arc blowing device according to any one of the preceding claims, characterized in that the electric arc is divided into two sections routed in opposition to two arc extinguishing chambers located in the same opposite mean plane one from the other, the two arc sections carrying out a mutual gas blowing in the direction of their arc extinguishing chamber due to the creation of an overpressure between them. Electric arc blowing device according to any one of the preceding claims, characterized in that the modular electrical appliance comprises, between the half-shells forming the housing, a median wall with an appearance parallel to the long sides, separating a coil which is housed in a housing on one of its faces of the contacts arranged on the other face, said faces having reliefs and orifices forming conduits and chambers, in combination with the components and the corresponding reliefs formed on the half shells. Electric arc blowing device according to the preceding claim, characterized in that the centrifugation chamber is arranged on the contact side, and is supplied by a fraction of the air at the outlet of an arc extinguishing chamber . Electric arc blowing device according to one of claims 12 and 13, characterized in that a fraction of the air leaving each arc extinguishing chamber is sent into a channel located on the coil side. the middle wall, then reinjected via at least one orifice in a conduit on the side and upstream of the contacts. Electric arc blowing device according to one of claims 12 to 14, characterized in that a fraction of the air leaving each arc extinguishing chamber is sent via an orifice passing through the central wall, to a channel located on the other face of said wall, using the Venturi effect. Electric arc blowing device according to any one of the preceding claims, characterized in that the walls bordering each arc extinguishing chamber are provided with reliefs offset from one wall to the other, and interpenetrating without contact so as to stretch the electric arc forced to conform to the series of baffles thus created.

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