EP2804189A1 - Arc extinguising chamber for an electric protection apparatus and electric protection apparatus comprising same - Google Patents

Abstract

The present invention relates to an interrupting chamber (7) of an electrical protection apparatus comprising an arc-forming chamber enclosing a fixed contact (4) and a movable contact (3) which, at the moment of their separation, form an arc (a) between them, said arc forming chamber communicating with the inlet of a second so-called arc extinction chamber. This chamber is characterized in that it comprises a so-called balancing wall (14), substantially solid on at least its central portion, said wall being located downstream of the arc extinguishing chamber (9) and being shaped and arranged with respect to the arc extinguishing chamber (9), so as to brake the exhaust flow of the cutoff gases on the side i of the extinguishing chamber (9) where the gases go first and foremost. promoting the flow of exhaust gas flows on the opposite side j, said exhaust gas being stopped by the central portion of the wall (14) and escaping through the edges of the wall (14).

Description

TECHNICAL AREA

The present invention relates to the interrupting chamber of an electrical protection apparatus, comprising an arc-forming chamber enclosing a fixed contact and a movable contact, which, at the moment of their separation form an arc between them, said training chamber arc communicating with the entrance of a second chamber, said arc extinction.

STATE OF THE PRIOR ART

In known circuit breakers, in particular miniature limiting circuit-breakers, it has been observed that, after the switching of the arc, and the displacement thereof in the breaking chamber in the direction of the extinguishing chamber, phenomena of reclamation occur, which degrade more or less strongly the quality of the cut.

Some of these devices, such as those described for example in the documents EP 1 017 072 or FR 2,471,661 , comprise elements forming insulating gates situated downstream of the arc extinguishing chamber, and whose orifices are intended to allow the passage of the gases generated during the arc cutting. The role of this plastic grid placed against the extinguishing chamber and downstream thereof, is to evacuate and control the outflow so as to prevent the reclamation between fins at the rear of the extinguishing chamber, and to prevent the arc from settling downstream.

This insulating gate placed downstream of the extinguishing chamber is made either by an additional non-fusible piece (fiber or thermosetting plastic), which increases the cost, or by adding a suitable molded form with the thermoplastic case, which melts when the device is subjected to several successive shortcircuits, which further disrupts the exhaust gas cutoff.

It is known that these phenomena of reclamation are due to poor insertion of the arc into the extinguishing chamber, this faulty insertion being due to poorly controlled gas flow.

Indeed, in the majority of circuit breakers, some fins are reached first by the gases, inducing a flow of gases on the fins concerned. Indeed, the gases take the most direct path and therefore more easily to the side of the chamber opposite the contacts than to the other side of the chamber, the starting point of the gas being the contact zone.

Depending on the arrangement of the discharge channels downstream of the chamber, this first circulation can hinder or prevent the circulation of hot gases between the other fins, and thus prevent a balanced insertion of the arc over the total height of the chamber. Indeed, the arc is inserted where the gases are hottest so where the gases are the most conductive.

SUMMARY OF THE INVENTION

The present invention solves these problems and proposes a breaking chamber for an electrical protection device, as well as an electrical protection device comprising it, making it possible to improve the quality of the cutoff so as to improve the energy capacity of the apparatus. .

For this purpose, the subject of the present invention is a breaking chamber of the kind mentioned above, this breaking chamber being characterized in that it comprises a so-called balancing wall, substantially solid on at least its central portion, said wall being located downstream of the arc extinguishing chamber and being shaped and arranged with respect to the arc extinguishing chamber, so as to brake the exhaust flow of the cutoff gases on the side of the extinguishing chamber where the gases go first and to favor the flow of the exhaust gas streams on the opposite side, the exhaust gases being stopped by the central part of the wall and escaping by the edges of the wall . By these characteristics, the invention makes it possible to rebalance the circulation of the gases, by limiting the circulation in certain places where it was satisfactory in favor of another place where it was insufficient.

According to a particular preferred embodiment of the invention, said arc extinction chamber comprising a stack of cooling elements extending substantially parallel to each other, this chamber is characterized in that the aforementioned wall is very close to the arc extinguishing chamber on the side where the exhaust goes first and away from the chamber as one moves away from that side of the chamber so as to away from said chamber on the opposite side to the previous one of said arc extinguishing chamber.

This characteristic has the additional advantage of eliminating the use of an insulating grid usually used to prevent the arc from being established downstream of the chamber, and usually located by necessity very close to the chamber. This grid had indeed the disadvantage of melting at the time of the cut, which caused an obstruction impeding the flow of exhaust gas.

Indeed, this balancing partition performs the same function as the grid, in addition to its primary function which is to balance the flow of gas, does not need to be placed as close to the extinguishing chamber as the grid, present a very limited melting and vaporization, which allows it not to disturb the flow of gases, but is sufficient to maintain the arc in the chamber. In addition, this partition also has the advantage of being more robust than a grid, and to be easier to mold.

According to a particular characteristic of the invention, the aforesaid arc extinguishing chamber comprises a number of reduced cooling elements allowing the block formed by all of these cooling elements to be inclined relative to the base of the apparatus, and the aforesaid wall extends substantially parallel to the base of the apparatus.

According to another feature, the aforementioned wall extends at an angle of between 3 and 15 ° with the alignment direction of the aforementioned cooling elements.

According to another embodiment of the invention, said balancing wall has a variable width, this width being maximum on the side of the arc extinguishing chamber where the gases pass first, and being reduced more and more as and as one approaches the other side of said chamber.

According to a particular characteristic of the invention, the aforementioned wall is integral with the housing or the cover of the apparatus.

According to another embodiment of the invention, said arc extinguishing chamber comprising means for holding the cooling elements relative to each other, said wall being an integral part of these means for holding the cooling elements.

Advantageously, the aforementioned balancing wall is an integral part of the bottom wall of the aforementioned holding means of the cooling elements, said bottom wall comprising, around said balancing wall, slots extending substantially parallel to the elements of the cooling, and whose length varies from one end to the other of the wall.

Thus, according to this embodiment, the same part performs three functions, namely maintaining the fins, balancing the flow of gas, and the limitation of the risk of reclamation.

The present invention also relates to an electrical protection apparatus comprising at least one polar unit mounted in a housing, said polar unit having a breaking chamber having the aforementioned characteristics taken alone or in combination.

According to a particular characteristic, this device is a low-voltage electrical circuit breaker.

BRIEF DESCRIPTION OF THE DRAWINGS

• La figure 1 est une vue en plan d'un disjoncteur selon l'art antérieur, illustrant la partie intérieure de l'appareil,
• La figure 2 est une vue en plan similaire à la figure 1, d'un disjoncteur selon une réalisation particulière de l'invention,
• La figure 3 est une représentation graphique, illustrant la tension d'arc et le courant circulant dans l'appareil en fonction du temps, pour un appareil selon l'art antérieur et pour un appareil selon la réalisation préférée de l'invention,
• La figure 4 est une vue en plan similaire aux figures 1 et 2, d'un disjoncteur selon une seconde réalisation de l'invention,
• La figure 5 est une vue de dessous d'une cloison d'équilibrage équipant la chambre d'extinction d'arc d'un disjoncteur selon la figure 4,
• La figure 6 est une vue en plan similaire aux figures 1,2 et 4, d'un disjoncteur selon une autre réalisation de l'invention,
• Les figures 7 et 8 sont des vues de dessous d'un élément dit fibre grise destiné à équiper respectivement un disjoncteur selon l'art antérieur et un disjoncteur selon la figure 6, et
• Les figures 9 et 10 sont des vues similaires aux figures 1, 2, 4 et 6, d'un disjoncteur selon respectivement deux autres réalisations de l'invention.

But other advantages and features of the invention will become more apparent in the detailed description which follows and refers to the accompanying drawings given solely by way of example and in which:

• The figure 1 is a plan view of a circuit breaker according to the prior art, illustrating the inner part of the apparatus,
• The figure 2 is a plan view similar to the figure 1 of a circuit breaker according to a particular embodiment of the invention,
• The figure 3 is a graphical representation, illustrating the arc voltage and the current flowing in the apparatus as a function of time, for an apparatus according to the prior art and for an apparatus according to the preferred embodiment of the invention,
• The figure 4 is a similar plan view to Figures 1 and 2 of a circuit breaker according to a second embodiment of the invention,
• The figure 5 is a view from below of a balancing partition equipping the arc extinction chamber of a circuit breaker according to the figure 4 ,
• The figure 6 is a similar plan view to figures 1,2 and 4 of a circuit breaker according to another embodiment of the invention,
• The Figures 7 and 8 are views from below of a so-called gray fiber element intended to equip respectively a circuit breaker according to the prior art and a circuit breaker according to the figure 6 , and
• The Figures 9 and 10 are similar views to Figures 1, 2 , 4 and 6 of a circuit breaker according to two other embodiments of the invention respectively.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

On the Figures 1, 2 , 4 , 6 , 9, 10 , we see a miniature circuit breaker pole p comprising an insulating housing B having on its front face a maneuvering handle M and on its two narrow side faces, connection terminals 1,2. Inside the housing are housed, as is known per se, a movable contact 3 and a fixed contact 4.

The movable contact 3 is controlled by a control mechanism C connecting the aforesaid lever M to the movable contact for closing or opening the contacts.

In this housing are also housed a thermal trip unit 5 and an electromagnetic release 6 may cause, in case of overload or short circuit, an automatic opening of the contacts 3,4.

The lower part of the housing B encloses a breaking chamber 7 constituted by a first so-called arc-forming chamber 8, communicating with the inlet of a second chamber 9, said arc extinction, the latter comprising fins 10.

The movable contact 3 extends substantially perpendicular to the plane in which the plates extend, so as to stretch an arc between the contacts during their separation, whose initial direction is substantially parallel to the plates. The aforementioned breaking chamber 7 is delimited laterally by arc horns 11, 12 respectively electrically connected to the two aforementioned terminals. These arc horns are arranged to capture the arc drawn between the contacts during their separation.

As such a circuit breaker is well known to specialists, it will be useless to describe in more detail its arrangement or its operation.

On the figure 1 , the arc extinguishing chamber 9 of the circuit breaker simply has at its downstream part, a grid 13 made of a plastic material, advantageously molded with the housing or the cover of the device. The function of this grid is to prevent the arc from reforming behind the fins downstream of the arc extinction chamber.

On the figure 2 according to a preferred embodiment of the invention, the arc extinguishing chamber 9 comprises a so-called balancing wall 14 extending along a plane P inclined with respect to the alignment direction D of the separators 10, or still the plane of the base 22 of the apparatus, at an angle α of about 5 ° preferably, so that the balancing wall 14 is closer to the separators 10 on the side i where the gases enter first in the arc extinguishing chamber 9 (right side of the figure), and further away from the other side j (left side of the figure). Advantageously, this wall extends substantially over the entire width of the interrupting chamber, this width being defined parallel to the base of the apparatus and perpendicular to the plane of attachment of the apparatus. This wall is very close to the block of blades, that is to say almost in contact with it.

Note that the value of the aforementioned angle is advantageously between 3 and 15 °, and preferably 5 °.

It will be noted that this side where the wall 14 is closest corresponds to the opposite side to the fixed and movable contacts 4 and 3.

So, we see on the figure 2 that the wall 14 is closer to the extinguishing chamber 9 on the side of the arcuate horn 12 situated on the side of the fastening surface of the apparatus, and moves away gradually from this chamber when one goes towards the other side.

Advantageously, this wall 14 is molded with the housing or the cover of the device.

As illustrated on the figure 4 , according to another embodiment of the invention, the modulation of the exhaust section is obtained this time by a partition 14 extending substantially parallel to the rear face of the fin block, and having a width l more and more reduced, as illustrated on the figure 5 , so as to create, from one side to the other of the wall 14, an exhaust section s of increasing size, the exhaust section s being the smallest on the side where the gases enter first into the Arc extinguishing chamber 9. Advantageously, this wall has a trapezoidal shape.

On the figure 6 according to another embodiment of the invention, a piece already present in the apparatus is used, which part, called gray fiber 15, surrounds all the separators 10 on the exhaust side and is intended to maintain these separators so as to form a fin block A constituting the extinction chamber of the arc 9. This part is a part independent of the walls of the housing or the cover, and therefore has a temperature resistance better than the plastic material used for the partitions of the device. It is therefore not necessary to move it away, as is the case when using an inclined wall integral with the walls of the housing.

According to this particular embodiment, the modulation of the size of the exhaust section s is achieved by producing in the aforementioned part, on either side of a solid portion 16, openings 17 all of the same width, but whose length increases towards the end of the chamber located on the side j of the fixed contact 4, so as to create more exhaust on this side and less on the opposite side i.

According to the illustrated achievements on the Figures 9 and 10 , the size of the arc extinguishing chamber 9 is reduced by the fact that the number of cooling fins 18 is 10 compared to the number of fins, namely 12, used in the previously described embodiments.

According to the realization of the figure 9 , the alignment direction D of the fins extends substantially parallel to the base 22 of the apparatus, and it is the wall 14 which is inclined with respect to this alignment direction D and this base 22.

According to the realization of the figure 10 it is the fin block A which is inclined with respect to the base 22 of the apparatus, which is made possible by the fact that the number of fins is reduced. The balancing wall 14 extends in this case in a plane parallel to the base 22 of the apparatus, and is inclined with respect to the alignment direction D of the fins 18 of the chamber, by an angle of about 5 °, preferably.

On the Figures 1, 2 , 4 , 6 , 9 and 10 , the flow of gases generated during the cut is represented by arrows located inside the arc extinguishing chamber.

It will be noted that the invention, in all the embodiments described, makes it possible to eliminate the insulating gate provided in the prior art.

Note also that when the balancing partition is of uniform width, it must necessarily be inclined at an angle between 3 and 15 ° with respect to the alignment direction or the lower face of the cooling elements.

In the embodiment of the invention in which the balancing partition is of trapezoidal shape, this partition will preferably be parallel to the rear face of the cooling elements. In this case, we can play on the shape of the wall or on the angle of inclination, it can vary between 0 and 15 °.

Hereinafter will be described the operation of an apparatus according to the prior art, and according to the various embodiments of the invention, with reference to the figures.

On the figure 1 it can be seen that the flow of gas due to the formation of the arc separates into a part b passing through the arc extinguishing chamber 9 on one side i of this chamber, while another part c gas is discharged in a turbulence zone y, the insulating gate 13 placed downstream of the arc extinguishing chamber 9 thus having a direct exhaust zone u and a discharge zone v. Thus, as explained above, one i sides i, j of the extinguishing chamber 9 is reached first by the gas a, inducing a flow of gas on the fins 18a located on that side. This first circulation hinders or even prevents the flow of gas between the other fins 18b. This leads to a discharge of the gases upstream of the extinguishing chamber 9, and thus prevents a balanced insertion of the arc over the entire height of the extinguishing chamber 9.

On the figure 2 , the exhaust gases are stopped by the central portion 19 of the inclined wall 14 and escape through the outer edges 20 of the partition 14 in the direction of the exhaust port 21 provided in the housing B.

The presence of the inclined wall 14 creates, downstream of the arc extinguishing chamber 9, the side where the partition 14 is closest to the arc extinguishing chamber 9, a braked circulation zone w, and on the side where the partition 14 is furthest from the extinguishing chamber 9, a facilitated circulation zone x.

Thus, we obtain a rebalancing of the flow of gas through the extinguishing chamber 9, limiting the circulation between the first fins 18a in favor of the other fins 18b.

In addition, this preferred embodiment of the invention makes it possible to eliminate the plastic grid very close to the chamber in favor of this more distant partition, whose fusion and very limited vaporization does not disturb the flow of gases, but is sufficient to maintain the bow in the room.

Thus, thanks to the invention, a control of the flow of gases downstream of the chamber is obtained, which makes it possible to increase the average arc voltage, as illustrated in FIG. figure 3 which represents the arc voltage and the current flowing through the circuit breaker as a function of time, for a so-called reference product corresponding to the prior art and for an apparatus according to the preferred embodiment of the invention. Thus, the curves d and e represent the arc voltages respectively for the reference product and for an apparatus according to the invention, while the curves f, g represent the currents flowing through the circuit breaker respectively for these same devices. Note also the existence of a pressure drop of about 14% in the case of an apparatus according to the invention. The current shown on the left scale is in amperes, while the voltage shown on the right scale is in volts. The time on the abscissa is in seconds.

Thus we see on these curves, that thanks to the invention, the arc voltage rises faster and higher, thus allowing a better limitation (that is to say a current that rises less high and a zero current). obtained faster). As a result, the through-energy (l ² dt) is reduced from an energy point of view. This gives a gain of 20%: $$\left({\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="imgf0001.png"\; state="\{\{state\}\}">l</figure-callout>}}^{\mathrm{2}}\mathrm{dt\; ref}-{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="imgf0001.png"\; state="\{\{state\}\}">l</figure-callout>}}^{\mathrm{2}}\mathrm{invention}\right)/{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="imgf0001.png"\; state="\{\{state\}\}">l</figure-callout>}}^{\mathrm{2}}\mathrm{dt\; ref})=\mathrm{20}\%\mathrm{.}$$

According to the illustrated realization on the figures 4 and 5 , the partition 14 of degressive width provides, in the same manner as for the previous embodiment, a rebalancing of the flow of gas through the extinguishing chamber.

According to the illustrated realization on the Figures 6, 7 and 8 the known piece known as "gray fiber 15" is used to hold the fins 18 to form the arc extinguishing chamber 9, this part surrounding the exhaust-side chamber, on the one hand, ensure the function associated with the insulating grid 13 and, secondly, ensure a rebalancing of the flow of gases.

For this purpose, it can be seen that this fiber 15 comprises a bottom wall 23 having a solid portion 16 having a width degressive as in the case of the embodiment illustrated in FIG. figure 4 , this solid part fulfilling the same function with the same results as the partition according to the second embodiment illustrated on the figure 5 , the cutoff gases being braked by this solid part 16 and escaping through the edges 20 of said partition, through the openings 17 provided all around this solid portion 16.

Because the temperature resistance of the fiber is better than that of the plastic material used to make the partitions of the device and thus the insulating grid, this fiber does not need to be removed from the chamber.

The operation of the apparatus according to the two embodiments illustrated on the Figures 9 and 10 will not be described, because it corresponds to that of the apparatus according to the embodiment illustrated on the figure 2 .

Thus, thanks to the invention, a cut-off chamber of simple design has been made which makes it possible to reduce the relapses due to a bad insertion of the arc into the chamber, this bad insertion being itself due to a poorly controlled circulation of the gases. Thus, thanks to the elements provided by the invention downstream of the arc extinguishing chamber, it increases the gas flow upstream of the chamber and allows a complete insertion of the arc. This generates a gain in robustness of the device, without additional cost.

Thus, the cut is improved by controlling the arc voltage.

Indeed, the increase of the arc voltage reduces the energy to be absorbed by the device, improve the energy capacity of the devices, and thus limit all the damage due to a short circuit.

The invention also makes it possible to eliminate the insulating grid that is usually used, which leads to a rationalization in the design of the appliances in which this breaking chamber is intended to be used.

Of course, the invention is not limited to the embodiments described and illustrated which have been given by way of example.

On the contrary, the invention comprises all the technical equivalents of the means described and their combinations if they are carried out according to its spirit.

Claims (10)

A switchgear chamber of an electrical protection apparatus comprising an arc-forming chamber enclosing a fixed contact and a movable contact which, at the time of their separation, form an arc therebetween, said arc-forming chamber communicating with the entrance of a second so-called arc extinction chamber,
characterized in that it comprises a so-called balancing wall (14), substantially solid on at least its central portion, said wall (14) being located downstream of the arc extinguishing chamber (9) and being shaped and arranged with respect to the arc extinguishing chamber (9), so as to brake the exhaust flow of the cutoff gases on the side (i) of the arc extinguishing chamber (9) located at the opposite the fixed contact (4), the side where the gases go first, and to promote the flow of exhaust gas flows on the opposite side to the previous one, the exhaust gases being stopped by the central portion (19). ) of the wall (14) and escaping through the edges (20) of the wall (14). Cutoff chamber according to claim 1, said arc extinguishing chamber (9) having a stack of cooling elements (10) extending substantially parallel to each other, characterized in that said wall ( 14) is very close to the arc extinction chamber (9) on the i side where the exhaust gases go first and away from said chamber (9) as one s' away from this side of the chamber, so as to be remote from said chamber on the side opposite the preceding i, of said arc extinguishing chamber (9). Cutoff chamber according to claim 2, characterized in that the aforesaid arc extinguishing chamber (9) has a reduced number of cooling elements (10) allowing the block A formed by all of these cooling elements (10) to be inclined relative to the base (22) of the apparatus, and in that said wall (14) extends substantially parallel to the base (22) of the apparatus. Cutoff chamber according to claim 2 or 3, characterized in that the aforesaid wall (14) extends at an angle α between 3 and 15 ° with the alignment direction D of the aforementioned cooling elements (10). Cutoff chamber according to claim 1, characterized in that said balancing wall (14) has a solid central part and in that this solid central part has a variable width (l), this width (l) being maximum on the side the arc extinguishing chamber (9) where the gases pass first, and being increasingly reduced as one approaches the other side j of said chamber (9). Cutoff chamber according to any one of the preceding claims, characterized in that the aforementioned wall (14) is integral with the housing or the cover of the apparatus. Cutoff chamber according to any one of claims 1 to 5, characterized in that said arc extinguishing chamber (9) having means (15) for holding the cooling elements (10) relative to one another the aforementioned wall (14) is an integral part of these holding means (15) of the cooling elements (10). Cutoff chamber according to claims 5 and 7, characterized in that the aforementioned balancing wall (14) is an integral part of the bottom wall (23) of the aforementioned holding means (15) of the cooling elements (10), said bottom wall (23) having, around said balancing wall (14), slots (17) extending substantially parallel to the cooling elements (10), and whose length varies from one end to the other; other of the wall. Electrical protection apparatus comprising at least one pole unit mounted in a housing B, said pole unit having a breaking chamber (7) according to any one of the preceding claims. Low-voltage circuit breaker comprising at least one pole unit mounted in a housing B, said pole unit having a breaking chamber (7) according to any one of claims 1 to 8.

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