Electric arc-extinguishing device for an electrical protection apparatus, and electrical protection apparatus incorporating said device
The present invention relates to the field of electric arc extinguishing devices for an electrical protection apparatus, preferentially of modular type, and to the field of electrical protection apparatus, preferentially of modular type, that incorporate such electric arc extinguishing devices. As is known, an electrical protection apparatus comprises at least one pair of contacts which comprises a fixed contact and a movable contact. This pair of contacts can adopt two stable positions, namely a so-called closed position, in which the fixed contact and the movable contact are in contact, and an open position of the contacts, in which the movable contact is at a distance from the fixed contact. In case of the occurrence of a fault on the line to be protected by the electrical protection apparatus, a mechanical latch makes it possible to switch the pair of contacts from their closed position to their open position. In these conditions, an electric arc is created between the fixed contact and the movable contact and, more particularly, at their respective electrodes. In order to control this electric arc, an extinguishing chamber or switching chamber is generally provided in the electrical protection apparatus. This extinguishing chamber comprises an electric arc extinguishing device whose function is to split the electric arc formed at the pair of contacts into a plurality of small split electric arcs. In fact, in the electrical protection apparatus of modular type, a maximum compactness is sought. That is why, in order to increase the voltage of the electric arc and thus limit and rapidly lower the intensity for it to be equal to zero, so as to isolate the fault, it is known practice, rather than elongating the column of the electric arc and thus increasing its voltage, to split it into a plurality of small split electric arcs to obtain a similar, even enhanced, effect. This splitting of the electric arc is usually done by means of a plurality of conductive splitting plates that the extinguishing device comprises which are mounted parallel to one another. It has however been observed that, after the splitting of the electric arc, this plurality of small split electric arcs can become unstable in the plurality of splitting plates. More particularly, it may be that one of the split electric arcs escapes from the splitting zone to arrive in proximity to the inlet zone of the plurality of splitting plates, which provokes a restrike of the electric arc and a reduction of the voltage value, and then impacts the performance of the electrical protection apparatus. This restrike phenomenon can lead to the destruction of the electrical protection apparatus, even before the current has been able to be cut following the occurrence of the fault, which is undesirable. The documents US 2009/0255904 Al, FR 2 873 511 Al and US 2003/0094439 Al have already reported such a problem. In the document US 2009/0255904 Al, the aim is to coat at least one side of a splitting plate with an insulating material, except for a part situated behind the slot of the splitting plate, which does not have that coating. This solution presents the drawback of creating a very strong overpressure in the apparatus that can cause it to explode. In the document FR 2 873 511 Al, it is proposed to add insulating means forming an insulating barrier between the electrodes of the contacts and the upstream end of the assembly of splitting plates. These insulating means take the form of caps covering this upstream end. However, this solution does not make it possible to split the electric arc satisfactorily because of the presence of the caps and reduces the performance of the electrical apparatus. Moreover, the addition of caps is intrusive and increases the bulk. Finally, the document US 2003/0094439 A l teaches providing a plate made of insulating material in the assembly of splitting plates, either in place of a splitting plate, or in addition to the splitting plates. This solution also presents the drawback of reducing the performance of the electrical protection apparatus or that of increasing the bulk of the switching chamber. The purpose of the present invention is to overcome these drawbacks by proposing a solution that aims to avoid the restriking of the electric arc, that has a limited bulk and that aims to improve the performance and the robustness of the electrical protection apparatus in which the extinguishing device is intended to be incorporated. To this end, the invention relates to an electric arc extinguishing device for an electrical protection apparatus comprising: - a plurality of electric arc splitting plates disposed substantially parallel to one another and held together with a distance interval I between two adjacent splitting plates by two support elements disposed over at least a part of each lateral edge that each of the splitting plates comprises, each splitting plate further comprising an electric arc inlet slot, beginning at a bottom edge that each of the splitting plates comprises, the set of inlet slots forming an electric arc inlet zone arranged to guide the electric arc to an electric arc splitting zone, situated downstream of said inlet zone, in a first, electrical arc splitting direction, so as to split the electric arc into a plurality of split electric arcs, each electric arc inlet slot delimiting two branches that each of the splitting plates comprises, each branch having a width lbl that is variable according to the profile of the edge of the inlet slot or constant, - at least one electric arc anti-restrike element made of electrically insulating material, said at least one anti-restrike element being disposed facing a main face of at least one splitting plate, the extinguishing device is characterized in that: the main face comprises an upstream zone and a downstream zone, separate from one another, the upstream zone being situated on the surface of the branches and being delimited by the edge of the slot, and the downstream zone corresponding to the remaining surface of the main face, the main face further comprises a positioning zone for said at least one anti-restrike element facing which said at least one anti-restrike element is disposed, the positioning zone extending between a first median axis of the upstream zone and a second median axis of the downstream zone, said at least one anti-restrike element has a predetermined length Li configured to prevent the return of the electric arc, after it has been split into a plurality of split electric arcs, in a direction opposite the first, splitting direction, called second, restrike direction. The invention relates also to an electrical protection apparatus comprising: - at least one first line comprising a pair of contacts, respectively a fixed contact and a movable contact, - a control member for controlling the position of the movable contact, linked to the movable contact via a mechanical latch capable of switching between two stable positions corresponding respectively to the opening and closing of the fixed and movable contacts following an action on the control member, or of switching to an open position of the fixed and movable contacts following a mechanical action of at least one trip reflecting an electrical fault on said at least first line, - trip means comprising at least one magnetic actuator and/or thermal actuator and/or electronic actuator provided to actuate said at least one trip in order to trip the mechanical latch, and - at least one electric arc extinguishing chamber, the electrical protection apparatus being characterized in that the electric arc extinguishing chamber comprises the electric arc extinguishing device according to the present invention. The invention will be better understood from the following description, which relates to several preferred embodiments, given as nonlimiting examples, and explained with reference to the attached schematic drawings, in which: figure 1 is a plan elevation view of a modular line electrical protection apparatus, of circuit breaker type, according to the invention, showing a pair of contacts in the open position of the contacts and comprising an extinguishing chamber provided with an electric arc extinguishing device, figures 2A and 2B are schematic views in cross section from the side and from the front of the extinguishing chamber provided with an electric arc extinguishing device known from the prior art, figures 3A and 3B are schematic views in cross section from the side and from the front of the extinguishing chamber provided with an electric arc extinguishing device according to the invention, figure 4 is a perspective view of a support element, for holding the splitting plates of the electric arc extinguishing device according to the invention, which is provided with a plurality of anti-restrike elements in the form of a plurality of protruding portions, figure 5 is a perspective view of the electric arc extinguishing device according to the invention in a first variant embodiment comprising two support elements as illustrated in figure 4, figure 6A is a front view of the electric arc extinguishing device illustrated in figure 5, figure 6B is a side view of the electric arc extinguishing device illustrated in figure 5, with a portion of the support element partially removed to show an anti-restrike element in the form of a protruding portion, figure 7 is a perspective view of two support elements, for holding the splitting plates of the electric arc extinguishing device according to the invention, which are provided with a plurality of anti-restrike elements in the form of a plurality of protruding portions linked to one another, figure 8 is a perspective view of the electric arc extinguishing device according to the invention in a second variant embodiment comprising the two support elements illustrated in figure 7, figure 9 is a front view of an electric arc extinguishing device according to the invention in a third variant embodiment, showing a splitting plate which is coated on its main face with a coating layer forming an anti restrike element, figure 10 is a perspective view of a lateral wall of the modular electrical protection apparatus according to the invention, in an embodiment in which the lateral wall comprises, in the extinguishing chamber, a plurality of anti-restrike elements consisting of a plurality of protruding portions, figure 11 is a perspective view of the lateral wall of figure 10 on which an electric arc extinguishing device known from the prior art is mounted, figures 12 and 13 are schematic views of a splitting plate showing the main face which comprises an upstream zone, a downstream zone and a positioning zone, figure 14 shows curves A and B of the trend of the voltage as a function of time of an electrical protection apparatus incorporating the extinguishing device according to the invention, curve A, and of an electrical protection apparatus known from the prior art, curve B. An electric arc extinguishing device 1 for an electrical protection apparatus 2 comprises: - a plurality of electric arc splitting plates 3 disposed substantially parallel to one another and held together with a distance interval I between two adjacent splitting plates 3 by two support elements 4 disposed over at least a part of each lateral edge 5 that each of the splitting plates 3 comprises (figures 1, 2A, 3A, 5, 6B, 8 and 11) each splitting plate 3 further comprising an electric arc inlet slot 6, beginning at a bottom edge 7 that each of the splitting plates 3 comprises (figures 2B, 3B, 5, 6A, 8, 9, 11, 12 and 13), the set of inlet slots 6 forming an electric arc inlet zone 8 arranged to guide the electric arc to an electric arc splitting zone 9, situated downstream of said inlet zone 8, in a first, electric arc splitting direction D1, so as to split the electric arc into a plurality of split electric arcs EF (figures 2A, 2B, 3A, 3B, 5, 8 and 11) each electric arc inlet slot 6 delimiting two branches 10 that each of the splitting plates 3 comprises (figures 2B, 3B, 5, 6A, 8, 9, 12 and 13), each branch 10 having a width lbl that is variable according to the profile of the edge 6' of the inlet slot 6 (figure 13) or constant (figure 12), - at least one electric arc anti-restrike element 11, 11', 11" made of electrically insulating material, said at least one anti-restrike element 11, 11', 11" being disposed facing a main face 12 of at least one splitting plate 3 (figures 3A, 3B, 5, 6A, 6B, 8, 9 and 11). According to the invention, the extinguishing device 1 is characterized in that: the main face 12 comprises an upstream zone AM and a downstream zone AV, separate from one another, the upstream zone AM being situated on the surface of the branches 10 and being delimited by the edge 6' of the slot 6, and the downstream zone AV corresponding to the remaining surface of the main face 12 (figures 3A, 3B, 5, 8, 9, 12 and 13) the main face 12 further comprises a positioning zone P for said at least one anti-restrike element 11, 11', 11" facing which said at least one anti-restrike element 11, 1', 11" is disposed, the positioning zone P extending between a first median axis MI of the upstream zone AM and a second median axis M2 of the downstream zone AV (figures 5, 8, 9, 12 and 13), said at least one anti-restrike element 11, 11', 11" has a predetermined length Li configured to prevent the return of the electric arc, after it has been split into a plurality of split electric arcs EF, in a direction opposite the first, splitting direction Dl, called second, restrike direction D2 (figures 3A, 4, 5, 6A, 7, 8 and 9). Advantageously, said at least one anti-restrike element 11, 11', 11" is provided to be disposed only facing the positioning zone P, which makes it possible to propose an extinguishing device 1 of compact form, since said at least one anti-restrike element 11, 11', 11" remains confined in the positioning zone P, which offers the advantage of not increasing its bulk. According to the invention, said at least one anti-restrike element 11, 11',
11" cannot in any case be disposed outside of this positioning zone P. It is therefore particularly suited for integration in a compact electrical protection apparatus 2 and notably one of modular type. Furthermore, this particular selection makes it possible not to degrade the performance levels of the electrical protection apparatus 2 in which it is intended to be incorporated. This is because said at least one anti-restrike element 11, 11', 11" forms a barrier to the movement, in the second, restrike direction D2, of a split electric arc EF, which is situated either on the column of the split electric arc EF, or at the feet of the split electric arc EF (figures 3A and 3B). This barrier to the movement advantageously opposes a low resistance to the entry of the electric arc, which has been created between the movable contact 16 and the fixed contact 15 because of the particular configuration of said at least one anti-restrike element 11, 11', 11", when the latter moves in the first, splitting direction D1. Finally, because said at least one anti-restrike element 11, 11', 11" is made of electrically insulating material, the latter provides a significant and optimal arc voltage gain by gas-generating effect and by increasing the pressure in the electric arc extinguishing chamber. Consequently, by virtue of this advantageous configuration, initially, the electric arc, which has been created between the movable contact 16 and the fixed contact 15, upon the opening thereof, moves in the inlet zone 8, then, in a second stage, the electric arc is split at the bottom of the slot 6. A plurality of split electric arcs EF is then created in the splitting zone (figures 3A and 3B). Because of the instability of the phenomenon, a split electric arc EF, which would be directed in the second, restrike direction D2 toward the inlet zone, would be prevented, by virtue of said at least one anti-restrike element 11, 11', 11", from returning in the inlet zone 8. The restriking of the electric arc is thus avoided and the voltage of the electric arc is not diminished by the instability due to the restriking. Moreover, upon the splitting, a gas generating effect occurs which increases the voltage of the electric arc (see bump directly after the time tl' on the curve A in figure 14). The splitting of the electric arc continues (see plateau after the bump and up to the time t2' on the curve A in figure 14). Then, the electrical voltage decreases (see variation from the time t2' on the curve A in figure 14), a sign that the electric arc has been extinguished. Advantageously, the fact that the restriking of the electric arc is avoided and because of the gas-generating effect, the electric arc is extinguished more rapidly than in the prior art. The comparison of the curves A and B in figure 14 shows that the reduction of the electrical voltage at the times t2, t2' occurs more rapidly for the curve A than for the curve B. Finally, the comparison of the curves A and B in figure 14 shows that the plateau between the times tl' and t2' of the curve A is smoother than that of the curve B for the time interval between t Iand t2 which exhibits a plurality of peaks due to the successive restrikes. The result thereof is that, by virtue of the solution proposed by the present invention, the configuration of said at least one anti-restrike element 11, 11', 11" does not impact the performance of the electrical protection apparatus 2, and, on the contrary, enhances the performance of the electrical protection apparatus 2. Consequently, by disposing said at least one anti-restrike element 11, 11', 11" only and selectively facing the positioning zone P and such that it extends along the predetermined length L1, the compactness, the gas-generating effect and the performance of the extinguishing device according to the invention are enhanced. The first and second median axes Ml, M2 each extend in a transverse direction which is in the direction of the width 11 of the splitting plate 3. Each splitting plate 3 comprises two main faces 12. Preferably, the greater dimension of extension of said at least one anti-restrike element 11, 11', 11" extends in a longitudinal direction substantially at right angles to the lateral edge 5 of said at least one splitting plate 3, facing which the anti-restrike element 11, 11', 11" is disposed (figures 3B, 5, 6A, 8, 9 and 11). Preferentially, said at least one anti-restrike element 11, 11', 11" is disposed upstream of the electric arc splitting zone 9 (figures 3A and 3B). This arrangement forms an obstacle preventing the return of a split electric arc EF which would be situated in the splitting zone 9 in the second, restrike direction D2, toward the inlet zone 8, without hampering either the passage of the electric arc, or the splitting of the electric arc and without creating additional bulk. Preferably, the predetermined length Li is less than (figures 3B, 5, 6A, 9 and 11) or equal to (figure 8) a width 11 of the splitting plate 3. In this case, the predetermined length Li is, preferentially, at least greater than or equal to three quarters of the width lbl of the branch 10.
In a first possibility according to the invention, said at least one anti-restrike element 11, 11" consists of a protruding portion of predetermined length Li which protrudes from at least one of the two support elements 4 (figures 3B, 4, 5, 6A, 6B, 7, 8) or from at least one separate support piece (figures 10 and 11). The separate support piece can consist of a part of an enclosure of the electrical protection apparatus 2, for example a lateral wall 23 of the enclosure, a portion of which is situated at the level of the electric arc extinguishing chamber 22. The protruding portion can consist of an elongate element, preferentially rectilinear. This particularly advantageous disposition according to the first possibility makes it possible to exploit the existence of the two support elements 4 whose first function is to support the splitting plates 3, or of a separate support piece, to dispose said at least one anti-restrike element 11, 11" thereon. The result thereof is also an ease of implementation of the present invention during the assembly of the electrical protection apparatus 2, since no other additional piece needs to be added or attached. According to a specific feature of this first possibility according to the invention, said at least one of the support elements 4 comprises a plate 13 comprising two large lateral edges 14 and said protruding portion of said at least one anti-restrike element 11 protrudes from one of the large lateral edges 14 (figures 3B, 4, 5, 6A, 6B, 7, 8). The plate 13 is preferentially perforated. According to a first variant embodiment of this first possibility, each support element 4 comprises a plate 13 comprising a plurality of protruding portions forming a plurality of anti-restrike elements 11 and the protruding portions of one of the plates 13 being situated facing the protruding portions of the other of the plates 13 (figures 5, 6A and 6B). In this case, it is sufficient to modify the two support elements 4 known from the prior art, to add said protruding portions to them and to replace them. No other additional piece needs to be added. This disposition is particularly suited to the industrialization of the solution. Indeed, preferentially, the pair of plates 13, optionally perforated, each provided with protruding portions, constitutes two pieces. Each piece then has a comb form with an L-shaped section in which the teeth correspond to the protruding portions (figure 4). These pieces can be made by molding. For example, these plates 13 provided with the protruding portions can be made of a polymer material, for example polyamide. In the nonlimiting example illustrated in figures 4, 5, 6A and 6B, each perforated plate 13 has two substantially mutually parallel rows Ri, R2 of aligned perforations 13'. One of the rows R2 is situated in immediate proximity to the lateral edge 14 from which the protruding portions extend. The protruding portions of length Li and of thickness e are substantially parallel to one another and are spaced apart from one another by a regular interval by a perforation 13'. The protruding portions consist of rectilinear elongate elements. One perforated plate 13 has fourteen protruding portions. Each row Ri, R2 has thirteen perforations 13'. There are thirteen splitting plates 3. One perforation 13' is provided to form a fixing with a tongue 3' protruding from the lateral edge 5 of the splitting plate 3. The tongues 3' are arranged to be fitted into the perforations 13'. According to a second variant embodiment of this first possibility, each support element 4 comprises a plate 13 comprising a plurality of protruding portions and the protruding portions of one of the plates 13 are linked to the protruding portions of the other of the plates 13, so as to form a plurality of anti-restrike elements 11 of predetermined length Li substantially equal to the width 11 of the splitting plate 3 (figures 7 and 8). The plate 13 is preferentially perforated. In this case, it is sufficient to modify the two support elements 4 known from the prior art, to add to them said protruding portions of each support element 4 which meet at their free ends and to replace them. No other additional piece needs to be added. This disposition is particularly suited to the industrialization of the solution. Indeed, preferentially, the two plates 13, optionally perforated, and the protruding portions constitute a single piece. Handling is therefore facilitated, as is the assembly of the extinguishing device 1. In the nonlimiting example illustrated in figures 7 and 8, each perforated plate 13 has two substantially mutually parallel rows R, R2 of aligned perforations 13'. One of the rows R2 is situated in the immediate proximity to the lateral edge 14 from which extend the protruding portions which, in this example, are in the form of rectilinear elongate elements. More particularly, the plurality of rectilinear elongate elements form a center distance between the two perforated plates 13 which are held parallel to one another and at a distance. Each rectilinear elongate element has a length L and a thickness e. The plurality of rectilinear elongate elements are substantially parallel to one another and are spaced apart from one another by a regular interval by a perforation 13'. There are fourteen of these rectilinear elongate elements. Each row RI, R2 has thirteen perforations 13'. There are thirteen splitting plates 3. A perforation 13' is provided to form a fixing with a tongue 3' protruding from the lateral edge 5 of the splitting plate 3. The tongues 3' are arranged to be fitted into the perforations 13'. Preferentially, according to the invention, the first possibility and its variant embodiments, said at least one anti-restrike element 11 is disposed facing and at a distance from the main face 12 of at least one splitting plate 3 (figure 6B). In this case, there is no contact between said anti-restrike element 11 and the main face 12. According to a second possibility according to the invention, said at least one anti-restrike element 11' consists of at least one coating layer extending only over all or part of the positioning zone P (figure 9). In this case, it is sufficient to deposit a coating layer over the or over each main face 12 of one or more splitting plates 3. No other additional piece needs to be added. Preferentially, according to the invention, the first possibility and its variant embodiments, and the second possibility, said at least one anti restrike element 11, 11', 11" is disposed facing and in contact with the main face 12 of at least one splitting plate 3. Preferably, the electric arc extinguishing device 1 comprises a plurality of central anti-restrike elements 11, 11', 11" which each extend between two adjacent splitting plates 3 (figures 3A, 6B, 8 and 11). In this case, the thickness e of the anti-restrike element 11, 11', 11" is, preferably, strictly less than the distance interval I between two adjacent splitting plates 3 and greater than half the distance I between two splitting plates 3. This advantageous disposition makes it possible to facilitate the insertion/incorporation of said at least one anti-restrike element 11, 1', II" between two adjacent splitting plates 3. Moreover, the resistance to the splitting of the electric arc, that said at least one anti-restrike element 11 could provide, is thus limited. Preferably, the electric arc extinguishing device 1 comprises at least one extreme-end anti-restrike element 11, 11', 11" disposed facing an extreme-end splitting plate 3 (figures 3A, 3B, 5, 6A, 8 and 11). As figures 3A to 8 illustrate, the extinguishing device 1 has thirteen splitting plates 3, including two extreme-end splitting plates 3, twelve central anti-restrike elements 11 and two extreme-end anti-restrike elements 11. Thus, the extinguishing device 1 can be configured so that, between each adjacent splitting plate 3, there is disposed a central anti restrike element 11, in other words, for a number n of splitting plates 3, n-1 is the number of central anti-restrike elements 11. Furthermore, the extinguishing device 1 can be configured so that, facing the two extreme-end splitting plates 3, there is disposed an extreme-end anti-restrike element 11, in other words two extreme-end anti-restrike elements 11 in total. As figure 1 illustrates, an electrical protection apparatus 2 comprises: - at least one first line comprising a pair of contacts, respectively a fixed contact 15 and a movable contact 16, - a control member 17 for controlling the position of the movable contact 16, linked to the movable contact 16 via a mechanical latch 18 capable of switching between two stable positions corresponding respectively to the opening (figure 1) and the closing of the fixed 15 and movable 16 contacts following an action on the control member 17, or of switching to an open position of the fixed 15 and movable 16 contacts following a mechanical action of at least one trip 19, 19' reflecting an electrical fault on said at least first line, - trip means 20 comprising at least one magnetic actuator 21 and/or thermal actuator 21' and/or electronic actuator provided to actuate said at least one trip 19, 19' in order to trip the mechanical latch 18, and - at least one electric arc extinguishing chamber 22. According to the invention, the electrical protection apparatus 2 is characterized in that the electric arc extinguishing chamber 22 comprises the electric arc extinguishing device 1 according to the invention. According to a first embodiment of the invention, the electrical protection apparatus 2 comprises an enclosure which comprises two lateral walls 23, the electric arc extinguishing chamber 22 being delimited at least by the two lateral walls 23 on at least one of which said at least anti-restrike element 11" is disposed (figures 10 and 11). This particularly advantageous disposition makes it possible to exploit the existence of at least one lateral wall 23, whose main function is to mechanically hold the various components of the electrical protection apparatus 2, to dispose said at least one anti-restrike element 11" therein. The result thereof is also an ease of implementation of the present invention at the time of assembly of the electrical protection apparatus 2, since no other additional piece needs to be added. It is possible in this case not to modify the support elements 4 which then preferentially take the form of two perforated plates 13 comprising two substantially mutually parallel rows R1, R2 of aligned perforations 13'. Furthermore, when the lateral walls 23 are manufactured by molding, said at least anti-restrike element 11" is preferentially molded or overmolded when the latter are manufactured. For example, the lateral walls 23 and said at least anti-restrike element 11" can be made of a polymer material, for example polyamide. According to a specific feature of this first embodiment of the invention, at least one of the lateral walls 23 comprises a plurality of anti restrike elements 11" consisting of a plurality of protruding portions of predetermined length Li (figures 10 and 11). In the nonlimiting example illustrated in figures 10 and 11, the protruding portions of length Li and of thickness e are substantially parallel to one another and are spaced apart from one another by a regular interval. The protruding portions consist of rectilinear elongate elements. In this case, either just one of the lateral walls 23 can comprise the plurality of anti-restrike elements 11", or each of the lateral walls 23 can comprise the plurality of anti-restrike elements 11". In the electric arc extinguishing chamber 22, the voltage of the electric arc Uarc satisfies the following known relationship: Uarc=Ue+EOd, with Ue a component linked to the fixed and movable contacts 15, 16 and EOd a component linked to the column of the electric arc and whose value is proportional to the length of the column of the electric arc. As an example, the component Ue can be of the order of 18 volts, whereas the second component EO can be a few volts per millimeter. It therefore follows from this relationship that, to increase the voltage of the electric arc Uarc, it is better to split the electric arc into a multitude of split electric arcs EF, in order to maximize the predominant term Ue, rather than elongate the electric arc, and this is the choice which is made in the present invention which seeks to prioritize compactness. More particularly, the electric arc extinguishing chamber 22 can be subdivided into three subassemblies. In the first subassembly, there is the fixed contact 15 and the movable contact 16. Preferentially, the fixed contact 15 comprises an electrode or contact pad 24, which can be made of graphite silver alloy (AgC). The movable contact 16 can, for its part, be made of silver-plated copper (Cu/Ag). The electric arc is formed in this first subassembly at the time of opening of the fixed/movable contacts 15, 16. In the second subassembly, also called prechamber, there are two conductive horns 25 and 26 which face one another and which delimit the prechamber 27. Their function is to guide the electric arc to the plurality of splitting plates 3. One of the conductive horns 25 bears the fixed contact 15. The conductive horns 25, 26 are preferentially made of mild steel coated with copper or nickel. The conductive horns 25, 26 are divergent from the first subassembly to the third subassembly. The prechamber 27 can also comprise two insulating cheeks 27' facing one another and which are mounted on the lateral walls 23. For example, these insulating cheeks 27' can be made of polymer, such as polyamide. The function of the insulating cheeks 27' is to form exhaust channels C for the expulsion of the ionized gases created within the electric arc extinguishing chamber 22. In the third subassembly, there is the electric arc extinguishing device 1 according to the invention. This third subassembly therefore comprises at least one plurality of electric arc splitting plates 3 disposed substantially parallel to one another and held together with a distance interval I between two adjacent splitting plates 3 by two support elements 4 disposed over at least a part of each lateral edge 5 that each of the splitting plates 3 comprises. One of the conductive horns 26 is extended into this third subassembly. The splitting plates 3 can be made of mild steel coated with copper or nickel. The two support elements 4 can be made of insulating material, for example insulating cardboard. The width 11 of the splitting plates 3 occupies substantially all the width lm of the electrical protection apparatus 2, this width being able to be that of a module, as explained hereinbelow (figures 2B and 3B). The width 11 can lie substantially between 13 and 15 millimeters, whereas the width lm of the electrical protection apparatus 2 can be 18 millimeters. The electrical protection apparatus 2 according to the invention is preferably of modular type, and thus has a width lm that is a multiple of a module, that is to say that the distance between the two lateral walls 23 of the enclosure of the electrical protection apparatus 2 corresponds to a multiple of a standardized value, called module. The width of a module is substantially of the order of 18 millimeters. Preferably, the electrical protection apparatus 2 has a width lm of a single module (figures 2B and 3B). The electrical protection apparatus 2 can consist of a circuit breaker or a differential circuit breaker, preferably of modular type. The electrical protection apparatus 2 can be provided to protect a single line (single-pole electrical protection apparatus 2) or multiple lines (multi-pole electrical protection apparatus 2). The first line can comprise a first connection terminal 28 and a second connection terminal 29 between which the fixed contact 15 and the movable contact 16 are disposed. The first connection terminal 28 is preferentially provided to be linked electrically to the electrical network, whereas the second connection terminal 29 is, preferentially, provided to be linked electrically to a load of an electrical installation. For example, as figure 1 illustrates, the fixed contact 15 can be linked electrically to the first connection terminal 28 and the movable contact 16 can be linked electrically to the second connection terminal 29. Preferentially, the magnetic actuator 21 is linked electrically, on the one hand, to the first connection terminal 28 and, on the other hand, to the fixed contact 15, between the latter. Preferably, the magnetic actuator 21 comprises a coil 30 surrounding a translationally movable core 31 that can strike the trip 19, so as to actuate the mechanical latch 18. The movable core 31 is configured to move in the event of a short circuit. Preferentially, the thermal actuator 21' is linked electrically, on the one hand, to the second connection terminal 29 and, on the other hand, to the movable contact 16, between the latter. The thermal actuator 21' can consist of a bimetallic strip, linked electrically or not to the movable contact 4 by a flexible conductor (not represented) such as a conductive braid, arranged to actuate the trip 19' under the effect of a deformation of the bimetallic strip so as to actuate the mechanical latch 18. Advantageously, the bimetallic strip is deformed by direct or indirect heating of the flexible conductor, in the event of a prolonged overcurrent. Obviously, the invention is not limited to the embodiments described and represented in the attached drawings. Modifications are still possible, notably from the point of view of the construction of the various elements or by substitution of equivalent techniques, without in any way departing from the scope of protection of the invention.