Electrical interruption arrangement housed in an arc extinguishing chamber, arc extinguishing chamber, moulded case circuit breaker employing same, method for assembling an arc extinguishing chamber, and method for assembling a circuit breaker

Abstract

The present invention discloses an electrical interruption arrangement used in conjunction with an arc extinguishing chamber, said chamber comprising a casing, a plurality of metal plates, a cover slidably secured in a front opening, and a fixed terminal arranged on a lower wall, said fixed terminal comprising a second end portion provided with a fixed contact on the side thereof facing an upper wall located inside said casing of said extinguishing chamber, said contact support portion extending from the second end portion to the vicinity of a first terminal coupling portion, and wherein said fixed contact is secured to said end portion closest to the terminal coupling of an arc guide made of magnetic material, said arc guide being positioned on the side of the contact support portion facing the lower wall. The invention further discloses a moulded case circuit breaker employing said arc extinguishing chamber, said circuit breaker comprising a movable contact that partially extends inside said arc extinguishing chamber.

Description

“ELECTRICAL INTERRUPTION ARRANGEMENT ARRANGED IN AN ARC EXTINGUISHING CHAMBER, MOLDED CASE CIRCUIT BREAKER USING THE SAME, ASSEMBLY PROCESS OF AN ARC EXTINGUISHING CHAMBER AND CIRCUIT BREAKER ASSEMBLY PROCESS” TECHNICAL FIELD

[0001] The present invention belongs to the technological field of switching and maneuvering devices for protecting electrical circuits, and more particularly an arc-extinguishing chamber applied to a low-voltage molded-case circuit breaker, operated by an operating handle, wherein said arc-extinguishing chamber is included in a main enclosure of said circuit breaker, in which, in addition to said chamber and arc-extinguishing system, said circuit breaker comprises a rotary contact system, and preferably a thermomagnetic trip assembly or an electronic trip assembly, capable of establishing and interrupting current conduction in a power supply network. BACKGROUND OF THE INVENTION

[0002] As is known from the state of the art, molded case circuit breakers can operate based on thermal, magnetic, thermomagnetic or even electronic principles, through the movement of electrical contacts, and can be used, above all, to protect electrical circuits subject to short circuits and / or electrical overloads generated by electrical current levels that exceed a previously established nominal limit, through the connection of input and output terminals, connected to the electrical power supply network to be protected.

[0003] Circuit breakers fundamentally function in a manner analogous to electrical switches, that is, they function by changing the electrical conduction state of an electrical circuit between "on" and "off." In addition to operating automatically, protecting the circuit, conventional circuit breakers include, among other things, an on-off operating handle that can be operated by a user.

[0004] Circuit breakers are designed to have a short-circuit interrupting rating, which specifies a maximum theoretical current that a circuit breaker is designed and tested to withstand, repeatedly and safely, without causing physical or operational damage to the circuit breaker's integrity. If this short-circuit current, for example, is increased from 20 kA to 100 kA at a nominal voltage of 415 V, the circuit breaker must meet or exceed stringent standards published in standards such as the IEC (International Electrotechnical Commission) and UL (Underwriters Laboratories) for mechanical strength, dielectric strength, and other performance requirements, with respect to any temperature rise. For example, defects in the enclosure construction that expose parts of the device to the external environment cannot be tolerated.

[0005] A conventional way normally used for said circuit breaker to withstand higher interrupting currents is to increase the size of the electrical components (such as electrical contacts) and structural (enclosure) of said circuit breaker to handle higher levels of internal forces and pressures generated by the current interruption process, which, in turn, increases the overall construction size of the circuit breaker. However, increasing the overall size of a circuit breaker is undesirable in installations with limited space or that deviate from available commercial standards. A desirable solution in these cases is a design improvement that allows the circuit breaker to interrupt with higher interrupting currents, complying with the relevant standards, but without increasing its physical enclosure dimensions.

[0006] Typically, during the intense milliseconds that a short-circuit fault lasts, gas and particles from ablated components must be expelled and directed through the exhaust outlet of said circuit breaker out and away from the enclosure.

[0007] One technique used to limit circulating energy is to provide arc-extinguishing structures, such as conductive plates arranged with air gaps between each plate, commonly known as arc-extinguishing chambers. Passing the arc through such structures can aid in its extinction and thus limit short-circuit current interruption and the resulting current spike.

[0008] It is also known from the prior art that the regions near the extinguishing chamber present high acting forces, which must be withstood to minimize damage to the enclosure during an operation involving opening the contacts and releasing the short-circuit current. These factors are crucial in achieving the interrupting capacities obtained, typically certified for the safety of the circuit breaker's operation.

[0009] To this end, the state of the art presents different enclosure configurations. One commonly cited solution involves fixed and movable contact systems distributed within the enclosure of a circuit breaker constructed with simple enclosure walls, that is, containing only a single wall between the operating components and the exterior of the circuit breaker.

[0010] Conventional single-wall circuit breakers, known to those skilled in the art, have a fixed contact system and a moving contact system mounted side-by-side, directly distributed within the volume of said enclosure. Typically, said fixed contacts are supported directly on a base, and the moving contacts are supported on a contact support, which directs the opening and closing operation of said moving contacts. An extinguishing chamber is mounted separately from the contact system and positioned above the fixed contacts, and may partially receive the moving contacts.In the state of the art, when it is desired to increase the robustness of said enclosure of said circuit breaker, so that it can withstand greater nominal interrupting capacities, double enclosure constructions are used, comprising a construction of an individual cassette-type interrupting enclosure per interrupting current path pole, which may comprise at least power supply terminals and load terminals, having between them said fixed and movable interrupting contact system, in addition to an additional enclosure, which surrounds said cassette-type enclosure.

[0011] The use of cassette-type enclosures in three-pole circuit breakers, for example, involving other main operating and functioning components, such as an operating handle, which can commonly have on / off / tripped positions, among others, where said cassettes commonly have a split housing for their individual pole constitution, in addition to an external housing that encloses said cassettes, providing structural advantages in switching devices due to the double enveloping of the enclosure, as already known in the prior art. Furthermore, this technology allows the modularization of the circuit breaker poles, making them versatile in terms of component management.

[0012] There is also a clear difference in costs between a single-case circuit breaker and a double-case cassette circuit breaker, as the double-wall construction naturally increases the proportional width dimensions of the device, which goes against the desired dimensions and cost control due to the inevitable expenditure of larger construction materials.

[0013] Cassettes containing extinguishing chambers are known, or in single-wall circuit breakers, there may be extinguishing chambers directly arranged inside them.

[0014] It is perceived in the current technique in single-wall circuit breakers, that during the tests a repulsion effect of the said high-speed extinction chambers can occur when arranged directly distributed inside single-wall circuit breakers, having lateral direction components and towards the upper part, causing damage to the casing and making an increase in the capacity of interruption in this type of construction. This occurs due to the nature of the construction, where, on one side, the circuit breaker base is supported by a wall or bottom, and the cover, which contains fastening means at the top, can commonly present potential structural weaknesses resulting from these repulsive forces, as detected in interruption tests.

[0015] Therefore, there is a need to improve the performance of the interrupting capacity and facilitate the assembly of molded case circuit breakers of the type that uses predominantly single-walled enclosures, creating in them a more robust assembly, similar to a cassette-type molded case circuit breaker, with improvements in the structural reinforcements contained only in said extinction chamber, involving said fixed and mobile contacts, but at a lower cost.

[0016] Alternatively, in the construction of double-walled building enclosures, some more robust extinguishing chamber solutions are already known. However, they fail to offer only a single extinguishing chamber robust enough for high current ranges, which reduces the need for cassette-type enclosures with enclosed contact systems. Configuring a double enclosure can generate material savings, since it is known that the extinguishing chamber region is where the arc-flash force components are most damaging. DESCRIPTION OF THE STATE OF THE ART

[0017] An electrical switching arrangement and mounting method arranged on a pole of a break chamber is described in the prior art patent EP2024983, comprising a fixed and movable contact arrangement, assembled in a simple manner. It is proposed that the fixed contact support be formed with a retaining opening, and that the arc-interrupting guide device be in the form of a recessed element that can be fitted into the retaining opening in the fixed contact support. This prior art solution includes the assembly of a terminal busbar near the arc divider in an arc-extinguishing chamber housing. The busbar is inserted so that it closes an opening perpendicular to the dividing plates of said arc-extinguishing chamber.

[0018] Patent JPS63118150U discloses an arc extinguishing chamber with a structure for a circuit breaker, which teaches how to prevent arc gas pressure from being applied directly to a surrounding housing. It is configured to extinguish an arc generated when a fixed contact and a moving contact are separated from each other, having an exhaust passage guiding arc gas generated by the opening, during a short-circuit interruption, to an exhaust port, conventionally formed by a molded groove or formed by a hollow tube. It is taught that when the exhaust passage is formed by a molded groove, greater resistance is required due to the arc gas pressure, which leads to the problem of having to increase the thickness of said molded groove.It can be seen that said extinguishing chamber is formed by a main body of magnetic material, a dividing plate and a gas exhaust plate, in addition to an adjacent conductive terminal positioned in the lower part of said chamber, which are mounted in a niche of one of the poles of a circuit breaker. forming an arc extinguishing chamber assembly. Furthermore, the patent describes how to increase arc voltage and thereby improve arc extinguishing performance by sufficiently elongating the arc in the arc extinguishing chamber, using a guide, dividing plates, and exhaust plates as passageways.

[0019] Furthermore, the prior art describes in patent US5589672A an arc extinguishing device, made of insulating molded housing material, applied to a circuit breaker consisting of a movable contact support configured adjacent to the fixed contact support, capable of coming into contact with said fixed contact, wherein the insulating structure includes a pair of side walls facing each other and a plurality of grooves where plates are inserted laterally into said grooves, to be stacked vertically, when said circuit breaker is assembled. It can be seen that a "U"-shaped configuration of the fixed contact contributes to the introduction of a portion of the region of said fixed contact into said insulating arc extinguishing device. It is noted that said fixed contact was designed in a "U" shape mounted on the lower part of said insulating structure with the intention of bringing it closer to the "V"-shaped arc divider plates towards the gas outlet.

[0020] In another sample of construction of an arc extinguishing chamber, in patent JP09171762A of the prior art, a fixed contact designed in a “U” shape mounted on the lower part of said insulating structure and a mobile contact terminal, provided in a rotatable manner between each other, where the casing of said chamber is also described. The arc extinguishing housing partially houses a movable contact support through an opening on the side facing the center of rotation of the contact system, and on the opposite side, an arc gas outlet cover. Note that the aforementioned housing, as well as the arc gas outlet cover, are shown fitted into the groove of one of the circuit breaker poles.

[0021] A circuit breaker capable of achieving high current interruption rates is described in patent BR112014029579, which employs enclosures containing individual interruption modules (cassettes) per pole. Among other things, it teaches the use of adhesive between the cassette housing halves, citing this as a barrier to gas and pollution that could otherwise damage the internal components. The patent also teaches that a gas vent at the bottom is detrimental to a circuit breaker's interrupting capacity.

[0022] Patent EP1247285A2 teaches an arc chamber for low voltage circuit breakers, which can be easily mounted inside the pole of a circuit breaker, does not require complicated assembly steps, is highly reliable, easy to manufacture and has a parallelepiped-shaped construction, with multiple dividing plates, comprising at least one opening in the upper part and one opening in the upper part, specifically built to reduce costs.

[0023] However, the problem with the state of the art, particularly in the construction of single-wall circuit breakers, where the construction of extinguishing chambers inserted inside the pole of a circuit breaker, is that they are not robust enough, so they cannot withstand the pressures generated by short circuits adequately, or otherwise it can be seen that there is room for improvement in the structural robustness in the region of the extinguishing chamber for interruption devices, including a simplification of construction, in order to avoid the use of cassettes including contact systems, which are more complex and expensive in concept.

[0024] Possibilities remain for improvement in the construction of a structural reinforcement solution in the arc extinguishing chamber region, enabling economically viable and simpler constructions. SUMMARY OF THE INVENTION

[0025] It is one of the objectives of the present invention to provide an electrical interruption assistance arrangement arranged in an arc extinguishing chamber, comprising at least one fixed contact mounted inside said arc extinguishing chamber, providing robustness and efficiency to the device.

[0026] Another objective of the present invention is to provide an arc extinguishing chamber that cannot be dismantled in the production process, increasing productivity, quality, and logistical gains.

[0027] Another objective of the present invention is to provide a robust arc extinguishing chamber that withstands greater internal pressure during arc extinguishing operations following an electrical contact opening event in an interruption device.

[0028] Another objective of the present invention is to reduce a component of forces resulting from the flow of gases towards the bottom of the base of a molded case circuit breaker housing, so that this buoyancy force, resulting from the release of gases originating from the instantaneously dissipated energy, whether directed solely to a gas outlet, during the opening of the electrical interruption contacts by the action of said circuit breaker or other extinguishing device.

[0029] It is a further object of the present invention to provide a molded case circuit breaker with a simple arc extinguishing chamber of the type of construction comprising said chamber housed in a niche of a current path pole of a simple case circuit breaker.

[0030] Another objective of the present invention is the use of double walls restricted only in the construction of the enclosure of said arc extinguishing chamber, offering superior extinguishing capabilities when compared to conventional, low-cost extinguishing chambers, avoiding such interruption systems known as cassettes incorporating electrical contact systems (which include a complete system of fixed and mobile contacts inside).

[0031] It is also an object of the present invention to completely seal the lower part of the arc extinguishing chamber.

[0032] Another object of the present invention is to provide an arc extinguishing chamber cover with a preferably orthogonal sliding assembly of the direction of the gas outlet flow towards the holes of the gas outlet cover.

[0033] It is another object of the invention to completely seal the upper part of the arc extinguishing chamber.

[0034] It is another object of the present invention to form a closed double-wall duct of structural reinforcement only in the region of the extinguishing chamber, aligned with the current path of a circuit breaker.

[0035] These objectives are preferably achieved by means of an electrical switching arrangement arranged in an arc extinguishing chamber, comprising:

[0036] a parallelepiped-shaped molded enclosure with two side walls, a front opening, a rear wall including holes, a bottom wall and an top wall, said side walls comprising, on their inner surface and in the front opening, a plurality of grooves spaced apart for receiving metal plates separated from each other by an exchange space;

[0037] at least one fixed terminal, comprising a contact support portion that receives a fixed contact positioned in the internal region of said housing;

[0038] - at least one movable contact, positioned on a movable contact arm of a contact system of at least one current path pole, which enters a front opening of said enclosure, partially projecting into said enclosure to open or close said current path with said fixed contact;

[0039] - a cover comprising gas removal holes;

[0040] - said enclosure comprising within it a second end portion of said terminal fixed introduced through said anterior opening into a groove adjacent to said lower wall; and

[0041] - said cover being positioned in a sliding manner on at least one pair of guide rails on said side walls, closing said front opening of said enclosure, orthogonally in relation to said fixed terminal.

[0042] According to a preferred embodiment of the present invention, said upper wall of said enclosure may comprise at least one opening hole for guiding the fixing of said lid in a sliding manner on said enclosure of said extinguishing chamber, and at least one opening slot extending longitudinally from said at least one hole to a front opening of said enclosure.

[0043] Furthermore, according to a preferred embodiment, the present invention features a lid having at least one longitudinal protuberance corresponding to said at least one orifice and at least one said opening slit in the vicinity of the front opening of said enclosure of said extinguishing chamber; said lid further comprising gas removal orifices for ejecting gases generated from the generation of an electric arc, which forms inside said enclosure of said arc extinguishing chamber.

[0044] Further, each side wall of said cover comprises at least one guide rail extending in a longitudinal direction on said side walls of said enclosure of said arc extinguishing chamber, so as to guide the sliding of said lid onto said casing, closing a previous opening thereof.

[0045] The fastening between a cover and a housing, which together form the extinguishing chamber, can be constructed using assembly techniques involving friction, pressure between the elements, and can also be additionally fastened with thermal welding, or through the use of adhesives, with a similar effect. In addition to the advantages of the present invention, solely by its aforementioned fitting system, the fastening of said enclosure cover of said extinguishing chamber can commonly be complemented, for example, by the cover of the main enclosure of a circuit breaker, which can block the disassembly of said extinguishing chamber cover, comprising or not reinforcing grooves, positioned orthogonally in relation to the flow of gas outlet passages, generated by the opening of the fixed and movable contacts towards the gas outlet holes, purposely positioned in this way.

[0046] The present invention also provides a molded case circuit breaker, comprising an electrical switching arrangement arranged in an arc extinguishing chamber, wherein a first terminal coupling end portion is fixed to a first end of said circuit breaker, including a fixed contact support, and further comprising a movable contact with a movable contact arm, which passes through an opening in the rear wall and projects into said enclosure of said arc extinguishing chamber, wherein said movable contact arm of a contact system comprises a slewing bearing fixed to the base of the housing of said circuit breaker (not shown), allowing it to said movable contact arm rotatably alternates between closed or open positions, relative to said fixed contact.

[0047] Furthermore, according to the present invention, the gas removal ports are arranged towards and connected to a gas outlet exchange space present in the enclosure of said circuit breaker, wherein said exchange space is positioned close to the portion of a first terminal coupling end in said circuit breaker.

[0048] Said circuit breaker, according to the present invention, comprises at least one cover, positioned above the cover of the enclosure of said arc extinguishing chamber, providing final assembly fixation between said cover and said enclosure of said arc extinguishing chamber, so as to extend a blocking of removal or deformation of said cover in the assembly, but more significantly, during the moment of current interruption, where the forces resulting from an opening of electrical contacts acting on said arc interrupting device are active in a sudden and intense manner, as already mentioned and known to the person in the art.

[0049] The circuit breaker according to the present invention comprises, among other operating components, a niche that receives said electrical switching arrangement arranged in said arc extinguishing chamber, fixed contact support and mobile contact system, which provides assistance in containing the deformations resulting from the aforementioned forces, specifically in the regions close to said arc extinguishing chamber.

[0050] The objects and advantages of the present invention will become clearer from the following description: detailed description of the examples and drawings, not limiting the scope of protection of the said invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 shows a top perspective view of a molded case circuit breaker, according to a preferred embodiment of the present invention.

[0052] Figure 2 shows a longitudinal sectional view of a molded case circuit breaker, and the indication of a Detail "A", according to a preferred embodiment of the present invention.

[0053] Figure 3 shows a longitudinal sectional view of a molded case circuit breaker, according to the state of the art.

[0054] Figure 4 illustrates a top perspective view of said molded case circuit breaker, without a closing cover, according to a preferred embodiment of the present invention.

[0055] Figure 5 illustrates another top perspective view of said molded case circuit breaker without cover and without one of the arc extinguishing chambers, showing a recess of one of the current interruption path poles of said circuit breaker, according to a preferred embodiment of the present invention.

[0056] Figure 6 illustrates an exploded view of a component arrangement arranged in said arc extinguishing chamber, in addition to a sequence of introduction of a cover, fixed terminal, fixed contact and extinguishing plates inside a housing, according to a preferred embodiment of the present invention.

[0057] Figure 7 shows the aforementioned assembled arc extinguishing chamber.

[0058] Figure 8 illustrates a longitudinal cross-sectional perspective view of an electrical switching arrangement arranged partially in said arc extinguishing chamber, in a configuration mounted on said circuit breaker, in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE DRAWINGS

[0059] Although the present invention may be susceptible to different embodiments, a preferred embodiment is shown in the following detailed presentation, with the understanding that the present description should be considered an exemplification of the principles of the invention, and that it is not intended to limit the present invention to what is described and illustrated.

[0060] Figure 1 shows, in top perspective, a molded case circuit breaker (10) comprising a base (10C) and a cover (100), at least one fastener (101), in addition to an operating handle (10D), a first end (10A) and a second end (10B) for connecting the power supply or load opposite each other, and an indication of a cutting plane “XY”, in which an interruption current path pole (10H) is contained (better shown in section in Figure 2), according to the present invention.

[0061] Figure 2 shows the molded case circuit breaker (10) in a longitudinal “XY” cross-section plane, comprising a said first end (10A) and a said second end (10B) for connecting the power supply or load, opposite each other, positioned longitudinally on said base (10C), in addition to a handle (10D) for operating on / off switch, the cover (100) and a tripping mechanism (10E) of a current interruption electrical contact system (10F). Furthermore, said circuit breaker (10) comprises positioned in a niche (15) (best seen in Figure 5) said electrical contact system (10F) comprising a movable contact (90) positioned on a movable contact arm (91), said movable contact (90) passing through an opening (91A) of said base (10C) and through the front opening (31) of a rear wall (32) partially projecting into an enclosure (30) of an arc extinguishing chamber (20), it being possible to visualize that said enclosure (30) comprises a lower wall (33) and an upper wall (34).A first terminal coupling end portion (81) of a fixed terminal (80) is fixed to a first electrical supply or load end (10A) through a fastener (86) such as a screw or similar, comprising a fixed contact support portion (83) receiving a fixed contact (84), and may include in other embodiments other components such as a strand (not shown), and a second electrical supply or load connection end (10B), which form a current path pole (10H) (seen in Figure 1) of said circuit breaker (10).

[0062] Said electrical contact system (10F), together with said mobile contact (90), also comprises a slewing bearing (92) which is bushed and integrated with said electrical contact system (10F), said electrical contact system (10F) bushed in said base (10C) (not shown) of said circuit breaker (10), allowing the mobile contact arm (91) to alternate between the closed and closed positions. open with said fixed contact (84) of said fixed contact support portion (83). Furthermore, an indication of Detail “A” presented later in Figure 8, in accordance with the present invention.

[0063] In Figure 3 it can be seen another circuit breaker (10'), of the state of the art, seen in a longitudinal section plane “XY” similar to that presented in Figure 2. In said section “XY” it is seen a first fixed terminal (80') of a current path pole (10H'), in which said fixed terminal (80') is fixed in a first end (10A') of electrical power or load connection, comprising a fixed contact support portion (83') comprising an arc guide (85') and a fixed contact (84'), and may include other components such as a rope (not shown), and a second end (10B') of power or load connection, which form a current path interruption pole, similar to that seen in Figure 1 of said circuit breaker (10).Furthermore, said circuit breaker (10') comprises positioned in a niche (15') (similar to niche 15 seen in Figure 5), a system of electrical contacts (10F') comprising a mobile contact (90'), positioned on a mobile contact arm (91'), which passes through an opening (91A') of a base (10C'), projecting directly into said niche (15') of a housing (11') of said circuit breaker (10'), (formed by a base 10C' and a cover (100'), and partially within an arc extinguishing chamber (20'), where said fixed terminal (80') can be seen arranged directly below a housing (30'), which has an opening (21') in its positioned lower portion. directly on said internal wall (10D') of said base (10C') of said circuit breaker (10').

[0064] According to Figure 4, said molded case circuit breaker (10) is shown in top perspective view without said cover (100), in a preferred embodiment of the present invention, comprising said first power supply or electrical load connection end (10A) and said second power supply or electrical load connection end (10B), opposite each other, in addition to said tripping mechanism (10E) of said current interruption electrical contact system (10F), in addition to arc extinguishing chambers (20), arranged inside said niche (15) (best seen in Figure 5) of said base (10C), which together with said cover (100) form said housing (11) of said circuit breaker (10).

[0065] According to Figure 5, said circuit breaker (10) is shown in a top perspective view without said cover (100) comprising niches (15) related to the arrangement of the interruption components of at least one current path pole (10H), where said arc extinguishing chambers (20) are also arranged, said mobile contact arm (91) comprising said mobile contact (90), having its end (93) furthest from said electrical contact system (10F), according to the present invention.

[0066] Furthermore, according to Figure 5, said circuit breaker (10) comprises housings (16) for at least one fastener (101) for said cover (100) (seen in Figure 1).

[0067] According to Figure 6, said arc extinguishing chamber (20) is shown in exploded perspective view, comprising said enclosure (30) in the shape predominantly of a parallelepiped, comprising two closed side walls (30a, 30b), a front opening (31), a rear wall (32), a closed lower wall (33) and a closed upper wall (34), defining a portion of said enclosure (30) of said arc extinguishing chamber (20). Said side walls (30a, 30b) comprise, on their inner surface, in the front opening (31), merely as an example of embodiment, a plurality of spaced grooves (35), in said side walls (30a, 30b), parallel to each other. Furthermore, according to said Figure 6, said arc extinguishing chamber (20) also comprises a plurality of metal plates (40) separated from each other by an exchange space (41) to be arranged in said plurality of grooves (35), in addition to a positioning groove (36) for said fixed terminal (80).The preferred arrangement of said slots is predominantly longitudinal with respect to said side walls (30a, 30b), one with respect to the other, or in other embodiments they may be arranged angularly with respect to said lower wall (33) for example, if not arranged parallel, but arranged at least in such a way as to allow the assembly of said metal plates (40) through said front opening (31). Figure 6 further illustrates that said housing (30) also comprises, in said upper wall (34), an embodiment of an orifice (50) connected to an opening slot (51), wherein said opening slot (51) extends longitudinally from said orifice (50) to said front opening (31).

[0068] Furthermore, according to Figure 6, it is seen that each side wall called (30a, 30b) can comprise preferably at least one guide rail (60) which extends in a longitudinal direction in said side walls (30a, 30b). In this sense, the presence of said orifice (50), of the opening slot (51) and of at least one guide rail (60) which has the function of assisting in the assembly and fixing of a cover (70) which is fitted, in a sliding manner, in the front opening (31), so that these elements serve as a guide for the sliding of said cover (70) in said enclosure (30). Still according to Figure 6, said arc extinguishing chamber (20) further comprises said fixed terminal (80) arranged on said lower wall (33), said fixed terminal (80) comprising a first terminal coupling end portion (81) which is arranged outside said enclosure (30) after assembly.A second end portion (82) of said fixed terminal (80) is disposed toward the rear wall (32) of said housing (30), and a fixed contact support portion (83) being projected from said second end portion (82) of said fixed terminal (80) in said housing (30), said second end portion (82) and said fixed contact support portion (83) being disposed within said housing (30) after assembly. Said fixed contact support portion (83) extends from said second end portion (82) to the vicinity of said first terminal coupling end portion (81). Furthermore, said fixed contact support portion (83) is provided, on its side facing said upper wall (34) of said housing (30) with a fixed contact (84), and said fixed contact (84) is preferably fixed at the end portion closest to the first end portion. of terminal coupling (81) of an arc guide (85) of magnetic material, with said arc guide (85) being positioned on the side of said fixed contact support portion (83) facing said bottom wall (33) of said housing (30).

[0069] Thus, according to Figure 6, in order for said lid (70) to be properly fitted to said housing (30), in a preferred embodiment according to the present invention, said lid (70) comprises a preferably central longitudinal protuberance (71), which slides and accommodates itself in said hole (50) and in said opening slot (51). Furthermore, said lid (70) comprises, on each of its sides, at least one longitudinal protuberance (72), which can be slidably mounted to allow fixing of said lid (70) on said at least one guide rail (60) on said side walls (30a, 30b) of said housing (30). In other embodiments, said housing (30) may comprise two or more guide rails on each side wall (30a, 30b) and said lid (70) may comprise two or more longitudinal protrusions (72) on each side.Final assembly occurs when a lower face (75) of said lid (70) can touch a counter face (37) of said housing (30). In an alternative embodiment, an additional closure can be presented, where a surface (76) of said lid (70) can touch a surface (38) of said housing (30).

[0070] Further, according to Figure 6, the cover (70) comprises gas removal holes (73) to eject gases generated when an electric arc forms inside the said housing (30). These gas removal holes (73) are arranged towards and frontally connected to an external gas outlet exchange space (74) (seen in Figure 8) present near a first end (10A) and near said first terminal coupling end portion (81) of said circuit breaker (10).

[0071] In Figure 7 it can be seen in a top perspective view of said assembled arc extinguishing chamber (20), where said second end portion (82) and said fixed contact support portion (83) (seen in Figure 6) are introduced into the internal part of said arc extinguishing chamber (20) (not visible), leaving externally only said first terminal coupling portion (81) of said fixed terminal (80). In the upper part of said assembled arc chamber (20), said longitudinal protuberance (72) of said cover (70) coupled to said orifice (50) and to said opening slot (51) of said enclosure (30) can be observed, closing the entire upper wall (34), in addition to an upper edge wall (77) of said cover (70).

[0072] According to Figure 8, detail “A” cited in Figure 2 is shown, in longitudinal section of said current path pole (10H), in the region of said electrical interruption arrangement arranged in said arc extinguishing chamber (20), where it can be seen that said circuit breaker (10) comprises said cover (100) comprising reinforcing ribs (100A) and housings (100B) for at least one fastener (101) which is fixed in said housing (16) of said base (10C) (seen in Figure 5), close to the gas outlet exchange space (74) and close to the first terminal coupling end portion (81), according to the present invention. invention. In the direction of said current path pole (10H), only two possible paths for gases to exit from said arc extinguishing chamber (20) are provided, these being identified as said gas removal ports (73) and said front opening (31), both purposely positioned longitudinally to a wall (10G) inside said base (10C) and an internal wall (100C) of said cover (100) of said circuit breaker (10). OPERATION OF THE INVENTION

[0073] During an interruption operation of the circuit breaker (10), the electrical contact system (10F) moves, separating the mobile contact (90) from the fixed contact (84), from a tripping mechanism (10E), through a previously defined interruption trigger configuration, initiating the formation of an electric arc, which must be dissipated preferably through the arc extinguishing chamber (20) of said circuit breaker (10).

[0074] It was noticed in the arc extinguishing chambers (20') known until then, flaws in the construction of conventional circuit breaker enclosures (10'), containing predominantly simple insulating walls, formed solely by a base (10C') and a simple-walled cover (100'), as cited in the prior art in Figure 3, where forces involved during said arc extinguishing start from the region close to the fixed contact (84') and the mobile contact (90'), where a generated electric arc is subsequently attracted towards an exchange space (41') of the metal plates (40'), aided by an arc guide (85') and by a contact support portion (83') of magnetic materials, and subsequently towards said arc holes gas removal (73'), subsequently connected frontally to an external gas outlet exchange space (74') of said circuit breaker (10'). In this configuration, where said fixed terminal (80') has contact with the internal part of said arc extinguishing chambers (20') of the state of the art through an opening (21') in the lower part, through which the fixed contact (84') fits, where there is the possibility that a shock wave with high forces acts directly on said base (10C'), being able to cause damage or even provoke a component of forces capable of expelling said extinguishing chamber (10') from said niche (15') towards said cover (100'), since said extinguishing chamber (10') does not have a specific anchoring.

[0075] The invention resolves structural robustness flaws perceived in the state of the art, in an unexpected or unanticipated manner, creating an arc extinguishing chamber (20) that is more resistant to expulsion from the base (10C) and also to deformations resulting from the electric arc, in which said arc extinguishing chamber (20) comprises a parallelepiped-shaped casing (30), comprising said groove (36) adjacent to the lower wall (33), which allows pre-assembly of said arc extinguishing chamber assembly (20) and in which said fixed terminal (80) is firmly positioned.

[0076] This positioning allows an increase in mechanical resistance, obtained by the mounting position of the fixed terminal (80) inside the fixing groove (36) in the housing (30), providing a complete entrapment of the extension of a second end portion (82) of said fixed terminal (80) inside said groove (36) of said housing (30) of the extinguishing chamber (20), which increases the mechanical strength of the fixing of said fixed terminal (80). Different from the known prior art, since the first terminal coupling end portion (81) of said fixed terminal (80) is fixed through a fastener (86) to a first end (10A) of the base (10C) of said circuit breaker (10), firmly securing said extinguishing chamber (20) together with said fixed terminal (80) to said base (10C) of said circuit breaker (10).

[0077] Additionally, a preferred embodiment incorporates an orthogonal mounting position of the cover (70) on the housing (30), allowing the fixed terminal (80) to be trapped after mounting.

[0078] When this preferred embodiment is used in a circuit breaker (10) comprising the cover (100), which comprises in the upper part the inner wall (100C) of said cover (100) and the wall (34) of the arc extinguishing chamber (20) and comprising in the lower part the lower wall (33) of said arc extinguishing chamber (20) and the wall (10G) of the base (10C) of said circuit breaker (10), they together form a double-walled duct, aligned with the current path (10H).

[0079] The aforementioned upper double-wall duct comprises the upper wall (34) of the extinguishing chamber (20) positioned adjacent to the inner wall (100C) of the cover (100) of the circuit breaker (10). The aforementioned lower double-wall comprises the lower wall (33) of said extinguishing chamber (20), positioned adjacent to the wall (10G) of the base (10C) of said circuit breaker (10).

[0080] According to Figures 2 and 8, the cover (100) of the circuit breaker (10) can be seen arranged above the upper wall (34) of the cover (70) and of the housing (30) of the extinguishing chamber (20), where said cover (100) can preferably contain ribs (100A), which can reinforce a final assembly fixation between said cover (70) and said housing (30), assisted by at least one fastener (101) for joining between said cover (100) and the base (10C), which is capable of blocking a movement of displacement, deformation, or unwanted removal of said cover (70) of said arc extinguishing chamber (20), during the action of the shock forces resulting from the expansion of the gas of the electric arc generated by the opening of the contacts (84, 90) of said circuit breaker (10). In other configurations, said lid (100) may rest with the inner wall (100C) directly on the upper surface of said lid (70), providing a similar technical blocking effect.In order to ensure an additional fixation between said lid (70) and said housing (30), said lid (70) and said housing (30) may be additionally fixed to each other by thermal welding, or adhesives, or another similar type of chemical locking. In the case of the presence of said ribs (100A) in the previously chosen embodiment, it is expected that these may be coincident with said upper edge wall (77) of said lid (70), or with said longitudinal protuberance (71), to avoid a possibility of opening said extinguishing chamber (20).

[0081] Differently from what the state of the art taught, presenting fixed contact terminals (80') externally positioned in the lower portion of said extinguishing chambers (20'), or having only the fixed contact portion (84') positioned inside it, through openings (21') that do not fix the arc extinguishing chamber (20') to said fixed terminal (80'), allowing a passage of gas in the lower part of said chambers (20') or even in the upper part according to the state of the art, the present invention presents ways of blocking these possible gas leaks, both in the lower part of the openings (21'), and additionally in the upper part of said extinguishing chamber, in addition to proposing fixation to said fixed terminal at the base of the circuit breaker (10).In preferred embodiments of the present invention, a fixed terminal (80) is positioned and fixed inside the housing (30) of the extinguishing chamber (20), preferably by introducing a second end portion (82) of said fixed terminal (80) into a groove (36) adjacent to the bottom wall (33), which allows a pre-assembly of said arc extinguishing chamber assembly (20) and in which said fixed terminal (80) is firmly positioned, which may additionally contain in the closing assembly the lid (70) in a predominantly orthogonal direction with respect to said fixed terminal (80) and to the flow of gases, additionally supporting a first end portion (81) of said fixed terminal (80) through a fastener (86) on the base (10C).The closure of said lid (70) with respect to said housing (30) is supported by said longitudinal protuberance (71) which can slide towards said hole (50) and said opening slot (51), forming a robust assembly, slidingly mounted via at least one said guide rail (60).

[0082] Additionally, said lid (70) comprising the longitudinal protuberance (71) may be constructed with at least one longitudinal protuberance (72) to ensure a fixation of said lid (70) in said housing (30), which are preferably implemented positioned orthogonally in relation to the base (10C) or the exchange space (41). Said longitudinal protuberance (72) of said lid (70) is constructed so that it can slide on a guide rail (60) so as to embrace the side walls (30a, 30b), so that the forces generated by the shock wave, even if they may deform the housing (30) and said lid (70) of said quenching chamber (20), provide a greater capacity to resist these deformations without failing, since assembly fittings are implemented in a structured manner.In this way, the invention provides a more resistant arrangement to the forces generated by the magnetic flux and gases generated by the electric arc, which start from the region close to the fixed contact (84) and mobile contact (90) during opening, with a larger portion magnetically attracted by the arc guide (85) towards the exchange space (41) of the metal plates (40), which attracts the gas outlet flow towards the gas removal holes (73), during an opening of the contacts (84, 90) in said arc extinguishing chamber (20). The displacement of the electric arc towards the metal plates (40) tends to present an increase in the flow velocity and at the same time a reduction in pressure, the closer the gas approaches the gas outlet holes (73), when compared to its origin during opening, close to the fixed contact (84) and mobile contact (90), forming capable force components. to generate a thrust, which contribute to the tendency of the arc extinguishing chamber (20) to be expelled towards the lid (100). Furthermore, in the present invention, any portion of this flow that may move to the lower part of said arc extinguishing chamber (20) is blocked by the lower wall (33) preferably closed at the bottom, a result of the additional constructive concept of the present invention, which results in greater control of the gas flow. In the upper part, in a similar way, through the upper wall (34), complemented by said lid (70), they together result in the closing of the upper part of said extinguishing chamber (20), in relation to the control of the gas flow.

[0083] In this way, preventing resulting forces from acting in the orthogonal direction to the current path (10H) and towards said cover (100) is something to be avoided, and achieved by the present invention, proportionally reducing higher costs of structural reinforcement, or even achieving superior results in the extinguishing capacity of the extinguishing chamber (20), or even when compared to the known cassettes, which incorporate contact systems such as (10F), reducing material costs in said circuit breaker (10).

[0084] It was noted from the prior art that publications focused on teaching assemblies, increasing the resistance of the chamber or alternatively of the arc extinguishing grids, arc cooling, or improving the resistance performance of said chamber, but in an isolated manner. Unlike the others, the present invention resolves the possibility of leakage of arc gas flux generated in said chamber, which resulting from high energy and rapid shock waves, which continued to propagate their energy beyond the boundaries of the construction of the so-called current extinction chambers, visibly perceptible.

[0085] In particular, in the lower part of said circuit breaker (10') of the state of the art, when this shock wave of gases resulting from the extinction of the arc close to said fixed contact (84') and mobile (90') in the construction of said extinction chamber (20') it is noticeable that this configuration of the present invention reduces the possibility of a catapult effect, as can be seen in Figure 3 of the state of the art in section, where in the lower part of said arc extinction chamber (20') which does not have a fixation in relation to said fixed terminal (80') and the opening (21') can additionally be seen, where expanding gases can press directly on the internal wall of said base (10D'), at least in the space between said fixed terminal (80') and said fixed contact support portion (83'), generating a vertical force component, capable of pushing said extinction chamber (20') in a direction predominantly opposite to said base (10C').

[0086] The final assembly of said cover (100), which may additionally comprise ribs (100A) on the upper part of said circuit breaker (10), wherein said cover (100) secured by at least one fastener (101) through the housing (100B) in the housing (16) of said base (10C) configures said enclosure (11) of the present invention. This assembly, in addition to securing the insulating outer part of said circuit breaker (10), locks and provides additional robustness to said fixed terminal (80), when in a preferred configuration, in which said fixed terminal (80) is previously mounted inside said slot (36) of said casing (30) of said arc extinguishing chamber (20), and of said cover (70) which is mounted orthogonally to the direction of the current path (10H), avoiding disassembly and possible unwanted displacement of said fixed terminal (80) or said extinguishing chamber (30).

[0087] Finally, it can be observed that this configuration gives said arc extinguishing chamber (20), seen in Figures 2, 4, 5, 6, 7 and 8, an increase in its mechanical resistance capacity during electric arc extinguishing, added to an increase in the gas outlet velocity, derived from the volume reduction caused by the resulting proportional confinement of a double sealing layer, which prevents gas leaks in both the lower and upper parts of said arc extinguishing chamber (20). These gases are expelled more efficiently through said gas removal holes (73) of said cover (70), following a flow aligned with the current path pole (10H) of the circuit breaker (10).This combination results in an improvement in the exit speed of the hot gas from the arc extinguishing chamber (20), unparalleled in the state of the art, and which extends the useful life and resistance capacity of said arc extinguishing chamber (20) in relation to the acting forces resulting from the magnetic flux and the shock wave generated by the electric arc inside the enclosure (30). There is still a small portion of gases that can return through said previous opening (31), but absorbed by the interior volume of said circuit breaker (10), which has a greater volumetric capacity. However, proportionally, the effect of the return of gases is clearly. perceives lower, due to the attraction generated by the plates (40) towards the exchange space (41) that attracts the gases in the direction of the exit flow towards the gas removal holes (73), due to the front opening (31) having small passage dimensions and because it does not exert a tear-off force on said upper cover (100), different from the state of the art.

[0088] In other embodiments, the housing (30) may comprise two or more holes (50) or two or more opening slits (51), in addition to having a plurality of spaced grooves (35) constructed non-parallel to each other. In another configuration, the upper wall (34) of the housing (30) may be constructed without any hole, being provided with a protuberance, similar to the longitudinal protuberance (71) and said hole (50) being constructed in a wall of said lid (70), being considered solutions obvious to the person in the art and having a similar structural effect. Another variant embodiment could be to construct, for example, a chamber in the lower external part of the housing (30), in a similar way to the groove (36), to accommodate said fixed terminal (80), fitting it on the outside of the housing (30), but with a similar reduction of the catapult effect, which should be considered within the scope of the present invention, and having a similar technical effect.

[0089] Therefore, according to a preferred embodiment of the present invention, the chamber (20) may have at least one orifice (50) and at least one opening slot (51) which may be implemented both in said casing (30) and in said lid (70) in a similar manner, or other similar means of fitting.

[0090] Although the present invention has been described with respect to certain preferred embodiments, it should be understood that it is not intended to limit the invention to those particular embodiments. Rather, it is intended to encompass all possible alternatives, modifications, and equivalencies within the spirit and scope of the invention.

Claims

- at least one fixed terminal (80) comprising a housing (30) shaped in the shape of a parallelepiped with two side walls (30a, 30b), a front opening (31), a rear wall (32), a bottom wall (33) and an top wall (34), said side walls (30a, 30b) comprising, on their inner surface and in the front opening (31), a plurality of grooves (35) spaced apart for receiving metal plates (40), separated from each other by an exchange space (41); - at least one fixed terminal (80) comprising a contact support portion (83) receiving a fixed contact (84) within said housing (30);- at least one movable contact (90), positioned on a movable contact arm (91) of a system of electrical contacts (10F) of at least one current path pole (10H), which are positioned through a front opening (31) of said housing (30), partially projecting into said housing (30) for opening or closing said current path (10H) with said fixed contact (84); characterized in that - said housing (30) comprises in its interior a second end portion (82) of said fixed terminal (80) introduced through said front opening (31) into a groove (36) adjacent to said bottom wall (33).

2. Electrical switching arrangement arranged in an arc extinguishing chamber (20) comprising, a housing (30) shaped in parallelepiped shape with two side walls (30a, 30b), a front opening; (31), a rear wall (32), a lower wall (33) and an upper wall (34), said side walls (30a, 30b) comprising, on their inner surface and in the front opening (31), a plurality of grooves (35) spaced apart from each other for receiving metal plates (40), separated from each other by an exchange space (41); - at least one fixed terminal (80), comprising a contact support portion (83) receiving a fixed contact (84) inside said housing (30); - at least one movable contact (90), positioned on a movable contact arm (91) of a system of electrical contacts (10F) of at least one current path pole (10H), which are positioned through a front opening (31) of said housing (30), partially projecting into said housing (30) for opening or closing said current path (10H) with said fixed contact (84); - a cover (70) comprising gas removal holes (73);characterized in that - said cover (70) is slidably positioned on at least one pair of guide rails (60) on said side walls (30a, 30b), closing said front opening (31) of said enclosure (30), orthogonally with respect to said slot (36) of said enclosure (30).

3. Electrical switching arrangement arranged in an arc extinguishing chamber (20), according to claim 1, characterized in that said arc extinguishing chamber (20) has a closed bottom wall (33).

4. Electrical switching arrangement arranged in an arc extinguishing chamber (20) according to claim 1, characterized in that said arc extinguishing chamber (20) has a closed upper wall (34).

5. Electrical switching arrangement arranged in an arc extinguishing chamber (20) according to claim 1, characterized in that a first terminal coupling end portion (81) of said fixed terminal (80) is arranged on the outside of said enclosure (30).

6. Electrical switching arrangement arranged in an arc extinguishing chamber (20) according to claim 2, characterized in that said upper wall (34) of said enclosure (30) can comprise at least one hole (50) for a fastening of said cover (70). 7.Electrical switching arrangement arranged in an arc extinguishing chamber (20) according to claim 6, characterized in that at least one opening slot (51) of said upper wall (34) extends longitudinally from said at least one orifice (50) to the front opening (31).

8. Electrical switching arrangement arranged in an arc extinguishing chamber (20) according to claim 6, characterized in that said cover (70) has at least one longitudinal protuberance (71) corresponding to said at least one orifice (50).

9. Electrical switching arrangement arranged in an arc extinguishing chamber (20) according to claim 8, characterized in that said cover. (70) may have at least one longitudinal protuberance (71) corresponding to said at least one said orifice (50) accompanied by at least one said opening slot (51). Electrical switching arrangement arranged in an arc extinguishing chamber (20) according to claim 2, characterized in that each said side wall (30a, 30b) comprises at least one guide rail (60), said at least one guide rail (60) extending in a longitudinal direction on said side walls (30a, 30b) so as to allow a sliding guide (72) for mounting said cover (70) on said housing (30).

11. Electrical switching arrangement arranged in an arc extinguishing chamber (20), according to claim 2, characterized in that said cover (70) has gas removal holes (73) arranged in the region of the front opening (31) of said enclosure (30). 12.Electrical switching arrangement arranged in an arc extinguishing chamber (20), according to claim 1 and 2, characterized in that said electric arc is formed from the energy dissipated instantaneously during an opening between said fixed contact (84) and said movable contact (90), circulating through a plurality of metal plates (40), separated from each other by an exchange space (41) and aligned with a current path (10H) of said circuit breaker (10).

13. Electrical switching arrangement arranged in an arc extinguishing chamber (20), according to claim 2, characterized in that the fixing. between said cover (70) and said casing (30) can be made by thermal welding.

14. Arc extinguishing chamber, wherein an arc extinguishing chamber (20) comprises a housing (30) molded with two side walls (30a, 30b), a front opening (31), a rear wall (32), a bottom wall (33) and an top wall (34), said side walls (30a, 30b) comprising, on their inner surface and in said front opening (31), a plurality of grooves (35) for receiving metal plates (40) separated from each other by an exchange space (41), characterized in that said housing (30) comprises in its interior a groove (36) adjacent to said bottom wall (33) and a cover (70) slidingly positioned on guide rails (60) of side walls (30a, 30b) closing a front opening (31) of said housing (30), orthogonally with respect to the bottom wall (33). 15.Molded case circuit breaker, said circuit breaker (10) characterized in that it comprises an arc extinguishing chamber (20) as defined in any one of the preceding claims, wherein a said first terminal coupling end portion (81) of a said fixed terminal (80) is fixed through a fastener (86) to a first end (10A) of the base (10C) of said circuit breaker (10). Molded case circuit breaker according to claim 15, characterized in that gas removal ports (73) are arranged towards and connected to a gas outlet exchange space (74) of the circuit breaker. (10), said exchange space (74) being proximate to said first terminal coupling end portion (81).

17. Molded case circuit breaker according to claim 15 or 16, characterized in that said circuit breaker (10) comprises a wall (10G) of a base (10C) receiving an arc extinguishing chamber (20) comprising a said housing (30) and a closing cover (70), having a cover (100) positioned above a said cover (70), ensuring a final assembly fixation between said cover (70) and said housing (30), so that said cover (100) can block the removal of said cover (70) from said arc extinguishing chamber (20).

18. Circuit breaker according to any one of claims 15 to 17, characterized in that said circuit breaker (10) comprises a recess (15) in said current path pole (10H) receiving said arc extinguishing chamber (20). 19.Method for assembling an arc extinguishing chamber as defined in claim 14, characterized in that it comprises the steps of: - introducing a plurality of metal plates (40) arranged in the plurality of grooves (35) of a casing (30) of said arc extinguishing chamber (20); - introducing the second end portion (82) of a fixed terminal (80) comprising the fixed contact (84) into a groove (36) of said casing (30) of said arc extinguishing chamber (20); - positioning a cover (70), comprising at least one longitudinal protuberance (71) that slides until it fits into at least one hole (50); and. - pushing said prepositioned cover (70) until a lower face (75) of said cover (70) touches a bearing face (37) of said housing (30).

20. Method of arranging electrical switching arranged in a circuit breaker, characterized in that it comprises the steps of: - introducing an arc extinguishing chamber (20) formed by the process defined in claim 19 into a niche (15) formed in a base (10C) of said circuit breaker (10); - assembling - at least one end (93) furthest from a movable contact (90), positioned on a movable contact arm (91) of a contact system (10F) of at least one current path pole (10H), which passes through an opening (91A) enters a front opening (31) of said housing (30), partially projecting into said housing (30) for opening or closing a current path (10H) with a fixed contact (84);- fixing said first terminal coupling end portion (81) of a said fixed terminal (80) via a fastener (86) to a first end (10A) of said circuit breaker (10); and - fixing a cover (100) to the upper part of said circuit breaker (10) via housings (100B) and at least one fastener (101) to the housing (16) of said base (10C) so as to block a removal of said cover (70) and said arc extinguishing chamber (20), housed in said niche (15) of said circuit breaker (10).

21. A process for assembling a circuit breaker, said circuit breaker (10) according to claim 15, comprising the steps of:; - introducing an arc extinguishing chamber (20) formed by the process as defined in claim 20 into a niche (15) formed in a base (10C) of said circuit breaker (10); - fixing a said first terminal coupling end portion (81) of a said fixed terminal (80) via a fastener (86) to a first end (10A) of said circuit breaker (10);- fixing a cover (100) to the upper part of said circuit breaker (10) by means of housings (100B) and at least one fastener (101) to the housing (16) of said base (10C) so as to block a removal of said cover (70) and of said arc extinguishing chamber (20) housed in said niche (15) of said circuit breaker (10), characterized in that: - said walls (34, 77) closed together with an internal wall (100C) of said cover (100) in the upper part and a lower wall (33) of said arc extinguishing chamber (20) together with a wall (10G) of said base (10C) closed in the lower part of said circuit breaker (10), form a closed double-walled duct aligned with said current path (10H).;

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