Fuse and related manufacturing method

Abstract

The fuse includes at least one blade fuse (4), the blade fuse having a reduced portion (46A) formed therein that defines a cross section (P4). The fuse also includes a pair of arc guards (6) made of an elastic material, each arc guard of a pair facing each other on a respective main surface of the blade fuse. Each arc guard includes an inner surface (66) facing toward the blade fuse, a front surface (62) facing toward the reduced portion, and a rear surface (64) facing away from the reduced portion. At least one perforation (80) is formed in the blade fuse near the reduced portion, each perforation being at least partially closed by the inner surfaces (66) of two arc guards of the same pair, each perforation leaving a cavity between the two arc guards of the same pair.

Description

[Technical Field]

[0001] The present invention relates to fuses and related manufacturing methods. [Background technology]

[0002] A fuse is an electrical component that includes two terminals and is capable of interrupting current flow between the two terminals in the event of an overcurrent exceeding a limit called the fuse rating. The two terminals are electrically connected to each other by at least one blade fuse secured to an insulator and disposed within a cavity formed in the insulator. One or more blade fuses may be connected in parallel to the two terminals, depending on the size of the fuse. References to a blade fuse may be substituted for other blade fuses, if multiple blade fuses are present.

[0003] Blade fuses are made of a conductive material with a predetermined electrical resistance and a predetermined fusing temperature. In normal operation, current passes through the blade fuse, and the temperature of the blade fuse remains below the fusing temperature. In the event of an overcurrent, the temperature of the blade fuse rises and exceeds the fusing temperature at one or more points, causing at least a portion of the blade fuse to melt and irreversibly interrupt the flow of current. Blade fuses have a reduced diameter between the two poles and the connections. Cross-sectional area Such intermediate portion includes at least one intermediate portion having a "reduced" cross section Each reduction is called cross section Each shrinking portion of the blade offers a greater resistance to electrical current than the rest of the blade. cross section In the event of an overcurrent, the blade preferably shrinks. cross section It melts down.

[0004] reduction cross sectionWhen the fuse melts, an electric arc is generated, and electricity continues to flow until the arc is extinguished. The electric arc, defined as the plasma state of matter, causes intense localized heating that promotes fusion of the blade fuse. This change in state of the blade fuse material due to thermal and electrical conditions, in turn promotes the maintenance and extension of the electric arc.

[0005] It is known practice to place silicone arc guards on blade fuses to limit the propagation of arcs.

[0006] For example, in US-5,596,306, the reduction cross section The arc guards confine the electric arc but do not have a positive effect on the extinction time of the electric arc. Summary of the Invention

[0007] The present invention is intended to remedy these problems, more particularly by proposing a fuse with better performance.

[0008] To this end, the present invention provides at least one blade fuse formed from a sheet having two opposing major surfaces extending along a longitudinal axis of the blade fuse, each blade fuse having a reduced diameter defining a cross section in the blade fuse; cross section at least one blade fuse including a portion formed with two connection terminals, one connected to each blade fuse; - a pair of arc guards made of elastic material, each of which is opposed to the respective main surfaces of the same blade fuse, and each arc guard has an inner surface facing the blade fuse and a contracting surface facing the blade fuse; cross section The front is oriented in the direction of the cross section an arc guard including a rear surface facing away from the arc guard; This invention relates to a fuse comprising:

[0009] At least one perforation has shrunk cross section and each of the perforations is at least partially closed by the inner surfaces of two arc guards of the same pair, and each perforation forms a cavity between the two arc guards of the same pair. In accordance with the present invention, for each blade fuse, the ratio of the number of groups of perforations measured along the longitudinal axis of the blade fuse is Cross-sectional area This blade fuse has a reduced Area of ​​the cross section The smallest of Cross-sectional area is 5 times, preferably 10 times larger than the

[0010] Thanks to the present invention, blade fuses including perforations at least partially covered by an arc guard have significantly shorter extinguishing times than blade fuses without perforations. The perforations facilitate the progression of the electric arc, which is extinguished more quickly than would be the case without the arc guard. Therefore, for a fuse of a given rating, i.e., suited to a given voltage and / or power, it is possible to design a more compact and therefore more economical fuse.

[0011] According to advantageous but non-essential aspects of the invention, such fuses may incorporate one or more of the following characteristics, taken alone or in any technically feasible combination: -Reduced to blade fuse cross section and a perforation is formed on both sides of the first pair of arc guards, and the fuse includes a second pair of arc guards in addition to the first pair of arc guards, and the first and second pairs of arc guards each have a reduced diameter. cross section At least partially closing the perforations formed on both sides of the The perforations have an elongated shape and are arranged along their length parallel to the longitudinal direction of the blade fuse. -The perforations extend parallel to the longitudinal direction of the blade fuse beyond the rear face of the arc guard to form a rear vent. The rear vent has a length of 0.1 mm to 10 mm, preferably 0.5 mm to 8 mm, and more preferably 1 mm to 5 mm. -The perforations extend parallel to the longitudinal direction of the blade fuse beyond the front face of the arc guard to form a front vent. The front vent has a length of 0.1 mm to 5 mm, preferably 1 mm to 3 mm. -The front and rear surfaces of each arc guard are separated by a length of 5mm to 30mm. -The front of the Arc Guard and the opposing shrink cross section The distance between the boundary lines is 0.5 mm to 20 mm, preferably 1 mm to 15 mm, and more preferably 2 mm to 12 mm. The arc guard is made of an elastomer material having a hardness measured on the Shore A scale of 20 to 90, preferably 40 to 70. The arc guard is made of an elastomeric material, preferably silicone. For at least the first pair of arc guards, the arc guards are made of preformed material, while a layer of adhesive is interposed between the blade fuse and the inner surface of each arc guard of the pair, with the inner surface facing one main surface of the blade fuse, so as to fix each arc guard to the blade fuse. The fuse includes a frame that is received in a cavity in the body of the fuse and limits movement of the blade fuse relative to the body by spacers and / or shims.

[0012] The present invention also relates to a method of manufacturing such a fuse, the fuse comprising a reduced diameter portion defining a cross section of the blade fuse. cross section The method includes at least one blade fuse having - providing at least one perforation in the blade fuse on one side of the cross section; -reduced so that each perforation is at least partially closed by an arc guard; cross section a step of assembling two arc guards of a first pair on respective main surfaces of the blade fuse adjacent to the first pair, the ... cross section the distance between the boundary lines is 1 mm to 15 mm; Includes.

[0013] Advantageously, the method includes, before the assembly step, a step consisting of manufacturing a first pair of two arc guards, the arc guards being made of a cross-linked elastomeric material and having flat inner surfaces, and during the assembly step, interposing a layer of adhesive between the inner surface of each arc guard and a respective main surface of the blade fuse so as to adhere the first pair of arc guards to the blade fuse.

[0014] The invention will be better understood and other advantages will become more apparent in the light of the following description of several embodiments of fuses in accordance with the principles of the invention, given by way of example only and with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a fuse including multiple blade fuses and an arc guard according to a first embodiment of the present invention, with some components shown diagrammatically for ease of reading. [Figure 2] FIG. 2 is a view of the fuse of FIG. 1 as seen along arrow II in FIG. 1, with some parts omitted for ease of reading. [Figure 3] FIG. 3 is a schematic perspective view showing an enlargement of the blade fuse and arc guard of FIG. 1 along arrow III in FIG. [Figure 4] FIG. 4 shows two schematic views of the same blade fuse and arc of FIG. 1 on inserts a) and b). [Figure 5] FIG. 5 is a view similar to FIG. 4 showing the same blade fuse and arc for another embodiment of the invention. [Figure 6] FIG. 6 is a view similar to FIG. 4 showing the same blade fuse and arc for another embodiment of the present invention. [Figure 7] FIG. 7 is a graph showing the progression of current through a blade fuse according to the prior art or an embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing steps in a method for manufacturing a blade fuse and an arc arrester according to an embodiment of the present invention. [Figure 9] FIG. 9 is a view similar to FIG. 3 showing a blade fuse and arc according to another embodiment of the present invention. [Figure 10] FIG. 10 shows two schematic views of the same blade fuse and arc of FIG. 9 on inserts a) and b). DETAILED DESCRIPTION OF THE INVENTION

[0016] The fuse 2 is shown in Figure 1. The fuse 2 includes a body 20, shown diagrammatically in dotted lines, and two connection terminals 22.

[0017] The body 20 is made of an insulating material, such as ceramic. The body 20 generally has the shape of an elongated cylinder that defines a longitudinal axis A2 of the fuse 2. In the illustrated example, the body 20 has a parallelepiped shape, i.e., the body 20 is a cylinder of rectangular sections. In non-limiting variations, the body 20 has elliptical or circular sections. The transverse direction is defined as the direction perpendicular to the axis A2. Thus, the transverse cross-section of the fuse 2 is a plane perpendicular to the axis A2.

[0018] In the illustrated example, the terminals 22 are arranged on two opposite faces of the body 20, each perpendicular to the axis A2. Each terminal 22 has the shape of a cylinder with an oval section and is generally parallel to the axis A2. A slot 24 is made through each terminal 22. Each terminal 22 includes a plate 26 intended for assembling the fuse 2 in a fuse holder, not shown.

[0019] The body 20 of the fuse 2 includes a cavity V20 within which the blade fuses 4 are housed. Each blade fuse 4 includes two opposing mounting ends 40, each connected to one of the terminals 22. The blade fuses 4 are therefore electrically connected in parallel to the terminals 22. In other words, each terminal 22 is connected to one of the respective mounting ends 40 of each blade fuse 4.

[0020] The number of blade fuses 4 is four here, but this number may vary depending on the size of fuse 2, particularly the voltage and amperage for which fuse 2 is designed. When fuse 2 includes multiple blade fuses 4, the blade fuses 4 advantageously have the same structure and operate in the same manner. The blade fuses 4 of fuse 2 are preferably identical. Any discussion of one blade fuse 4 may be substituted for other blade fuses 4.

[0021] The blade fuses 4 are components made of a conductive material and have an electrical resistance and a melting point. The material of the blade fuses 4 is preferably a metal, such as silver (Ag). Each blade fuse 4 here has an elongated rectangular shape, with its long sides aligned parallel to the axis A2. Each blade fuse 4 has a constant width measured transversely to the axis A2.

[0022] Each blade fuse 4 here has a symmetrical shape with respect to a transverse plane P4 and is formed as a sheet having two opposing major surfaces extending along a longitudinal axis A2 and including flat portions separated by a transverse fold line 42. In the illustrated example, the flat portions of the same blade fuse 4 lie in the same average plane, and the average planes of each blade fuse 4 are parallel to one another and define major axes denoted A4. Axis A4 is an axis transverse to axis A2. Alternatively, the flat portions of the same blade fuse 4 do not all lie in the same average plane.

[0023] A row of holes 44 is formed in a portion of the flat portion of each blade fuse 4, each row of holes 44 being oriented transversely to axis A2 and having a reduced diameter. cross section In other words, each blade fuse 4 defines a reduced cross section 46 includes an intermediate portion between the two fastening ends 40.

[0024] Each blade fuse 4 has a cross section At level 46, shrink cross section 46. ​​Therefore, when electricity flows between the terminals 22, the blade fuse 4 shrinks. cross section In the event of an overcurrent, the material of the blade fuse 4 melts, preferably shrinking. cross section Happens at 46.

[0025] In the illustrated example, each blade fuse 4 is cross section 46, for example, the hole 44 is cross section 46 have different diameters. Therefore, when an overcurrent occurs, some shrinkage occurs. cross section 46 other shrinks cross section It is likely to blow faster than 46. Blade fuse 4 is a single type of shrinkage cross section 46, the response curve "breaking time / breaking current" has a predetermined pattern. cross section 46, a response curve is obtained by superimposing the response curves corresponding to each part, and this aspect will not be described in further detail herein.

[0026] In the illustrated example, fuse 2 also includes a frame 48 housed in cavity V20 of body 20. Frame 48 is not essential to, but contributes to, the practice of the invention described herein. Frame 48 serves, among other things, to assemble body 20 to the rest of fuse 2 and to hold blade fuses 4 and protect them, for example, during manufacture of fuse 2. Blade fuses 4 are actually very thin and flexible; blade fuses 4 may have a thickness on the order of 0.1 mm or less.

[0027] The frame 48 is made of an insulating, preferably rigid, material, such as a synthetic material, optionally reinforced with inorganic fibers, such as glass fibers. By way of non-limiting example, the reinforcement 48 may be made of polyimide (also referred to as PI), polyetheretherketone (also referred to as PEEK), polytetrafluoroethylene (also referred to as PTFE), polyamide (also referred to as PA), silicone or polyphenylsulfone (also referred to as PPSU).

[0028] In the illustrated example, the frame 48 includes two side panels 50 facing each other and connected to each other by a spacer 52. The structure of the frame 48 is not limiting.

[0029] Each panel 50 includes a notch 54 on one side facing the other panel 50 for holding a blade fuse 4 .

[0030] 2, the spacers 52 are shown in cross section, while the side panels 50 are not shown. The spacers 52 are here grouped into two stacks 56 of five spacers 52 each, with each stack 56 here positioned near the mounting end 40 of the blade fuse 4. The blade fuse 4 is thus held by being sandwiched between two adjacent spacers 52, with the two spacers 52 located at the end of each stack 56 supported inside the cavity V20 of the body 20. When the body 20 is assembled with the rest of the fuse 2, the spacers 52 limit the amplitude of movement of the blade fuse 4 relative to the rest of the fuse 2.

[0031] In addition to the blade fuse 4 and frame 48 housed in cavity V20 of body 20, cavity 20 is typically filled with a powder that absorbs part of the energy of an electric arc that appears during an overcurrent, contributing to faster arc extinction and current interruption. Although not shown, this powder is preferably in the form of micrometer particles, such as silica sand.

[0032] In the illustrated example, the reduction of each blade fuse 4 cross section One of the 46, reference 46A, is located across a cross-section that coincides with cross-section P4. cross section Mainly considering 46A, but reducing cross section What is valid for 46A is that in general other reductions cross section I understand that it can be replaced with 46.

[0033] Arc Guard 6, which can be seen in cross section in Figure 2 and enlarged in perspective in Figure 3, is cross section It is located near 46A. cross section46A, four arc guards 6 are arranged symmetrically with respect to the cross-sectional plane P4 on the one hand and with respect to the blade fuse 4 on the other hand. Thus, two arc guards 6 located on the same side of the cross-sectional plane P4 form a pair 60 of arc guards 6, and the arc guards 6 of the same pair 60 are respectively opposite each other on the respective main surfaces of the same blade fuse 4.

[0034] In the illustrated example, two pairs 60 of arc guards 6 are connected to a single reduced cross section In a variant not shown, the two pairs of arc guards 60 are separated from each other by a plurality of shrink cross section They are separated by 46 or 46A.

[0035] The arc guards 6 have similar shapes and operate in the same way. In particular, the arc guards 6 of the same pair 60 are preferably identical. cross section The four arc guards 6 located near 46A are considered to be identical.

[0036] The arc guard 6, also called "arc suppressor", is made of an elastic material, i.e. a material that is able to deform under the influence of mechanical stress and to return to its initial shape when this mechanical stress is interrupted.

[0037] In the illustrated example, the arc guard 6 is made of an elastomer material, such as polysiloxane, also known as silicone.

[0038] Silicone materials that have already been cross-linked are solid materials that have a defined shape and are easy to handle, and can be cut and / or machined to particularly tight dimensional tolerances, whereas uncross-linked silicone materials are generally in the form of doughs that do not have a defined shape.

[0039] The fuse 2 also includes shims 58 connected to the blade fuses 4 or the arc guard 6 so as to immobilize the fuse 2 with respect to the blade fuses 4, particularly during assembly or handling of the fuse 2. Thus, during assembly of the fuse 2, handling forces are distributed among all of the blade fuses 4, reducing the risk of damaging the blade fuses 4.

[0040] The shim 58 also allows the blade fuse 4 to be secured relative to the frame 48, when the frame 48 is present, and / or relative to the body 20 when the fuse 2 is fully assembled. Optionally, when the frame 48 is present, a portion of the shim 58 cooperates with a notch 54, or other shape or machining (not shown), formed in the frame 48 to limit movement of the blade fuse 4 relative to the frame 48. More generally, the frame 48 limits movement of the blade fuse 4 by the spacer 52 and / or the shim 58. Thus, the blade fuse 4 is protected by the frame 48 during assembly of the fuse 2. This is economically advantageous, as the assembly process can be performed more quickly with a reduced probability of failure.

[0041] In the example of Fig. 2, the shims 58 each have the shape of a parallelepiped. Advantageously, the shims 58 are made of the same material as the material of the arc guard 6, for example an already cross-linked elastomeric material such as silicone. In Fig. 2, the shims 58 and the arc guard 6 are shown schematically. In particular, the ratio between the dimensions of the arc guard 6 and the dimensions of the shims 58 is not limiting.

[0042] In the illustrated example, the blade fuse 4 is reduced in size. cross section 46A is aligned on the cross section P4, and the arc guards 6 are disposed on both sides of the cross section P4. cross section The portions of the shim 58 located near 46A are located on the same side of the cross section P4 and are interposed between the two arc guards 6 belonging to the two adjacent blade fuses 4, respectively.

[0043] Advantageously, the shim 58 is secured to the blade fuse 4 or the arc guard 6 by adhesive, or in a manner similar to that described later in this specification, and the arc guard 6 is attached to the blade fuse 4.

[0044] Alternatively, if the arc guard 6 is in contact with a shim 58, the shim 58 is integral with the arc guard 6. Such an arc guard 6 contributes to the extinguishing of the arc on the one hand and to maintaining the blade fuse 4 on the other hand.

[0045] When the fuse 2 is fully assembled, the shim 58 is slightly compressed in the direction of the axis A4. In particular, the arc guard 6 is slightly compressed in the direction of the axis A4 by the shim 58.

[0046] When the frame 48 is present, a portion of the shim 58 cooperates with the frame 48 such that the arc guard 6 is compressed in the direction of the axis A4.

[0047] Next, reduce cross section Blade fuse 4 with 46A and this reduction cross section 3, a subassembly including two pairs of arc guards 60 positioned near 46A will be described.

[0048] Each arc guard 6 here has an elongated parallelepiped shape and cross section 46A along its length, the length of each arc guard 6 being equal to the width of the blade fuse 4. In a variant not shown, each arc guard 6 has a length greater than the width of the blade fuse 4. Each arc guard 6 is arranged along the length of the blade fuse 4, parallel to the arc guard 6. cross section 46A and the opposite side of the front surface 62, in other words, the reduction cross section 46A and a rear surface 64 facing away from the front surface 62. A length L6 is defined as the distance separating the front surface 62 and the rear surface 64.

[0049] Each arc guard 6 has an inner surface 66 facing the major surface of the blade fuse 4 and an outer surface 68 opposite the inner surface 66. The thickness L7 of the arc guard 6 is defined as the distance separating the inner surface 66 and the outer surface 68.

[0050] reduction cross section The two boundary lines 70 of 46A are parallel to the cross section P4, are located on both sides of the cross section P4, and are cross section 46A, and the two boundary lines 70 are defined as two lines including the cross section 46A. Each boundary line 70 is located tangent to at least one hole 44 in the cross section 46A and the front surface 62 of the adjacent arc guard 6. In the example shown in FIG. cross section The holes 44 in 46A are all aligned and have the same diameter, so the boundary line 70 is cross section 46A is tangential to all holes 44.

[0051] For each arc guard 6, this arc guard 6 and the opposing shrink cross section The distance L8 between the front surface 62 of the arc guard 6 and the opposing reduced cross section 46A to the portion of the perimeter 70 closest to the boundary line 70, measured parallel to the axis A2.

[0052] Each arc guard 6 is advantageously assembled to the blade fuse 4 by adhesive bonding. To this end, for each arc guard 6, a layer of adhesive 72 is interposed between the inner surface 66 and the opposing face of the blade fuse 4 so as to secure the arc guard 6 to the blade fuse 4. In other words, each arc guard 6 is adhesively bonded to the blade fuse 4. To ensure that each arc guard 6 is properly secured to the blade fuse 4, each inner surface 66 is preferably flat.

[0053] When two arc guards 6 of the same pair 60 are fixed to the blade fuse 4, the inner surfaces 66 of the arc guards 6 of the same pair 60 overlap each other.

[0054] Each adhesive layer 72 is preferably thin, i.e., has a thickness of between 10 μm and 0.5 mm, preferably less than 0.1 mm. Each adhesive layer 72 is preferably uniform, i.e., adhesive layer 72 has a constant thickness across the entire inner surface 66.

[0055] In some examples, the adhesive layer 72 is applied directly to the blade fuse 4, and then the arc guard 6 is placed over the blade fuse 4 and then held stationary to allow time for the adhesive to cure.

[0056] Preferably, the inner surface 66 of the arc guard 6 is pre-bonded, i.e., the adhesive layer 72 is applied directly to the inner surface 66 of the arc guard 6. The pre-bonded arc guard 6 is then placed over the blade fuse 4 and then held stationary by a device, such as a holding clamp, to allow time for the adhesive to cure. The holding clamp is not shown. Depending on the composition of the adhesive layer 72, the attachment of the arc guard 6 to the surface of the blade fuse 4 may be instantaneous. "Instantaneous" means that the adhesive layer 72 takes only a few seconds, e.g., less than 10 seconds, to cure, which is very short compared to the curing time of non-crosslinked silicone materials.

[0057] Adhesive layer 72 may be applied, for example, by spraying. Alternatively, adhesive layer 72 may be a so-called "double-sided" adhesive, i.e., an adhesive layer comprising a substrate such as a paper or insulating polymer sheet coated on both sides with respective adhesive films. The use of a double-sided adhesive facilitates assembly of fuse 2.

[0058] During use, the fuse 2 generates heat due to the flow of electricity, and the fuse 2 may reach temperatures in excess of 100°C, e.g., 150°C to 200°C, which may persist for months or even years. The adhesive used to secure the arc guard 6 to the blade fuse 4 is selected to withstand these operating conditions. However, if the fuse 2 melts and an electric arc occurs, the adhesive may be exposed to the electric arc. The adhesive is selected to avoid an exothermic reaction when subjected to the electric arc.

[0059] By way of non-limiting example, the adhesive may be an inorganic adhesive such as a silicone adhesive, or an organic adhesive such as a cyanoacrylate adhesive, an epoxy adhesive, or even a vinyl or acrylic, or aliphatic, or polyurethane, or neoprene adhesive. Depending on the type of adhesive used, surface activation may be required, for example, on the inner surface 66 of the arc guard 6.

[0060] In FIG. 4, the fuse 2 according to the present invention is cross section 46A, i.e., on both sides of cross-section P4, the blade fuse 4 includes perforations 80 formed in the blade fuse 4. In the first embodiment, the perforations 80 are covered by the arc guard 6, i.e., the perforations 80 are completely sealed in the direction of axis A4 by the inner surface 66 of the arc guard 6 unless the fuse 2 is blown. However, the inner surfaces 66 of the arc guards 6 of each pair 60 do not contact each other in the direction of longitudinal axis A2 so as not to obstruct the corresponding perforations 80. Therefore, each perforation 80 forms a cavity between the two arc guards 6 of the same pair 60.

[0061] The same blade fuse 4 is shown in inserts a) and b) of FIG. 4, with insert b) showing a portion of the blade fuse 4 of insert a) along a cutting plane 4b on insert a).

[0062] Next, reduce cross sectionThe principle of operation of the blade fuse 4, which includes the arc guard 6 arranged near the 46A and covering the hole 80, will be explained in a schematic manner. When excessive current flows through the blade fuse 4 connected to the circuit, it shrinks. cross section 46A melted and reduced cross section An electric arc appears at 46A. As long as this arc exists, electricity continues to flow through blade fuse 4, the material in blade fuse 4 continues to melt, and the arc shrinks. cross section The arc continues to propagate away from 46A. As the arc length increases, the arc voltage increases. Eventually, when the arc voltage reaches a value greater than the circuit potential, the arc is extinguished and no further current flows through the blade fuse 4. The time from the moment the arc is struck until the electric arc is extinguished defines the interrupting time of the fuse 2.

[0063] In the context of the present invention, the pair 60 of arc guards 6 forms a containment zone between them that channels ion products generated by the arc as the arc advances. cross section 46A, in a preferential direction parallel to the axis A2. The arc thus channeled advances faster than in the absence of the arc guard 6, as in the prior art. As the arc advances faster, the arc voltage also rises faster, and the arc extinction moment is reached sooner. Thanks to the arc guard 6, the cutting time of the blade fuse 4 is shorter. In other words, the reduction cross section The fuse 2 with arc guards 6 on both sides of 46A has a faster disconnect time.

[0064] The perforations 80 reduce the amount of material that is melted during the progression of the electric arc once the arc reaches the front surface 62 of the arc guard 6. The progression of the arc is therefore faster than it would be without the perforations 80, as illustrated in Figure 7. The perforations 80 are unobstructed by the arc guard 6 in a direction parallel to the axis A2 of the fuse 2 so as not to impede the progression of the electric arc.

[0065] As long as the arc has not reached the arc guard 6, the arc's speed of travel is not significantly affected by the arc guard 6, i.e., the arc's speed of travel is the same as what would occur if there were no arc guard. cross section If you are too far away from 46A, the effect of Arc Guard 6 will be unnecessarily delayed.

[0066] Conversely, Arc Guard 6 has been reduced cross section If it is too close to 46A, when an arc appears, the heat released by the latter will be too great and there is a risk that the material of the arc guard 6 will be destroyed, for example by carbonization. cross section 46A heats up more than other parts of the blade fuse 4. Arc guard 6 shrinks cross section If the arc guard 6 is too close to 46A, it may age faster, especially harden, which is not preferable for reasons explained later in this specification. cross section The distance L8 between the boundary line 70 is 1 mm to 15 mm, preferably 3 mm to 10 mm, and more preferably 4 mm to 8 mm. Good results are obtained when the distance L8 is equal to 6 mm.

[0067] To ensure that the arc guard 6 has a significant containment effect and prevents the arc from bypassing the arc guard 6, the arc guard 6 must have a particularly sufficient thickness L7. Therefore, each arc guard 6 has a thickness L7 greater than 0.2 mm, preferably greater than 0.5 mm, and more preferably greater than 1 mm. Good results are obtained when the thickness L7 is equal to 2 mm. The thickness L7 is not limited, for example, except for practical reasons, particularly regarding space during assembly of the fuse 2. Therefore, the thickness L7 is less than 20 mm, preferably less than 10 mm, and more preferably less than 5 mm.

[0068] For the containment effect of the arc guard 6 to be significant, the electric arc must also flow long enough for the arc voltage to reach the circuit voltage before appearing on the rear surface 64 of the arc guard 6. If the length L6 of the arc guard 6 is too short, the electric arc will appear on the rear surface 64 of the arc guard 6 and then continue to travel at the same speed as it would without the arc guard. Therefore, each arc guard 6 has a length L6 greater than 5 mm, preferably greater than 7 mm. The length L6 is not limited except for practical reasons, such as space constraints. Therefore, the length L6 is less than 30 mm, preferably less than 25 mm, and more preferably less than 20 mm.

[0069] The hardness of the elastic material of the arc guard 6 has a significant impact on the shortening of the interruption time of the fuse 2. The elastic material of the arc guard 6 has a hardness rated on a scale called Shore A, which ranges from 0 for very soft materials to 100 for very hard materials. Materials that are too soft, with a Shore A hardness of less than 20, have insufficient containment effect. A hardness of greater than 40 is preferred.

[0070] Conversely, any arc guard 6 made from a material that is too hard will not perform well. Therefore, the material for the arc guard 6 is selected to have a Shore A hardness of less than 90. However, under the operating conditions of the fuse 2, the arc 6 is exposed to temperatures exceeding 100°C or 150°C, and elastomers tend to harden over time. Therefore, the material for the arc guard 6 is selected so that its Shore A hardness remains less than 90 even after aging. Therefore, the Shore A hardness of the new material for the arc guard 6 is preferably selected to be less than 70.

[0071] Therefore, the arc guard 6 is made of a material having a hardness of 20 to 90, preferably 40 to 70, measured on the Shore A scale.

[0072] Surprisingly, the state of mechanical compression of the arc guards 6 has a positive effect on reducing the interruption time of the fuse 2. Advantageously, when the fuse 2 is assembled, the arc guards 6 are slightly compressed in a direction parallel to the axis A4, i.e., perpendicular to the major faces of the blade fuse 4 where these arc guards 6 are located. When the fuse 2 is assembled, each arc guard 6 is compressed and has a thickness L7 that is less than 99%, preferably less than 98%, and more preferably less than 95% of the thickness L7 that this same arc guard 6 has when not subjected to external stress.

[0073] Compression of the same pair of arc guards 6 is performed by a specific device such as a compression clamp and / or, if a frame 48 is present, via, for example, a shim 58 .

[0074] Compression clamps are not shown. If retaining clamps are used during assembly to secure the arc guard 6 and allow time for the adhesive to cure, these retaining clamps advantageously also function as compression clamps, and are left in place on the arc guard 6 once the adhesive layer 72 has cured.

[0075] Advantageously, the perforations 80 each have an elongated shape, with their length parallel to the axis A2 of the fuse 2, in other words, parallel to the longitudinal direction of the blade fuse 4. Schematically, the elongated perforations 80 provide a channel parallel to the longitudinal axis A2 for facilitating the progression of an electric arc. In the first embodiment of the invention, each perforation 80 has a length, measured parallel to the longitudinal axis A2 of the fuse 2, substantially equal to the length L6 of the arc guard 6 closing that perforation 80.

[0076] The perforations 80 made on one side of the transverse plane P4 are preferably symmetrical to the perforations 80 made on the other side of the transverse plane P4. Perforations 80 located on the same side of the transverse plane P4 form a group of perforations 80. In the first embodiment, the perforations 80 of the same group are therefore completely closed by the inner surfaces 66 of the two arc guards 6 of the same pair 60.

[0077] In the illustrated example, each group of perforations 80 includes three perforations 80, although this number is not intended to be limiting. Alternatively, each group of perforations 80 may include a single perforation 80, or two perforations 80, or four or more perforations.

[0078] The perforations 80 of the same group are preferably aligned with one another in a direction perpendicular to the blade fuses 4, in other words perpendicular to the axis A2, ie arranged in a row.

[0079] In the example illustrated in insert a) of FIG. 4, the perforations 80 have rectangular sections. In non-limiting variants, the perforations 80 have an oval or rhomboidal shape, or more generally an oval shape. The shape of the perforations 80 depends in particular on the method for producing the perforations 80, which may be produced, but is not limited to, by stamping, laser cutting or electrolysis. The perforations 80 of the same group preferably have the same shape.

[0080] For each group of perforations 80, the more numerous the perforations 80 are and the wider they are as measured parallel to the transverse direction of the blade fuse 4, the greater the electrical resistance as measured parallel to the axis A2 of the fuse 2 and the greater the path of that group of perforations 80. cross section Unlike 46 or 46A, the purpose of the perforations 80 is not to facilitate the initiation of an electric arc in the event of an overcurrent, but to provide a passageway that favors the progression of the arc once it reaches the arc guard 6.

[0081] For each blade fuse 4, the number of groups of perforations 80 measured along the longitudinal axis of the blade fuse 4 is Cross-sectional area This blade fuse 4 has a reduced Area of ​​the cross section The smallest of 46 or 46A Cross-sectional area is 5 times, preferably 10 times larger than the

[0082] Preferably, the perforations 80 of the same group are regularly spaced laterally across the blade fuse 4 to avoid locally weakening the material of the blade fuse 4 or creating hot spots when electricity flows through the blade fuse 4.

[0083] Blade fuses 4 and arc guards 6 conforming to second and third embodiments of the present invention are shown in Figures 5 and 6, respectively, and blade fuses 4 and arc guards 6 conforming to a fourth embodiment of the present invention are shown in Figures 9 and 10. Elements similar to those in the first embodiment are given the same references and operate in the same manner. The following description will focus primarily on the differences between each embodiment and one or more of the previous embodiments.

[0084] The second embodiment shown in FIG. 5 is significantly different from the first embodiment in that the perforations 80 are reduced. cross section 46A and protrudes from the side of the arc guard 6 opposite. The same blade fuse 4 is shown in inserts a) and b), with insert b) showing the portion of the blade fuse 4 of insert a) along cutting plane 5b on insert a).

[0085] Each perforation 80 extends parallel to the longitudinal axis A2 of the fuse 2 beyond the rear surface 64 of the adjacent arc guard 6. cross section 46A, and includes a rear portion located on the side opposite to the rear surface 64, which protrudes from the rear surface 64 and forms a rear vent 82 through which the perforations 80 open.

[0086] When an arc travels between the arc guards 6 of the same pair 60, the rear vent 82 allows for faster evacuation of products generated by the arc, particularly molten metal or other ionized products. Rapid evacuation of these products reduces arc instability and reduces the time required to achieve complete interruption of the current.

[0087] For each perforation 80, the length L82 is the reduction, measured parallel to the longitudinal axis A2 of the fuse 2. cross section46A and the rear surface 64 of the adjacent arc guard 6. Therefore, the length L82 represents the length of the rear vent 82. The length L82 is 0.1 mm to 10 mm, preferably 0.5 mm to 8 mm, and more preferably 1 mm to 5 mm.

[0088] Thus, in the second embodiment, the perforations 80 of the same group are partially closed by the inner surfaces 66 of the two arc guards 6 of the same pair 60 .

[0089] The third embodiment shown in FIG. 6 is significantly different from the second embodiment in that the perforations 80 are reduced. cross section 46A. The same blade fuse 4 is shown in inserts a) and b) of Figure 6, with insert b) showing the portion of the blade fuse 4 of insert a) along a cutting plane 6b on insert a).

[0090] Each perforation 80 extends beyond the front surface 62 of the arc guard 6 and parallel to the longitudinal axis A2 of the fuse 2. Thus, each perforation 80 has a reduced cross section 46A, which protrudes from the front surface 62 and forms a front vent 84 through which the perforations 80 open. Thus, in the third embodiment, the perforations 80 in the same row are partially closed by the inner surfaces 66 of the two arc guards 6 of the same pair 60.

[0091] As the arc advances toward the arc guard 6 of the same pair 60, the front vent 84 allows a portion of the molten metal and / or other ionized products generated by the arc to be reduced. cross section 46A and cavity V20 is filled with sand, so that these ionized products no longer help maintain the arc.

[0092] For each perforation 80, the length L84 is the reduction in length measured parallel to the longitudinal axis A2 of the fuse 2. cross section46A and the front surface 62 of the adjacent arc guard 6. Therefore, length L84 represents the length of one of the front vents 84. Length L84 is 0.1 mm to 5 mm, and preferably 1 mm to 3 mm.

[0093] Figure 7 shows the reduced size of the blade fuse 4, which has different characteristics. cross section 7 shows a graph 700 illustrating the progress of the current through blade fuse 4, including 46 A. The performance of fuse 2, in particular, is improved once the fuse is reduced. cross section It is rated by its interruption time, which is the time required for the current to be counteracted once the 46A fuse has been initiated.

[0094] Curve 99 shows that blade fuse 4 is shrinking. cross section The current transition when there is no arc guard in the vicinity of 46A is explained. An electric arc occurs at time t0. The current 99 The time to failure is t 99 Equivalent to -t0.

[0095] Curve 100 illustrates the current profile when blade fuse 4 includes arc guard 6 but does not have perforations 80 as described above. cross section Two pairs of 60 arc guards 6 are arranged on both sides of the 46A current. 100 It becomes zero at t 100 Equal to -t0, the breaking time of the blade fuse 4 including the arc guard 6 is approximately 40% shorter than the breaking time of the blade fuse 4 without the arc guard.

[0096] Curve 200 illustrates the progression of current when the blade fuse 4 includes arc guards 6 in accordance with the first embodiment of the present invention described above, i.e., when perforations 80 are formed in the blade fuse 4 between the arc guards 6 of the same pair 60. The current is 200 It becomes zero at t 200The breaking time of the blade fuse 4 that is equal to -t0 and includes the arc guard 6 with the perforations is approximately 45% shorter than the breaking time of the blade fuse 4 that does not include the arc guard.

[0097] Curve 300 shows the results when blade fuse 4 includes arc guard 6 in accordance with the second embodiment of the present invention described above, i.e., when perforation 80 is reduced from arc guard 6. cross section The current flow when the current is projected to the opposite side of 46A is explained. The current flows from the time t 300 It becomes zero at t 300 The breaking time of the blade fuse 4 including the arc guard 6 with perforations and rear vent 82, which is equal to -t0, is approximately 50% shorter than the breaking time of the blade fuse 4 without the arc guard.

[0098] Curve 400 shows the results when blade fuse 4 includes arc guard 6 in accordance with the third embodiment of the present invention described above, i.e., when perforation 80 is reduced. cross section 46A side and reduced cross section The transition of the current when both sides of the arc guard 6 are protruding from the arc guard 6 opposite to the current 46A will be explained. 400 It becomes zero at t 400 The breaking time of the blade fuse 4 including the arc guard 6 with perforations 80, front vent 84 and rear vent 82, which is equal to -t0, is approximately 60% shorter than the breaking time of the blade fuse 4 without the arc guard.

[0099] FIG. 7 illustrates the improved performance, as measured by reduced time to break, of fuse 2 in accordance with the present invention compared to prior art fuses with and without arc guard 6. cross section The fuses 2 according to the first, second and third embodiments of the present invention, in which the perforations 80 located on the same side of the arc guard 6 of the same pair 60 are at least partially blocked by the arc guard 6 of the same pair 60, can further significantly improve the performance of the fuses 2 compared to the prior art. cross section 46A. In a variation not shown, one or more perforations 80 are formed on both sides of the cross sectionOn one side of 46A, this reduction cross section At least one perforation 80 formed near 46A also contributes to the extinguishing of the electric arc.

[0100] In the illustrated example, a reduced diameter portion located at the center of the blade fuse 4 is used to explain the present invention. cross section Only on both sides of 46A are perforations 80 and arc guards 6. Naturally, the blade fuse 4 is reduced in size. cross section Shrinkage other than 46A cross section 46, other perforations of the type of perforation 80, as well as other arc guards of the type of arc guard 6, are included in these reductions. cross section 46 as needed.

[0101] According to a variant not shown, the perforations 80 may be two or more reduced cross section Reduction of types 46 and / or 46A cross section As mentioned above, the perforations 80 and the arc guard 6 have shapes with precise dimensions, which depend in particular on the size and rating of the fuse 2, the reduction cross section The size of the hole 44 of 46A can be changed.

[0102] The method of manufacturing the fuse 2, which will be described in particular with reference to FIG. 8, therefore involves reducing the cross section P4 on one side. cross section The method includes a step 800 that comprises providing at least one perforation 80 in the blade fuse 4 near 46A.

[0103] The method then includes reducing the arc guard 6 so that the perforation 80 is at least partially closed. cross section The method includes a step 802 of assembling two arc guards 6 of the same pair 60 on each main surface of the blade fuse 4 near 46A. If the perforations 80 have a length greater than the length L6 of the arc guards 6, a front vent 84 and / or a rear vent 82 are provided.

[0104] When the arc guard 6 is to be assembled to the blade fuse 4 by gluing during the assembly step 802, the manufacturing process includes, prior to the assembly step 802, a step 804 of manufacturing two arc guards 6 of the first pair 60, the arc guards 6 being made of a preformed elastic material, in particular a crosslinked elastomer such as silicone, each having a flat inner surface 66. In a non-limiting manner, the arc guards 6 are manufactured, for example, by molding, and the inner surface 66 is optionally modified by machining. According to another example, a calibrated strip of elastic material is manufactured, for example, by calendering, having a width equal to the width of the blade fuse 4 to which the arc guard 6 is to be adhered, the calibrated strip having a thickness equal to the thickness L7 of the arc guard 6. The arc guards 6 are then cut from this calibrated strip. One or more of the faces of the arc guard 6 may be machined to modify their shape, in particular the inner surface 66, which is preferably flat to promote adhesion of the adhesive layer 72, and the inner surface 66, which is preferably reduced. cross section The front surface 62 facing in the direction of 46A is machined.

[0105] Next, during assembly step 802, a layer of adhesive 72 is interposed between the inner surface 66 of each arc guard 6 and the respective major surface of the blade fuse 4, after which the arc guards 6 are shrunk. cross section The arc guards 6 are arranged on the same side of the cross section P4, and the front faces 62 of the arc guards 6 are reduced so that the distance L8 between the front face 62 of each arc guard 6 and the nearest boundary line 70 is 1 mm to 15 mm. cross section It is aimed at 46A.

[0106] A fourth embodiment of the blade fuse 4 and arc guard 6 shown in FIGS. 9 and 10 is a reduced cross sectionThe fourth embodiment is similar to the third embodiment in that perforations 80 formed near 46A protrude from the front and rear surfaces 62, 64 of the arc guards 6 to form front vents 84 and rear vents 82, respectively. Each of the perforations 80 is at least partially closed by the inner surfaces 66 of the two arc guards 6 of the same pair 60, and each perforation 80 leaves a cavity between the two arc guards 6 of the same pair 60. As with the other embodiments, the arc guards 6 of the fourth embodiment are made of an elastic material, here silicone, and are associated by the pairs 60 and fixed to the blade fuses 4 by a layer of adhesive 72 interposed between the blade fuses 4 and the inner surfaces 66 of each arc guard 6 of the corresponding pair 60.

[0107] Among the main differences between the blade fuse 4 and arc guard 6 of the fourth embodiment compared to the previous embodiments, the perforations 80 are elongated ovals, the length of which runs parallel to the longitudinal axis A2 of the fuse 2. Meanwhile, the blade fuse 4 here has folds 86 on the front and rear faces 62 and 64 of the arc guard 6. In the illustrated example, the folds 86 lie in a plane parallel to the transverse plane P4. The front vent 84 and the rear vent 82 extend above these folds 86. Thus, the front vent 84 is reduced in size. cross section In the illustrated example, the rear vents 82 of each pair 60 of arc guards 6 are directed toward the respective reduction cross section 46. ​​According to the naming conventions used herein, cross section The rear vent 82 relative to 46A is therefore reduced cross section This is a front vent for one of the 46.

[0108] Such a structure of the blade fuse 4, including the fold 86, allows for a more compact structure compared to a blade fuse 4 without a fold.

[0109] In all of the illustrated embodiments, the arc guard 6 is made of an elastic material, in particular an elastomeric material such as silicone. Optionally, the arc guard 6 may contain mineral and / or organic particles, which are added to the elastic material in the form of powder and / or fibers. These particles serve to adjust the properties of the material of the arc guard 6, for example, to adjust the Shore hardness of the material, and / or to serve as mechanical reinforcement. The material of the arc guard 6 is then a reinforced material, also called a composite material, which includes a matrix made of an elastic material, in particular an elastomeric material such as silicone. In contrast to a reinforced material, a material without added particles is called a "raw material."

[0110] According to a variant not shown, the arc guard is made of a foamed elastic material, i.e. a material containing gas bubbles and having an average porosity of more than 50%, preferably more than 60%, more preferably more than 70%, the average porosity being defined for a given part as the ratio of the volume of gas bubbles contained in that part to the total volume of that part.

[0111] According to another variant not shown, the arc guard 6 consists of several layers of material stacked together, at least one of which is made of a resilient material as described above, in particular an elastomeric material such as silicone. According to an example, the layers have well-defined properties, in particular well-defined hardness characteristics, and the layers of material are advantageously assembled together by gluing.

[0112] Many other embodiments are possible.

[0113] In particular, the features of the blade fuse 4 and arc guard 6 according to the present invention, particularly the structural features of the arc guard and its manufacturing method, can be implemented independently of the body 20 including the frame 48 described above, and can be implemented in conventional fuse bodies. In particular, the perforations 80 can be used independently of the frame 48.

[0114] Features described above with respect to one embodiment or variant may be implemented with respect to the other embodiments and variants described above, to the extent technically feasible.

Claims

1. at least one blade fuse (4) formed from a sheet having two opposing major surfaces extending along a longitudinal axis (A2) of said blade fuse, each blade fuse including a portion formed with a reduced cross section (46, 46A) defining a transverse cross section (P4) of said blade fuse; - two connection terminals (22), one connected to each blade fuse; - a pair (60) of arc guards (6) made of elastic material, the arc guards of the same pair facing each other on the respective main faces of the same blade fuse, each arc guard having an inner surface (66) facing towards the blade fuse, a front surface (62) facing towards the reduced cross section, and a rear surface (64) facing away from the reduced cross section; A fuse (2) comprising: at least one perforation (80) is formed in the blade fuse (4) near the reduced cross section (46A), the perforations (80) located on the same side of the transverse plane (P4) forming a group of perforations, each of which is at least partially closed by the inner surfaces (66) of the two arc guards (6) of the same pair (60); - each perforation forms a cavity between two of said arc guards of the same pair, For each blade fuse (4), the cross-sectional area of ​​the group of perforations (80) measured in a plane perpendicular to the longitudinal axis of the blade fuse (4) is five times greater than the smallest cross-sectional area of ​​the reduced cross-sectional areas (46 or 46A) provided in the blade fuse (4); where: - the perforations (80) extend parallel to the longitudinal direction (A2) of the blade fuse (4) beyond the rear face (64) of the arc guard (6) to form a rear vent (82); and / or - the perforations (80) extend parallel to the longitudinal direction (A2) of the blade fuse (4) beyond the front surface (62) of the arc guard (6) to form a front vent (84); Fuse (2).

2. 2. The fuse (2) of claim 1, wherein for each blade fuse (4), the cross-sectional area of ​​the group of perforations (80) is ten times greater than the smallest cross-sectional area among the reduced cross-sectional areas (46 or 46A) provided in that blade fuse.

3. 3. The fuse (2) of claim 1 or 2, wherein the perforations (80) are formed in the blade fuse (4) on both sides of the reduced cross section (46A), and the fuse includes a second pair of arc guards (60) in addition to the first pair of arc guards (6), and the first and second pairs of arc guards at least partially close the perforations formed on both sides of the reduced cross section, respectively.

4. 3. The fuse (2) of claim 1 or 2, wherein the perforations (80) have an elongated shape and are arranged along a length of the perforations parallel to the longitudinal direction (A2) of the blade fuse.

5. The fuse (2) of claim 1, wherein the rear vent (82) has a length (L82) of 0.1 mm to 10 mm.

6. The fuse (2) of claim 5, wherein the rear vent (82) has a length (L82) of 0.5 mm to 8 mm.

7. The fuse (2) of claim 6, wherein the rear vent (82) has a length (L82) of 1 mm to 5 mm.

8. The fuse (2) of claim 1, wherein the front vent (84) has a length (L84) of 0.1 mm to 5 mm.

9. The fuse (2) of claim 8, wherein the front vent (84) has a length (L84) of 1 mm to 3 mm.

10. The fuse (2) according to claim 1 or 2, wherein the front surface (62) and the rear surface (64) of each arc guard (6) are separated by a length (L6) of between 5 mm and 30 mm.

11. The fuse (2) according to claim 1 or 2, wherein a distance (L8) between the front surface (62) of the arc guard (6) and the boundary line (70) of the opposing reduced cross section (46A) is 0.5 mm to 20 mm.

12. The fuse (2) according to claim 11, wherein a distance (L8) between the front surface (62) of the arc guard (6) and the boundary line (70) of the opposing reduced cross section (46A) is 1 mm to 15 mm.

13. The fuse (2) according to claim 12, wherein a distance (L8) between the front surface (62) of the arc guard (6) and the boundary line (70) of the opposing reduced cross section (46A) is 2 mm to 12 mm.

14. 3. The fuse (2) according to claim 1 or 2, wherein the arc guard (6) is made of an elastomeric material having a hardness of 20 to 90 measured on the Shore A scale.

15. The fuse (2) of claim 14, wherein the arc guard (6) is made of an elastomeric material having a hardness of 40 to 70 measured on the Shore A scale.

16. 3. The fuse (2) according to claim 1 or 2, wherein the arc guard (6) is made of an elastomeric material.

17. 17. The fuse (2) of claim 16, wherein the arc guard (6) is made of silicone.

18. 3. The fuse (2) of claim 1 or 2, wherein for at least a first pair (60) of arc guards (6), the arc guards (6) are made of a preformed material, and a layer (72) of adhesive is interposed between the blade fuse (4) and the inner surface (66) of each arc guard (6) of the pair to secure each arc guard to the blade fuse, the inner surface facing one of the main surfaces of the blade fuse.

19. 3. The fuse (2) of claim 1 or 2, wherein the fuse includes a frame (48) housed in a cavity (V20) in a body (20) of the fuse and limiting movement of the blade fuse (4) relative to the body by spacers (52) and / or shims (58).

20. A method of manufacturing a fuse (2), the fuse including at least one blade fuse (4) having a reduced cross section (46, 46A) defining a cross section (P4) in the at least one blade fuse (4), the method comprising: - providing (800) at least one perforation (80) in said blade fuse (4) on one side of said cross-section (P4); - assembling (802) two arc guards (6) of a first pair (60) on respective main surfaces of the blade fuse (4) near the reduced cross sections (46, 46A) so that each perforation (80) is at least partially closed by the arc guard (6), wherein the distance (L8) between the front surface (62) of each arc guard (6) and the boundary line (70) of the opposing reduced cross section is between 1 mm and 15 mm; A method for manufacturing a fuse (2) according to claim 1 or 2, comprising:

21. 21. The manufacturing method of claim 20, wherein the method includes, before the assembling step (802), a step of manufacturing (804) two arc guards (6) of a first pair (60), the arc guards (6) being made of a cross-linked elastomeric material and having flat inner surfaces (66), and wherein during the assembling step, a layer of adhesive (72) is interposed between the inner surface (66) of each arc guard and a respective major surface of the blade fuse so as to adhere the arc guards (6) of the first pair (60) to the blade fuse.

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