fuse

Abstract

To provide a fuse with a rated voltage of 350V or more and a rated current of 5A or more that exhibits appropriate breaking performance even when an inductance is included in the circuit in which it is used. [Solution] The fuse includes a plurality of recesses (8) extending in a second direction intersecting a first direction in which a pair of non-fuse portions of the conductor (7) are aligned, and having an opening on one of the plate surfaces of the conductor (7), and an arc-extinguishing silicone portion (S) formed by filling the recesses (8) with arc-extinguishing silicone and curing the same. The arc-extinguishing silicone portion (S) has a shape that convex toward the opening and does not completely fill the recesses (8), and the cross section of the recess (8) viewed from the second direction has a V-shaped cross section. The length (L1) of the opening of the recess (8) measured in the first direction is 2 to 2.7 mm, and the depth (D1) from the opening surface of the opening to the bottom of the recess (8) is 1.2 to 1.7 mm. The volume of the arc-extinguishing silicone portion (S) is at least 1 / 2 but less than 2 / 3 of the internal volume of the recess (8).

Description

[Technical Field]

[0001] This invention relates to a fuse in which a space within a case containing a plate-shaped conductor with one or more fusible portions and a pair of non-fusible portions on either side of the fusible portion is filled with a filler material that acts as an arc-extinguishing agent. [Background technology]

[0002] Patent Document 1 (JP 2022-126059 A) discloses a fuse element having at least three or more concave curved portions, in which an arc-extinguishing material is applied and fixed only to the surface of the concave portions within the curved portions. The carbide formed when at least a portion of the arc-extinguishing silicone portion is carbonized by heat of 1000°C or higher generated during an arc occurrence must be discontinuous and not excessively distributed along the length, ideally applied only to the concave portions. However, no prior studies have examined the effects of the shape of the concave portion and the amount of arc-extinguishing silicone filled within the concave portion on the fuse resistance, or the effects of the presence of carbide that appears after an arc occurs. For example, if the cross-sectional shape of the concave portion is U-shaped, the flow path during normal current flow, not during current interruption, becomes longer, resulting in increased resistance and watt loss. Furthermore, because a U-shaped cross-sectional shape of the concave portion increases the internal volume, overfilling the arc-extinguishing silicone with the aim of improving arc-extinguishing performance can result in excessive carbide, which reduces insulation resistance after interruption. In particular, in applications where fuses with a rated voltage of 250V or more and a rated current of 5A or more are used, a decrease in insulation resistance after breaking must be absolutely avoided.

[0003] In the fuse disclosed in Japanese Patent Laid-Open Publication No. 2025-16071 (Patent Document 2) previously proposed by the applicant, fusing portions and non-fusing portions are alternately provided on a conductor, and recesses having openings on one side of the conductor's plate surface are formed in the non-fusing portions, extending in a second direction Y intersecting a first direction X in which the non-fusing portions are arranged, the cross section of the recesses as viewed from the second direction Y is V-shaped, and the recesses are filled with arc-extinguishing silicone. In particular, in this fuse, when the rated voltage is 250 V or higher and the rated current is 5 A or higher, the length of the opening of the recess as measured in the first direction X is 2 to 4 mm, the depth from the opening surface of the opening to the bottom of the recess is 0.4 to 1 mm, and the arc-extinguishing silicone does not completely fill the recess. The inventor identified these dimensional limitations after discovering that if the length of the opening measured in the first direction is shorter than 2 mm and the depth from the opening surface of the opening to the bottom of the recess is shallower than 0.4 mm, the arc-extinguishing performance will not be substantially improved; if the length of the opening measured in the first direction is longer than 4 mm and the depth from the opening surface of the opening to the bottom of the recess is deeper than 1 mm, the path over which current flows during normal current flow will become longer, resulting in increased resistance and watt loss; and if the arc-extinguishing silicone portion completely fills the recess, the creepage distance of the carbide surface that appears after arc extinguishing will become shorter, causing a problem of lowering the insulation resistance. Furthermore, with the structure of this conventional invention, the arc-extinguishing silicone part fits into the V-shaped recess in cross section, allowing it to be applied to the appropriate length and depth, and by shortening the path when current is normally passed through it, it is possible to suppress increases in resistance and watt loss.It has also been confirmed that this suppresses the formation of a conductive path due to the carbonized layer that forms near the fusion part, allowing the arc-extinguishing silicone part to fully demonstrate its arc-extinguishing performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-126059 [Patent Document 2] Japanese Patent Application Publication No. 2025-16071 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it has been discovered that when the fuse disclosed in Patent Document 2 is used to interrupt abnormal current in a circuit containing inductance as a fuse with a rated voltage of 350 V or more and a rated current of 5 A or more, an arc current may continue to flow during the interruption operation, preventing the fuse from safely interrupting the circuit and causing the fuse to burn out. However, it was unclear how this problem could be solved with the fuse structure disclosed in Patent Document 1.

[0006] The purpose of this invention is to provide a fuse with a rated voltage of 350V or more and a rated current of 5A or more that exhibits adequate interruption performance even when the circuit in which the fuse is used contains inductance. [Means for solving the problem]

[0007] The fuse that this invention aims to improve comprises a plate-shaped conductor having at least one fusion portion and a pair of non-fusion portions on either side of the fusion portion, a case for accommodating the conductor, arc-extinguishing sand filled in the space within the case, recesses provided in each of the pair of non-fusion portions and extending in a second direction intersecting the first direction in which the pair of non-fusion portions are aligned, the recesses having an opening on one side of the plate surface of the conductor, and arc-extinguishing silicone portions formed by filling the recesses with viscous arc-extinguishing silicone and hardening it, and has a rated voltage of 350 V or more and a rated current of 5 A or more.

[0008] According to the inventor's research, when the fuse structure described in Patent Document 1 is used with a rated voltage of 350V or higher, the arc-extinguishing performance deteriorates due to insufficient contact area between the arc-extinguishing sand and the unwelded portion of the conductor, even if the cross-sectional shape of the recess is V-shaped. Furthermore, when the circuit using the fuse includes an inductance and the time constant L / R of the circuit increases, the arc current tends to continue to flow, preventing the arc current from being cut off and resulting in fuse burnout. The inventor suspected that the cause of this problem lies in the relationship between the length of the recess's opening measured in the first direction X, the depth from the opening surface to the bottom of the recess, and the shape and amount of arc-extinguishing silicone filled in the recess. Therefore, the inventor created test fuses under various conditions and conducted confirmation tests to identify conditions under which burnout would not occur when the circuit using the fuse includes an inductance.

[0009] If the arc-extinguishing silicone portion is shaped to be convex toward the opening, does not completely fill the recess, but has a volume equal to or greater than half the volume of the recess, and the depth from the opening surface of the opening to the bottom of the recess is increased without increasing the length of the opening measured in the first direction, watt loss increases, but the contact length of the arc-extinguishing silicone portion extending along the inner surface of the recess increases. As a result, the contact area between the inner surface of the recess and the arc-extinguishing silicone portion increases, which is thought to prevent a decrease in arc-extinguishing performance. Furthermore, the deeper the arc-extinguishing silicone portion penetrates into the recess, the more difficult it is for the carbonized portion of the arc-extinguishing silicone portion generated by the arc-extinguishing function to reach the surface portion of the arc-extinguishing silicone portion within the recess. As a result, it is thought that a decrease in insulation resistance due to the carbonized portion on the exposed surface of the arc-extinguishing silicone portion is suppressed. The inventors speculated that these phenomena combined to prevent continuous arc current flow even when an inductance is included in the circuit when using a fuse. This inference is based on experimental results showing that the fuse does not burn out, and it is unclear what phenomenon actually prevents the arc current from continuing to flow. Furthermore, even if the depth of the recess is increased, if the volume of the arc-extinguishing silicone portion is less than half the internal volume of the recess, the length of the arc-extinguishing silicone portion extending along the inner surface of the recess cannot be increased, making the increase in depth to the bottom of the recess pointless. Furthermore, if the volume of the arc-extinguishing silicone portion is more than two-thirds the internal volume of the recess, the amount of arc-extinguishing silicone portion that is not used for arc extinguishing increases, resulting in waste. Furthermore, if the length of the recess opening measured in the first direction is shortened as much as possible, the overall longitudinal dimension of the conductor can be shortened even when multiple recesses are formed in the conductor, contributing to the miniaturization of the fuse.

[0010] Based on the above findings, in a first aspect of the present invention, a fuse having a rated voltage of 350V or more and a rated current of 5A or more comprises a plate-shaped conductor 7 having at least one fusible portion 71A-71D and a pair of non-fusible portions (73A and 73B, 73B and 73C, 73C and 73D, 73D and 73E) on either side of each of the fusible portions 71A-71D, a case for accommodating the conductor 7, arc-extinguishing sand filling the space within the case, a plurality of recesses 8 provided in each of the pair of non-fusible portions, extending in a second direction intersecting the first direction in which the pair of non-fusible portions are aligned, and having an opening on one side of the plate surface of the conductor, and arc-extinguishing silicone portions S formed by filling and curing arc-extinguishing silicone into the plurality of recesses 8. The arc-extinguishing silicone portions S have a shape that convex toward the openings and do not completely fill the recesses, and the plurality of recesses 8 have a V-shaped cross-sectional shape when viewed from the second direction. The length of the openings of the plurality of recesses 8 measured in the first direction is 2 to 2.7 mm, and the depth from the opening surface of the opening to the bottom of the recess is 1.2 to 1.7 mm. The volume of the arc-extinguishing silicone part S is 1 / 2 or more and less than 2 / 3 of the internal volume of the recesses 8.

[0011] In a second aspect of the present invention, a fuse having a rated voltage of 350V or more and a rated current of 5A or more includes a plate-shaped conductor 7 having at least two fusible portions 71A-71D and a pair of non-fusible portions (73A and 73B, 73B and 73C, 73C and 73D, 73D and 73E) on either side of each of the at least two fusible portions 71A-71D, a case for housing the conductor 7, arc-extinguishing sand 3 filling the space within the case, a plurality of recesses 8, 8' provided in each of the pair of non-fusible portions, extending in a second direction intersecting the first direction in which the pair of non-fusible portions are aligned, and having openings on one side of the plate surface of the conductor, and arc-extinguishing silicone portions S, S' formed by filling and curing arc-extinguishing silicone portions 8, 8'. The arc-extinguishing silicone portions S, S' have a shape that convex toward the openings and do not completely fill the recesses. The recesses 8, 8' have a V-shaped cross section when viewed from the second direction. Of the recesses, two recesses 8' located adjacent to both ends of the conductor 7 have an opening length of 1 to 2 mm measured in the first direction, and a depth of 0.8 to 1.5 mm from the opening surface of the opening to the bottom of the recess 8'. Of the recesses, one or more recesses 8, excluding the two recesses 8' located adjacent to both ends of the conductor 7, have an opening length of 2 to 2.7 mm measured in the first direction, and a depth of 1.2 to 1.7 mm from the opening surface of the opening to the bottom of the recess. The volume of the arc-extinguishing silicone portions S, S' is between 1 / 2 and 2 / 3 of the internal volume of the recesses 8', 8.

[0012] According to the second aspect, in addition to the effects of the first aspect, the dimensions of the two recesses 8' provided at both ends of the conductor are smaller than the dimensions of the other recesses 8, which has the advantage of shortening the dimensions of the conductor 7 and reducing the longitudinal dimension of the fuse. Furthermore, since the fusing portion is present on only one side of the two recesses 8' provided at both ends of the conductor, reducing the shape and dimensions of the recesses 8' does not affect the arc-extinguishing performance. [Brief explanation of the drawings]

[0013] [Figure 1]1A is a plan view of the fuse of the first embodiment, FIG. 1B is a cross-sectional view of the fuse, and FIG. 1C is a vertical-sectional view of the fuse. [Figure 2] 3A and 3B are enlarged views of the main part of the fuse of the first embodiment. [Figure 3] FIG. 1 shows the results of a 1000V test on the fuse disclosed in Patent Document 1 and the fuse of the first embodiment of the present invention, when an inductance is not included in the circuit in which the fuse is used, and when an inductance is included. [Figure 4] 10(A) and 10(B) are diagrams showing examples of conductors used in a second embodiment, which are different from the conductors constituting the fuse element. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0015] FIG. 1(A) is a plan view of a fuse 1 according to a first embodiment, FIG. 1(B) is a cross-sectional view of the fuse 1 according to the present embodiment, and FIG. 1(C) is a longitudinal-sectional view of the fuse 1 according to the present embodiment. The fuse 1 according to the present embodiment includes an outer container 15 composed of an insulating cylindrical body 5 filled with arc-extinguishing sand 3 and a pair of cap-shaped electrodes 9 and 11 fitted to both ends of the cylindrical body 5 and electrically connected to a conductor 7 constituting the fuse element. The cylindrical body 5 is integrally molded from ceramic. The cap-shaped electrodes 9 and 11 each include bottom wall portions 9A and 11A facing the openings 51 and 53 of the cylindrical body 5, and cylindrical peripheral wall portions 9B and 11B extending upright from the peripheral edges of the bottom wall portions 9A and 11A.

[0016] Conductor 7 is formed integrally by pressing a thin, elongated metal plate for a fuse made of silver or copper. Conductor 7 is configured by four fusion portions 71A to 71D (the number of fusion portions varies depending on the rated voltage of the fuse) each having a predetermined width (specifically, 0.1 to 2 mm) and five non-fusion portions 73A to 73E (the number of non-fusion portions varies depending on the rated voltage of the fuse) each having a width (specifically, 2 mm) longer than the width of fusion portions 71A to 71D (portions with lower electrical resistance than fusion portions 71A to 71D and less likely to melt than fusion portions), which are arranged alternately in the longitudinal direction of conductor 7, i.e., the first direction X [Fig. 1(C)].

[0017] The four fusible portions 71A to 71D are arranged in a tilted or oblique state with respect to an imaginary center line extending in the first direction X (fusible portions are not generally arranged obliquely). The five non-fusible portions 73A to 73E are each provided with a small recess 8' in the non-fusible portions 73A and 73E at both ends, and a recess 8 larger than the recess 8' is provided in the non-fusible portion 73B located between the two fusible portions 71A and 71B, the non-fusible portion 73C located between the two fusible portions 71B and 71C, and the non-fusible portion 73D located between the two fusible portions 71C and 71D. As shown in FIG. 2(B), the recess 8' provided in the non-fusible portions 73A and 73E at both ends is provided with an arc-extinguishing silicone portion S' filled with viscous arc-extinguishing silicone. The recesses 8 provided in the non-fusible portions 73B to 73D between adjacent pairs of non-fusible portions (73A and 73B, 73B and 73C, 73C and 73D, 73D and 73E) also have arc-extinguishing silicone portions S filled with viscous arc-extinguishing silicone as shown in Figure 2(A).

[0018] The arc-extinguishing silicone parts S, S' do not completely fill the recesses 8, 8'. In this embodiment, the arc-extinguishing silicone parts S, S' have a shape that convexly extends toward the openings 8A, 8'A of the recesses 8, 8'. The viscosity of the arc-extinguishing silicone before hardening and the amount of the arc-extinguishing silicone filled into the recesses 8 are determined so that the tops of the surfaces of the arc-extinguishing silicone parts S, S' facing the openings 8A, 8'A do not extend beyond the openings 8A, 8'A. In this embodiment, the volume of the arc-extinguishing silicone parts S, S' is at least one-half but less than two-thirds the internal volume of the recesses 8, 8'. These conditions are preferred application conditions found by the inventor through tests in order to ensure that the arc-extinguishing silicone parts S, S' fully exhibit their arc-extinguishing function in fuses with a rated voltage of 350 V or more and a rated current of 5 A or more, to prevent a decrease in insulation resistance due to the presence of carbonized silicone parts that appear after arc extinguishing, and to prevent a continuous flow of arc current even when an inductance is included in the circuit in which the fuse is used; they are not the result of theoretical analysis.

[0019] The arc-extinguishing silicone preferably used in this embodiment has a viscosity μ before hardening of 100 (Pa·s)≦μ≦300 (Pa·s), and is heat-resistant to temperatures of 250°C or higher. A silicone-based material that satisfies these conditions is, for example, the silicone-based material sold by ThreeBond Co., Ltd. under the product number "1209" [viscosity 140 (Pa·s)]. Using a silicone resin with this viscosity allows the arc-extinguishing silicone portion S to be shaped so that it protrudes toward the opening 8A, making it difficult for the carbonized arc-extinguishing silicone to form a continuous conductive path.

[0020] The carbonized layer formed by carbonizing at least a portion of the arc-extinguishing silicone portions S, S' due to heat of 1000°C or higher generated when an arc occurs needs not to be excessively thick in the longitudinal direction, and ideally should be applied to the recesses. In this embodiment, similar to the fuse of Patent Document 1, the small recesses 8' and the large recesses 8 have a V-shaped cross-section when viewed from the second direction Y. As a result of various tests conducted by the inventors, it was found that for fuses with a rated voltage of 350 V or higher and a rated current of 5 A or higher, the length L2 of the opening 8'A of the small recesses 8' having a V-shaped cross-section is preferably 1 to 2 mm, and the depth D2 of the small recesses 8' is preferably 0.8 to 1.5 mm. It was also found that the length L1 of the opening 8A of the large recesses 8 having a V-shaped cross-section is preferably 2 to 2.7 mm, and the depth D1 of the recesses 8 is preferably 1.2 to 1.7 mm.

[0021] When the recesses 8, 8' satisfy these conditions, the arc-extinguishing silicone portions S, S' are shaped such that the depths D1, D2 of the arc-extinguishing silicone portions S increase with increasing distance from the non-fuse portions (73A to 73E). Using recesses 8, 8' of this shape allows the amount of arc-extinguishing silicone to gradually decrease with increasing distance from the fusible portion that melts due to the arc. As a result, this embodiment can suppress the formation of a conductive path due to a carbonized layer formed near the fusible portion, thereby fully demonstrating the arc-extinguishing performance of the arc-extinguishing silicone portions S and preventing a decrease in insulation resistance after a circuit breaker operation and thus preventing the arc current from continuing to flow. In particular, in this embodiment, the depth D1 of the three large recesses 8 sandwiched between the fusible portions is nearly twice as deep (0.4 to 1 mm) as the recesses of the conventional fuse disclosed in Patent Document 1. Furthermore, the depth D2 of the small recesses 8 at both ends is also deeper (0.4 to 1 mm) than the recesses of the conventional fuse disclosed in Patent Document 1. Increasing the depth D1 of the recess 8, particularly that sandwiched by the fusion portion, increases the length of the arc-extinguishing silicone portion S extending along the inner surface 8B of the recess 8, but does not increase the area of ​​the surface portion of the arc-extinguishing silicone portion S exposed within the recess. This is presumably why the length of the recess and the length of the arc-extinguishing silicone portion S extending along the inner surface 8B of the recess 8 become appropriate, contributing to the production of the above-mentioned effect. Even if the depth D1 of the recess 8 is increased, if the volume of the arc-extinguishing silicone portion S is less than half the internal volume of the recess 8, the length of the arc-extinguishing silicone portion S extending along the inner surface of the recess 8 cannot be increased, and therefore increasing the depth D1 to the bottom of the recess 8 becomes meaningless.

[0022] Figure 3 shows the results of a 1000V test for the fuse disclosed in Patent Document 1 and the fuse according to the first embodiment of the present invention, with and without an inductance of 116 μH in the circuit in which the fuse is used. The fuse in Patent Document 1 is a conventional fuse with a rated voltage of 250 V or more and a rated current of 5 A or more, while the fuse according to this embodiment (the present embodiment) has a rated voltage of 350 V or more and a rated current of 5 A or more. In this embodiment, the length of the openings of the two recesses 8' measured in the first direction is 1.8 mm, the depth from the opening surface of the opening to the bottom of the recess 8' is 1.3 mm, the length of the opening of the recess 8 measured in the first direction is 2.6 mm, and the depth from the opening surface of the opening to the bottom of the recess is 1.5 mm, and the volume of the arc-extinguishing silicone portion is half the internal volume of the recesses 8' and 8'.

[0023] When neither the conventional product nor the product of this embodiment contained an inductance in the circuit used, the interruption results were good when a current of 1000 V and 10,000 A was passed through the product. However, when an inductance of 116 μH was included in the circuit used, the interruption results when a current of 1000 V and 10,000 A was passed through the product showed that the conventional product was burned, while the product of this embodiment interrupted the current and showed no change in appearance. This is presumably evidence that the product of this embodiment did not allow the arc current to continue flowing after the interruption.

[0024] This test example shows that, if the circuit in which the fuse is used does not contain inductance, the provision of an arc-extinguishing silicone portion improves interruption performance and limits the amount of heat generated during interruption, that providing an arc-extinguishing silicone portion in a V-shaped recess increases insulation resistance after arc extinguishing, and that the insulation resistance can be increased by appropriately adjusting the amount of arc-extinguishing silicone portion provided in a deeper V-shaped recess.However, if the circuit in which the fuse is used contains inductance, it was found that there is a high possibility of the fuse burning out if the length dimension measured in the first direction of the opening of the V-shaped recess and the depth dimension are not set to values ​​within an appropriate range.

[0025] Tests were conducted by changing the viscosity of the interrupting silicone and the amount of filling into the recess. It was confirmed that, when recess 8 used in the fuse of this embodiment has a length of 2 to 2.7 mm measured in the first direction (X direction) of opening 8A, a depth of 1.2 to 1.7 mm from the opening surface of opening 8A to the bottom of recess 8, and the arc-extinguishing silicone portion fills recess 8 up to two-thirds, the fuse will not burn out even if an inductance is included in the circuit using the fuse. Furthermore, although this differs depending on the type of arc-extinguishing silicone, it was also confirmed that even with arc-extinguishing silicones other than the one used in this example, it is possible to form an arc-extinguishing silicone portion with a shape that is convex toward the opening, as long as the viscosity μ before curing is 50 (Pa s)≦μ≦300 (Pa s).

[0026] In the above test, the inductance value contained in the circuit was 116 μH, but the test confirmed that the inductance value that can be contained in the circuit in this example is 150 μH or less. Note that the upper limit of the inductance that can be contained in the circuit will vary depending on the dimensions of each part of the conductor, the amount of arc-extinguishing silicone filled, and the type of arc-extinguishing silicone, so it is not specified here; however, if the dimensions of each part of the conductor or the type of arc-extinguishing silicone are changed, the upper limit can be determined by conducting tests.

[0027] Furthermore, in the above embodiment, the depth of the small recesses 8' provided in the non-fusible portions 73A and 73E at both ends is made shallower than the depth of the large recesses 8, and the arc-extinguishing silicone portions S' are formed in the small recesses 8', but it is of course possible to make the small recesses 8' the same shape as the large recesses 8, and form the arc-extinguishing silicone portions S' inside them.

[0028] 4A and 4B show the shape of the conductor 7 as the fuse element used in the second embodiment. In this example, the number and shape of the fusing portions 71A to 71D are different from those in the first embodiment shown in FIG. 1, but other points are the same as those in the embodiment shown in FIG. 1.

[0029] In this embodiment, the above-mentioned specific arc-extinguishing silicone is used, but it goes without saying that other arc-extinguishing silicones can be used as long as they have viscosity and arc-extinguishing performance equivalent to those of the above-mentioned specific arc-extinguishing silicone. [Industrial Applicability]

[0030] According to the present invention, a fuse with a rated voltage of 350V or more and a rated current of 5A or more can be provided that exhibits appropriate interruption performance even when the circuit in which the fuse is used contains inductance. [Explanation of symbols]

[0031] 1 fuse 3 Arc-extinguishing sand 5 Cylinder 7 Conductors 71A to 71D fused parts 73A to 73E Non-fused parts 9,11 Cap-shaped electrode

Claims

1. A fuse with a rated voltage of 350V or more and a rated current of 5A or more, a plate-shaped conductor having at least one fusible portion and a pair of non-fusible portions on both sides of each of the at least one fusible portion; a case for accommodating the conductor; Arc-extinguishing sand filled in the space within the case; a plurality of recesses each provided in the pair of non-fuse portions, each extending in a second direction intersecting a first direction in which the pair of non-fuse portions are aligned, and each having an opening on one surface of a plate surface of the conductor; an arc-extinguishing silicone portion formed by filling and curing the arc-extinguishing silicone into the plurality of recesses; the arc-extinguishing silicone portion has a shape that is convex toward the opening and does not completely fill the recess, The plurality of recesses have a V-shaped cross section when viewed from the second direction, the length of the openings of the plurality of recesses measured in the first direction is 2 to 2.7 mm, and the depth from the opening surface of the openings to the bottom of the recesses is 1.2 to 1.7 mm; A fuse characterized in that the volume of the arc-extinguishing silicone portion is equal to or greater than 1 / 2 and less than 2 / 3 of the internal volume of the recess.

2. A fuse with a rated voltage of 350V or more and a rated current of 5A or more, a conductor having at least two fusible portions and a pair of non-fusible portions on both sides of each of the at least two fusible portions; a case for accommodating the conductor; Arc-extinguishing sand filled in the space within the case; a plurality of recesses each provided in the pair of non-fuse portions, each extending in a second direction intersecting a first direction in which the pair of non-fuse portions are aligned, and each having an opening on one surface of a plate surface of the conductor; an arc-extinguishing silicone portion formed by filling and curing the arc-extinguishing silicone into the plurality of recesses; the arc-extinguishing silicone portion has a shape that is convex toward the opening and does not completely fill the recess, The plurality of recesses have a V-shaped cross section when viewed from the second direction, two recesses among the plurality of recesses provided adjacent to both ends of the conductor have openings each having a length measured in the first direction of 1 to 2 mm, and a depth from an opening surface of the opening to a lowermost portion of the recess is 0.8 to 1.5 mm; the length of the opening of one or more of the plurality of recesses, excluding the two recesses provided adjacent to both ends of the conductor, measured in the first direction is 2 to 2.7 mm, and the depth from the opening surface of the opening to the bottom of the recess is 1.2 to 1.7 mm; A fuse characterized in that the volume of the arc-extinguishing silicone portion is equal to or greater than 1 / 2 and less than 2 / 3 of the internal volume of the recess.

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