DE2927660A1 - LV high current fuse - has ribbon substrate with slots limiting heat transfer to fuse ends - Google Patents

Abstract

The low voltage fuse ruptures at high current levels, with a high degree of reliability. The fuse consists of a ribbon (1) carrying a thin layer of soft solder. The ribbon has a series of narrow sections created by round and oval cut-out sections spaced along its length. Oval section groups of holes (7) are spaced approximately equally limiting the heat transfer of the fuse ends. The fuse centre section has a densely spaced group of two lines (6, 9), across the ribbon width, of round holes, localising the most sensitive region between them which itself carries the fuse active material.

Description

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Title of the invention One-piece fusible link for electrical fuses Field of application of the invention

The invention relates to a one-piece fusible conductor for electrical fuses with a soft solder application and cross-section reduced te η constrictions of different recess widths, which have a certain switch-off characteristic and low Exhibits aging. Such fusible conductors are used in particular in low-voltage high-performance fuses.

Characteristics of the known technical solutions

Fusible conductors are provided with an active ingredient application in order to achieve a certain switch-off characteristic and with cross-section-reducing constrictions to improve the short-circuit switching capacity. Especially with fusible conductors made of copper, because of the high risk of oxidation, the temperature distribution also in nominal operation is designed so that the temperature distribution has a maximum in the area of application of the active substance such that the alloy formation can take place quickly with the conventional triggering current. At all other points, the fuse element should be operated below the oxidation temperature. In order to achieve this, it has already been suggested that a cross-sectional

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to apply reduced recesses (US Pat. No. 2,864,917). In this embodiment, however, it cannot be prevented that the power loss achieved at these points is dissipated on both sides to the remaining fuse element parts.

A further aim is to increase the ratio of solder application to base material. To the associated negative To reduce the effects on the short-circuit disconnection capacity, it is already known in the vicinity of the active substance-carrying Place additional cross-sectional constrictions - and thus places of increased temperature - to create the after Melting of the active ingredient should be wetted by the same and, after appropriate diffusion, the separation of the It is also possible to provide only one additional cross-sectional constriction between two locations carrying the active substance (AT-PS 212 406),

The disadvantage of this arrangement is that the solder is transported from the solder depot to the reaction parts with a reduced cross-section must become. This process is particularly difficult after a long period of operation due to the reduced wetting ability of the Conductor difficult and there is a change in the electricity tent behavior the fuse.

For the reasons mentioned, it follows that it is advantageous when the reaction occurs where the active ingredient was originally applied. At this point the reaction temperature must be can be achieved · For the sake of reducing power dissipation and preventing excessive The aim is to age the conductor, the temperature maximum to reach at the drug-carrying site and the to keep the rest of the conductor relatively cool

For this, let known, in pairs and at a small distance from the drug-carrying Place short-circuit current limiting narrow points

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to be arranged (DE-AS 1 286 621), but it must be expected that from a certain arc burning time a drop due to the burning together of the two partial arcs the arc voltage occurs, which can lead to failure of the fuse link

In order to circumvent these deficiencies, it has also been suggested to arrange the active ingredient in a hole in front of a constriction. This hole should leave a current-carrying cross-section, the effective cross-section of which is smaller than that Cross-sections which cause the short-circuit current limitation (DE-AS 2 4-28 569). However, this design has significant Technological disadvantage, as the active ingredient cannot be continuously applied to the primary material for the melter.

Object of the invention

The aim of the invention is to eliminate the cited compartment parts and in particular a low-loss, low-aging and technologically advantageous fusible conductor with a lifted short-circuit scarf ability to create.

Explain the essence of the invention

The object of the invention is to provide a fusible link with Welchlot application through an appropriate combination of different constrictions in terms of power loss and short-circuit switching capacity to optimize. In particular, the desired temperature distribution should be with the maximum in the active ingredient-carrying Area through the greatest possible utilization of the power loss that is necessarily generated in the conductor in order to achieve this the desired shut-off characteristics without impairment the short-circuit switching capacity can be achieved.

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The object is achieved according to the invention by adding one short-circuit current limiting device Narrow points and one only used for additional heating of the reaction point and for the accumulation of heat Narrow points of larger cross-section are arranged on both sides and in the immediate vicinity of the point carrying the active substance and the two narrow cross-sections are approximately inversely proportional to the distances from the active substance-carrying point behavior.

A second short-circuit current limiting constriction is arranged at a distance from the constriction used for the accumulation of heat, which is roughly equal to or greater than the distance from this to the first short-circuit current limiting constriction

Furthermore, further short-circuit current limiting narrow points can be arranged at intervals that correspond to the distance between the preferably correspond to the above-described short-circuit current limiting constrictions.

Execution example

The invention is to be explained in more detail using an exemplary embodiment and the associated drawing.

The fusible conductor shown in the figure consists of a homogeneous strip 1 made of silver or copper or of the same plated material and is provided with an active ingredient 2. Additional cutouts can be made at the point of application of the active ingredient 9 may be provided to support the desired temperature distribution.

At the distance 3 from this application of active substance 2 is a short-circuit current limiting narrowing 4 and in the distance another narrowing 6 serving for heat build-up attached.

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The distances 3 and 5 are chosen so that the distance to Active ingredient is low. The constriction 4 has to the adjacent short-circuit current limiting constrictions 7 and 10 approximately the same distance 8 as the other adjacent narrow points 7 or 7 and 10 with each other. The distance 3 of the short-circuit current limiting narrow points 4 to the drug-carrying point 2 is greater than the distance 5 to the constriction used for the accumulation of heat 6. The distances between these two cross-section reductions from the one carrying the active ingredient Their remaining cross-sections are roughly inversely proportional.

With the proposed design, a considerable reduction in the power loss is achieved through the combination of the different narrow points and their arrangement.

The even distribution of the short-circuit current-limiting narrow points also leads to a given fusible link length a maximum of short-circuit switching capacity.

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Claims (1)

Invention claim: | One piece of existing fusible link in the form of a tall strip with soft solder and reduced cross-section Narrow points, characterized in that each has a short-circuit current limiting Narrow points (4) and one only the additional heating of the reaction point and the heat build-up Serving constrictions (6) of larger cross-section on both sides and in the immediate vicinity of the active substance-carrying point (2) are arranged and their distances to the drug-carrying Place (3; 5) are approximately inversely proportional to the narrow cross-sections (4; 6). 2 · Fusible conductor according to item 1, characterized in that a second short-circuit current-limiting constriction (10) in a distance (11) from the constriction (6) serving for the accumulation of heat is arranged, which is approximately equal to or greater than the distance from this Engeateilβ (6) to the first short-circuit current limiting Narrows (4) 3 · Fusible conductor according to items 1 and 2, characterized in that the current-limiting narrow points (4; 7 and 10) are below one another have approximately the same distance (Θ) 4. fusible link according to item 1, characterized in that the Carrying active ingredient · Point (2) additional cross-sectional constrictions (9) has « 030009/0636