JPH0230137B2 - DENRYOKUHYUUZUEREMENTO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power fuse element used in a current limiting fuse or the like.

Conventionally, power fuse elements for current-limiting fuses to protect equipment from short-circuit currents or overload currents have been made of low-melting metal parts such as gold-silicon alloys with low melting points, whereas fuse elements are made of silver wires with high melting points. It was constructed by connecting them in series.
If a current with a low magnification of the rating flows through this current-limiting fuse due to overload, etc., it will fuse and arc only in the low-melting metal part, and the heat from the arc will thermally decompose the surrounding arc-extinguishing tube. By generating arc extinguishing gas, the arc is extinguished and the low magnification current is interrupted.

Additionally, if a current with a high magnification of the rating flows through this current-limiting fuse due to a short circuit between phases, the fuse element such as a silver wire and the low-melt metal part will instantly melt and vaporize, melting the arc-extinguishing sand around it. The high magnification current was cut off by diffusing and cooling to form a molten product with high and low resistance.

In this case, if current-limiting fuses have the same current capacity, it is better to use two or more fuse elements such as silver wires with smaller wire diameters. For example, in a current limiting fuse in which many fuse elements, each with a low melting metal part, are connected in parallel around an insulating core, the radial size of the molten product at the time of shutoff is smaller than in the case of one fuse element. To become
The fuse ring diameter can be made smaller. However, in the case of the low-magnification current interruption, all the low-melt metal parts are not fused at the same time, but are fused one by one, and the other low-melt metal parts are not fused, so the unfused low-melt metal A current flows through the fuse element, and no voltage is applied to the fuse element having the fused low-melt metal portion until all the low-melt metal portions are fused. Therefore, the gap that occurs in the fused low-melt metal portion remains small, so when the last remaining unfused low-melt metal portion is fused and voltage is applied to all fuse elements, the gap that remains is small. In the gap, the withstand pressure is insufficient and the spark re-ignites.

The purpose of the present invention is to eliminate such drawbacks.
To provide a power fuse element in which two or more high-magnification current-interrupting elements are electrically connected in parallel to each end of one low-melt metal part for low-magnification current interrupting covered with an arc-extinguishing tube.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings. Electrodes 3 are fitted to both ends of an insulator tube 2 of a fuse link 1, and an insulating core 4 is provided inside the insulator tube 2 with electrodes at both ends. It is supported by 3. On the outer circumferential surface of the insulating core 4, a first fuse element 5 and a second fuse element 6 made of silver wire for interrupting high-power current are spirally wound. These first and second fuse elements 5, 6
are electrically connected to both ends of a single low-melt metal part 7 for low-magnification current interruption made of gold-silicon alloy, etc., as shown in FIG. are connected in parallel to each other.
The low melting metal portion 7 and the first and second fuse elements 5, 6 near both ends thereof are covered with an arc extinguishing tube 8 made of tetrafluoroethylene or the like.
Further, arc-extinguishing sand 9 is filled around the insulating core 4 in the insulating tube 2.

Now, when a current with a low magnification relative to the rating flows through the fuse link 1 configured as described above, the single low-melting metal portion 7 at one location takes charge of the entire fuse, causing it to melt. When the gap is blown, the gap is opened until the withstand pressure is removed, and the first and second gaps are opened.
Fuse elements 5, 6 are shut off simultaneously.
Therefore, there is no risk of restriking in the low melting metal portion 7.

In addition, in the embodiment described above, there may be three or more fuse elements 5, 6 such as silver wires.

Further, in another embodiment shown in FIG.
The second fuse elements 5 and 6 are connected to each other by welding or the like, and plugs 10 made of asbestos or the like are fitted inside both ends of the arc extinguishing tube 8. These first and second fuse elements 5, 6
is made by twisting and pressing two silver wires.

As described in detail above, the present invention is characterized in that a single low-melt metal part 7 for low magnification current interruption made of a gold-silicon alloy or the like is coated with an arc-extinguishing tube 8. By electrically connecting two or more high-power current interrupting elements 5, 6 in parallel, not only can the effects of the original multiple elements be sufficiently obtained, but also Since there is only one low-melting metal part 7 for the entire fuse that melts when a low magnification current flows, the gap at the time of melting opens until the withstand voltage is removed, and each fuse element 5, 6
Since both are cut off at the same time, there is no risk of re-ignition in the low melting metal portion 7, and the low magnification current is stabilized and improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a current limiting fuse using the power fuse element of the present invention, FIG. 2 is a sectional view showing essential parts of the invention, and FIG. 3 is a sectional view showing another embodiment. Fuse link...1, Insulating core...4, Fuse element...5,6, Low melting metal part...7,
Arc-extinguishing tube...8, arc-extinguishing sand...9.

Claims (1)

[Claims] 1 Low-melt metal part 7 for low magnification current interruption made of gold-silicon alloy etc. coated with arc extinguishing tube 8
A power fuse element characterized in that two or more high magnification current interrupting elements 5, 6 made of silver wire or the like having a high melting point are electrically connected in parallel to each end of the fuse element.