JPS6115567Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of a current limiting fuse, and in particular, it is possible to securely wind an arc-extinguishing tube that covers a part of the fuse element around a small diameter winding core, and at the same time, especially when cutting off a low current. This invention relates to a structure in which the internal pressure of an arc extinguishing tube is increased to effectively shut off the arc.

In recent years, current-limiting fuses for cutouts have been developed that can be directly applied to conventionally used high-voltage cutouts due to the problem of increased breaking capacity or natural disasters. This current limiting fuse uses an insulating tube with a relatively small diameter so that it can be attached to the existing high voltage cutout as described above. Since the purpose of this fuse is to cut off the entire area, the low point metal part that forms the low current cutoff section is covered with an arc extinguishing tube. However, the above-mentioned arc extinguishing tube uses an organic substance such as a silicone rubber tube or a Teflon tube, and in order to contain the arc as much as possible and increase the internal pressure of the tube during low current interruption, the tube is thick compared to its diameter. , and has strength. Therefore, during assembly, it is difficult to tightly wind and fix the tube around the outer circumferential surface of the thin-diameter winding core, and the tube lifts up and inevitably comes into contact with the inner wall of the insulating tube. or approach. For this reason, particularly during a low-voltage cutoff, the high-temperature vaporized gas of the fuse element released from the end of the arc-extinguishing tube licks the inner wall surface of the insulating tube, causing uneven heat damage or burnout of the tube. Furthermore, if the separately wound fuse element floats up, it may catch on or come into contact with the insulating tube when it is inserted into the insulating tube during assembly, damaging the element made of the cut silver wire.

The purpose of this proposal is to ensure that these fuse elements, especially the arc-extinguishing tube, are in close contact and fixed to the outer peripheral surface of the winding core, and at the same time seal the end of the arc-extinguishing tube to effectively increase the pressure inside the tube and ensure interruption when a small current is interrupted. Both ends of an insulating tube made of crystallized glass or synthetic resin such as FRP are closed by fixing the upper and lower electrodes, and a thin winding core made of inorganic insulator is placed in the center of the insulating tube. A fuse element is tightly wound around the outer circumferential surface of the winding core, which is connected to a low-distance point metal with a part covered with an arc-extinguishing tube made of an organic insulator, and a high-resistance wire is placed inside the winding core. These resistance wires and both ends of the fuse element are connected to the upper and lower electrodes, and the insulating tube is densely filled with arc-extinguishing sand, and the end of the arc-extinguishing tube is connected with an insulating string. The present invention provides a current limiting fuse structure characterized in that the arc-extinguishing tube is tied and fixed to the outer peripheral surface of the winding core at the same time as the arc-extinguishing tube is sealed.

Examples of the present invention will be described below.

1 is a thin insulating tube made of crystallized glass or synthetic resin such as FRP; 2 is an upper electrode fixed to the top of the insulating tube and closing the open end 1a; 2a;
3 is the insertion blade of the upper electrode, 3 is the lower electrode fixed to the lower part of the insulating tube and closes the opening end 1b, 3a is the insertion blade, and 4 is a thin winding core made of an inorganic material such as alumina porcelain. A ribbon-shaped silver wire 5 with a notch on the outer peripheral surface 4a and a part of the silver wire are made of silver, lead, tin, etc.
A fuse element 7 connected or connected in series with a low separation point metal 6 made of bismuth or an alloy thereof is wound and both ends are connected to the upper electrode 2 and the lower electrode 3, respectively.

8 is an arc-extinguishing tube made of organic insulator that is covered around the low-distant metal, and is made of silicone rubber or Teflon tube with a thick wall compared to the diameter, and is particularly effective against the rise in internal pressure when interrupting low current. I am trying to withstand it. Similarly to the above, reference numeral 9 indicates that the end 8a of the arc extinguishing tube is closed in order to increase the pressure inside the tube and ensure more arc extinguishment during low current interruption, and at the same time, the arc extinguishing tube that is closely wound around the winding core closes the outer periphery of the tube. This is an insulating string that is tied and fixed so that it does not rise above the surface 4a, and cotton or synthetic fiber strings are used. Reference numeral 10 denotes a spiral high resistance wire inserted into the center of the winding core, and its both ends are connected to the upper electrode 2 and lower electrode 3, and are connected in parallel to the fuse element 7 . 11 is a fusing indicator 1
2 is a display body case for storing the above-mentioned winding core 4.
the upper end 4 so that it is located at the center within the insulating cylinder.
b is engaged with a latch-shaped guide fitting 13 which is engaged with the through hole 2b in the center of the upper electrode, and the lower end 4c is fitted into the recess 11a in the upper part of the display case.
Further, the lower protrusion 11b of the display case and the display 12 are fitted into the center hole 3b of the lower electrode 3 and the hole 14a formed at the center of the protective cover 14.

The protective cover 14 is attached to the outer periphery of the insulating tube and is made of a synthetic resin having heat resistance and mechanical strength, and is intended to particularly reinforce the lower part where the arc extinguishing tube is located. 15 is a buffer rubber, and 16 is a filler. Reference numeral 17 indicates a glass fiber tube coated on the outer circumferential surface of the display case, and reference numeral 18 indicates arc-extinguishing sand densely filled in the inside 1c of the insulating cylinder and the winding core.

The present invention consists of the above-mentioned structure. After the fuse element is wound around the outer circumferential surface of the winding core, the end of the arc extinguishing tube is placed over the low distance point metal connected to the winding core, and the end of the arc extinguishing tube is tied and sealed with an insulating string. As a result of being tightly fixed to the core, the pressure inside the tube is effectively increased especially during low current interruption, and the pressure effect not only ensures arc extinguishing, but also ensures that arc extinguishing sand does not enter the arc extinguishing tube. Therefore, the generation of arc-extinguishing gas due to the arc of the same tube is not hindered and the interruption performance does not deteriorate. In addition, since the fuse element wound around the assembled winding core does not easily move or come off, it can be inserted smoothly into the insulating cylinder, which has the effect of increasing workability, and is thus effective in practice. .

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a current limiting fuse showing an embodiment of the present invention, and Figure 2 is a fuse element wound around the outer circumferential surface of a winding core, and the end of an arc extinguishing tube partially covered with an insulating string. A partially cutaway external view showing the state in which the arc extinguishing tube is tied and fixed to the outer circumferential surface of the winding core. Figure 4 is a longitudinal section showing the fuse element. Figure, 5th
The figure is a sectional view taken along the line AA in FIG. 4. 1... Insulating tube, 2... Upper electrode, 3... Lower electrode, 4... Winding core, 4a... Outer circumferential surface, 5... Silver wire,
6...Low point metal, 7 ...Fuse element,
8... Arc extinguishing tube, 8a... End, 9... Insulating string.

Claims (1)

[Scope of utility model registration request] Both ends of an insulating tube made of crystallized glass or synthetic resin such as FRP are closed by fixing the upper and lower electrodes, and a core made of a thin inorganic insulator is placed in the center of the insulating tube. A fuse element connected to a low-melting point metal and partially covered with an arc-extinguishing tube made of an organic insulator is tightly wound around the outer circumferential surface of the core, and a high-resistance wire is inserted into the core. and both ends of the fuse element are connected to the upper and lower electrodes, and the insulating tube is densely filled with arc-extinguishing sand, and the end of the arc-extinguishing tube is sealed with an insulating string, and at the same time the arc-extinguishing tube is connected to the upper and lower electrodes. A current limiting fuse characterized by a tube tied and fixed to the outer circumferential surface of the winding core.