JPS5938692B2 - current limiting fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a current-limiting fuse provided with a display device for displaying the cut-off state of the fuse.

The general structure of a high-voltage current-limiting fuse for power use equipped with a display device is to arrange element guides at both ends of a hollow cylindrical insulator tube, and between the element guides at both ends, a plurality of elements made of good conductors are connected according to the rating. The periphery of the element is filled with particulate arc extinguishing agent and sealed with electrode caps at both ends.

In the center of the display line, a display line consisting of a wire with a higher resistance than the element is placed between the electrode caps at both ends, and a display is placed on the electrode cap at one end to indicate a cutoff operation when the display line is extinguished after the element arc is extinguished. Many devices are used.

Next, to explain the breaking operation and problems of conventional high-voltage current-limiting fuses for electric power, after the fuse cuts off an excessive current such as a short-circuit current, the pressure rises inside the fuse insulator due to the arc energy during the cutting. In rare cases, the explosion occurred within a few seconds, and in the worst case scenario, it was thought that it would lead to personal injury.

As a result of various studies on these phenomena, the following was found.

When interrupting a short-circuit current, the arc generated due to melting and vaporization of the element and display wire causes the accumulated arc energy to increase the pressure inside the fuse insulator (approximately several tens of atmospheres) and the surrounding area during fuse assembly and operation. When moisture, etc. enters the fuse tube, the arc energy at the time of disconnection causes the moisture to vaporize and expand in volume, causing abnormal bulges in the electrode caps at both ends, which have the weakest mechanical strength. At the same time, it was found that if the electrode cap was unable to absorb it, an explosion would occur several seconds after the insulator ruptured or was cut off.

One way to improve this kind of problem is to use waterproof paper as a waterproofing and pressure relief valve, but due to the high temperature (approximately 1000°C) when the fuse is cut off, it may burn out and lead to a fire accident. There were problems such as damage due to vibrations from other devices.

An object of the present invention is to provide a safe current-limiting fuse that will not cause a fire accident.

In order to achieve this objective, the pressure relief display device of the present invention includes:
An insulating despy having a pressure relief hole attached to an electrode cap, an indicating cap disposed outside the insulating despy and having an indicator spring inside, and an indicating line attached to the indicating cap and passing through the pressure relief hole. The above purpose is achieved by using an insulating member that gasifies this holding part at the heating temperature when cutting the display line. There is a particular thing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below using a high-voltage current-limiting fuse 1 for power use shown in FIGS. 1 to 3.

The insulating tube 2 has electrode caps 3 attached to both ends.

The electrode cap 3 is fitted at one end with a protective cover 5 having one or more discharge holes 4 made of transparent insulating material.

A guide plate 6 and a support plate 7 are interposed between the electrode cap 3 and the end of the insulating tube.

A fuse wire 8, for example, silver, is fixed to the guide plate 6, and the fuse wire 8 is written between both electrode caps.
It is in contact with arc extinguishing agent 9 filled in the insulating tube.

The pressure relief display device X is supported by a support plate 7.

The support plate 7 has an insulating despy 10 mounted in a hollow hole formed in the center, and a display cap 11 is disposed between the support plate and the protective cover 5.

An indicator wire 12 made of a material with higher resistance than the fuse wire 8 passes through the pressure release hole 10A and the hollow hole 11A formed in the insulating despee 10 and the indicator cap 11.

Crimp terminals 13 provided at both ends of the display line 12 engage with the display cap 11 and are disposed between the display gaps at both ends.

The display spring 14 disposed within the display cap is connected to the display line 1
2, the display spring 14 is compressed and the second
When energy is stored as shown in Figure A and the display line 12 is cut, the stored energy is released as shown in Figure B.

The holding part 15 which is in contact with or molded on one end of the insulation despee corresponding to the arc extinguishing agent 9 is connected to the pressure release hole 1 of the insulation despee 10.
This prevents external moisture, humidity, etc. from entering the insulated tube from 0A, prevents rusting and corrosion of the fuse wire 8, indicator wire 12, etc., and prevents arc quenching agent from absorbing water and deterioration due to moisture absorption. A display spring 12 prevents the protective cover from flying out in one direction.

The holding member is an insulating material such as fluorine resin, silicone resin, or urea resin, and this insulating material has a temperature of 200 (C).
When the temperature exceeds that level, it is instantaneously thermally decomposed (fixed → liquid → vaporized) and gasified into fluorine, hydrogen gas, etc., which is diffused and deposited in the particles of the arc extinguishing agent 9.

When an excessive current such as a short-circuit current flows through the power high-voltage current-limiting fuse 1, the fuse wire 8 melts and extinguishes the arc, and the short-circuit current continues to transfer to the display line 12, and the display line instantly changes to approximately Heated to about 1000°C, the holding part 15 is gasified, and the pressure release hole 10A is opened as shown in FIG. It diffuses and evaporates into each particle and acts as a cooling agent.

Therefore, the holding part can prevent fire accidents and is extremely safe.

In the above-mentioned embodiment, the case where the pressure relief display device is supported by the support part has been described, but the pressure relief display device may be directly attached to the electrode cap.

For example, an insulating despy may be attached to a hollow hole formed in an electrode cap, a display cap and a display spring may be placed on the outer electrode cap side and an insulating despy's side, and a holding portion may be placed inside the insulating despy.

As described above, according to the current limiting fuse of the present invention, fire accidents are unlikely to occur and it is safe.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view of a main part of a high-voltage current-limiting fuse for electric power shown as an embodiment of the present invention, and FIGS. 2A and 2B are side sectional views of the pressure relief display device of FIG. 1. 1...-Current limiting fuse, 2...Insulating tube, 3
... Electrode cap, 8 ... Seuse wire,
9... Arc extinguishing agent, 10... Insulation pipe, IOA... Pressure release hole, 11... Display cap, 12... Display line, 14...-Display spring, 15... Holding section.

Claims (1)

[Claims] 1. A fuse wire is placed between the electrode caps that seal both ends of the insulating tube, and there is an indicator wire that commutates the current caused by the fuse wire and fuses it, and an indicator wire that holds the indicator wire and releases the pressure when it blows. A pressure display device is provided on the electrode cap, and the pressure release display device includes: an insulating despy having a pressure relief hole attached to the electrode cap; an indicating cap disposed outside the insulating despy and having a display spring inside; The device consists of an indicator line attached to the cap and passing through the pressure relief hole, and a holding part that holds the indicator line and seals the pressure release hole, and the holding part has a heating temperature at the time of melting. A current-limiting fuse characterized by using an insulating member that is gasified by