JPH0241813Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a high-voltage cut-out fuse.
In particular, it relates to improvements in overload small current interrupting performance and improvements in lead wire release prevention structure.

Conventionally, in this type of fuse, the fusible body is usually installed at the back from the opening of the arc-extinguishing tube, that is, near the head of the fuse. If the head terminal is lengthened and a fusible material is installed near the arc extinguishing tube opening, the arc time will be very short if the fuse blows due to a small overload current, that is, a current around 160% to 500% of the fuse rated current. The arc heat generated may damage the fuse holder, or the arc may not be extinguished, resulting in cut-out damage. In addition, in recent years, in order to prevent various accidents caused by lightning on power distribution lines, a differential insulation method that weakens the insulation strength near the bushings of pole-mounted transformers has become popular. However, high-voltage cut-out fuses still cannot be said to provide complete protection against lightning surges that occur multiple times in succession, which is called multiple lightning. The reason for this is that once the fuse operates, the gap between the electrodes opens wide, so any lightning surge that occurs continuously after the fuse operates is applied to the external electrode of the fuse holder, causing an external flash of the holder and causing an arc short circuit. This is because it may cause the high voltage cutout to break and become incapable of shutting off.

Therefore, it has been desired to develop a holder in which the head terminal is made longer so that the fuse electrode interval after fuse operation is shorter than the holder electrode interval. By making the head terminal longer, if the fusible body is installed near the opening of the arc extinguishing tube, that is, near the opening of the holder, the lightning surge that occurs after the fuse is operated will be able to travel between the tip of the head terminal and the tip of the lead wire. and is applied simultaneously between the holder electrodes,
By reducing the distance between the tip of the head terminal and the tip of the lead wire to lower the discharge voltage, an arc short circuit occurs inside the holder, and the arc current is completely interrupted in half a wave. However, as mentioned above, fuses in which a fusible material is installed near the opening of the arc-extinguishing tube have unstable performance in interrupting small overload currents and have not been put into practical use.

Therefore, in view of the above-mentioned current situation, the purpose of this invention is to make the head terminal long so that even if a fusible body is installed near the arc-extinguishing tube opening, it is possible to stably cut off small overload currents. The present invention aims to provide an improved structure, and furthermore, with this improved structure, the structure for preventing release of lead wires is also improved at the same time.

As is clear from Patsien's law, it is known that the discharge voltage is closely related to the pressure and the distance between the electrodes. When a fuse is shut off and fired, the internal pressure increases due to the gas generated from the arc extinguishing tube, but if a fusible material is installed near the opening, the generated gas is rapidly released to the outside, so the internal pressure decreases. It doesn't go up. As a result, the arc time is prolonged, resulting in unstable interruption. Therefore, in this invention, the head terminal is lengthened and the fusible body is installed near the opening of the arc extinguishing tube, and part or all of the fusible body is attached to an insulated pipe having an outer diameter smaller than the inner diameter of the arc extinguishing tube. This prevents the pressure generated in the arc extinguishing tube from being rapidly released to the outside, and ensures that the internal gas pressure increases after the fuse is operated.

The following table shows a conventional general type in which the fusible body is installed near the head (a) and a comparative example in which the head terminal is lengthened and the fusible body is installed near the opening (b). ,
This is a table comparing the arcing time of the small current interruption test results of the improved type (c) based on this invention.

Test fuse arc time General type (A) 10 to 30 cycles Comparative example (b) 30 to ∞ cycles Improved type (c) 2 to 10 cycles *Test conditions are as follows.

Test voltage: 7200V Test current: 50A Circuit power factor: 0.6 This insulated pipe is generally straight.
By molding the fusible side into a flat shape, the pressure increasing effect can be further enhanced. The mounting structure for the insulated pipe is to either press fit the outer end into the connection between the lead wire and the fusible body (if a fastener is used, use that fastener), or insert it all the way to the lead wire and secure it with adhesive, etc. A method of fixing in a closed state is considered, and a more effective pressure increase can be obtained by using a closed state. Further, the cross-sectional shape is not limited to a circular shape, but may be a polygonal shape. Note that if the end on the head terminal side is also sealed with a sealing plug, it will be more effective in increasing the gas pressure generated when the fusible material is fused. Furthermore, the pressure effect was further improved by making the insulated pipe have a double structure, and the test results were good. In addition, filling the gap between the double pipes with an arc extinguishing agent will provide an even greater effect.

By the way, in conventional fuses, in order to prevent the lead wire from being released and hanging down after the fuse is operated, a part of the lead wire is made of brass or plated with nickel and is located near the opening of the fuse holder. Attach a stopper made of copper pipe material, and place this stopper between the open end of the fuse holder and the display tube during low current operation.
A device has been devised to prevent the lead wire from sagging by locking the lead wire in a taut state. However, when the fuse is activated due to an accidental large current on the power distribution line, this stopper flies out with great force, which is extremely dangerous and poses a risk of injury to humans.

Therefore, in this invention, this metal stopper is eliminated, and the above-mentioned pressure boosting insulating pipe is made of relatively lightweight, non-metallic material such as insulating paper material such as kraft paper or press boat, or synthetic resin insulating material. This insulated pipe can also be used as a stopper by being made of a material with a length that allows it to be held in a tensioned state between the protruding display tube and the open end of the fuse holder during low current operation. During small current operation, stable breaking performance is achieved due to the boost effect mentioned above, and the fuse holder is held tightly between the open end of the fuse holder and the display tube, preventing the lead wire from dangling. It also has the role of a stopper to prevent accidents, and when operated by large currents due to accidents, the discharge speed is slow due to its light weight, and its mechanical strength is relatively weak compared to metal pipes, so it can be shattered by the discharge pressure. The structure was such that it was destroyed in a scattered manner and did not pose any danger to the human body.

In this way, the initial purpose can be achieved only by constructing the above-mentioned booster insulated pipe from a relatively lightweight non-metallic material, but the function as a stopper during low current operation is insufficient. In addition, in order to more reliably achieve breakage and release properties during accidental high current operation, it is necessary to have relatively bending strength, but relatively weak resistance to destruction due to excessive internal pressure such as during accidental high current operation. It is desirable to have a structure. From this point of view, the cylindrical wall of the insulated pipe itself is made relatively thin so that it is easily broken against excessive internal pressure such as large current due to an accident. By fixing multiple reinforcing materials such as long wires, rods, and strips along the circumferential surface of the cylindrical wall, it can withstand internal pressure generated during small current operation and has a stopper function. It is desirable to have a structure that has enough bending strength to exhibit this. That is, for example, a structure in which a plurality of linear reinforcing materials are arranged and fixed on an insulating paper material and processed into a pipe shape can be considered.

To further explain below with reference to the attached drawings, the first
The figure is a longitudinal cross-sectional view showing an embodiment of the high-voltage cut-out fuse according to this invention. It is placed between. Reference numeral 5 designates an insulated pipe for boosting pressure and a stopper, which is the main part of this invention, and is made of a relatively lightweight non-metallic material, and a fastener 6 connects the fusible body 2 and the lead wire 4. The outer end is press-fitted and fixed. Note that a structure may be adopted in which sealing is performed using a water-repellent sealing material or adhesive. Note that it is also possible to connect the fusible body 2 and the lead wire 4 without using the fastener 6, and in this case, it is sufficient to press-fit and fix the lead wire 4 into the connecting portion. Note that the code 7 is a fuse holder, and 8
9 is a spring, 9 is a display barrel, and 10 is a barrel stopper.

Figure 2 shows a small current operating state, and when the fusible body 2 is fused, the coated insulated pipe 6 prevents the internally generated gas pressure from being rapidly released to the outside, thereby ensuring a rise in the internal gas pressure. between the open end of the fuse holder 7 and the display cylinder 9 fitted on the outer periphery of the open end of the fuse holder 7 and projected by the elastic force of the spring 8. The structure is such that the insulating pipe 6 is held in a stretched state to prevent the risk of electric shock due to the lead wire 4 hanging down.

FIG. 3 shows an accidental high current operation, in which the insulating pipe 5 is blown to the outside. At this time, unlike conventional metal stoppers, the release speed is slow due to its light weight, and its mechanical strength is relatively weak, so it will be broken into pieces due to excessive internal pressure, so there will be no harm to the human body. There's no danger.

Figures 4A and 4B show the main parts of the fuse according to the above embodiment. In Figure A, the outer end of the insulating pipe 5 is press-fitted into the fastener 6 to cover a part of the fusible material. An example is shown. In addition, in Fig. B, an insulating pipe 5 whose outer end is press-fitted into the fastener 6 and whose inner end is fitted into the end of the head terminal 1 to cover the entire fusible body 2 is shown. It shows. FIG. 5 shows an insulated pipe with the above-mentioned truss-like end,
FIG. 6 shows an example in which the cross-sectional shape is polygonal.

A to C in FIG. 7 are illustrations of the fixed state of the insulated pipe, where A is press-fitted into the fastener 6, B is the one using a sealant or adhesive, and C is the one using the sealant or adhesive. It is fixed to the lead wire 4 by using both.

8A and 8B are double-structured insulated pipes in which both the outer cylinder 5a and the inner cylinder 5b are fixed to the fastener 6 with an adhesive. Both the outer cylinder and the inner cylinder may be molded from the same material, or they may be made of different materials, such as kraft paper and plastic. Furthermore, it is also conceivable to fill the space between the two with an arc extinguishing agent. In Figure B, an example in which the inner cylinder is particularly shortened is shown.

FIG. 9 shows a more preferable structural example,
An example of an insulated pipe is shown in which a relatively thin cylindrical wall 5c is combined with a plurality of reinforcing members 5d to provide bending strength. That is, in this example, a plurality of reinforcing members 5d are arranged and fixed on an insulating paper and processed into a cylindrical shape with the reinforcing members 5d facing inward. With this kind of structure, it is strong enough to withstand the internal pressure required to stably cut off small overload currents, and has sufficient bending strength to perform the stopper function. Due to the easy breakage of the cylindrical wall 5c, the reinforcing material 5d falls apart in response to excessive internal pressure such as during high current operation. It can be done.

Note that the reinforcing material is not limited to the case where it is provided on the inner surface of the cylindrical wall, but may be provided on the outer surface, or when the cylindrical wall has a double structure, it can be interposed between both. Further, the reinforcing members do not necessarily have to be placed side by side in close contact with each other as shown in the drawings. Furthermore, as shown in FIG. 10, it is also possible to arrange the reinforcing material 5e in a state in which it has a star-shaped hollow part, and various shapes can be applied to both the cylindrical wall and the cross-sectional shape of the reinforcing material hollow part. can.

As is clear from the detailed explanation above, the high-voltage cut-out fuse according to this invention has a long head terminal and a fusible body installed near the open end of the arc-extinguishing tube, and all or part of this fusible body. is covered with a relatively lightweight, non-metallic insulated pipe, so when operating with a small overload current, reliable and stable shutoff is possible due to the increased pressure effect of the insulated pipe, and it also has the function of a stopper. On the other hand, when operated by an accidental large current, the release speed is slow due to its light weight, and since its mechanical strength is relatively weak, it will be broken into pieces by excessive internal pressure, so it will not be harmful to the human body. Therefore, we were able to provide a high-voltage cut-out fuse that is safe and has good interrupting performance, without any danger.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an embodiment of the high voltage cut-out fuse according to this invention, Fig. 2 is a longitudinal sectional view of the same showing a small current operating state, and Fig. 3 is an operating state due to an accidental large current. A longitudinal sectional view showing the
is a longitudinal sectional view of the same essential part, B is a longitudinal sectional view showing another example, FIG. 5 is a longitudinal sectional view showing another example of the insulated pipe, and FIG. 6 is another example of the cross-sectional shape of the insulated pipe. 7A, B, and C are illustrative diagrams of the fixed state of the insulated pipe, FIG. 8 A, B are illustrative diagrams of the double insulated pipe, and FIG. 9 is an illustrative diagram of the insulated pipe in another state. FIG. 10 is a cross-sectional view showing another example of the cross-sectional shape. 1... Head terminal, 2... Fusible body, 3... Arc extinguishing tube, 4... Lead wire, 5... Insulating pipe.

Claims (1)

[Claims for Utility Model Registration] 1. A high-voltage device in which a fusible material is stretched between the head terminal and the lead wire, the entire body is covered with an arc-extinguishing tube, and the fuse holder is attached to a fuse holder having an indicator tube on the outer periphery of the opening end. In a cut-out fuse, the head terminal is lengthened and the fusible body is installed near the open end of the arc-extinguishing tube, and the outer end is relatively lightweight and is fixed to the connection between the fusible body and the lead wire or to the lead wire itself. A part or all of the fusible body is covered with a non-metallic insulated pipe, and this insulated pipe prevents contact between the protruding display tube and the open end of the fuse holder when the fuse is operated at a small current. A high-pressure cut-out fuse characterized by having a length that is locked in a taut state between the fuses. 2. The insulating pipe is made of a relatively thin cylindrical wall and a plurality of reinforcing materials such as wires, rods, strips, etc. that are approximately the same length as the cylindrical wall and are attached along the peripheral wall surface of the cylindrical wall. A high-voltage cut-out fuse according to claim 1 of the utility model registration claim. 3. The high voltage cut-out fuse according to claim 1 or 2, wherein the inner end of the insulating pipe is fitted to the end of the head terminal. 4. The high-pressure cut-out fuse according to claim 1, 2, or 3 of the utility model registration claim, in which the insulating pipe has a dual structure of inside and outside.