JPH0239331Y2 - - Google Patents

Description

[Detailed Description of the Invention] In recent years, high-voltage cutout current-limiting fuses have been used for primary side protection in pole-mounted transformers for high-voltage distribution lines.

This current-limiting fuse has superior features such as a larger breaking capacity than the generally used discharge type fuse, and does not emit an arc or generate sound when breaking, so its use is gradually expanding. be.

By the way, the dimensions (shape) of the above-mentioned current-limiting fuse for high-pressure cut-out are different because the high-pressure cut-out body for the release type fuse can be used as is when installing it.
Basically, it is almost the same as a discharge type fuse cylinder. In other words, both fuses are compatible. Therefore, as a current limiting fuse, the diameter of the insulating tube is much smaller than that of a general type current limiting fuse with the same rating, and it is natural that the diameter of the insulating tube is smaller than that of the fuse element wound inside the insulating tube. The winding core has also become smaller. Therefore, unlike current limiting fuses for high-voltage cutouts, it is not possible to incorporate a fuse blowout indicating member such as an indicator or a coil spring into the winding core. A storage cylinder made of synthetic resin having a slightly larger diameter is directly connected to the winding core in the axial direction thereof, and the above-mentioned display member is incorporated into the directly connected storage cylinder.

However, in the above-mentioned structure, since the storage cylinder is made of synthetic resin, the following problems still occur.

In other words, since the storage tube has low heat resistance, the fuse element cannot be directly wound around its outer circumferential surface in the same way as the outer circumferential surface of the winding core, so the overall length of the fuse element is shortened by that amount, and when a large current is interrupted, Because a sufficient arc voltage could not be secured, a large current-limiting effect could not be obtained, and at the time of interruption, the outer circumferential surface of the insulating cylinder was thermally decomposed by the arc, generating decomposed gas, which increased the internal pressure of the insulating cylinder. When the power is cut off, the storage cylinder may be damaged by the arc heat, creating a hole and the arc or arc-extinguishing material may enter through the hole, causing the display body and coil spring to malfunction. It was hot.

The present invention solves these problems without increasing costs, without major design changes, and by simple assembly. 2 is directly connected to the end of the same winding core 2 in order to extend the winding core 2 in the axial direction, and the storage cylinder 3 is made of synthetic resin and has a diameter slightly larger than that of the winding core 2 and has a display member such as the display body 11 incorporated therein. The fuse element 6 is spirally wound over the entire length of the outer peripheral surfaces 2b and 3a, and the winding core 2, storage cylinder 3, and fuse element 6 are connected to the insulating cylinder 1 made of an inorganic material such as crystallized glass. Upper and lower auxiliary electrodes are placed in the center of the fuse element 6 and fixed to the respective ends of the fuse element 6 to close the upper and lower opening ends 1c and 1b of the insulating cylinder 1. Once connected to 25 and 14, both electrodes 2
5 and 14 to the upper and lower electrodes 22 and 17 fixed to the outer periphery of both the upper and lower ends of the insulating cylinder 1, respectively,
Further, arc-extinguishing material 2 is placed in the insulating space 1d in the insulating cylinder 1.
In the current limiting fuse for high-pressure cutout filled with 7, the outer circumferential surface 3a of the storage tube 3 made of synthetic resin is coated with a glass fiber tube 4 having high heat insulation properties to cover the outer circumferential surface 3a. Furthermore, we propose a current-limiting fuse for high-pressure cutout, characterized in that the fuse element 6 is wound around the tube 4.

Examples of the present invention will be described below.

Reference numeral 1 denotes an insulating tube made of an inorganic material such as crystallized glass that has excellent pressure resistance and heat resistance, and is smaller in diameter than an insulating tube used in a general current limiting fuse. Reference numeral 2 denotes a pipe-shaped winding core made of an inorganic material such as alumina or magnesia sintered body, and a storage cylinder 3 made of synthetic resin is directly connected to one end of the winding core on the lower electrode side in the axial direction of the winding core. The winding core 2 and the storage tube 3 are made by fitting the end 2c of the winding core 2 into the recess 3b formed in the upper part of the storage tube 3, and then pouring adhesive 10 tightly into the gap between the two. Directly connected. Reference numeral 4 indicates a glass fiber tube having high heat insulation properties and is attached to the outer circumferential surface 3a of the storage tube 3 to cover the outer circumferential surface 3a. Reference numeral 5 indicates a resistance wire for displaying fusing, which is inserted into the hollow part 2a of the winding core 2, and is a coil. It is shaped like this. Reference numeral 6 denotes a fuse consisting of a silver wire 7 which together with an arc extinguishing material 27 constitutes a large current cut-off section, and a low melting point metal 8 which together with an arc extinguishing tube 11 connected in series to the silver wire 7 and which will be described later constitutes a small current fusing section. The element 6 is arranged in a spiral manner with a uniform pitch over the entire length of the outer circumferential surface 2a of the winding core 2 made of an inorganic material and also on the outer circumferential surface 3a of the storage tube 3 covered with the glass fiber tube 4. It is rolled. In addition, storage tube 3
The outer circumferential surface 3 of the cylinder 3 is coated on the outer circumferential surface 3a of the cylinder 3.
The glass fiber tube 4 used to cover the tube 4 is thin in order to prevent the fuse element 6 wound on the tube 4 from coming close to the inner wall surface of the insulating cylinder 1 as much as possible. In other words, the gap (space) formed between the element 6 near the housing tube 3 and the inner wall surface of the insulating tube 1 is also sufficiently filled with the arc-extinguishing material 27.

Reference numeral 9 denotes an arc extinguishing tube placed over the low melting point metal 8. The tube 9 is made of a material such as silicone or polyethylene that generates arc extinguishing gas by an arc, and together with the low melting point metal 8 constitutes a small current fusing section. . Reference numeral 11 denotes an indicator housed in the storage cylinder 3c, which is designed to fly out of the cylinder when the fuse is blown to notify its status, and is secured by a high-resistance wire 5 led out from one end of the winding core 2. Retained. That is, after the high resistance wire 5 is once latched to the latching part 3d at the top of the storage tube 3, the tip of the extra length is inserted through the latching hole 3e, and the tip is inserted into the support hole 11a at the top of the display 11. Pass it through and pull it out again through the upper locking hole 3e and pull it up. In this state, insert the locking plug 12 into the same locking hole 3e and fix the line to lock the display 11. I try to keep it. The display body 11 has a coil spring 1 interposed in a compressed state between a locking cutout 11b formed in the middle of the display body 11 and an upper inner end surface 3f of the cylinder.
3, it is always urged to pop out of the cylinder. Reference numeral 14 denotes a cap-shaped lower auxiliary electrode that is in close contact with the outer surface of the flange portion 3g formed at the lower part of the storage cylinder 3. The auxiliary electrode 14 The display body ₁ is positioned by being fitted into the engagement recess 14a formed in the inner bottom surface 14d1 of the display body 1, and further protrudes slightly outside the cylinder.
The lower end 11c of the electrode 14 is connected to the outer bottom surface 14a ₃ of the same electrode 14.
It is fitted into a protrusion hole 14b which is formed in and protrudes outward. Reference numeral 14c denotes a connection hole, and one end of the high resistance wire 5 for blowout indication and one end of the silver wire 7 of the fuse element are inserted into the same hole and connected to the auxiliary electrode 14 by soldering. 1
Reference numeral 5 denotes an adhesive for bonding the storage tube 3 and the lower auxiliary electrode 14. The adhesive 15 is applied in advance to the flange portion 3a formed at the bottom of the storage tube 3, and the flange 3a is attached. The flange 3a is brought into close contact with the inner bottom surface 14d ₁ of the lower auxiliary electrode 14, and in this state, the flange portion 3a is coated in advance, and the flange 3a is brought into close contact with the inner bottom surface 14d ₁ of the lower auxiliary electrode 14. In this state, the gap formed between the outer peripheral end of the flange 3a and the lower part of the attachment part 14d of the lower auxiliary electrode 14 is also filled with the adhesive 15 to fix the storage tube 3 and the lower auxiliary electrode 14 together. This also maintains airtightness at _a portion of the inner bottom surface 14d of the lower auxiliary electrode 14. 16 is front end 1
6d is opened and the rear end 16c is closed, and the rear end 1
A display small hole 16a and an engagement recess 16e are provided at the center of the display body 6c, and a lower electrode 1 is provided in a part thereof.
This is a bag-shaped reinforcing cover made of pressure- and heat-resistant synthetic resin or crystallized glass, which has a notch 16b into which the connecting portion 17a of No. 7 fits, and closes the lower open end 1b of the insulating tube 1. In this way, the lower end outer surface 1a of the insulating tube 1, where the lower auxiliary electrode 14 fitted to the lower end outer surface 1a of the insulating tube and the connecting conductive plate 18 integral with the electrode are located, is covered. In other words, it is attached to the cover 16 up to the vicinity of the lower electrode 17, and when it is attached, it is attached to the protruding hole 14b formed protrudingly on the external bottom surface _14d3 of the attachment part 14d of the lower auxiliary electrode 14. The cover is designed to fit into the engagement recess 16e of the rear end 16c of the cover, and to prevent the lower end 11c of the display 11, which slightly protrudes from the engagement protrusion 3h at the lower end of the storage tube 3, from protruding outside the cover. It is fitted into the small hole 16a for the display at the rear end 16c. 19 is an adhesive for fixing the reinforcing cover 16 to the insulating tube 1; 20 indicates a batskin. 17 is a lower electrode with an insertion blade located in the middle of the insulating cylinder 1 and fixed to its outer peripheral surface; 18 is a crank-shaped connection connecting the fuse element 6 and the lower electrode 17 via the lower auxiliary electrode 14; It is a conductive plate, and the plate is integrally connected to the side peripheral surface 14d ₂ of the lower auxiliary electrode 14. Reference numeral 22 denotes an upper electrode with an insertion blade that is adhesively fixed to the outer periphery of the upper end 1e of the insulating cylinder 1 so as to close the upper opening 1c of the insulating cylinder 1, and 23 is a cylindrical electrode formed to protrude in the axial direction of the insulating cylinder 1. The upper electrode screw 24 is screwed into the threaded part 22b on the outer periphery of the protruding part 22a of the upper electrode 22, and the cylindrical mounting part 24a with a part of the side circumferential surface opened is attached to the outer periphery of the upper end 2e of the winding core 2. This is a guide metal fitting 24 that supports the same-volume core 2 at the center of the insulating cylinder 1 by fitting a locking portion 24c formed in a latch shape into the inner wall surface 22c of the protruding portion 22a. 2, the upper end side is the locking relationship between the locking part 24c of the guide metal fitting 24 and the inner wall surface 22c of the protruding part 22a, and the lower end side is the engaging protrusion 3h of the storage cylinder 3 and the engaging recess 14a of the lower auxiliary electrode 14, The protruding hole 14b of the lower auxiliary electrode 14, the engagement recess 16e of the reinforcing cover 16, and the side surface 14d ₂ of the lower auxiliary electrode
The lower end outer surface 1a of the insulating tube 1 is positioned at the center of the insulating tube 1 by the fitting (engagement) relationship between the reinforcing cover 16 and the lower end outer surface 1a of the insulating tube 1. In other words, it's heart-warming.

Reference numeral 25 denotes a plate-shaped upper auxiliary electrode fitted into the blind hole 23a of the upper electrode screw, and the other end of the high resistance wire 5 for fusing display led out from the upper open end 2d of the winding core 2 is attached to the electrode. Silver wire 7 of fuse element 6
One end of the electrode is once passed through the small connection hole 25a and pulled out to the outside, and then the tip is bent and connected to the outer surface of the auxiliary electrode 25 with solder.
Reference numeral 27 indicates an arc-extinguishing material such as quartz sand that is densely filled in the insulating space 1d within the insulating cylinder 1.

In the current limiting fuse with the above configuration, current flows through the path of upper electrode 22 - upper auxiliary electrode 25 - fuse element 6 - lower auxiliary electrode 14 - connecting conductor plate 18 - lower electrode 17, and is normally in parallel with fuse element 6 . There is almost no flow through the high resistance wire 5 for displaying fusing, which is connected to the .

Next, when a fault current flows and it is a current with a low magnification, the fuse element 6 is fused at its low melting point metal 8 and an arc is generated at the same part, but this part is covered with an arc extinguishing tube 9. The arc is extinguished by the arc-extinguishing gas generated from the tube. Further, a part of the arc is diffused into the arc-extinguishing material 27 and extinguished, and the electric path is interrupted. In this case, at the same time as the fuse element 6 blows out, the fault current transfers to the high-resistance wire 5, and in order to melt it, the display body 11, which is biased by the coil spring 13, is inserted into the display body small hole 16a of the reinforcing cover 16.
This indicates that the fuse has blown (operated) by protruding beyond the cover. In this case, since the locking step portion 11b of the display body 11 locks into the engagement recess 14a of the lower auxiliary electrode 14, the display body 11 is prevented from protruding too much from the display body small hole 16a.

In addition, if a large current flows other than the above, such as due to a short circuit accident, the fuse element 6
The arc is fired all at once over its entire length, and the arc is diffused into the arc-extinguishing material 27, extinguished, and the main circuit is cut off.

In this case, a large current flows through the high-resistance wire 5 at the same time as the fuse element 6 fires, and the same resistance wire is also cut off, so that the display 11 protrudes in the same manner as described above to indicate that the fuse has blown.

The present invention has the above-mentioned configuration, and since the fuse element 6 can be wound around the outer peripheral surface 3a of the storage tube 3, the total length of the fuse element is increased accordingly, and the breaking performance can therefore be improved. .

Moreover, at the same time, when the housing cylinder 3 is shut off, generation of gas due to thermal decomposition due to the arc is prevented, thereby suppressing an increase in the internal pressure of the insulating cylinder and preventing destruction of the insulating cylinder.

Further, a part of the resistance wire 5 for fusing indication is disposed in the storage tube 3 together with the display body 11, and the resistance wire is fused at this portion when the circuit is cut off. is also insulated by a glass fiber tube with high heat insulation properties coated on its outer peripheral surface 3a, so that heat dissipation of the resistance wire 5 can be prevented as much as possible, and when the fuse is blown, heat generation of the resistance wire is promoted and guaranteed By cutting the same line, the display body 11 in the same cylinder can be operated accurately.

In addition, the glass fiber tube 4 used as a heat insulating member is easily available, has high heat insulating properties, is inexpensive, and has features such as being easily attached to the outer peripheral surface 3a of the storage tube 3. This is extremely advantageous for industry.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a longitudinal sectional view of a current-limiting fuse for high-pressure cutout showing an embodiment of the invention, and Fig. 2 is a partially cutaway view showing the state of the fuse during assembly. 3 is a right side view of FIG. 2, FIG. 4 is a vertical sectional view showing the assembled state of the storage tube, and FIG. 5 is a left side view of the guide fitting.
FIG. 6 is a sectional view taken along the line AA in FIG. 5. 1...Insulating cylinder, 1a...Lower end outer surface, 1b...Lower opening, 1c...Upper opening end, 1d...Insulating space, 2... Winding core, 2a...Hollow part, 2b...Outer peripheral surface, 3...Storage cylinder, 3a...Outer circumferential surface, 3b...Recess, 3c...Inside of storage cylinder, 4...Glass fiber tube, 6 ...Fuse element, 14...Lower auxiliary electrode, 17...Lower electrode, 22...upper electrode,
25... Upper auxiliary electrode, 27... Arc-extinguishing material.

Claims (1)

[Scope of utility model registration request] The winding core 2 is made of an inorganic material such as alumina, and the winding core 2 has a slightly larger diameter than the winding core directly connected to the end of the winding core 2 to extend in the axial direction, and an indicator member such as a display member 11 is inside. The fuse element 6 is wound spirally over the entire length of the outer circumferential surfaces 2b and 3a, and the winding core 2, the housing cylinder 3, and the fuse element 6 are connected to the storage cylinder 3 made of synthetic resin incorporating the The insulating tube 1 made of an inorganic material such as crystallized glass is placed in the center of the insulating tube 1 and is hermetically housed, and both ends of the hermetically housed fuse element 6 are connected to both upper and lower open ends 1c of the insulating tube 1.
Both upper and lower electrodes 22 are connected to the upper and lower auxiliary electrodes 25 and 14 fixed to the respective open ends of the insulating cylinder 1 to close the insulation tube 1b, and then further fixed to the outer periphery of the upper and lower ends of the insulating cylinder 1 via the electrodes 25 and 14. . The outer peripheral surface 3 is covered with a glass fiber tube 4 having heat insulating properties.
A current-limiting fuse for high-pressure cutout, characterized in that the above-mentioned fuse element 6 is further wound around the tube 4, covering the same tube 4.