JPH0222927Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention consists of a fuse element in which a low melting point alloy part and a silver wire part are connected in series, and an extinguishing tube is placed on the outer periphery of the low melting point alloy part, and the fuse element is housed in an insulating tube. The purpose of this project is to improve a full-area high-voltage, current-limiting fuse in which both ends of the stored element are connected to upper and lower electrodes fixed to the upper and lower outer peripheries of an insulating tube, and the insulation space of the insulating tube is filled with an arc extinguisher. It is an object of the present invention to provide a structure that can perform the interrupting operation reliably without thermally destroying the insulating cylinder even when the energy is the maximum (current value).

In high-voltage power distribution lines, current-limiting fuses are used alone or in switches and high-voltage cut-outs because they have a larger breaking capacity than conventional discharge type fuses, are silent and flameless, and are safer. It is used by being incorporated into switches such as Recently, as shown in Fig. 2, a fuse element in which a silver wire and a low melting point alloy wire of gold alloy are connected in series is used, and a halogen compound, such as fluorocarbon resin or Full-area high-voltage cut-out current-limiting fuses, which are made of glass fiber covered with an extinguishing tube made of silicone-impregnated material and are capable of interrupting small current areas, have come into widespread use. However, such current-limiting fuses for full-area high-voltage cut-outs are designed to be smaller and lighter in order to improve their performance and to be incorporated into other equipment as mentioned above, and the diameter of the insulating cylinder is smaller than that of conventional fuses. It is much smaller than the previous one. Therefore, the insulating space, that is, the inner diameter of the insulating cylinder in the fuse is naturally narrow, and especially in a structure in which the fuse element is wound around the core and housed in the insulating cylinder, there is a gap between the fuse element wound around the core and the insulating cylinder. The distance between the inner wall surfaces becomes even closer. If a fuse with such a structure is broken and the current is broken at the maximum arc energy (approximately 2000A for a high voltage current limiting fuse with a rated current of 7 to 15A), a high resistance is generated. As the particle size of the body substance becomes particularly large, the highly heated high-resistance substance reaches (contacts) the inner wall surface of the insulating tube made of inorganic glass or porcelain, and the heat locally damages the insulating tube. It can be heated and destroyed by uneven heat.

That is, when a large current is cut off, the fuse element melts and vaporizes over its entire length, and when the melted and vaporized fuse element becomes clogged, the arc diffuses into the extinction agent surrounding the element, forming a high-resistance material. That is, the high-resistance material is formed along the spirally wound element over the entire length of the outer peripheral surface of the core. Therefore, if the inner diameter of the insulating tube is extremely small, such as a current-limiting fuse for high-voltage cut-outs, if the winding core, or fuse element, is not housed in the center of the insulating tube, the element will be placed on one of the inner walls of the insulating tube. In this state, a large current is interrupted and a high-resistance substance is formed.The highly heated high-resistance substance comes into contact with the inner wall surface of the insulating cylinder, which causes uneven heat generation of the cylinder. cause destruction.

This proposal is proposed in view of the above points, and includes a fuse element 5 in which a low melting point alloy portion 3 and a silver wire portion 4 are connected in series, and an arc extinguishing tube 20 is placed over the outer periphery of the low melting point alloy portion 3. The element 5 is wound spirally around the outer periphery of the winding core and hermetically stored inside the insulating tube 1. Both ends of the housed element 5 are connected to upper and lower electrodes 7 and 8 fixed to the top and bottom of the insulating tube 1, respectively, and the insulating tube 1 is further insulated. In a current-limiting fuse for full-area high-voltage cut-out, in which the space 1b is filled with an extinguishing agent 6 and the core is directly connected and extended to the display storage case 13 at its lower end, a guide fixed to the upper end of the core is provided. A flare-shaped widened part 22a centered on the axis of the winding core is formed on the metal fitting 22, and the upper electrode 7 of the widened part 22a is formed.
The fuse element 5 is installed at the center of the insulating tube 1 by engagement with the lower cover 16 and the center of the lower cover 16 attached to the lower end of the insulating tube 1 of the display storage case 13. It is characterized by:

Hereinafter, an embodiment will be described in which the technical idea of the present invention is realized in a current-limiting fuse for high-voltage cutout.

Reference numeral 1 denotes an insulating cylinder made of inorganic glass or alumina porcelain, and inside the cylinder there is a winding core 2 made of cordierite or alumina sintered body, and a winding core 2 that extends spirally over its entire length against the outer peripheral surface 2a of this winding core 2. Fuse element 5 is wound.

The fuse element 5 is made by connecting a low melting point alloy part 3 and a silver wire part 4 in series.
An arc extinguishing tube 20 is placed over the outer peripheral surface of the tube. Reference numerals 21 denote openings 20 at both ends of the tube 20 to prevent the disinfectant 6 from entering the tube 20.
The glass fiber seal plug inserted in a is shown. Winding core 2 and fuse element 5 configured as above
The low melting point alloy part 3 covered with the extinguishing tube 20 is hermetically housed in the insulating tube 1 so that it is located between the upper electrode 7 and the lower electrode 8 fixed to the upper and lower outer peripheries of the insulating tube 1. After storing these, further insulating cylinder 1
The insulating space 1b inside is filled with a quenching agent 6 made of silica sand, quartz, or the like. Reference numerals 7 and 8 denote an upper electrode and a lower electrode with insertion blades 7a and 8a fixed to the upper and lower outer peripheries of the insulating cylinder 1, and the upper end opening 7b of the electrode 7 has a latch-like shape fitted to the upper end of the winding core 2. The expanded portion 22a of the guide fitting 22 is engaged with the tapered inner wall surface 7c of the upper electrode, so that the winding core 2 is supported at the center within the insulating cylinder 1. Reference numeral 9 denotes a resistance wire for display disposed within a hollow winding core, and one end of the resistance wire 9 and one end 4a of the silver wire 4 are connected to a heat insulating cushion material 10 such as asbestos that closes the opening 7b. The upper electrode 7 is connected to the upper electrode 7 by soldering to a plate-shaped metal cap 11 which is led out through the cap and is closely attached to the outside thereof. 12 indicates the solder. Reference numeral 13 denotes a display storage case made of an insulating member (synthetic resin) located at the lower end of the insulating tube 1, and the case includes a guide portion 13a provided at one end of the case that protrudes in the axial direction. 2b, and are directly connected to extend the same winding core 2 in the axial direction. Reference numeral 9 denotes a display resistance wire disposed inside the winding core 2. The wire is once connected to the display body 14 housed in the display body storage case 13, and its remaining length is connected together with the silver wire portion 4 of the fuse element 5. It is connected to one end 17a of the conductive plate 17. A display spring 15 is interposed in a compressed state between the locking step 14a of the display 14 and the upper end 13b of the storage case 13, and always urges the display 14 in the pop-out direction (downward).

Reference numeral 17 designates a conductive plate which is clamped and fixed between the insulating tube and the lower cover 16 when the lower cover 16 is attached to the insulating tube 1, and its one end 17a is located in the lower end opening 1c of the insulating tube 1, and the above-mentioned Gotoku silver wire part 4
and further connect it to the lower end outer surface 1d from the lower end of the insulating cylinder 1.
The other end 17b extending upward along the line is connected to the lower electrode 8 by a screw 18. 16 is a bag-shaped lower cover attached to the lower end outer surface 1d of the insulating cylinder 1 so as to cover the conductive plate 17, and the rear end 16a
An engaging recess 16b and a display small hole 16c are provided in the center of the
The engaging recess 16b therein is fitted into the lower end 13c of the storage case 13, and the display body 14, which has a rounded tip 14b, is inserted into the display small hole 16c so that the tip 14b extends outside the cover 16. It is fitted into the small hole 16c to the extent that it does not protrude. 1
Reference numeral 9 denotes an insulating heat-insulating member made of sheet-like asbestos, which is disposed between the inner wall surface 1a of the insulating cylinder 1 and the fuse element and display housing inner case 13.

Now, in a fuse with the above structure, if a fault current flows and it is a large current, the fuse element of the fuse will instantly explode over its entire length, and the generated arc will diffuse into the de-articulating agent and cause a high current. A resistive material is produced, which restores the insulation and completes the interruption. In this case, a high-temperature, high-resistance material is produced by the arc and the extinguishing agent.
Since the winding core is housed in the center of the insulating tube, the insulating tube is not locally heated, and uneven heat damage is prevented. In this case, when the fuse element 5 melts, the same current flows through the display resistance wire 9 connected in parallel with the fuse element 5.
The resistance wire is then fused and the display body 14, which is constantly biased in the pop-out direction, is caused by the display spring 15.
This indicates that the fuse has been blown out (cut off) by popping out from the cover body small hole 16c of the lower cover 16. Further, when displaying, the display body 14 has its locking steps 7 and 14a connected to the engagement recess 16 of the lower cover 16.
b, the display body 14 is prevented from protruding too far.

Next, if the fault current is small, the low melting point alloy part 3
The arc is fused and the arc extinguishing tube 20 placed over the alloy part is thermally decomposed by the heat generated by the arc to generate arc extinguishing gas, thereby extinguishing the arc and interrupting it. Incidentally, the display body makes a protruding motion in the same manner as described above to indicate that the fuse has blown.

This proposal consists of the above-mentioned configuration, including interruption at the current value where the arc energy is maximum (when the rated current is 7A to 15A and the breaking current is about 2000A),
In other words, even when the high-resistance substance generated by the generated arc and the filled extinguishing agent reaches its maximum particle size, the axis of the winding core is centered on the guide fitting 22 fixed to the upper end of the winding core. A flared expanded portion 22a is formed, and the expanded portion 22a engages with the upper electrode 7 and the center of the lower cover 16 attached to the lower end of the insulating cylinder 1 of the display storage case 13. As a result, the fuse element 5 is installed in the center of the insulating tube 1, so the winding core and the fuse element are centered and are always housed in an accurate position at the center of the insulating tube. Even in the case of an insulating cylinder with an inner diameter (inner diameter), contact of the highly heated high-resistance material formed when a large current is cut off with the inner wall of the insulating cylinder is prevented, and uneven heat breakdown due to local overheating of the insulating cylinder is prevented.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a full-area high-voltage cutout current-limiting fuse showing an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view showing a fuse element. DESCRIPTION OF SYMBOLS 1...Insulating tube, 1b...Insulating space, 3...Low melting point alloy part, 4...Silver wire part, 5...Fuse element, 6...Extinguishing agent, 7...Upper electrode, 8...Lower part Electrode, 13...Display storage case, 20...
Extinction tube.

Claims (1)

[Scope of utility model registration request] A fuse element 5 in which a low melting point alloy part 3 and a silver wire part 4 are connected in series and an arc extinguishing tube 20 is placed on the outer periphery of the low melting point alloy part 3 is spirally wound around the outer periphery of a winding core and placed inside the insulating cylinder 1. The both ends of the housed element 5 are connected to the upper and lower electrodes 7 and 8 fixed to the upper and lower parts of the insulating tube 1, and the insulating space 1b of the insulating tube 1 is filled with an arc extinguisher 6, and the Place the display case 1 at the bottom end of the core.
In the current-limiting fuse for full-area high-voltage cut-out in which the winding core 3 is directly connected and extended, a flap-like widening part 22a centered on the axis of the winding core is formed on the guide fitting 22 fixed to the upper end of the winding core, and the widening part 22a is formed around the axis of the winding core. Engagement of the portion 22a with the upper electrode 7 and the display storage case 1
By engaging the center of the lower cover 16 attached to the lower end of the insulating cylinder 1 of No.
A full-area type high-voltage cutout current-limiting fuse, characterized in that the fuse is installed at the center of an insulating cylinder 1.