JPH0243322B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a current limiting element unit used to protect equipment used for power transmission or distribution, such as insulators and transformers, from abnormally high voltage caused by lightning. The present invention relates to a method of manufacturing the current limiting element unit.

In the conventional method of manufacturing current limiting element units, after attaching terminals to both ends of the current limiting element in a contact manner,
The method of covering them with an insulating material may cause the relative position of the current limiting element and the terminal to become incorrect during the work, resulting in a change in electrical characteristics, or the contact pressure may become loose, causing a connection failure. Another disadvantage is that the current limiting element may be deteriorated by moisture coming out of the insulating material for coating. In addition, there is also the drawback that it would be necessary to spend a great deal of time and money to prevent these problems.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a current limiting element unit that eliminates the above-mentioned drawbacks, allows easy manufacturing, and prevents increases in product weight and cost. It is something to do.

The drawings showing the embodiments of the present application will be described below. Reference numeral 1 denotes the arm of a utility pole, which, as is well known, is grounded to the earth via a grounding wire. Reference numeral 2 denotes a high-voltage pin insulator (for example, a No. 10 solid high-voltage pin insulator) as an example of an insulator, one end of which is fixed to the cross arm 1 with a support bolt 3 and a nut 4, and the other end is fixed to an electric wire. As is well known, a high-voltage power distribution line 5 is fixed to the part with a bind wire 6. The high voltage distribution line 5 is an insulated wire. Next, lightning protection device 7
I will explain about it. 8 is a support piece, which is attached to the nut 4
It is fixed to armrest 1 by. This support piece 8
is made of metal material. Reference numeral 10 denotes a current limiting element unit, which is attached to the tip of the support piece 8 with a nut 11. Reference numeral 12 denotes a flashing ring surrounding the insulator 2, which is attached to the current limiting element unit 10 using a set screw 13.
It is attached to. Next, the current limiting element unit 10
I will explain in detail. 15 is a current limiting element, which is a cylindrical element made of a material mainly composed of zinc oxide mixed with a trace amount of metal oxide, and then fired at a high temperature of 1200 to 1300°C, which becomes a sintered body. There is. This element 15 has excellent voltage nonlinearity.
Electrode surfaces 15a and 15b are formed on the upper and lower end surfaces of this element 15 by spraying metal such as silver or alumina. A terminal 16 is made of a metal material such as stainless steel, brass, or copper, and has a contact portion 17 that contacts the electrode surface 15a, a rotation prevention portion 18, a connection portion 19, and the like. The connecting portion 19 has a female threaded hole so that the set screw 13 can be screwed therein. Reference numeral 20 denotes a terminal, which is made of the same material as the terminal 16, and this terminal 20 has a contact portion 21 that contacts the electrode surface 15b, a rotation prevention portion 22, a connection portion 23, and the like. Furthermore, the connection part 23
is constituted by a threaded rod, into which the nut 11 can be screwed. Next, 25 is a holding cylinder which can maintain the contact state between the electrode surfaces 15a, 15b of the current limiting element 15 and the contact parts 17, 21 of the terminals 16, 20, and is made of epoxy, ABS, AAS, It is formed using a synthetic resin material with excellent insulation properties, such as urea resin. This holding cylinder 25 consists of a main body 26 and a lid 27 screwed onto the main body 26. 25'
indicates the threaded part. The main body 26 is formed with the contact portion 21 of the terminal 20 embedded therein. 28 indicates a support portion. On the other hand, in the lid body 27, reference numeral 29 denotes a through hole and a contact portion 1 of the terminal 16.
It is a part through which parts other than 7 are inserted,
The contact portion 17 is connected to the current limiting element 1 around the through hole 29.
It serves as an annular presser portion 30 for pressing against 5. Next, 31 indicates a pleated outer cylinder, which is made of resin material such as epoxy, ABS, AAS, or neoprene.
It is formed by molding a material with excellent weather resistance and electrical insulation properties, such as a rubber material such as butyl, for example, by injection molding, casting, or transfer molding. Also, upper and lower terminals 1 are provided on the surface of this outer cylinder 31.
A large number of pleats 32 are formed to increase the creepage distance between 6 and 20. Reference numeral 33 indicates a filler filled in the space between the outer cylinder 31 and the terminal 16 or 20. As the filler 33, a material that remains rubber-like even after being naturally cured after being filled is used. Also, as the filler 33, silicon-based materials are preferable because they are excellent in heat resistance, cold resistance, water resistance and weather resistance, as well as electrical insulation properties.

In the case of the above structure, if an abnormal high voltage is applied due to lightning or other causes to the high voltage distribution line 5 whose insulation coating has been damaged near the insulator 2 for some reason, the above-mentioned damage to the high voltage distribution line 5 An arc is generated from the damaged part of the coating toward the arm 1 or the insulator metal fitting 2a that is grounded. In this case, since the flashing ring 12 is present between the high voltage distribution line 5 and the cross arm 1, discharge is started between the damaged part of the coating and the flashing ring 12. The current due to the discharge flows through the flash ring 12, the terminal 16, and the current limiting element 1.
5. Flows to the ground through the terminal 20, the support piece 8, the cross arm 1, and the ground wire. In this case, since the current limiting element 15 has excellent voltage non-linearity, the response to the abnormally high voltage is fast, and the discharge current based on the discharge is discharged in the order of several tens of microseconds. Therefore, even if an arc occurs due to the above-mentioned abnormal high voltage, the current limiting element will only allow the arc current caused by the abnormal high voltage to flow, and will block the superposition of the commercial frequency for the subsequent 50 or 60 cycles. and cut off the following flow.

Since the above operation is performed, in the above case, the arc does not lick the surface of the high voltage pin insulator 2 due to the presence of the flash ring 12, and damage to the high voltage pin insulator 2 is prevented. With,
Uneven heat damage to the insulator 2 due to the occurrence of follow-on current is also prevented. Further, fusing of the high voltage distribution line 5 due to the occurrence of follow-on current is also prevented.

Next, the manufacturing procedure of the current limiting element unit 10 will be explained. First, the current-limiting element 15 is placed in the main body 26 of the holding cylinder in which the terminal 20 is installed, so that the electrode surface 15b is in contact with the contact part 2.
1 so as to be in surface contact with the electrode surface 15a of the current limiting element 15, and the contact portion 17 of the terminal 16 is brought into surface contact with the electrode surface 15a of the current limiting element 15. Next, the lid body 27 is inserted into the through hole 29 with the terminal 16 inserted thereinto. The covering screw portion 28 is screwed together. As a result, the presser part 30 is attached to the contact part 1 of the terminal 16.
7 to seal the inside of the holding cylinder 25, and a contact part 17 between the presser part 30 and the support part 28,
The current limiting element 15 and the contact part 21 are sandwiched, and the electrode surface 15
The positioning state of a, 15b and the contact portions 17, 21 and the contact pressure at each surface contact portion are maintained.

On the other hand, apart from the above operations, a mold 36 as shown in FIG. 4 is prepared. FIG. 4 shows one of the two halves of the mold, and a mold having a symmetrical shape is fitted with this mold 36 via a guide pin 37.

The semi-finished product 42 of the current limiting element unit formed as described above is placed in the molding space 4 of the mold 36.
Place it approximately in the center of 3. In this case, the terminals 16 and 20 in the semi-finished product 42 are each
8 and 39 and inserting the mounting holes 40 of these inserts 38 and 39 into the fixing pin 41 of the mold 36, the semi-finished product 42 is fixed so as not to move relative to the mold 36. do. In this state, the other mold (not shown) is placed over the mold and the mold is clamped.

Furthermore, apart from the above operations, an outer cylinder material, that is, a material for forming the outer cylinder is prepared. When AAS resin is used as an example of the outer cylinder material, the granular resin raw material is dried at 70 to 75°C for about 3 hours. The dried material is then heated to melt it. In that case, if the temperature exceeds 210°C, the raw materials will burn, so avoid raising the temperature higher than that (140 to 180°C is appropriate). Once the material as described above is ready, it is transferred from a well-known injection molding machine to the spool 4 of the mold 36.
4. Inject into the molding space, that is, between the inner surface of the mold 36 and the outer surface of the semi-finished product 42 via the runner 45 and gate 46. In the case of the above injection, the mold is prepared in advance.
The temperature is preferably 40 to 60°C, and the injection speed is preferably medium. Also, the injection pressure is 50Kg/cm ²
It is best to start at (gauge pressure) and gradually increase it. When the injection as described above is completed and the injected outer cylinder material has solidified, the mold clamp is loosened to separate the molds, and the inserts 38, 3 are inserted using the protruding pins 47, 47.
Make 9 stick out. Inserts 38 and 39 at both rear ends
from each terminal 16, 20. Next, the current limiting element unit 10 is completed by filling with the filler 33.

As described above, in the present invention, when manufacturing the current limiting element unit 10, the pleated outer cylinder 31 surrounding the current limiting element 15 is surrounded by a fluid outer cylinder material by plastic means. This has the effect that the current limiting element 15 can be surrounded in a highly watertight state and a highly insulated state can be maintained. Moreover, when the current-limiting element 15 is surrounded by a fluid outer cylinder material, the current-limiting element 15 is firstly positioned by the holding cylinder 25, and secondly, the current-limiting element 15 is positioned at the contact portion with the terminals 16 and 20. After satisfying three conditions in advance: maintaining contact pressure in that area and thirdly blocking flow of the fluid outer cylinder material to the current limiting element 15 side, the outer cylinder material is , the holding cylinder 25 is simply inserted into the mold 36 (the first to third injection molds are injected).
The above-mentioned material can be injected into the mold 36 without having to be careful about the above-mentioned problems), and the above-mentioned enclosing work can be carried out with good workability.

Furthermore, in the above manufacturing method, the holding cylinder 25 and the pleated outer cylinder 31 are both insulators, and they are integrated to achieve the same effect of maintaining insulation of the current limiting element 15. Outer cylinder 31
The advantage of this is that it can be made thin to reduce weight and cost. This has the effect of making it possible to provide a product that does not increase the weight or cost of the product as a whole, even though an extra holding cylinder 25 is used as described above.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and Fig. 1 is a partial front view showing how the current limiting element unit is used, and Fig. 2 shows the positional relationship among the flashing ring, support piece, insulator, and current limiting element unit. FIG. 3 is a longitudinal sectional view of the current limiting element unit, and FIG. 4 is a plan view of the mold. 15... Current limiting element, 16, 20... Terminal, 25
...Holding tube, 31...Folded outer cylinder, 36...Molding mold.

Claims (1)

[Claims] 1. Insert a current-limiting element with terminals in contact with one end and the other end into a mold for forming a pleated outer cylinder so that there is a space between the periphery of the current-limiting element and the mold. By injecting a fluid outer cylinder material for forming the pleated outer cylinder into the space and solidifying it, an insulating pleated outer cylinder is attached around the current limiting element in an encircling manner. In a method for manufacturing a current limiting element unit, the current limiting element with terminals in contact with one end and the other end is placed in advance in a solid holding cylinder made of an insulating material. Then, the positioning and contact pressure at the contact portion between the current limiting element and both terminals are maintained, and the flow of the outer cylinder material toward the current limiting element is blocked, and then the holding cylinder is The holding cylinder is charged into the mold so that there is a space between the peripheral surface of the holding cylinder and the inner surface of the mold, and then the outer cylinder material is injected into the space, and the outer cylinder material is poured into the holding cylinder. A method for manufacturing a current limiting element unit, characterized by solidifying it integrally with a current limiting element unit.