JPH0566723B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a current limiting element unit, and in particular, to a current limiting element unit, which is connected to a terminal fitting at both ends by screws, and which is installed in a machine using a reinforcing pipe in which the current limiting element is housed. The present invention relates to a current limiting element unit that increases productivity without sacrificing physical strength and electrical stability.

[Conventional technology]

For example, in high voltage or extra high power distribution lines,
In order to protect equipment, supporting glass, insulated wires, etc. from dielectric breakdown caused by lightning surges, current-limiting element units with lightning protection functions are installed directly connected to or close to these equipment.

Figure 4 shows a conventional current-limiting element unit, which includes a non-driving current-limiting element 1 that is mainly composed of zinc oxide and has excellent voltage non-linearity, and electrodes 2 ( For example, the upper and lower terminals 3 and 4 that are connected via a thin plate of aluminum, silver, etc., these current limiting elements 1, and the rubber that directly covers and molds the outer peripheral surfaces of the upper and lower terminals 3 and 4 except for a part. It is composed of an insulator 5. This rubber insulation 5 not only insulates and covers the current limiting element 1 and the upper and lower terminals 3 and 4, but also has the function of electrically and mechanically holding these elements and terminals together.

However, since the rubber insulation 5 generally uses EPT (ethylene propylene rubber) in consideration of various properties such as moldability, insulation properties, and tracking resistance, it tends to lack mechanical strength.
This may cause looseness between the element and the terminal, resulting in poor contact between the two, or may cause the electrodes 2 made of aluminum, silver, etc. formed by thermal spraying on both the upper and lower end surfaces of the element to peel off. In this case, it may be possible to simply increase the thickness of the rubber insulating member in order to improve its strength, but such a measure would not only not provide a fundamental solution, but would also require a longer vulcanization time during molding due to the increased thickness. Therefore, there is a risk that the element may be heated unnecessarily and the characteristics may change.

It is also possible to cover the insulating member with a synthetic resin that has mechanical strength, such as an epoxy resin that has properties relatively similar to those of EPT, but it may be exposed to a harsh outdoor environment for a long time. It cannot be said that it has sufficient reliability in terms of durability and electrical characteristics to be used.
Furthermore, the adhesion of the resin to the elements and terminals during molding is improved.
Since it is inferior to EPT, there is a risk that rainwater may enter through the gap formed between the two, leading to a decrease in insulation.

Therefore, a current limiting element unit (Utility Model Application No. 59-177905) shown in FIG. 5 was developed. This current-limiting element unit is a prismatic current-limiting element made of a sintered body whose main component is zinc oxide, and has excellent voltage nonlinearity and non-current characteristics at commercial frequencies. 6, and upper and lower electrodes 7 and 8 are formed on each of the upper and lower end surfaces of the current limiting element 6 by spraying metal such as silver or aluminum. The upper and lower electrodes 7 and 8 are connected to upper and lower terminals 9 and 10.
is connected. The upper and lower terminals 9 and 10 are the first
Insulating member 11 (for example, polyphenylene oxide resin [PPO] or noryl resin [PET],
The connection is fixed using polyester (thermoplastic) [PBT], etc.). The first insulating member 11 is surrounded by a second insulating member 12 (e.g., ethylene propylene rubber [EPT]).

According to this current limiting element unit, the outer circumferential surface of the current limiting element 6 and the electrode connection portions of the upper and lower terminals 9 and 10 are made of a synthetic resin having mechanical strength and excellent heat resistance. At the same time, from the outside of the first insulating member 11, a second insulating member 11 made of rubber having excellent heat resistance and tracking resistance is added.
Since the insulating member 12 is coated and molded so as to be in close contact with the upper and lower terminals 9 and 10 and the first insulating member 11, mechanical strength can be further increased without reducing electrical insulation, weather resistance, and tracking resistance. . In addition, since it is double coated and molded, it is reliably waterproof against the intrusion of rainwater, etc., so there is no deterioration in insulation.Furthermore, the second insulating member 12 made of EPT is heated during vulcanization molding. However, in this case, this heat is blocked as much as possible by the first insulating member 11, so that characteristic deterioration due to unnecessary heating of the current limiting element is not caused.

[Problem that the invention seeks to solve]

However, in the conventional current limiting element unit shown in Fig. 4, multiple steps are required to perform double coating molding on the current limiting element.
It has the disadvantage that it takes a lot of time to produce each piece, reduces productivity, and is unsuitable for mass production.

[Means and actions for solving problems]

The present invention has been made in view of the above,
In order to improve productivity without reducing mechanical strength or electrical stability, a current limiting element is built into the reinforcing pipe with multiple openings, and the terminal fitting and reinforcing pipe are screwed together. After electrically connecting the terminal fitting and the current limiting element, a current limiting element unit is provided in which the outer periphery of the reinforcing pipe and the gap between the reinforcing pipe and the current limiting element are filled with a rubber mold body.

〔Example〕

Hereinafter, the current limiting element unit according to the present invention will be explained in detail based on the attached drawings.

FIG. 1 is a sectional view of a current limiting element unit 15 according to the present invention. The current limiting element unit 15 mainly includes a reinforcing pipe 16 (for example, an FRP pipe, etc.) and zinc oxide contained in the reinforcing pipe 16.
Discontinuous current limiting element 1 with excellent voltage nonlinearity
7 and electrodes 2 provided on both end surfaces of the current limiting element 17
5a, 25b (for example, thin plates or vapor deposition of aluminum, silver, etc.) and the two current limiting elements 17a, 17b, and a disc-shaped spring 18 that urges the current limiting elements 17a, 17b to the outside. , terminal metal 19a screwed into both ends of the reinforcing pipe 16,
19b, and a rubber mold 20 (for example, EP rubber, ethylene propylene rubber, etc.) that is filled in the outer periphery of the current limiting element unit 15 and the gap between the reinforcing pipe 16 and the current limiting element 17.

A rubber mold 20 is placed around the outer periphery of the reinforcing pipe 16.
A plurality of openings 21 are provided for guiding the inside of the terminal, and thread grooves 22 are provided at the inner periphery of both ends for screw-fitting with terminal fittings.

The terminal fittings 19a and 19b each have a threaded groove 23 on the outer periphery of the end thereof for threaded engagement with the reinforcing pipe 16.
is provided.

As shown in FIGS. 2A and 2B, the spring 18 has the function of urging the spring 18 outward against a certain external pressure so as to obtain multi-contact with the current limiting elements 17a and 17b, for example.

In the above configuration, the current limiting element unit 15 according to the present invention is connected in parallel to equipment, supporting glass, etc. in a high-voltage or extra-high power distribution line, and when an abnormal voltage such as a lightning surge occurs. , the valve action of the current limiting element 17 protects the equipment, supporting glass, etc. from dielectric breakdown.

Next, the manufacturing process of the current limiting element unit according to the present invention will be explained.

First, as shown in FIG.
Two current-limiting elements 17a and 17b formed therein and a spring 18 are housed (the spring 18 is interposed between the current-limiting elements 17a and 17b). Second,
As shown in FIG. 3B, the terminal fittings 19a and 19b are screwed onto both ends of the reinforcing pipe 16. In this state, the current limiting elements 17a and 17b in the reinforcing pipe 16 are
The position within the reinforcing pipe 16 is fixed by the external pressure caused by the screw fitting of the terminal metals 19a and 19b and the biasing force of the spring 18. Third, rubber molding is performed around the reinforcing pipe 16 in a state where the terminal fittings 19a and 19b are fitted. As a result, the rubber mold 20 enters around the reinforcing pipe 16 and from the opening 21 of the reinforcing pipe 16, and the void inside the reinforcing pipe 16 is also filled with the rubber mold 20.
more tightly packed.

Mechanical strength is also guaranteed because the void in the reinforcing pipe 16 is filled with the rubber mold 20 as described above.

〔Effect of the invention〕

As explained above, according to the current-limiting element unit according to the present invention, the current-limiting element is built in the reinforcing pipe having a plurality of openings, and the terminal fitting and the current-limiting element are connected by screwing the terminal fitting and the reinforcing pipe. After electrical connection, a rubber mold is filled in the outer periphery of the reinforcing pipe and the gap between the reinforcing pipe and the source element, improving productivity without reducing mechanical strength or deteriorating electrical stability. be able to.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the current limiting element unit according to the present invention, Fig. 2 A and B are structural explanatory diagrams of the spring used in the current limiting element unit according to the present invention, and Figs. 3 A and 3 are
4 and 5 are explanatory diagrams showing the structure of a conventional current limiting element unit. Explanation of symbols, 15...Current limiting element unit, 16
... Reinforcement pipe, 17a, 17b ... Current limiting element,
19a, 19b...terminal fitting, 20...rubber mold, 21...opening, 22, 23...screw groove.

Claims (1)

[Claims] 1. A current limiting element having a predetermined mechanical strength and non-linearity is housed inside, has a plurality of openings on the circumferential surface, and is screwed to terminal fittings at both ends. A reinforcing pipe having a threaded portion, and a rubber mold body applied from the outer periphery of the reinforcing pipe, formed on the outer periphery of the reinforcing pipe, and filling a gap between the reinforcing pipe and the current limiting element through the opening. A current limiting element unit, characterized in that the terminal fittings screwed to threaded portions at both ends of the reinforcing pipe are in close contact with the electrode surface of the current limiting element due to their screwing force.