JPH03187112A - Bushing - Google Patents

Abstract

PURPOSE:To avoid danger such as rupture and scattering by comprising filler composed of single silicon gel or composite substance of silicon gel and inorganic grain insulating material. CONSTITUTION:Filler which is composed of single silicon gel or composite substance of silicon gel and inorganic grain insulating material is comprised. The silicon gel 18 has not only excellent electrical and thermal property but also has cohesion and adhesion in a gelatin form after curing. As a result, if an insulating tube 11 is damaged or broken due to lopsided heat, because it is separated in pressure from an electric apparatus mainframe no rupture occurs resulting from inner pressure. The cohesion and adhesion of the silicon gel prevents the fragments of an insulator portion from scattering. It is thus possible to ensure safety that is free from rupture and scattering if damages such as crack, rib-chipping, etc., to the bushing insulating tube 11 take place.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to bushings, and more particularly to their internal insulation configuration.

(Prior Art) As is well known, bushings are used to insulate lead wires of electrical equipment such as circuit breakers and transformers, cable heads, and through-wall bushings.

The general structure of this bushing is that a center conductor is passed through a porcelain insulator tube, and the gap between the center conductor and the insulator tube is filled with an insulating medium.

Depending on the type of this insulating medium, oil-filled bushings.

There are SF, gas bushing, etc.

By the way, in recent years, due to the demand for reducing the space of substations, S
Since there are many applications in which gas is used as an insulating medium, the bushing for a gas circuit breaker shown in FIG. 2 will be explained as an example.

Gas circuit breakers rely on the unique thermochemical properties and electrical negativity of SF, a gas, and take advantage of its excellent arc extinguishing performance and insulation properties. In the figure, bushings for the gas circuit breaker are placed above both ends of a horizontally arranged metal pressure tank 1.

A porcelain insulator tube 2 is attached, and a center conductor 3 is fixed therein by passing through it vertically.

- On the other hand, the inside of the pressure tank 1 is an arc extinguishing chamber, and the S
F, gas is filled with a pressure of approximately 5 kgf/d and sealed off. The gap between the inner surface of the insulator tube 2 and the center conductor 3 is filled with SF and gas 4 at the same pressure as in the pressure tank 1, so as to ensure internal insulation.

(Problem to be Solved by the Invention) However, with the bushing configured as described above, the porcelain insulator tube may have some abnormality, such as mechanical damage (cracks, breakage, etc.) or electrical damage (thermal breakage, etc.). (This is because insulators are susceptible to uneven heat destruction when exposed to arcs due to floodover, etc.) If the insulators are exposed to arcing due to floodover, etc., the gas pressure inside the insulators will cause the insulators to rupture or scatter, which is extremely dangerous. .

Moreover, the accident in this case is not only limited to this, but because the circuit breaker cannot fulfill its original mission as a protective device, there is a risk that it will develop into a serious accident.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a bushing that is safe and easy to manufacture and maintain without causing any risk of rupture or scattering even if abnormalities such as cracks or poor seals occur in the insulator tube. It is something.

[Structure of the invention]

(Means for Solving Problem No. 111) The present invention includes an insulator tube, an insulator penetrating through the insulator tube, an upper insulator tube supported by an upper flange of the insulator tube, and a lower insulator tube supported by an insulator provided at the lower part of the insulator tube. A silicone gel alone or a composite of silicone gel and inorganic granular insulating material, which is filled in the gap between the center conductor and the insulator tube, has a gap in the upper part, and has a conductive coating on its surface. It is constructed from a filler consisting of:

(Function) The silicone gel used as a filler not only has excellent electrical and thermal properties, but also has an agar-like, sticky and adhesive property after hardening, and has an insulating strength that is approximately 5 kgf/
Corresponds to aJ pressure.

Therefore, even if the insulator is damaged or unevenly heated, it will not burst due to internal pressure because it is separated from the pressure inside the electrical equipment body. In addition, the adhesiveness of silicone gel,
IA! The adhesion property also prevents fragments of the porcelain part from scattering. These effects ensure that the silicone gel remains within the insulator, and the insulation performance against the operating voltage can be maintained.

Therefore, even if damage such as cracks or chipping occurs in the bushing insulator tube, it is safe without bursting or scattering, and moreover, it is possible to ensure the protection performance for the main body of the electrical equipment.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention.

In the figure, metal flanges 12a and 12b are provided at both ends of the insulator tube 11, and the lower flange 12
An insulating spacer 13 is provided at b. A contactor 14 is provided at the center of the insulating spacer 13, and the lower end of the center conductor 15 is in contact with the contactor 14. This center conductor 15 has its upper portion fixed to the flange 12a on the upper side of the insulator tube 11,
An upper terminal 17 is provided at the end that passes through the upper cover 16 that closes the upper end of the insulator tube 11, so that it can be connected to the main circuit. Further, the gap between the insulator tube 11 and the center conductor 15 is filled with silicone gel 18 as an insulating medium.

The general characteristics of this silicone gel 18 are as shown in Table 1. Before filling, two liquids, liquid A (main ingredient) and liquid B (curing agent), are mixed at a ratio of about 1=1. Its viscosity is 800-1
000 CP, it has excellent fluidity and can be easily filled into narrow spaces.
l(g), it can be easily degassed in a few minutes.

Furthermore, after being filled, it hardens after about 16 hours at room temperature, but this is because the hardening process utilizes an addition reaction.

No by-products are generated during the reaction, the withstand voltage does not decrease during the reaction, and electricity can be applied immediately after filling.

Furthermore, after curing, it is in a gel state intermediate between a liquid and a solid. This characteristic is shown in Table 2.

Electrical and thermal properties unique to silicone (siloxane),
Softness, stickiness, and adhesion peculiar to gel (low crosslinking density),
Many features such as vibration absorption performance and stress relaxation due to the low elastic modulus can be utilized.

(The following is a margin) Table 1 However, since the volumetric expansion coefficient is somewhat large, a gap 19 is provided at the upper end of the insulator tube 11 in consideration of expansion and contraction due to temperature changes. A coating film 20 is formed on the uppermost surface of the silicone gel 18 in the gap 19 by conductive surface treatment, and is fixed at the potential of the center conductor 15 to suppress partial discharge in the gap 19.

On the other hand, the lower side of the bushing is fixed to the wall plate 21 of the pressure tank of the circuit breaker, and is connected to the arc extinguishing chamber via the contact 14.

In one or more embodiments, the gap between the insulator tube 11 and the center conductor 15 is filled with silicone gel 18, but it may also be filled with, for example, glass bulbs (indicated by reference numeral 22 in FIG. 1) as an insulating filler. The silicone gel 18 may be filled in the manner described above, thereby reducing the amount of silicone gel. Furthermore, the bushing of the present invention is not limited to use in gas circuit breakers, but can also be used in transformers and the like.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be obtained. That is, even if an abnormality occurs in the insulator tube portion of the bushing due to cracks or poor sealing, there will be no rupture or scattering and it is safe because the gas is separated. Silicone gel has adhesion, adhesion, and sealing properties, so it does not leak like oil or gas, and can maintain insulation performance over a long period of time, allowing it to maintain its function as a protective device for electrical equipment. In addition, the structure of the sealing part is simplified, and handling workability during and after filling is also good, making manufacturing and maintenance easier and improving economical efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a partially cutaway front view of a conventional gas circuit breaker using gas as an insulating medium.

Claims (1)

[Claims] an insulator tube; a center conductor that passes through the insulator tube; an upper part is supported by the upper flange of the insulator tube; and a lower part is supported by an insulator provided at the bottom of the insulator tube; this center conductor and the insulator tube; It is characterized by being composed of a silicone gel alone or a filler consisting of a composite of silicone gel and an inorganic granular insulating material, which is filled in the voids between the silicone gel and the voids above and has a conductive film formed on its surface. bushing.