JPH0393417A - Insulation structure of gas insulated electric machine - Google Patents

Abstract

PURPOSE:To reduce the size of electric equipment or container to be placed in insulating gas by arranging a rod type charging section having hemispheric end section in the insulating gas and forming an epoxy resin insulating layer, mixed with material having high dielectric constant, on the hemispheric surface. CONSTITUTION:A hemispheric surface 4ao is formed at the end of a rod type charging section projecting outward from an electric equipment. A hemispheric surface 4ao having curvature approximately same as the radius of a movable contactor 4a is formed at the rear end of the movable contactor 4a. An epoxy resin insulating layer 9 is formed on the outer circumference of the hemispherical surface 4ao, and the thickness of the insulating layer 9 is increased around the hemispheric surface 4ao. The insulating layer 9 is composed of epoxy resin mixed with substance having high dielectric constant, e.g. barium titanate. and applied tightly onto thr hemispheric surface 4ao. By such arrangement, strength of electric field at the charged section can be suppressed end insulating characteristic at the end of rod type charging section of an electric equipment can be improved without enlarging the profile or the installation area of the electric equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an insulation structure for electrical equipment housed in a gas-insulated switchgear or the like.

(Prior Art) In FIG. 3 showing an example of a conventional gas insulated switchgear,
A high-pressure vacuum circuit breaker 2 is housed in the front part of the box body 1, which has a front door 1a on the left side and has an airtight structure filled with sulfur hexafluoride gas (hereinafter referred to as insulating gas). A new circuit switch 4, which opens and closes by moving a rod-shaped movable contactor 4a with an operating arm 4b, is attached to the section and the floor, and the front end of the switch 4 is connected to the circuit breaker 2 through a conductor 3. Further, on the rear wall of the box body 1, a bus bar 5 attached to the paddle 7 airtightly penetrates the left and right side plates (not shown) of the box body 1 with insulating pushers (not shown), and from this bus bar 5, conductors are respectively connected. 3 is connected to the rear terminal of the new circuit device 4 on the ceiling. Furthermore, a cable head 6 is attached to the rear of the floor of the box 1, and is connected by a conductor 3 to a rear terminal of a disconnector 4 attached to the center of the floor.

By the way, in gas-insulated closed switchboards in which electrical equipment is housed and electrical equipment is connected between them by conductors, the ends of live parts are made with a large curvature in order to prevent discharge due to electric field concentration. Since this is not possible with a rod-shaped end such as the rear end of the movable contact 4a, a large spherical shield ring 8 is attached as shown in FIG.
For example, Japanese Patent Laid-Open No. 60-128807). This is because the insulating gas exhibits strong electrical negativity, and dielectric breakdown is determined by the maximum electric field strength.

(Problems to be Solved by the Invention) However, this shield ring 8 not only takes time to manufacture, but also physically restricts the arrangement of adjacent devices.

For example, in FIG. 3, the operating arm 4b and conductor 3 connected to the rear terminal of the new circuit device 4 must be placed avoiding the shield ring 8. Furthermore, as the interphase dimension of the disconnector 4 increases, not only does the external size become larger, but also the increased weight of the shield ring 8 increases the operating force of the operating arm 4b. As a result, the box body 1 also becomes larger, and the characteristics of a gas-insulated closed switchboard are lost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain an insulating structure for electrical equipment that does not increase the diameter of the end of the equipment used in an insulating gas, and does not increase the external size or installation area of the equipment to which it is applied.

[Structure of the Invention] (Means and Effects for Solving the Problems) The present invention provides an insulating structure for an electrical device used in an insulating gas, in which the end of a rod-shaped live part protruding outward from the electrical device is made into a hemispherical surface. , this hemisphere is made of, for example, barium titanate (
By closely covering the electrical field with an insulating material made of epoxy resin mixed with a material with a high dielectric constant such as BaTiO3), the electric field strength of the above-mentioned live parts can be suppressed, and electricity can be transmitted without increasing the external size and installation area of the applicable equipment. This is an insulation structure for electrical equipment that improves the insulation properties of the end of the rod-shaped live part of the equipment.

(Example) Hereinafter, an example of the insulating structure for an electrical device of the present invention will be described with reference to FIG.

FIG. 1 shows an example in which the insulating structure of the electrical equipment of the present invention is applied to the rear end of the movable contact 4a of the disconnector 4 shown in FIG. , movable contact 4
A hemispherical surface 4ao having a radius of curvature approximately equal to a is formed, and an insulating layer 9 made of epoxy resin is formed on the outer periphery of this hemispherical surface 4ao, and this insulating layer 9 is thicker around the hemispherical surface 4ao.

Note that the operating arm 4b has the same configuration as the conventional method.

Here, the insulating layer 9 contains epoxy resin as a main component,
For example, powder 10 of a material having a high dielectric constant, such as barium titanate (BaTiOi), strontium titanate, and a pb-based composite perovskite compound, is mixed and cast. In this case, by casting with the hemispherical surface 4ao facing downward, the powder 10 with a large dielectric constant will precipitate,
It collects on the surface of the insulating layer 9.

This is because, while the specific gravity of epoxy resin is 1.2, for example barium titanate has a higher specific gravity of 5.4, so when these are mixed and poured into a liquid form, the barium titanate, which has a higher specific gravity, precipitates and hardens. This is to do so. Therefore, in the insulating layer 9 in the region in contact with the metal of the movable contactor 4a, there is less powder 1o having a large dielectric constant. In order to create the composition of the components of the insulating layer 9 in this manner, the volume ratio of the epoxy resin to the powder 10 may be reduced to half or less of the powder 1G. That is, near the surface of the insulating layer 9, a large amount of powder 10 is hardened with epoxy resin, and near the movable contact 4a, most of the powder 10 is made of epoxy resin.

In the insulation structure of electrical equipment configured in this way, the relative permittivity near the surface of the insulating layer 9 is approximately twice as large as the relative permittivity of the epoxy resin (generally 4 to 6), and The capacitance of increases.

Thereby, the surface of the insulating layer 9 becomes easily charged, and the surface of the insulating layer 9 is charged with an electric charge having the same polarity as the polarity of the voltage applied to the movable contact 4a.

Generally, when an electrode is coated with an insulating layer, it has the effect of suppressing electron emission from the electrode, suppressing electric field strength by the insulating layer, and increasing the apparent radius of curvature of the electrode by the insulating layer, thereby increasing the withstand voltage. Therefore, the fact that the insulating layer is more likely to be charged to the same polarity as the applied polarity means that the effect of increasing the apparent radius of curvature is more likely to occur. In other words, an epoxy resin with a high dielectric constant can improve the withstand voltage. (Note: Of course, in Fig. 1, the epoxy resin thickness of the insulating layer 9 is the required thickness, for example, for rated voltage 77h1 withstand voltage value impulse voltage 400kv, 400k▼/40kv/mm = 10
Furthermore, in this insulation structure, the flashover path runs from the boundary between the exposed surface of the movable contact 4a and the insulation layer 9, that is, from point A shown in FIG. After that, it becomes the grounded metal surface E. For this reason, as described above, dielectric breakdown in the insulating gas is determined by the maximum electric field strength, so the electric field strength at point A must be suppressed. This is because the relative permittivity of the insulating layer 9 is greater than the relative permittivity of the insulating gas (1), so a triple bond between the metal live part, the solid insulating layer, and the gas insulating layer is formed in this part, increasing the electric field strength. This is because it has electric field specificity. However, the electric field strength at point A is suppressed to a minimum because the dielectric constant of the insulating layer 9 is kept to a minimum to prevent powder lO from being mixed in, so the dielectric constant does not become as large as at the bottom of the hemispherical surface 4ao, and the electric field strength decreases. can prevent a rise in

As a result, the hemispherical surface 4ao, which is close to the ground metal plate E and has the maximum electric field strength, has an apparently large radius of curvature of the electrode due to the insulating layer 9 having a large dielectric constant, suppressing the electric field strength, and
Since the specific dielectric constant is prevented from increasing at the point, electric field singularity in which the electric field strength increases is less likely to occur. In addition, the withstand voltage characteristics with respect to the ground metal plate E can be improved.

Therefore, without increasing the size of the end of electrical equipment used in insulating gas as in the past, the external size of the equipment can be reduced.
By taking advantage of the characteristics of gas-insulated switchgear aimed at miniaturization, it is possible to obtain an insulation structure for electrical equipment that can reduce the ground area.

If point A in FIG. 2 is sufficiently far away from the ground metal plate E and the electric field strength is small, increase the amount of powder 10 mixed into the insulating layer 9 to increase the dielectric constant of the entire insulating layer 9. It also has the effect of suppressing the electric field strength.

In addition, in FIGS. 1 and 2, when there is a risk that the boundary between the hemispherical surface 4ao and the insulating layer 9 may peel off due to expansion or contraction of the movable contact 4a due to operation or stoppage of equipment, for example, A stress relaxation layer such as a silicone resin adhesive may also be provided.

Alternatively, the movable contact 4a may be made of a copper rod for only the current-carrying part on the left side, and the part to which the insulating layer 9 is applied may be made separately (note: the material may also be iron or AI) and connected to the left side with screws. In this case, there is an advantage that the movable contactor 4a can be manufactured more easily.

[Effects of the Invention] According to the above-mentioned first aspect of the present invention, the end of the rod-shaped charged part provided in an insulating gas is made into a hemispherical surface, and a material having a large relative permittivity is mixed into this hemispherical surface to form an insulating layer made of an epoxy resin. Since the maximum electric field strength is suppressed and the withstand voltage characteristics are increased by forming an insulating gas, it is possible to obtain an insulating structure for electrical equipment that can downsize electrical equipment and storage devices used in insulating gas.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view showing an embodiment of the insulating structure for electrical equipment of the present invention, Fig. 2 is a partially enlarged sectional view of Fig. 1, and Fig. 3 is an example of application of the conventional insulating structure for electrical equipment. FIG. 4 is an enlarged view of the main part of FIG. 3.

Claims (1)

[Claims] In an electrical device that is housed in a box filled with insulating gas and in which the end of a rod-shaped live part protrudes outward, the end of the rod-like live part is made into a hemispherical surface, and this hemispherical surface is made of a material with a high dielectric constant. An insulation structure for gas-insulated electrical equipment characterized by being cast-molded using epoxy resin mixed with powder.