JPH0732528B2 - Cast insulator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cast insulator that supports a charging part of a high voltage electric device such as a gas insulated switchgear.

[Prior Art] FIG. 2 shows a gas-insulated conductor portion for connection with each device of a gas-insulated switchgear using a conventional cast insulator shown in, for example, Japanese Patent Publication No. 63-33368. Inside the cylindrical gas-insulated container (5), the conductor (7) is placed on the central axis thereof.
(7) is fixed via the insulating spacer (1) and the contact portions (8) and (8). The insulating spacer (1) comprises a high voltage side conductor (2) having a high voltage side electric field control electrode (3) and a grounding metal fitting (9) having a ground side electric field control electrode (4) made of thermosetting resin. It is a support member connected via an insulating part (6). Other electric devices (not shown) are connected to the other ends of the conductors (7) and (7). Also conductor (7)
Between the parts (7), the contact parts (8) and (8) are electrically connected to each other through the high-voltage side conductor (2) and a current flows. Insulating gas such as SF ₆ gas is sealed in the container in order to electrically and sufficiently insulate these high voltage charged parts from the gas insulating container (5).

Here, the electric field control electrodes (3) and (4) are (A) and (B) in the figure.
It has a function of relaxing the electric field in the portion indicated by, preventing the electric field from concentrating, and maintaining the dielectric strength of the insulating spacer (1). Therefore, it is an essential electrode for obtaining the insulating spacer (1) having excellent insulating properties.

[Problems to be Solved by the Invention] As described above, it has been a problem to embed an indispensable electric field control electrode as an embedded metal in an insulating spacer while mechanically maintaining sufficient strength. . Therefore, conventionally, the electric field control electrodes (3), (4), etc., are made of a porous sintered alloy such as tin, copper, bronze, etc., and the thermosetting resin is impregnated from the surface to the inside to cast an insulator. Had formed. Therefore, good mechanical strength could be maintained due to the contact surface between the porous sintered metal and the resin.

On the other hand, with the recent trend toward higher voltage and higher capacity of electrical equipment,
There is a demand for large-sized cast insulators with a diameter of more than 1 m as insulating spacers for gas-insulated switchgear for high voltage. However, when such a large-scale grounding-side electric field control electrode for an insulating spacer is conventionally made of the above-mentioned metal material, the wall thickness becomes large, which leads to an increase in weight and makes the manufacturing difficult. In addition, since the surface of the sintered metal has irregularities, there are various problems that it is difficult to maintain good withstand voltage performance for a long time in a high voltage electric field.

The present invention has been made to solve the above problems, and even if it is a large-sized insulating spacer, it can be easily manufactured with a light weight, and it has good mechanical strength. The purpose of the present invention is to obtain a cast insulator with high withstand voltage characteristics, which keeps the adhesion between various electrodes and resin for a long time.

[Means for Solving the Problems] The cast insulator according to the present invention is an embedding metal member made of one kind of metal selected from the group consisting of zinc and lead, and integrally hardened with the embedding metal member. A cast insulator, which is formed by a molded body of thermosetting resin mixed with an electrically insulating inorganic filler, wherein the amount of the inorganic filler mixed with the thermosetting resin is The coefficient of thermal expansion in the cured state of the mixture of thermosetting resins mixed with the filler is set to be substantially equal to the coefficient of thermal expansion of the selected metal.

[Operation] In the cast insulator according to the present invention, the thermosetting resin in which an appropriate amount of the inorganic filler is mixed has almost the same thermal expansion coefficient as the embedded metal fitting made of zinc or lead. Does not occur between embedded metal fittings.

[Embodiment] A cast insulator according to the present invention, which is an embodiment of the first embodiment,
It will be described with reference to the drawings. FIG. 1 is a partial sectional view of a gas-insulated switchgear using the cast insulator of the present invention as an insulating spacer (1).

In the figure, conductors (7) and (7) are supported and fixed on the central axis of a cylindrical gas-insulated container (5) through insulating spacers (1) and contact portions (8) and (8). There is. The insulating spacer (1) is composed of a high voltage side conductor (2) having a high voltage side electric field control electrode (3 ') and a grounding metal fitting (9) having a ground side electric field control electrode (4'). It is a supporting member connected via an insulating portion (6) made of a thermosetting resin. Other electric devices (not shown) are connected to the other ends of the conductors (7) and (7). Also conductor (7) (7)
Between the contacts (8) (8) and the high voltage side conductor (2) are electrically connected and a current flows. Insulating gas such as SF ₆ gas is sealed in the container in order to electrically and sufficiently insulate these high voltage charged parts from the gas insulating container (5).

The insulating spacer (1) is, for example, a zinc electric field control electrode (3 ') formed by pressing or squeezing.
Along with the high-voltage side conductor (2) and the grounding metal fitting (9) each having (4 '), they are integrally cast using epoxy resin with alumina (Al ₂ O ₃ ) as a filler. .

Since the respective electric field control electrodes (3 ') and (4') having a function of relaxing the electric field for the purpose of not causing the electric field concentration act on the portions shown by (A) and (B) in FIG. Insulation characteristics can be obtained. The electric field control electrodes (3 ') and (4') on the high voltage side and the ground side are required to have good adhesion as an embedded metal fitting. Therefore, in this embodiment, these are manufactured by pressing zinc or squeezing to give good adhesion. That is, the coefficient of thermal expansion of zinc is 31 × 10 ^-6 1 /
° C (The Institute of Metals: Metal Data Book). On the other hand, the epoxy resin used here is adjusted to have a coefficient of thermal expansion of 32 × 10 ⁻⁶ 1 / ° C. by filling an appropriate amount of the above-mentioned alumina. Therefore, even if thermal expansion and contraction occurs due to temperature change, only a very small amount of stress is generated between the resin and the metal, and it is possible to withstand mechanically enough. The insulating part (6) made of the resin containing the filler and the electric field The adhesion with the control electrodes (3 ') and (4') is kept strong. Generally, peeling occurs due to thermal expansion and contraction between the electric field control electrodes (3 ') (4') on the side of the high voltage electric field and the resin containing the filling material, and if a gap is formed, partial discharge occurs, and if it occurs for a long time In the end, it may lead to dielectric breakdown. However, in the above-described structure of the present invention, the electric field control electrodes (3 ') and (4') having a smooth surface are embedded in the resin containing the filler to eliminate such a fear and maintain a good insulation state for a long time.

Since the electric field control electrodes (3 ') and (4') are made of zinc,
The surface can be processed much smoother than the sintered alloy. Therefore, there is no possibility of causing dielectric breakdown due to the electric field concentration on the uneven portion of the surface, and good insulation performance is maintained for a long time. Furthermore, since zinc, which is a metal, is superior in mechanical strength to the sintered alloy, the electric field control electrode (3 ') of the present invention in FIG. 1 is used.
As can be seen from (4 ') in comparison with those of the conventional example in FIG. 2, it is possible to manufacture a lightweight electrode having a thinner structure. Therefore, a large electrode constituting a large cast insulator as an insulating spacer for a gas insulated switchgear for high voltage and large capacity can be manufactured relatively lightly.

In the above examples, an alumina-filled epoxy resin was described as an example of an insulator, but even if a general inorganic filler such as silica (SiO ₂ ) is appropriately mixed, the coefficient of thermal expansion can be adjusted to an electrode metal. Similar effects can be achieved by approaching that. Also, the same effect can be obtained by using a thermosetting resin other than the epoxy resin. Even when lead (coefficient of thermal expansion 29 × 10 ⁻⁶ 1 / ° C.) is used instead of zinc as the electrode material, the same effect can be obtained by adding a little more filler than in the above-mentioned examples.

In this embodiment, aluminum or aluminum alloy is used for the high voltage side conductor (2). Because this part is shielded by the high-voltage side electric field control electrode (3 '), the electric field strength is low, and due to the difference in thermal expansion coefficient between resin and aluminum alloy, the high-voltage side conductor should be used. (2)
Since there is no problem even if a gap occurs between the insulating part (6) and the insulating part (6), it is possible to use an aluminum alloy or the like with an emphasis on enhancing the current carrying capacity.

[Effects of the Invention] As described above, according to the present invention, an embedding metal fitting, which is required to have good adhesiveness for being integrally embedded in a thermosetting resin containing a filler during casting, is formed of zinc or lead. Since the cast insulator is formed by using, the embedded metal fitting has almost the same thermal expansion coefficient as the resin portion, and the surface of the embedded metal fitting can be finished smoothly. Therefore, there is no risk that this embedded metal fitting will form a gap with the resin as an electric field relaxation electrode of the insulating spacer for high electric field, and there will be no electric field concentration due to the unevenness of the surface of the embedded metal fitting. This has the effect of obtaining a cast insulator that maintains its insulating properties for a long time. In addition, since the embedded metal such as zinc or lead can be thinned and the weight increase can be reduced as compared with the sintered metal, the above cast insulator can be easily enlarged.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a gas-insulated conductor portion for connecting to each device of a gas-insulated switchgear using a cast insulator as an insulating spacer according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a gas-insulated conductor portion for connecting with each device of a gas-insulated switchgear using a conventional cast insulator. In the figure, 1 is an insulating spacer, 3'is an electric field control electrode, 4 '
Is a ground side electric field control electrode, and 6 is an insulating part.

Claims (1)

[Claims] 1. An embedding metal member made of one type of metal selected from the group consisting of zinc and lead, and an electrically insulating inorganic filler mixed and hardened integrally with the embedding metal member. A cast insulator made of a thermosetting resin molded body, wherein the mixing amount of the inorganic filler with respect to the thermosetting resin is the curing of the mixture of the thermosetting resin mixed with the inorganic filler. The cast insulator, wherein the coefficient of thermal expansion in the above state is set to be substantially equal to the coefficient of thermal expansion of the selected metal.