JPH0333151Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention is an embedded metal fitting used in high voltage electrical equipment such as gas insulated sealed switchgear (GiS), conduit aerial cable (GiB), high voltage switchboard, etc. This invention relates to an insulating spacer.

[Prior art and its problems]

FIG. 1 is a side sectional view showing how the insulating spacer is used, and shows an example of its application to GiS. In the figure, 1 is a sealed GiS container containing an insulating gas 2, 3 is a cylindrical or round bar-shaped GiS high voltage conductor, and 4 is an insulating spacer. Insulating spacer 4
is an embedded fitting 5A connected to the high voltage conductor 3 by a connecting member 9 and kept at the same potential as the high voltage conductor;
Supporting metal fittings 7 provided inside the grounded closed container 1
It consists of an embedded metal fitting 5B connected by a bolt 8 to the earth potential and kept at ground potential, and an insulator 6 made of a cylindrical thermosetting resin cured material into which the embedded metal fittings 5A and 5B are integrally molded, and an insulating spacer 4. At the time of manufacture, the embedded metal fittings 5A and 5B are set at a predetermined position in a casting mold, for example, and liquid casting resin is injected into the mold and heated to harden to form the embedded metal fittings 5.
A and 5B are integrally molded into the insulator 6. Further, the dotted lines in the figure are equipotential lines indicating the potential distribution in the insulating spacer 4 and the insulating gas space 2 when a voltage is applied between the high voltage conductor 3 and the sealed container 1. In the case of the figure, a pair of embedded metal fittings 5A, 5
Since the insulation distance in the insulator 6 is shortened by B, the equipotential line 10 is formed in the insulator between both embedded electrodes.
are approaching each other, and the electric field in this area is high. However, at the boundary between the outer periphery of the insulator 6 and the insulating gas 2, the distance between the equipotential lines increases, and the electric field along the creeping surface of the insulator 6 increases. Embedded metal fittings 5A, 5 to weaken
The electric field is controlled by B. In this way, the insulating spacer has the following roles: to firmly support the high voltage conductor 3 in a predetermined position, to insulate the high voltage conductor 3 and the sealed container 1 with the insulator 6, and to protect the gas near the insulating spacer. There is a need for the role of controlling the electric field of the insulator 6 and maintaining the withstand voltage of the creeping surface of the insulator 6.

FIG. 2 is a side sectional view of a cylindrical insulating spacer. In the figure, the embedded fittings 5A and 5B are designed to keep the electric field in the insulator 6 as low as possible and
In order to control the electric field along the creeping surface of the mounting bracket, it is formed into a hemispherical bar shape as shown in the figure, and the surface of the embedded fitting in contact with the insulator 6 is roughened by sandblasting, knurling, etc. This increases the adhesive strength between the embedded metal fitting and the insulator, and reduces the mechanical stress such as the load of the conductor applied to the insulating spacer, electromagnetic mechanical force, etc., and the thermal stress applied to the insulating spacer due to temperature changes of the high voltage conductor 3. Measures are taken to prevent the bond between the insulator and the insulator from peeling off, and to prevent mechanical damage to the insulator or dielectric breakdown due to this.

However, a problem has arisen in that the insulating spacer configured as described above occasionally suffers dielectric breakdown during a much shorter usage time than originally expected, and there is a need for improvement in the withstand voltage life characteristics.

[Purpose of invention]

This idea was created in view of the above-mentioned situation.
The purpose of this invention is to provide a resin molded insulating spacer with a good balance of mechanical performance and withstand voltage life performance.

[Key points of the idea]

In this invention, several types of model insulating spacers with different surface roughnesses of embedding metal fittings ranging from 1 to 50 microns were made, and a high AC electric field was applied that caused dielectric breakdown in 100 to 1000 hours to improve the surface roughness and resistance. As a result of experimental studies by the inventors of this application to elucidate the correlation with voltage life characteristics, it was revealed that the withstand voltage life characteristics decrease rapidly in the area where the surface roughness is 30 microns or more, especially 40 microns or more. Based on the results of this study and the results of the study on adhesive strength, the range of surface roughness of the embedded metal fittings was determined by 5.
The above-mentioned objective was achieved by limiting the electric field to ~40 microns and applying the electric field to a portion of the surface of the embedded metal fitting that exceeds at least 50% of the maximum electric field on the surface of the embedded metal fitting to be charged.

[Example of idea]

The present invention will be explained below based on examples.

Figure 3 is a side sectional view of a model insulating spacer used in an experiment to investigate the correlation between surface roughness and withstand voltage life characteristics of embedded fittings, and Figure 4 is an experiment to investigate the relationship between surface roughness and tensile shear adhesive strength. FIG. 2 is a structural diagram of a test piece used for In FIG. 3, embedded metal fittings 15A and 15B are used which have almost the same dimensions and shape as the actual insulating spacer shown in FIG. 2, but with several different surface roughnesses in the range of 1 to 50 microns.
The minimum insulation distance D between both embedded electrodes of the insulator 16 is shortened to one-fifth to one-tenth that of the actual insulation spacer, and the model insulation spacer shown in the figure is formed. The withstand voltage life test was conducted on 20 spacers each with different surface roughness, by continuously applying AC high voltage that would cause dielectric breakdown in a maximum of 1000 hours, and determining the breakdown time for each model. It is something. In other words, insulating spacers used in high-voltage electrical equipment are required to have high reliability, with the probability of insulation breakdown at the end of life being, for example, 1/1000 or less, assuming the equipment's lifespan is, for example, 50 years. In order to shorten the life test time, an electric field acceleration test method is used, which shortens the insulation distance D and at the same time increases the maximum electric field in the insulator by applying a voltage higher than the working voltage, reducing the life time to 1000 hours or less. This is to determine the withstand voltage life characteristics of the model insulating spacer.

Figure 5 is a graph showing the withstand voltage life test results of the model insulating spacer shown in Figure 3. The horizontal axis of the figure shows the surface roughness of the embedded metal fitting, and the vertical axis shows the surface roughness of the model spacer with a surface roughness of 1 micron. It expresses the relative value of withstand voltage life time with 50% breakdown time as 100. From the experimental results shown in the figure, the surface roughness is between 30 and 40, although there is some variation in the characteristics depending on the repetition of the experiment several times.
It was found that the relative value of withstand voltage life time clearly begins to decrease from around microns, and rapidly decreases in the region exceeding 40 microns. This experimental result far exceeds the imagination that the surface roughness of embedded metal fittings would affect the withstand voltage life characteristics, which was a vague concern in the past. Assuming that metal fittings were used, the withstand voltage life time would have been reduced to 1/50 of the best condition.

On the other hand, as shown in Fig. 4, two metal plates 12A, 12
The relationship between the surface roughness of the bonded surface and the tensile shear adhesive strength was investigated using a lap joint type test piece in which B was bonded with the same thermosetting resin 13 as the model spacer shown in Fig. 3 under the same heat curing conditions.
As shown in Figure 6, the adhesive strength begins to increase when the surface roughness is a few microns, increasing by 25% at 40 microns, and 25% at 50 microns.
It increases by 30% in microns, and it is expected that the bond strength will further increase if the surface roughness is made even rougher.

From the above study results, it is clear that surface roughness that is finer than the surface roughness of the embedded metal fittings that provides sufficient adhesive strength has a noticeable effect on the withstand voltage life characteristics, and that the mechanical strength of the insulating spacer is significantly affected. It has become clear that more than focusing on improvements, it is necessary to give consideration to preventing a decline in withstand voltage life characteristics.

The insulating spacer of the present invention was developed based on the above study results, and in an insulating spacer equipped with embedded fittings as shown in FIG. By limiting the allowable range of the surface roughness of the embedded metal fittings at the adhesive part to 40 microns and the lower limit to 5 microns, the insulation achieves a good balance between adhesive strength and withstand voltage life characteristics. It is intended to provide a spacer. In other words, the upper limit of surface roughness is
By limiting the diameter to 40 microns, the decrease in voltage withstand life can be suppressed to about 1/3 to 1/6, and the adhesive strength can be improved by approximately 25% compared to mirror finish, resulting in improved voltage withstand life performance. It is possible to provide an insulating spacer that maintains both adhesive strength and adhesive strength fairly well. On the other hand, by limiting the lower limit to 5 microns, it is possible to maintain the withstand voltage life performance at almost the best condition, and also to obtain the effect of improving the adhesive strength. In addition, by limiting the degree of surface finishing performed prior to surface roughening to, for example, about 6-s,
It is possible to prevent an increase in the time required for surface processing of the embedded metal fitting.

It should be noted that it is not necessary to maintain the surface roughness of the adhesive part between the embedded fitting and the insulator within the range of 5 to 40 microns; With rough surface processing,
The low electric field area of less than 50% can have a rough surface finish with emphasis on the effect of improving adhesive strength.
The reason why we set the range in which the surface roughness of 5 to 40 microns is maintained to be 50% or more of the maximum electric field value is because the surface roughness of other parts is limited to a roughness that reduces the withstand voltage life to 1/100 (60 microns or more). ), this was done to prevent the electric field concentration on this rough surface from becoming a new weak point in the insulation.

[Effect of idea]

As mentioned above, this invention is based on the new fact that the withstand voltage life of embedded metal fittings that are integrally molded into insulating spacers decreases rapidly when the surface roughness of the embedded metal fittings exceeds 30 to 40 microns. The allowable range of surface roughness is limited to 5 to 40 microns. As a result, for example, by changing the surface roughness of an insulating spacer from 50 microns to a surface roughness of 30 to 40 microns, the withstand voltage life can be increased by almost two orders of magnitude, while the adhesive strength decreases by only a few percent. In addition, surface processing of 5 to 40 microns is applied only to the part that exceeds 50% of the maximum electric field applied to the surface of the embedded fitting, which affects the withstand voltage life characteristics, and other By roughening the surface of the part to strengthen the adhesive strength with the insulator as in the conventional case, it is possible to provide an insulating spacer with a well-balanced mechanical performance and withstand voltage life performance. In addition, the electric field used for insulating spacers, which was previously unknown and kept low, can be increased based on experimental results, allowing for reductions in the dimensions of insulating spacers and furthermore in insulation dimensions of high-voltage electrical equipment. I can contribute to that. Furthermore, by limiting the surface roughness of the embedded metal fittings to 5 to 40 microns, the base finishing and roughening of the embedded metal fittings can be simplified, and resin molded insulation has high reliability at low cost. Spacers can be provided.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a gas insulated electrical appliance showing the installation state of the insulating spacer, Fig. 2 is a sectional view of a columnar insulating spacer equipped with an embedded metal fitting, and Fig. 3 is a sectional view of a model insulating spacer according to an embodiment of the present invention. Cross section, 4th
The figure is a structural diagram of the tensile shear adhesive strength test piece, No. 5
The figure shows the surface roughness vs. withstand voltage life characteristic test results of the model insulating spacer according to the present invention, and FIG. 6 shows the surface roughness vs. adhesive strength test results of the adhesive strength test piece. 1... Airtight container, 2... Insulating gas, 3... High voltage conductor, 4... Insulating spacer, 5A, 5B, 15
A, 15B...Embedded metal fitting, 6,16...Insulator,
8, 9...Connection member.

Claims (1)

[Scope of utility model registration request] An embedded fitting connected to a live part or a grounded metal part of a high-voltage electric device is an insulating spacer integrally molded in an insulator made of a cured thermosetting resin, and the insulating spacer on the surface of the embedded fitting is The surface roughening is applied to the interface part of the embedded fitting, and the part where the maximum electric field applied to the surface of the embedded fitting is more than 50% is roughened to a surface roughness of 5 to 40 microns. Resin molded insulation spacer.