JPS63911A - Insulation of conductor employing scale mica piece - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Purpose of the Invention) (Field of Industrial Application) The present invention relates to a method for insulating conductors used in confined spaces such as underground substations and closed switchboards, and is particularly applicable to conductors that can be used under high voltage and high temperatures. This relates to a method of insulating conductors.

(Prior Art) Conventionally, insulating conductors used inside underground substations, closed switchboards, etc. into casings often relies only on structural materials such as insulators that support the conductors. In other words, if sufficient insulating space is secured between the casing and the conductor using structural materials such as insulators, there is no need to insulate the conductor itself, so the insulation applied to the conductor itself can be done only by applying varnish or using powder. The insulation was included.

However, as the volume of closed switchboards and the like increases, the voltage applied to the conductors also tends to increase. Even if -C lightning pressure becomes high, it would be good if enough space could be secured to withstand the voltage using a structural material such as glass, but if that much space were taken up, the casing would become large and would be impractical. Also, when the voltage becomes high, depending on the support structure of the conductor and the support material, a uniform potential distribution cannot be obtained at the contact area between the conductor and the support material, and a locally high central field occurs near the conductor. Corona will occur. When corona occurs, ozone from the corona accelerates oxidation and deterioration of the sounding material used inside the housing.

Therefore, instead of relying on structural support materials for insulation itself, the conductor itself is wrapped with polyimide tape or sheet that has a high breakdown voltage, or aramid tape or sheet that has mechanical strength, and in the post-process, it is impregnated with synthetic resin under vacuum pressure to become the conductor. An insulating layer is formed and this insulating layer is fixed to a housing using a support material. However, if an organic material such as polyimide or aramid is used for the insulating layer, if corona occurs, it will suffer damage due to corona. In other words, materials such as polyimide and aramid have poor corona resistance and are not preferred for use in areas where corona occurs. Therefore, it is conceivable to wind a material with strong corona resistance, such as mica tape or a sheet, and impregnate it with a synthetic resin.

(Problems to be Solved by the Invention) Formation of an insulating layer using mica tape or the like described above is applied to high-voltage rotary formation stator coils, etc., but in order to form mica tape or mica sheet, glass cloth, etc. The force must be reinforced with aggregate such as fiber or film.

In other words, in the case of mica tape, it can be broadly classified into flake mica and aggregated mica depending on the shape of the mica, but in both cases, it is impossible for mica alone to maintain the tensile strength necessary to insulate the conductor. . Therefore, for example, when producing flake mica, it is necessary to attach flake mica of an appropriate size to a reinforcing material such as glass cloth using adhesive, and in the case of composite mica, crushed mica pieces are processed using paper-making technology. As with mica foil, it must be attached to a reinforcing material such as glass cloth using adhesive.

Therefore, when applying conventional insulation technology to insulating conductors, it is necessary to use expensive mechanical insulation that requires bonding of mechanical insulation. In addition, by using aggregate, the thickness of the insulation layer, which is strong against corona, becomes thinner when the thickness of the insulation layer is constant. Furthermore, using an adhesive makes it difficult for the impregnating resin applied in the subsequent process to be impregnated, and since this adhesive is often a solvent type, there are many problems such as compatibility with the impregnating resin. There is.

Therefore, it is an object of the present invention to provide a method for forming an insulating layer made of scaly mica pieces in the vicinity of a conductor with the highest electric field without requiring the work of laminating scaly mica pieces or using an aggregate. purpose.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the present invention disperses scaly pieces in a solvent such as ethanol, and inserts a conductor and a Cu electrode into this dispersion liquid. A DC voltage was applied to make the mica pieces adhere to the conductor by electrophoresis, and then the conductor with the mica pieces was wrapped in a heat shrink tube, and the mica j1 was impregnated with a synthetic resin while being lightly pressed with lυ. , which is made by heating and curing synthetic resin.

(Function) According to the present invention, the mica pieces are formed in layers without using an adhesive, and since no aggregate is used, there are extremely many mica suspensions near the conductor where the electric field is most likely to concentrate, and the present invention provides corona resistance. An insulating layer with excellent properties can be formed.

(Example) An example of the present invention will be described using the drawings. The scale-like mica pieces used in the present invention are made by chemically and physically processing raw mica or scrap mica that is a by-product in the process of making raw mica.
Use a product that has been ground to a size of 0 to 300 mesh J. In other words, hard or soft material is heated to 700 to 800°C to remove some of the crystal water, immersed in an acid or alkali aqueous solution to make it easier to masturbate, and then cast with jet water at a high pressure. 3
A mica suspension was obtained by beating and pulverizing the mica to a size of 0.00 mesh, and the suspension was poured onto a surface to thoroughly drain water, and then heated to about 120° C. to form mica blocks in the form of scaly mica pieces. Note that the size of the mica block is preferably about 10 to 1,009 mm from the viewpoint of ease of dehydration and ease of use in the next step.

Next, mica blocks were added at a ratio of 50 to 2,009 mica blocks per liter of ethanol to prepare an ethanol solution 1 of scaly mica pieces. (Hereinafter referred to as a dispersion liquid.) This dispersion liquid 1 was gently stirred by a magnetic stirrer 2 so that the scaly mica pieces would not settle. Next, a conductor 3 to be insulated and an electrode 4 facing it were placed, and a DC voltage was applied to the conductor and the electrode gate. The voltage was also affected by the shape of the conductor and the distance between the opposing electrodes, but it was 30-13
0 ■, and the time is 0.05 to 0.2 for about 20 to 90 seconds.
It was possible to form an insulating layer 5 of scale-like mica pieces with a thickness of about m. Further, as a result of performing the same operation as above by temporarily stopping stirring when voltage was applied, an even thicker insulating layer of 0.1 to 0.4 m could be obtained. Further, after forming an insulating layer under the above conditions, ethanol was scattered in a chamber and the half-dried state was re-applied to the ethanol solution of the scale-like mica pieces at 0 jff [and the same voltage was applied again. An insulating layer was obtained. After repeating this quietly 6 times, the result was 0.8 to 1.
．． An insulating layer of about 4M1 was obtained. By further repeating the process, an insulating layer of 2#lII+ or more was obtained, but when the conductor was removed from the ethanol solution, some scaly mica pieces were observed to flow out. Incidentally, when the conductor is taken out from the dispersion liquid, it is possible to prevent the mica pieces from flowing out by scattering the ethanol while rotating the conductor gently.

Next, the conductor 3 on which an insulating layer of scaly mica pieces of about 1.5 m has been formed is placed in a heat shrink tube 6, and the scaly mica pieces are lightly pressed with the shrinkage force caused by heating, making the mica 100%
was able to form an insulating layer. Here, in the insulating layer made of scaly mica pieces, the mica pieces stick to each other due to the pincer effect unique to mica, and will not peel off even without using an adhesive. However, mica pieces that are mechanically pulverized using a mixer or the like rather than being beaten with a stream of water have a scaly shape but have little pincer effect and easily peel off, so beating with a stream of water is preferable.

Next, after impregnating the heat-shrinkable tube with the impregnating resin under reduced pressure, a molding jig 7 is applied over the heat-shrinkable tube to wrap the insulating layer of the conductor, and the impregnating resin is hardened by heating to form a scaly mica. I was able to complete the insulating layer with pieces. As a result, the mica a in the vicinity of the conductor (within 0.5M from the conductor), where the electric field is most likely to concentrate, was 65% at most in the case of conventional mica tape-wound insulation, but according to the present invention, it can be increased to 85%. Ta.

In the illustrated example, the conductor has a rectangular bar shape, but the shape of the conductor may be arbitrary and may be intricately processed.

Next, the results of specific examples are shown in [Table].

The contents of each example shown in [Table] are as follows.

Example 1 A conductor and an electrode were placed in a dispersion in which 1 K9 of scaly mica particles having an average particle size of 60 mesh were added to 10 liters of ethanol, and a DC voltage i oov was applied for 55 seconds.

Example 2 After carrying out Example 1, ethanol was dispersed in a chamber and voltage was applied again under the same conditions. This operation was repeated five times.

Example 3 The conductor of Example 2 was covered with a heat-shrinkable sleeve made of Tetron glass blend, impregnated with L-impregnated resin in a vacuum, and heated and cured using a molding jig.

Example 4 The conductor of Example 2 was covered with four layers of heat-shrinkable fleece made of Tetron glass blend, impregnated with an impregnating resin under IA2, and heated and cured using a molding jig.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to form an insulating layer having excellent corona resistance with a large amount of mica hanging on the outside of a conductor without using an adhesive or a reinforcing material. Furthermore, if ethanol or the like is used as a dispersion liquid for mica pieces, drying at low temperatures becomes possible.Furthermore, since the mica pieces move in one direction using the cation method, even if the material of the conductor is copper, there will be no patina, etc. It has many effects such as there is no risk of it occurring.

[Brief explanation of the drawing]

Figure 1 shows the state in which mica pieces are attached to the conductor surface by electrophoresis in a dispersion liquid, and Figure 2 shows the state in which the impregnated resin is heated and hardened using a molding jig. be. 1... Dispersion liquid, 3... Conductor, 4... Electrode, 5...
- Insulating layer 6... Heat shrink tube, 7... Molding jig. Applicant's agent Hajime Sato

Claims (1)

[Claims] Dispersing scaly mica pieces in an organic solvent having an OH group,
A conductor and an electrode are inserted into this dispersion liquid, a DC voltage is applied, and scale-like mica pieces are attached to the conductor surface by electrophoresis.Then, the conductor with the scale-like mica pieces attached is placed in a heat shrink tube. A method for insulating a conductor using flaky mica pieces, characterized in that the tube is heat-shrinked to hold the flaky mica pieces, then impregnated with a synthetic resin, and further the synthetic resin is hardened by heating.