JPS6250924B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insulating tape or film that is advantageous in mitigating and reducing the concentration of electric field strength that occurs during power transmission on power transmission lines.

Typical locations where electric field strength concentrations tend to occur are at the terminations of power transmission lines, which can often cause breakdown of insulation.

Attempts to prevent dielectric breakdown by alleviating and reducing the concentration of electric field strength include methods using a standard stress cone that incorporates a semiconducting material into an insulating material, and alternately using an insulating film and a semiconducting wire film. This has been done by combining the two to form a stress cone, or by attaching an electric circuit to the terminal processing section. However, the standard stress cone method has the disadvantage that it is necessary to prepare molded products of various shapes and sizes depending on the power transmission line, and the combination of films requires advanced packaging for the processing section. It requires skill, and the finished product is bulky and ungainly. The installation of the electric circuit is also complicated and bulky and clumsy.

The present invention provides an insulating tape or film that effectively reduces the problems of these prior art methods and devices for mitigating and reducing field strength concentrations. According to the insulating tape or film of the present invention, the tape or film is applied to the terminal processing part of a power transmission line (including the terminal for connection), and a normal electrical insulating tape is wound over it to insulate it. by insulating or otherwise insulating the
The concentration of electric field strength generated in the processing section is relaxed and reduced, and local dielectric breakdown is prevented. The end-treated portion formed using the insulating tape or film of the present invention is only 1 to 3 mm thicker than the power transmission line and provides a good appearance.

Generally, when electric flux passes through materials with different dielectric constants, it has the property of being refracted and concentrated toward a dielectric material with a higher permittivity at the material interface.

Utilizing this property, it can be understood that by combining dielectrics with an appropriate dielectric constant or dielectrics with different dielectric constants, it is possible to moderate and reduce the appropriate dispersion of electric flux, that is, the concentration of electric field strength. .

The present invention provides a novel and useful insulating tape or film that was discovered as a result of various experiments based on the properties of electric flux.

The present invention is made by blending 150 parts by weight or less of a metal titanate and 30 parts by weight or less of carbon black with 100 parts by weight of a polymeric organic substance and uniformly dispersing the mixture to form a mixture. Insulating tape or film.

The insulating tapes or films of the present invention can be formed in one or more layers and have desirable flexibility and conformability to closely follow the termination of power lines.

The polymeric organic substances used in the present invention include plastics such as chlorinated polyethylene or halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride, and/or acrylonitrile-butadiene copolymers, neoprene rubber, nitrile rubber, etc. A rubber having a high dielectric constant is preferably selected.

Examples of titanate metal salts include barium titanate,
Examples include strontium titanate, magnesium titanate, and calcium titanate, but barium titanate is preferred from the viewpoint of availability and dielectric properties. Along with these metal titanates, zirconates such as barium zirconate and stannates such as barium stannate can be used, and these zirconates and stannates provide temperature stability.

The carbon black used preferably has an average particle size of about 50 μm or less and is selected to be uniform in size.

The present invention is essentially composed of a polymeric organic material such as an acrylonitrile-butadiene copolymer and polyvinyl chloride, a metal titanate such as barium titanate, and carbon black, but includes dioctyl phthalate (DOP), Plasticizers such as dibutyl phthalate (DBP), fillers such as talc and clay, stabilizers such as tribasic lead sulfate, lead stearate, dibasic lead phosphite, barium stearate, other lubricants, and vulcanization. agent, vulcanization accelerator, softener,
Appropriate amounts of known formulations such as anti-aging agents and tackifying resins can be added to obtain desired desired properties such as adaptability, flexibility, self-adhesiveness, and adhesive properties.

The amount of the metal titanate and carbon black is 150 parts by weight or less, preferably 2 to 100 parts by weight, practically 5 parts by weight, per 100 parts by weight of the polymeric organic substance.
~50 parts by weight, and the latter should be added in an amount of 30 parts by weight or less, preferably 0.5 to 20 parts by weight, practically 2 to 15 parts by weight, and 2 parts by weight of metal titanate. Below, an increase in dielectric constant cannot be expected;
If it exceeds 150 parts by weight, the resulting tape or film will have poor flexibility, which is not preferable. Further, if the carbon black is less than 0.5 parts by weight, the dielectric constant of the tape or film will be low, and if it is more than 30 parts by weight, the insulation properties will be impaired, which is not preferable.

The utility of the present invention in mitigating and reducing electric field strength concentrations is illustrated in detail by the following embodiments of the present invention. The middle part of the text indicates parts by weight. The breakdown voltage was measured using a spherical electrode with a diameter of 12.5 mm, and the voltage at which breakdown occurred was measured by applying a voltage at a boost rate of 1 KV/sec, and the dielectric constant was measured at 60 Hz using the Schering-Bridge method.

Example 1 The following formulation was mixed using an open roll maintained at 160-165°C, and then press-molded into a film having a thickness of 0.5 mm.

The dielectric constant and breakdown voltage of this film as a function of changes in the amount of carbon black and barium titanate added are shown in FIGS. 1A and 1B. The arrows in the diagram indicate the relationship between the vertical and horizontal axes of the chart.

Rubbery acrylonitrile-butadiene copolymer
100 parts dioctyl phthalate (DOP) 30 parts talc 50 parts carbon black Variable barium titanate (BaTiO ₃ ) Variable tribasic lead sulfate 0.5 parts Chromalon resin 10 parts Example 2 The following formulation was maintained at 160-165°C. The mixture was mixed using an open roll and formed into a film with a thickness of 0.25 mm using a calendar roll maintained at 160°C.

FIGS. 2A and 2B show the dielectric constant and breakdown voltage depending on the amount of carbon black and barium titanate added. The white circle in FIG. 2B corresponds to the plot in FIG. 2A, when 20 parts of barium titanate is mixed with 5 parts of carbon.

Polyvinyl chloride resin 100 parts Rubbery acrylonitrile-butadiene copolymer
10 parts dioctyl phthalate 60 parts talc 20 parts carbon black Variable barium titanate Variable lead stearate 2.5 parts As is clear from the above examples, the insulating tape or film of the present invention has excellent dielectric constant and breakdown voltage. However, the fact that it alleviates and reduces the concentration of electric field strength is remarkable.

[Brief explanation of the drawing]

FIGS. 1A and 1B are characteristic diagrams graphing the characteristics of Example 1, and FIGS. 2A and B are characteristic diagrams graphing the characteristics of Example 2.

Claims (1)

[Claims] 1. Insulating tape or insulating tape made by blending 150 parts by weight or less of a metal titanate and 30 parts by weight or less of carbon black into 100 parts by weight of a polymeric organic substance and uniformly dispersing the mixture. film.