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A method for forming a low partial discharge voltage transformer of 35kv or below

A technology of a voltage transformer and a molding method, which is applied in the fields of electrical manufacturing and power equipment to achieve the effects of good degassing effect, improved curing effect, increased toughness and anti-cracking performance

Active Publication Date: 2016-08-17
STATE GRID CORP OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there is no relevant report on the vacuum casting process of low partial discharge 35kV and below castable voltage transformers

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] The method for forming a low partial discharge 35kV voltage transformer in this embodiment includes the following steps:

[0029] (1) Preparation of castables:

[0030] The castable consists of the following raw materials in parts by weight: 100 parts of bisphenol A liquid epoxy resin, with a viscosity of 4000mPas at 25°C; 80 parts of acid anhydride curing agent methyltetrahydrophthalic anhydride, with a viscosity of 900mPas at 25°C; active silicon 260 parts of micropowder, the median diameter D50 of the particle size is 4 microns; 0.5 part of color paste, the color is red;

[0031] The batching method is: before batching, preheat the active silicon powder in a 110 °C oven for 12 hours, and then cool it to 60 °C with the furnace for use; when batching, add bisphenol A liquid epoxy resin into the epoxy resin mixing tank. Resin, 60% active silicon powder and color paste, control the temperature at 80 ℃, stir and vacuum for 6 hours to obtain epoxy resin mixture; add acid ...

Embodiment 2

[0040] The method for forming a low partial discharge 24kV voltage transformer in this embodiment includes the following steps:

[0041] (1) Preparation of castables:

[0042]The castable is composed of the following raw materials by weight: 90 parts of bisphenol A liquid epoxy resin, with a viscosity of 4500mPas at 25°C; 70 parts of acid anhydride curing agent methyltetrahydrophthalic anhydride, with a viscosity of 1500mPas at 25°C; active silicon 290 parts of micropowder, the median diameter D50 of the particle size is 3 microns; 0.5 part of color paste, the color is brown-red;

[0043] The batching method is: before batching, preheat the active silicon powder in an oven at 110 °C for 12 hours, and then cool it to 65 °C with the furnace for use; when batching, add bisphenol A liquid epoxy resin into the epoxy resin mixing tank. Resin, 50% active silicon powder and color paste, control the temperature at 65 ℃, stir and vacuumize for 4 hours to obtain epoxy resin mixture; add...

Embodiment 3

[0052] The method for forming a low partial discharge 10kV voltage transformer in this embodiment includes the following steps:

[0053] (1) Preparation of castables:

[0054] The castable is composed of the following raw materials by weight: 95 parts of bisphenol A liquid epoxy resin, with a viscosity of 7000mPas at 25°C; 76 parts of acid anhydride curing agent methyltetrahydrophthalic anhydride, with a viscosity of 2500mPas at 25°C; active silicon 310 parts of micropowder, the median diameter D50 of its particle size is 5 microns; 0.5 part of color paste, the color is red;

[0055] The batching method is: before batching, preheat the active silicon powder in an oven at 110 °C for 10 hours, and then cool it to 50 °C with the furnace for use; when batching, add bisphenol A liquid epoxy resin into the epoxy resin mixing tank. Resin, 40% active silicon powder and color paste, control the temperature at 50 ℃, stir and vacuumize for 2 hours to obtain epoxy resin mixture; add acid...

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Abstract

The invention discloses a forming method for a 35 KV and below potential transformer with a low partial discharge level, and belongs to the technical field of electrical manufacturing and power equipment. According to the forming method, before casting, a casting device is filled with a certain amount of SF6 gas, so that air gap can be reduced and partial discharge property of a product can be improved; during the casting process, a variable casting process is adopted at time intervals of 20-50 s after casting for 1-3 min every time, so that residual air in the material and the device can be removed effectively and electric properties of the product are improved; during a curing process, a stepped heating method is adopted so that the temperature is raised slowly and reaction speed can be controlled relatively smooth; and during a cooling process, a stepped cooling method is adopted so that both internal and external crack of the product which are caused by sudden cooling can be effectively prevented and a curing effect of the product can be improved. Experiments demonstrate that the potential transformer manufactured by the method of the invention has high qualified rate and good partial discharge property; and a partial discharge amount at 1.2 Um (48.6kV) is equal to or smaller than 10 pC.

Description

technical field [0001] The invention specifically relates to a method for forming a voltage transformer with a low partial discharge of 35kV and below, which belongs to the technical field of electrical manufacturing and power equipment. Background technique [0002] 35kV castable voltage transformers are widely used in switch cabinets and other power equipment, and are an important measurement and protection product. At present, the vacuum casting molding process is mainly used to produce 35kV cast voltage transformers in China, but almost all manufacturers have problems such as partial discharge exceeding the national standard and low partial discharge qualification rate of products. Partial discharge is an important cause of insulation damage. Excessive partial discharge will seriously affect the operating life and quality of 35kV cast-type voltage transformers, and it is easy to cause accidents such as insulation breakdown. Therefore, reduce the partial discharge of 35kV...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B29C39/00B29C39/42B29C39/24B29C39/38
Inventor 史鸿威陈延辉宋晓光陈晓丽龚浩李杏龙王茂玉
Owner STATE GRID CORP OF CHINA
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