Pressure gel forming method for multi-winding current transformer

A current transformer and pressure gel technology, applied in the manufacture of inductors, inductors/transformers/magnets, circuits, etc., can solve the problems of low product qualification rate, high partial discharge value, defects, etc., to reduce the labor intensity of workers, The appearance of the product is obvious and the production efficiency is high.

Active Publication Date: 2015-01-21
STATE GRID CORP OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For multi-winding current transformers, the secondary coil contains 2 to 4 windings, and the body composed of multi-winding coils is prone to exhaust dead ends during the manufacturing process, causing defects inside the cast body, which in turn affects the partial discharge level of the product
[0005] Chinese patent (application number: 201010202076.4) discloses a process for producing transformers by epoxy resin pressure gel method, including the following steps: body pre-baking, mold pre-heating, raw material

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] In this embodiment, the multi-winding current transformer pressure gel forming method includes the following steps:

[0032] (1) Pressure gel material preparation:

[0033] The pressure gel material is mainly composed of the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, the viscosity at 25°C is 4500mPas; 1200mPas; 300 parts of active silica powder, the median particle diameter is 4.5 microns; 2 parts of color paste, the color is red;

[0034] The batching method of the pressure gel material is as follows: before batching, preheat the active silica powder in an oven at 120°C for 15 hours, and cool it to 50°C with the furnace temperature for later use; when batching, take bisphenol A type epoxy resin, acid anhydride Curing agent, active silica powder and color paste, control the temperature of the mixing tank at 50°C, stir and evacuate until the vacuum degree is below 30Pa, and obtain a material system with a viscosity of 8440mPas and ...

Embodiment 2

[0046] In this embodiment, the multi-winding current transformer pressure gel forming method includes the following steps:

[0047] (1) Pressure gel material preparation:

[0048] The pressure gel material is mainly composed of the following raw materials in parts by weight: 95 parts of bisphenol A epoxy resin, the viscosity at 25 ° C is 5500 mPas; 75 parts of anhydride curing agent methyltetrahydrophthalic anhydride, the viscosity at 25 ° C is 2000mPas; 260 parts of active silica powder, the median particle diameter is 2.5 microns; 0.8 parts of color paste, the color is brownish red;

[0049] The batching method of the pressure gel material is as follows: before batching, preheat the active silica powder in an oven at 100°C for 24 hours, and cool it to 40°C with the furnace temperature for later use; when batching, take bisphenol A epoxy resin, acid anhydride Curing agent, active silica powder and color paste, control the temperature of the mixing tank at 50°C, stir and evac...

Embodiment 3

[0061] In this embodiment, the multi-winding current transformer pressure gel forming method includes the following steps:

[0062] (1) Pressure gel material preparation:

[0063] The pressure gel material is mainly composed of the following raw materials in parts by weight: 110 parts of bisphenol A epoxy resin, the viscosity at 25 ° C is 7000 mPas; 85 parts of methyl tetrahydrophthalic anhydride, an anhydride curing agent, the viscosity at 25 ° C 3000mPas; 320 parts of active silica powder, the median particle diameter is 9 microns; 2.5 parts of color paste, the color is red;

[0064] The batching method of the pressure gel material is as follows: before batching, preheat the active silica powder in an oven at 110°C for 10 hours, and cool it to 30°C with the furnace temperature for standby; when batching, take bisphenol A type epoxy resin, acid anhydride Curing agent, active silica powder and color paste, control the temperature of the mixing tank at 50°C, stir and evacuate ...

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Abstract

The invention discloses a pressure gel forming method for a multi-winding current transformer, and belongs to the technical field of electric manufacturing and electric equipment. According to the method, the traditional method that multiple windings are shielded respectively in a device correcting process is improved, the windings are combined and wrapped as a whole, and exhaust dead corners generated in the pouring process of the multi-winding current transformer are effectively avoided. In a transformer die preparation process, temperatures of different parts of a die are set, so that it is guaranteed that the curing process of gel materials which are injected firstly and the curing process of gel materials which are injected later basically keep consistent, and cracks generated due to an inconsistent curing contraction rate in the transformer are avoided. In the pressure gel forming process, viscosity of mixed materials is large, a certain period of time is needed when gas is exhausted from the inside of a product, and accordingly a staged material injection method is adopted. Besides, staged pressure maintaining can effectively avoid the situation that iron core magnetic permeability is reduced because of excessively large material injection pressure and accordingly error tests are not qualified, and therefore product quality and the pass percent are guaranteed.

Description

technical field [0001] The invention specifically relates to a pressure gel forming method for a multi-winding current transformer, which belongs to the technical field of electrical manufacturing and electrical equipment. Background technique [0002] Casting type current transformer is widely used in switchgear and other power equipment, and is a transformer that transmits information for measuring instruments, meters or protection devices. At present, the power industry has stricter requirements on the partial discharge indicators of high-voltage power transmission and transformation equipment, and the national standards have also been adjusted accordingly. The partial discharge requirements of oil-paper-insulated and gas-insulated high-voltage transformers have been changed from the original 10pC to the current 5pC . Based on the design of the structure and insulating medium, the partial discharge pass rate of the above two types of transformers basically reaches 100%, ...

Claims

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Application Information

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IPC IPC(8): H01F41/00H01F38/28B29C45/14B29C45/76
Inventor 陈晓丽史鸿威陈延辉王焕李杏龙宋晓光龚浩王茂玉
Owner STATE GRID CORP OF CHINA
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