Pressure gel forming method for multi-winding current transformer

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%, ...

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 pre-treatment and mixing, pressure injection and pressure holding , Solidification and cooling molding, the advantage is that the electrical products produced by this method are not easy to crack, the breakdown voltage and initial discharge voltage are high, and the partial discharge is ≤20pC. However, the qualified rate of the product is low (23.5%), and the partial discharge value is still high. , and does not solve the problem of controlling the partial discharge level of multi-winding current transformers