Cause of partial discharge in dry-type transformer

Insulators and metal bodies in dry-type transformers usually have several sharp corners and Burrs, so the electric field intensity affects the charge concentration on the sharp corners or burrs. This is because when the dry-type transformer acts on high electric field intensity, the charging ability of partial discharge is concentrated on the sharp angle.

　If the insulated dry type transformer is poured into a vacuum epoxy, the process can be poorly controlled, causing a partial discharge of the inner bubble. In general, epoxy insulators have several small gas gaps, and because the permittivity of the bubbles is much lower than that of the insulators, the electric field strength of the bubbles in the insulators is much higher than that of the adjacent insulators. If the electrical connection between the conductors is not good, the discharge will occur easily, which will seriously affect the suspended potential of the metal. If the air humidity is too high, the insulation strength of the transformer area is not enough, or the insulation of the dry-type transformer is damaged in the installation process, the idle time of the dry-type transformer is too long, the insulation material water quantity exceeds the standard, the whole body is affected by moisture, and the partial discharge is affected. When designing the insulation structure of dry-type transformer, the electric field intensity between layers or coils is too high, and the insulation Structure Design is unreasonable. When the quality of insulating material is not up to standard, the level of winding, drying and injection process is not enough. The level difference of the assembly process will affect the increase of the burr and distance in the high and low voltage lead production.