Causes Of Partial Discharge In Epoxy Resin Encapsulated Transformer

Insulators and metal bodies in epoxy resin encapsulated transformers usually have several sharp corners and burrs, so due to the influence of electric field strength, the charge is concentrated on the sharp corners or burrs. This is because when the dry-type transformer acts on high electric field strength, partial discharge charging Ability to concentrate discharge on sharp corners.

If the insulating epoxy resin encapsulated transformer is poured into the epoxy resin and flowed into the vacuum, if the process control is not good, it will cause internal bubbles to generate partial discharge. Generally speaking, epoxy insulators have several small air gaps. Since the dielectric coefficient of the bubbles is much lower than that of the insulator, the electric field strength of the bubbles in the insulator is much higher than that of the adjacent insulating material.

If the electrical connection between the conductors is not good, discharge is likely to occur, which has a serious impact on the floating potential of the metal.

The air humidity is too high, the insulation strength of the transformer area is insufficient, or the dry-type transformer is damaged by insulation during the installation process; the idle time of the dry-type transformer is too long, the amount of water in the insulating material exceeds the standard, and the whole body is damp, which affects partial discharge.

When designing the insulation structure of epoxy resin encapsulated transformers, the electric field strength between layers or between coils is too high, and the insulation structure design is unreasonable. When the quality of insulating materials is unqualified, the level of winding, drying and injection processes is not enough. The poor level of the assembly process will affect the increase of local emissions such as burrs and distances in the production of high and low voltage leads.