Transformer Function and Characteristics of Dry Cast Resin Transformer with Insulating Material

Transformer function and characteristics of dry resin transformer insulation materials: Dry type transformers (herein referred to as epoxy resin insulated transformers) are mainly used in places with high fire protection requirements, such as high-rise buildings, airports, oil depots, etc. Type of resin insulation: Epoxy tree refers to the insulation transformer. According to the characteristics of the manufacturing process, it can be divided into epoxy quartz sand mixture vacuum casting type, epoxy alkali-free glass fiber reinforced vacuum differential pressure casting type and alkali-free glass fiber wrapping impregnated type.

1) Epoxy quartz sand mixture vacuum casting insulation. This kind of transformer is made of quartz sand as epoxy resin filling material. The coil is wrapped by insulating varnish and wrapped in a coil casting mold. Under vacuum condition, the mixture of epoxy resin and quartz sand is used for drip irrigation. pouring. Because the casting process is difficult to meet the quality requirements, such as residual bubbles, local unevenness of the mixture and may cause local thermal stress cracking. Such insulated transformers are not suitable for use in areas with hot humid environments and large load changes.

2) Epoxy alkali-free glass fiber reinforced vacuum differential pressure casting insulation. The epoxy alkali-free glass fiber reinforcement is insulated with an outer layer of the insulation between the winding layers by an alkali-free glass short fiber glass mat. The outermost layer of the insulation wrap is generally 1 – 3 m thick and thin, mixed by epoxy resin castable ratio, and removed by high-vacuum vacuum casting, because the thickness of the wrap insulation is thin, when impregnated
When it is bad, it is easy to form a partial discharge point. Therefore, it is required that the mixing of the castable should be complete, and the vacuum should be completely removed. The low viscosity and casting speed of the castable are mastered to ensure the high quality of the wire bag impregnation during the casting process.

3) Alkali-free glass fiber wrapped impregnation insulation. The alkali-free glass fiber wrapped impregnated transformer is used to complete the coil interlayer insulation treatment and coil impregnation while winding the transformer coil. It does not require the winding forming mold in the above two methods of impregnation, but requires a small viscosity of the resin, and the resin should not leave tiny bubbles during coil winding and impregnation.