The commonly used insulating materials for oil-immersed transformers mainly include the following:
Transformer oil: Transformer oil is the most important liquid insulating material in oil-immersed transformers. Its insulating performance depends largely on the oil's withstand voltage. In transformers, transformer oil not only plays an insulating role, but also plays a role in heat dissipation and arc extinguishing.
Insulating varnish:Insulating varnish is an insulating material used to coat the surface of transformer components, with excellent insulating and moisture-proof properties.
It can effectively protect transformer components from moisture, dust and other pollutants, and improve the reliability and service life of the transformer.
Insulating paper: Insulating paper is a commonly used solid insulating material with excellent electrical insulation and mechanical strength. It is often used to make coils, windings and other components of transformers to ensure electrical isolation between components. There are many types of insulating paper, such as kraft paper, capacitor paper, etc., which are selected according to the different needs of the transformer.
Insulating paperboard: Insulating paperboard is a commonly used solid insulating material in oil-immersed transformers, mainly made of unbleached sulfate fiber. It has strong air permeability, oil absorption and water absorption, and its electrical performance will be improved after drying and oil immersion. The thickness of insulating paperboard is 0.5, 1, 1.5, 2.0, 2.5, 3.0 mm, and it is often used as soft paper tubes, stays, pads, phase partitions, iron yoke insulation, support insulation and corner rings for main insulation.
Cable paper: Cable paper is also made of sulfate pulp. It is often used as insulation wrapped around the outer surface of the conductor and interlayer insulation of the coil in transformers, as well as lead wrapping insulation.
Corrugated paper: Corrugated paper is reprocessed from cable paper. It has good electrical properties in oil, which is manifested as high average breakdown voltage and small tangent value of dielectric loss angle. Corrugated paper is mainly used for wrapping transformer outlets.
In addition to the above materials, solid insulating materials such as telephone paper (mainly used as coil wire insulation and coil end insulation, etc.), epoxy resin, rubber, wood, glass fiber, electric porcelain, polyester compounds, and insulating paint are also widely used in oil-immersed transformers.
In summary, there are many types of insulation materials for oil-immersed transformers, and each material has its specific uses and performance characteristics. In practical applications, it is necessary to select appropriate insulation materials based on the specific needs and working environment of the transformer.
