Which is the best insulation material for transformers

The main reason for the use of insulation materials in transformers is to isolate the electrical contact between different voltage levels and to ensure the safety and stability of the transformer. However, there is no single answer as to the “best” insulation material for a transformer, as the choice of the best insulation material depends on a number of factors, including the type of transformer (e.g., dry or oil-immersed), the operating conditions, the required electrical properties, the mechanical strength, the heat resistance, the weathering resistance, and the cost. Below we describe some of the commonly used transformer insulation materials.

What is the best insulation material for transformers?

Transformer Oil: Transformer oil is one of the common insulation materials inside the transformer. Its main role is to play a cooling and insulating role in the insulating structure. Transformer oil has good insulating and cooling properties, which can effectively improve the voltage resistance and heat dissipation ability of the insulating structure and protect the insulating structure from damage. At the same time, transformer oil also has good high temperature resistance, which can maintain stable insulation performance in long-term operation and prolong the service life of the equipment.

Insulation sheet: Insulation sheet is a commonly used insulation material. Its main components are resin and filler. Insulation sheet is used to make insulating structural components such as soft paper tubes, braces and pads. It has good mechanical and electrical strength. At the same time, the insulation sheet also has good temperature resistance, which can maintain stable insulation performance in high temperature environment to ensure the safe operation of the equipment.

Cable paper: It is made of pure sulfate wood pulp and has high mechanical strength and electrical strength. It is often used for interturn insulation and interlayer insulation of transformer windings.

Epoxy glass cloth sheet: It is made of fiberglass cloth bonded with epoxy resin and has high mechanical and dielectric properties, better heat resistance and moisture resistance. It is often used in the production of transformer insulating parts, such as insulation stays, partitions, insulation pads and so on.

Adhesive paper products: Adhesive paper products are usually rolled into tubes with single-sided adhesive paper coated with phenolic resin, and then are baked and painted. They have good electrical properties and mechanical strength ‌. Such as polyimide film, polyester film, etc., they not only provide electrical isolation, prevent current leakage and short circuit, but also prevent equipment overheating and aging. They are commonly used as insulation between transformer windings and iron cores, and between windings and windings.

PI (polyimide) : Pl is a high temperature insulation material with excellent high temperature resistance and mechanical strength, which is often used in high temperature areas of dry type transformers.

PET: PET is also a common insulation material. It has good insulation properties and heat resistance. It is often used in the low-voltage winding of dry type transformers. And it can maintain excellent physical and mechanical properties in a wide temperature range. Its long-term use temperature can reach 120℃, even at high temperature and high frequency, its electrical properties are still good ‌.

The optimal insulation material for the transformer needs to be selected according to the specific application scenarios and requirements. In practical applications, manufacturers will consider the characteristics of various insulation materials and application requirements to ensure the reliable operation of the transformer.