How to choose the insulation material of the transformer?

Insulation material is used to isolate the conductive material. Its main role is to protect the winding and core iron inside the transformer from the external electric field and to prevent circuit short circuit and leakage. The correct selection of suitable insulation materials is very important to improve the efficiency of the transformer.

How to choose the insulation material of the transformer?

1. Temperature rating

The temperature grade of insulation material is one of the important indexes to measure insulation performance. The higher the temperature level of the insulation material, the better the insulation performance. Different types of transformers can choose different temperature grades of insulation materials. For example, dry type transformers usually choose class H or class C insulation, while oil-immersed transformers choose class F or class H insulation.

2. Dielectric constant

Dielectric constant is a physical quantity inherent in the material itself, which measures the response ability of the material to the electric field. The lower the dielectric constant of the insulation material, the better the insulation performance. Therefore, the selection of insulation materials with low dielectric constant can improve the efficiency of the transformer.

3. Mechanical properties

The insulation material should have good mechanical properties, wear resistance, pressure resistance, heat resistance, corrosion resistance and other properties must meet the use of the transformer environment and working conditions.

4. Economy

The economy of insulation materials is also an important factor to consider when choosing insulation materials. Choosing economical insulation materials can reduce the cost of the transformer and save more energy in use.

Common insulation materials and their uses

Insulation board: They are used to make soft paper tube, brace, pad and other insulating parts, with good mechanical and electrical properties.

Cable paper: They are used for interturn insulation of transformer winding, interlayer insulation, etc., to improve the insulation performance of the winding.

Adhesive paper products: They are used for insulation between transformer winding and iron core, as well as tap-changer insulation.

Epoxy products: Epoxy products are used for impregnating and binding the glass ribbon of iron core columns. They can also be made into plates, rods, rings and tubes, as insulation parts. ‌

Varnished cloth or varnished cloth tape: Varnished cloth or varnished cloth tape is used to bind the bend of cable or the part that requires high quality. ‌

Why should a transformer use good insulation material?

1. Ensure the normal operation of the transformer

The insulation material can form an isolation layer between the conductive components and effectively prevent the occurrence of short circuit. In a transformer, various conductive components such as coils and cores need to be well isolated and protected to prevent short circuits between each other. The high resistivity of the insulation material can avoid the leakage of current and ensure the normal operation of the transformer.

2. Improve the insulation capacity of the transformer

At high voltage, the insulation material can significantly improve the insulation capacity of the transformer. This is because the insulation material has a high resistivity and can effectively prevent the current from passing through, thus ensuring that the transformer can also operate safely under high voltage.

3. Enhance the high temperature resistance of the transformer

Good insulation materials can effectively resist the influence of high temperature environment on the transformer, thus enhancing the high temperature resistance of the transformer. For example, insulation materials such as silicone rubber and phenolic resin can maintain good insulation and mechanical properties in high temperature environments, ensuring that transformers can also run stably in high temperature environments.

4. Improve the mechanical strength of the transformer

Insulation materials can also play a role in enhancing the mechanical strength of the transformer. For example, transformer insulation sheet can not only maintain good insulation performance at high temperatures, but also withstand a certain tensile and twisting force under mechanical stress, so as to ensure the stability and safety of the transformer.

5. Extend the service life of the transformer

The correct selection and use of insulation materials can significantly extend the service life of the transformer. If the insulation material is not selected properly or used improperly, it may lead to premature aging or damage to the transformer. High-quality insulation materials can maintain stable performance during a long time of use, thereby extending the service life of the transformer.