Why is insulation paper used in transformers?

In the huge structure of the power system, the transformer is a key core component, responsible for voltage conversion, power transmission and distribution. Insulation paper, as an indispensable insulation material inside the transformer, has multi-dimensional significance. The following will deeply analyze why transformers cannot do without insulation paper.

Excellent electrical insulation performance

High resistivity ensures insulation effectiveness

Insulation paper has extremely high resistivity, which enables it to effectively prevent current from flowing in unexpected paths. Inside the transformer, reliable insulation is required between the high-voltage winding and the low-voltage winding, as well as between the winding and the core to prevent electrical short circuits. The high resistivity of the insulation paper acts as a solid barrier to separate parts with different potentials. Taking the oil-immersed transformer as an example, the insulation paper is immersed in the transformer oil and together with the oil, it forms a composite insulation system. The transformer oil itself has certain insulation properties, and the addition of insulation paper further enhances the overall insulation effect, which greatly reduces the risk of short circuit failures caused by insulation breakdown.

High dielectric strength withstands electric field test

Dielectric strength is a key indicator to measure the ability of insulation materials to withstand voltage under the action of electric fields. Insulation paper has a high dielectric strength and can withstand the high electric field strength generated when the transformer is running. When the transformer is running at normal operating voltage, the insulation paper can maintain good insulation performance and will not break down. Even under abnormal conditions such as overvoltage, the insulation paper can withstand additional electric field pressure to a certain extent, providing a solid guarantee for the safe and stable operation of the transformer. For example, in the event of lightning overvoltage or operating overvoltage, the high dielectric strength of the insulation paper can prevent the insulation between the windings from being broken down and avoid damage to the transformer.

Significant mechanical support

Stable winding structure

The winding of the transformer is wound by wire. During operation, the winding will be affected by electromagnetic force and easily deformed or displaced. Insulation paper plays a key role in fixing the winding structure. It tightly wraps and supports the winding, like a solid skeleton, ensuring that the winding maintains a stable shape and position, and ensuring that the electrical clearance and insulation distance between the windings meet the standard requirements. In dry-type transformers, insulation paper is usually wound around the winding in a specific way to form a stable support structure to prevent the winding from becoming loose or deformed under the action of electromagnetic force.

Buffering mechanical stress

During the transportation, installation and operation of the transformer, it may be subjected to various mechanical stresses, such as vibration and impact. Insulation paper has a certain flexibility and elasticity, which can effectively buffer these mechanical stresses and protect the windings and other internal components from damage. When the transformer is subjected to external vibration, the insulation paper can absorb part of the vibration energy, reduce the direct impact on the windings, and thus extend the service life of the transformer.

Good thermal stability

Tolerance to high temperature environment

The transformer will generate heat during operation. When the load is large, the internal temperature will increase significantly. Insulation paper has good thermal stability and can maintain the stability of its physical and chemical properties in a certain high temperature environment. It will not deform, melt or decompose due to the increase in temperature, which ensures that its insulation performance and mechanical support are not affected. In some high-temperature areas or specific industrial application scenarios, the transformer needs to operate in a high-temperature environment for a long time. At this time, the thermal stability of insulation paper is particularly important.

Auxiliary heat dissipation function

Although the insulation paper itself is not an excellent thermal conductive material, it can still play a certain auxiliary role in the heat dissipation process of the transformer. The insulation paper works together with cooling media such as transformer oil or air to form an effective heat dissipation channel. The transformer oil can take away the heat on the surface of the insulation paper during the flow process, and the structure of the insulation paper also helps air circulation and promotes heat dissipation. In this way, the insulation paper helps to maintain the temperature balance inside the transformer and prevent the occurrence of local overheating.