Research on the Aging Mechanism of Oil Paper Insulation in Power Transformers

Study on the mechanism of aging of oil paper insulation in power transformers

1、 Introduction

As an indispensable equipment in the power system, the normal operation of power transformers relies on the protection of oil paper insulation. However, over time, oil paper insulation will gradually age, posing risks to the stable operation of transformers. Therefore, studying the aging mechanism of oil paper insulation in power transformers is of great significance.

2、 The main mechanism of aging of oil paper insulation

The main mechanisms of oil paper insulation aging include thermal aging, oxidative aging, and electric field aging.

1. Thermal aging: Thermal aging refers to the long-term exposure of oil paper insulation to high temperature environments. When the transformer operates for a long time, the oil paper insulation will be affected by high temperature, which can cause molecular chain breakage and physical structure damage of the insulation material. For example, when the temperature exceeds 100 ℃, cellulose will undergo degradation, producing a large amount of water and carbon dioxide, leading to the gradual brittleness and aging of insulation paper. At the same time, high temperature also promotes the decomposition of moisture in insulation materials, producing acidic substances, further accelerating the aging of oil paper insulation.

2. Oxidative aging: Oxidative aging refers to the chemical reaction that occurs in oil paper insulation under the action of oxygen, resulting in a decrease in the performance of the insulation material. Due to the fact that oil paper insulation is always immersed in oil, oxygen will enter the insulation layer through the permeation of oil, react with impurities and moisture in the oil, and form harmful substances, thereby affecting the insulation performance of the insulation material. This oxidation reaction will decompose oxides and acidic substances such as alcohols and aldehydes, ultimately forming sludge and producing a certain amount of CO and CO2. As the transformer continues to operate, these gases will continuously dissolve in the insulation oil, accelerating the aging process of oil paper insulation.

3. Electric field aging: Electric field aging refers to the aging of oil paper insulation during the operation of power transformers under the action of an electric field. The electric field will cause the polar molecules in the oil paper insulation to align in a directional manner, forming current channels and accelerating the aging of the insulation material. Especially under high voltage and high load conditions, the strong electric field makes oil paper insulation more prone to aging. In addition, the electric field can also cause changes in the insulation structure of transformers, such as causing confusion of electrons in the air gap, generating a large number of free electrons to accelerate throughout the electric field, damaging the structure of organic matter, and leading to aging.

3、 The impact and preventive measures of oil paper insulation aging

The aging of oil paper insulation can have a serious impact on the normal operation of transformers, such as reducing insulation performance, increasing heat dissipation difficulty, and shortening service life. In order to extend the service life of transformers and ensure safe operation, the following preventive measures can be taken:

1. Reduce operating temperature: By designing the heat dissipation system of the transformer reasonably, adding cooling devices, and improving heat dissipation capacity, the operating temperature of the transformer can be reduced, thereby delaying the aging rate of the oil paper insulation.

2. Maintain the excellent performance of oil quality: Regularly filter, dry, and test the insulation oil of transformers to reduce the content of moisture and impurities, maintain the excellent performance of insulation oil, and improve the service life of oil paper insulation.

3. Strengthen insulation monitoring: Regularly inspect and test the insulation layer of transformers, promptly identify problems, and take corresponding measures to slow down the aging rate of oil paper insulation. For example, methods such as sampling and measuring the degree of polymerization of paper or cardboard, or using high-performance liquid chromatography to measure the furfural content in oil can be used to determine the degree of aging of solid insulation.

4、 Conclusion

The aging of oil paper insulation in power transformers is a complex physical and chemical process involving the interaction of multiple aging mechanisms. In order to ensure the safe operation and prolong the service life of transformers, it is necessary to conduct in-depth research on the aging mechanism of oil paper insulation and take effective preventive measures.