Knowledge About Transformer Oil

Oil is an important fluid. We know that oil is extracted in many places around the world. We also know about oil extracted from plants such as sunflowers and nuts. If you want oil with the right properties, the oil must be refined. In this story, I want to limit myself to transformer oil. Transformer oil is extracted from petroleum and is therefore not good for the environment. Transformer oil must meet many requirements and requires a complex refining process. Therefore, switching to a different type of oil is not so simple and requires a lot of development work.

Transformer oils based on plants such as sunflowers have also been on the market for many years. Environmental aspects and low flammability are the main advantages, but viscosity and lubricating effect are unfortunately disadvantages. The use of such "green" oils in grid transformers is rapidly increasing, and large transformers will certainly follow in the future. Transformers can also be made from natural gas. You can use natural gas molecules as a kind of building block to make complex molecules (they call it synthesis). Such oils are purer than oils refined from petroleum.

Why is there oil in transformers?

The electrical insulation value of oil is about 20 times higher than that of air. The length of the insulator chain on a 150kV high-voltage tower is 1.5 meters. A 150kV winding under oil only requires a distance of 0.07 meters. Therefore, a high insulation value is required to limit the size of the transformer.

The core and winding must be cooled. Cooling with liquid is much better than cooling with air, which is another reason to choose oil.

But every advantage has its disadvantages. The oil must meet many requirements, both at the beginning of its service life and 30 years later. The oil must remain in good condition and not undergo too much chemical change. Therefore, the oil should not age too much. All of this places high demands on the oil itself and the production process of the factory.

Insulation performance: Transformer oil has excellent electrical insulation performance, which can effectively prevent the leakage and breakdown of current and ensure the safe operation of electrical components inside the equipment.

Cooling: Transformer oil can effectively cool the electrical and mechanical components inside the transformer, helping to maintain the normal operating temperature of the equipment.

Anti-oxidation and heat resistance: In order to maintain the long-term stability and performance of the oil, transformer oil usually has good anti-oxidation and heat resistance, and can withstand high temperatures and long-term operation.

Water resistance: Good water resistance can prevent moisture from entering the inside of the transformer and avoid the reduction of the insulation and mechanical properties of the oil.

Chemical stability: Transformer oil can maintain chemical stability during long-term use, and is not prone to decomposition or precipitation, ensuring long-term stable operation of the equipment.

Common types:

Mineral oil: Traditional transformer oil, usually extracted from petroleum, is relatively cheap and widely used in most power equipment.

Synthetic oil: Including synthetic hydrocarbons, polymers or silicone-based oils, etc., which have better oxidation resistance and thermal stability and are suitable for high voltage, special environments or applications requiring high performance.

Use and maintenance:

Refill and replacement: Regularly check the insulation and chemical properties of transformer oil, and replenish or replace as needed to ensure the safety and reliability of the equipment.

Environmental impact: Transformer oil should be used and disposed of with attention to environmental impact, as it may contain harmful substances such as polycyclic aromatic hydrocarbons (PAHs) and chlorides.

In short, transformer oil is an indispensable part of power equipment, and its performance directly affects the safety, reliability and operating cost of the equipment. With the advancement of technology, new synthetic oils are gradually replacing traditional mineral oils to meet higher working requirements and environmental standards.