1. Physical properties of transformer oil

Pure transformer oil is a colorless and transparent liquid. Its dielectric strength is much higher than that of air. It can fill the air gaps between various components in the oil tank, so that the internal insulating medium maintains good chemical and physical properties, and protects metals from corrosion. Maintaining a good insulation state of the transformer, in addition, the transformer oil also has a good heat dissipation effect, the oil circulation makes the winding and the iron core fully cooled, and improves the operating conditions, which is an important part of the safe and stable operation of the transformer. Usually, the density of transformer oil at 20℃ is 0.84~0.91, generally not more than 0.9. The smaller the density of the transformer oil, the easier the impurities and moisture in the oil are to precipitate, which is more beneficial to the safe and stable operation of electrical equipment. For example, at low temperatures, if there is moisture in the transformer oil, it may freeze, and the density of ice is 0.92. If the density of the oil is greater than 0.92, the ice will float in the oil and become a discharge channel, causing an electrical accident.

2. Transformer oil type

In my country, the grades of transformer oil are divided on the basis of freezing point, namely DB-10, DB-25, DB-45, where D stands for “power oil”, B stands for “transformer oil”, and the following numbers Indicates that the freezing points of the three types of transformer oil are -10°C, -25°C, and -45°C, respectively. For areas where the minimum temperature is not lower than -10°C, use DB-10 transformer oil, and for areas where the minimum temperature is lower than -10°C, use DB-25 or DB-45 transformer oil.

For more information about oil-immersed transformer oil, you can check this article: Determination of transformer oil quality

Transformer Oil Properties

Post time: Jan-20-2022