What Is Transformer Oil?

Transformer oil: It is a fractional distillation product of petroleum. Its main components are alkane, naphthenic saturated hydrocarbon, aromatic unsaturated hydrocarbon and other compounds. Commonly known as square shed oil, light yellow transparent liquid, relative density 0.895. Freezing point <-45 .

Transparent appearance, no suspended matter, sediment and mechanical impurities

Flash point (closed cup) 135

Kinematic viscosity (50 ) 9.6 × 10 ^-6 m ² / s

Acid value 0.03mgKOH / g

Pour point <-22

1. The oil in the transformer mainly plays a role of heat dissipation and cooling during operation;

2. Insulate and maintain the windings (maintain good insulation);

3. Transformer oil plays an arc-extinguishing role at the high-voltage lead and the contact point of the tap changer, preventing the generation of corona and arc discharge;

4. Transformer oil is widely used as a liquid seal in a hydraulic safety valve.

Transformer oil is a mineral oil obtained by distillation and refining in natural petroleum. It is a natural natural hydrocarbon with pure, stable, low viscosity, good insulation and good cooling properties. A mixture of compounds. Commonly known as square shed oil, light yellow transparent liquid, relative density 0.895. The freezing point is <-45 , and the specific heat capacity is about 0.5 (cal / g * degree). It is mainly composed of three hydrocarbons, the main components of which are naphthenes (about 80%), and the others are aromatic hydrocarbons and alkanes. In China, transformer oils include paraffin-based oils and naphthenic oils. Paraffin base oil is produced in Daqing, and naphthenic oil is produced in Karamay, Xinjiang.

A good transformer oil should be a clean and transparent liquid without sediments, suspended matter from mechanical impurities, and cotton-like matter. If it is contaminated and oxidized, and resin and sediment are generated, the transformer oil will deteriorate, and its color will gradually become light red until it becomes a dark brown liquid. When the transformer is faulty, the color of the oil will also change. Generally, it is not suitable to use the transformer oil when it is light brown. In addition, transformer oil can appear cloudy, milky, oily and dark. Transformer oil is cloudy and milky, indicating that the oil contains moisture. Dark oil color indicates aging of transformer oil insulation. The oil color is black, and there is even a scorching odor, which indicates that there is a fault inside the transformer.

Why DL / T572-95 " Transformer Operation Regulations" stipulates

Solutions to deal with transformer leakage:

1. Selecting seals of good material When transformers are overhauled and treated for leakage, seals with high temperature and oil resistance should be selected. The most commonly used sealing material in the domestic transformer industry is nitrile rubber. Its oil resistance mainly depends on the acrylonitrile content in the nitrile rubber. The higher the acrylonitrile content, the better the oil resistance, the greater the hardness, and the less difficult it is to deform. Generally, a nitrile rubber with a Shore hardness between 70 and 80 should be selected. When assessing the oil resistance of gaskets, gasket aging tests and compatibility tests with transformer oils should generally be performed. They should be immersed in hot oil at 120 ° C for 168h, and then measure the change rate of weight, volume and hardness, and select the Deformation is small, and meets standard seals.
2. Select high quality butterfly valve. Select ZF80 vacuum eccentric butterfly valve. Compared with ordinary butterfly valves, vacuum eccentric butterfly valves have greatly improved mechanical strength and surface finish, and this product also has the biggest advantage is that the double-layer seal is used at the interface with the transformer flange, which eliminates Oil leakage problem at transformer interface.
3. Welding with electric plugging Welding can be used for plugging of blowholes, trachoma, welds, and solder joints that are left over by transformers due to casting.
Before plugging welding, you should pinpoint the leak point. The smaller leak point can be directly welded to the leak point; the larger leak point should be filled with asbestos rope or metal filler, and then surfacing around, then use a small electrode High current rapid arc repair welding.
4, standard seal replacement process For transformers of different models and different capacities, whether it is flange connection or thread connection, the dust and rust on the connection surface must be removed before the seal is replaced. After the seal is cleaned, Apply sealant (usually 609 polymer liquid sealant) on both sides of the seal. After the sealant is dried for a period of time, the solvent and volatilize, then tighten the flange and screws.
5. Improve the level of installation technology, and prevent the leakage caused by improper installation method to correct the interface of the flange interface unevenly or deformed. If the misalignment cannot be corrected, the flange can be cut and re-welded. The interface must be parallel. It is advisable that the compression amount of the gasket is about 1/3 of its thickness during installation.
6. Quick sealing plugging plug This method is used for small leakage and dripping of transformers. It can be used for leaking points where the transformer radiator tube wall is thin and leaking points that are not suitable for welding with the leak plugging method. . When plugging with a plugging plug, you must thoroughly remove the oil, paint, and oxide from the plugging site to expose the metal to its original color. Then adjust the plugging glue according to the ratio, and plug the leaking part until it is not leaked.

(1) Freezing point (2) Water content; (3) Interfacial tension; (4) Acid value; (5) Water-soluble pH; (6) Breakdown voltage; (7) Flash point; (8) Volume resistivity; ( 9) Dielectric loss (10) Chromatographic analysis