Transformer oil is essential in our daily lives because many machines in our homes have transformers. The larger the transformer, the higher the heat of the transformer. If the heat cannot be dissipated, it will lead to a reduction in the life of the transformer. Transformer oil has cooling properties that can delay the life of the transformer.
Transformer oil: It is a mineral oil obtained from natural petroleum through distillation and refining. It is a mixture of liquid natural hydrocarbons obtained from the lubricating oil fraction in petroleum through acid and alkali refining to obtain pure and stable, low viscosity, good insulation, and good cooling performance. Its main components are alkanes, cycloalkane saturated hydrocarbons, aromatic unsaturated hydrocarbons, and other compounds. Transformer oil, also known as square shed oil, is a light yellow transparent liquid.
Good transformer oil should be a clean and transparent liquid, free of sediment, mechanical impurities, suspended solids, and cotton wool like substances. If it is contaminated and oxidized, and resin and sediment are generated, the quality of the transformer oil will deteriorate, and the color will gradually turn to light red until it becomes a dark brown liquid. When a transformer fails, the color of the oil can also change.
During the use of transformer oil, due to the aging and deterioration of the oil itself and the pollution of the external environment, the quality of transformer oil is deteriorated, affecting the insulation, heat dissipation, and arc suppression of the transformer; Due to the partial discharge heating of the insulator during the operation of the transformer, chemical gases are generated in the transformer oil.
If there is metal discharge, solid insulation, or thermal decomposition of oil inside the transformer during operation, gas in the transformer oil will escape or dissolve in the oil, and the flash point of the oil will decrease. Therefore, it is necessary to monitor, protect, and timely analyze the flash point of escaping gas through gas relays during operation. However, for transformers with early hidden dangers, the gas dissolved in the oil has not yet reached the level of escape. Generally, a chromatographic analyzer can be used to analyze the composition and content of the gas dissolved in the oil. For example, most of the gas generated by metal discharge is hydrogen; "The thermal decomposition of solid insulation (such as oil paper insulation) produces about 10 times more CO2 than CO in the gas, with a significant decrease in oxygen content, and a small amount of H2. When local overheating leads to the thermal decomposition of oil, a large amount of hydrocarbons are generated, but there is no evidence of rapid decomposition. If large areas of local overheating occur, a small amount of H2 is also generated.".
Based on the analysis results, it is possible to determine the nature of potential hazards and take appropriate measures as soon as possible. The purpose of filtration is to remove moisture and impurities from the oil, improve the electrical strength of the oil, protect the paper insulation in the oil, and also improve the physical and chemical properties of the oil to a certain extent. Distribution power transformers are mostly installed in outdoor environments, and the quality of insulating oil (transformer oil) is gradually deteriorated due to the impact of external impurities, contact with air, and high operating temperature of the equipment itself. The deteriorated insulating oil (transformer oil) will not have the proper insulation and cooling effects. In order to prevent the safe operation from being affected due to the deterioration of oil quality, regular oil production samples from the power distribution system in normal operation should be tested and analyzed, and the oil should be treated accordingly based on the analysis results. The inspection cycle for chemical supervision of power distribution operation oil is specified to be at least once every three years. Routine inspection items include acid value, water-soluble acid, flash point, breakdown voltage, and appearance.
