Operation time of transformer is long, so add oil to transformer is necessary. At the same time, the equipment change oil after overhaul. The electrical equipment is lack of oil that need to add, we need to choose oil which meet new oil standard and never use before. Add the same oil base ,same brand and same additive is the best way for transformer. The indicator of the replenish oil must be better than oil you used.
Different oil base should not mix with to use. Under the particular condition, we need to use different brand oil which follow the measured solidifying point of mixture oil to decide whether is suitable for this area or not. Mixture sample is better than single oil sample after oil experiment. If you mix different brand oil or used oil in the running oil, you need to measure solidifying point of mixture oil and carry aging test and fatlute experiment to observe sludge precipitation. If the oil without sediment, you can use it.
