The difference between the temperature of the transformer and the temperature of the surrounding air is called the temperature rise of the transformer.Temperature rise is one of the important indexes of transformer operation, which directly affects the insulation performance of transformer.
Too high temperature rise will accelerate the aging speed of insulation and shorten the service life of transformer.If the temperature rise is too low, the transformer is not fully utilized.Generally, the temperature that the insulation can withstand for a long time shall not exceed 90 ~ 95 ℃. If the temperature exceeds the allowable temperature, the service life of the insulation will be reduced by half for every 8 ℃ increase.
The regulation indicates that when the transformer operates continuously under the condition of no-load loss and short-circuit loss equivalent to 75 ℃, the temperature rise of each part of the transformer is higher than that of the surrounding air, and its value shall not exceed a specific value (for example, the allowable temperature rise of the winding is 65 ℃, and the allowable temperature rise of the core is 70 ℃), and the temperature of the surrounding cold air changes naturally, with the maximum value of 40 ℃.