As fast development of industrial applications and AI & its associated data centers, more & more transformers are requiring in the market. no matter is a substation transformer or a pad mounted distribution transformer, most of them are oil filled or oil immersed transformers. How many degrees can the temperature of an oil immersed transformer not exceed? The insulation level of conventional oil immersed transformers is generally Class A, with a winding temperature limit of 105 ℃, which is also the maximum allowable temperature for operation of oil immersed transformers.
Oil immersed transformers generally use Class A insulation level, for example, the winding temperature rise limit of S20 transformer is 60K; The temperature rise limit of the top layer oil is 53K, and the difference between the temperature of the oil immersed transformer and the surrounding air temperature is called the temperature rise of the transformer.
Normally, the outdoor temperature range is between -20 to 40 degrees Celsius, so the outdoor temperature+transformer temperature rise limit is the maximum allowable temperature for the transformer. It is generally not recommended that the temperature of the transformer should not exceed 105 degrees Celsius in summer.
But in winter, although the oil immersed transformer does not exceed 105 degrees Celsius, its harm is not small. For example, if the outdoor temperature in winter is -10 degrees Celsius, the temperature of the transformer should not exceed 70 degrees Celsius. At this time, transformers between 80 and 100 will experience insulation failure due to excessive temperature rise.
The Effect of Temperature on the Performance of Oil Immersed Transformers
IEC 600354 Table 1 has clear regulations on the temperature rise limit of transformers. If the temperature rise value of a normal oil immersed transformer is 60K or 65K, the allowable temperature range of the transformer will fluctuate with the temperature of the current season. The room temperature+temperature rise (65 or 60) is the maximum value of the current season.
If the temperature rise of the transformer is too high, it will cause short-term operation, which will cause the temperature of the transformer to be too high. The operating temperature of the transformer is too high, exceeding the insulation heat resistance of the transformer, causing insulation breakdown and increasing the vortex current of the transformer. As a result, the noise of the transformer will gradually increase, and the transformer will not be able to operate within 1-2 years.
The maximum temperature allowed for operation of an oil immersed transformer in summer is 105 degrees Celsius, but the maximum temperature allowed for operation varies depending on the season. This requires special attention when oil filled transformers are in operation.
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