Dry transformer overtemperature refers to the transformer winding temperature exceeds the insulation tolerance temperature, so that the insulation damage, resulting in the transformer can not work normally. In order to effectively protect and alarm the transformer overtemperature, many transformer manufacturers provide temperature control boxes to realize the functions of forced air cooling, overtemperature alarm and overtemperature tripping to the transformer by directly detecting the transformer winding temperature. The temperature detection of the transformer winding is to output the temperature signal to the temperature monitor through the thermistor embedded in the low-voltage coil, and then the temperature monitor outputs various signals to control the start and stop, alarm and trip of the fan. When the transformer is in operation, when the winding temperature is higher than 110℃, the temperature control box will start the fan for forced air cooling. If the winding temperature drops below 90℃, the fan will stop; If the temperature continues to rise, the temperature control box near 115 ° C will send out an overtemperature alarm audio signal; When the temperature exceeds 170℃, the trip signal is output to the 10kV protective trip circuit of the transformer, and the high-voltage side power supply is disconnected, thus the transformer is protected. Transformer manufacturers can also provide temperature display, always display the winding temperature, if necessary, through the temperature control box on the manual button, control the continuous operation of the fan.
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