The normal temperature range of dry-type transformers
Jul 30, 2021
Under normal circumstances, the temperature controller control settings during normal operation of the transformer: 80℃ automatically turn off the fan, 100℃ automatically turn on the fan, 130℃ high temperature alarm, 150℃ ultra-high temperature trip. At present, my country's dry-type transformers are classified according to the insulation level, there are (A), (E), (B), (F), (H), and (C) levels.
The temperature limits are as follows:
Insulation temperature class A E B F H C Maximum allowable temperature（℃） 105 120 130 155 180 220 Winding temperature rise limit（K） 60 75 80 100 125 150 |
The temperature of a normal working dry-type transformer reaches 95 degrees, which is already considered high, and the load cannot be increased. Low-voltage equipment generally requires that the temperature rise should not exceed 60 degrees (ie: ambient temperature + 60 degrees). Too high temperature will accelerate the aging of the equipment insulation and shorten the service life. The limit value of 125K is H-class insulation. The national standard "Dry-type Transformer" GB6450-1986 specifies the temperature rise limit of dry-type transformers.
1. For the coils of dry-type transformers, when Class A insulating materials are used, the maximum temperature rise should be less than 60K when the limit operating temperature is 105°C. When using Class E insulating materials, the maximum temperature rise should be less than 75K when the limit operating temperature is 120°C.
2. When using Class B insulating materials, the maximum temperature rise should be less than 80K when the limit operating temperature is 130°C. When using Class F insulating materials, the maximum temperature rise should be less than 100K when the limit working temperature is 155℃.
3. When using class H insulating materials, the maximum temperature rise should be less than 125K when the limit operating temperature is 180°C. When using Class C insulating materials, the maximum temperature rise should be less than 150K when the limit operating temperature is 220°C.
Most dry-type transformers now use Class H insulating materials, so generally the temperature of dry-type transformers should be below 180°C.
