Why the provisions of the maximum temperature of the provisions of the transformer 65 °?
Most big oil temperature increased load, the transformer internal fault, there is lack of oil performance security risks.
So we do need to limit oil temperature and protection tripping. Small capacity (630KVA less and outdoor) often do not have the oil temperature protection.
I have the original table 800KVA overload (secondary current 1500A), top oil temperature to over 90 degrees ......
Transformers and other electrical equipment temperature limit is determined by the level of insulation materials.
Insulation grade refers to the heat resistance of the insulation material used, divided into A, E, B, F, H grade. Allowable temperature rise is the limit of the temperature of the electrical equipment compared to the ambient temperature.
Insulation temperature class A grade E grade B grade F grade H grade
Maximum permissible temperature (° C) 105 120 130 155 180
Winding temperature limit (K) 60 75 80 100 125
Performance reference temperature (° C) 80 95 100 120 145
In the electrical equipment such as transformers, the insulating material is the weakest link. Insulation material is particularly susceptible to high temperature and accelerated aging and damage. Different insulation materials have different heat resistance, the use of different insulation materials, electrical equipment, the ability to withstand high temperatures are different. So the general electrical equipment is specified in the maximum temperature of its work.
You ask the question, the top of the oil temperature does not exceed 65 ℃, is in the case of rated load manufacturers consider a variety of factors to ensure that the insulation material is not damaged by the temperature limit. Under normal circumstances the top of the transformer oil temperature is the highest.
