What is the reason for the excessive temperature rise of the transformer

The transformer is one of the equipment with the lowest failure rate in the electrical equipment. In addition to man-made and load reasons, the most common fault of the transformer is the excessive temperature rise of the transformer. There are only a few reasons for the excessive temperature rise of the transformer. Here is a summary of the reasons why the transformer is too long and too high.

The most common fault of the transformer is the excessive temperature rise. So, what are the reasons for the excessive temperature rise of the transformer?

Ⅰ. The insulation between the silicon steel sheets of the transformer core is damaged. When such a fault occurs, the flash point of the oil drops and the Buchholz relay will operate frequently.

Ⅱ. Transformer internal winding failure, insulation damage, such failure, oil quality deterioration, gas action, three-phase winding DC resistance is unbalanced, three-phase voltage and current are abnormal, and the three-phase winding can be tested by the oil test analysis and the electric bridge , The judgment is determined. 

Ⅲ. Poor contact of the tap changer (out of gear), this fault can be analyzed through the oil product flash point drop. After the DC resistance test, check whether the voltage and current are normal. This kind of failure should be repaired by lifting the core and reinstalling the tap changer.

Ⅳ.  the internal and external wiring of the casing is in poor contact. This kind of fault can pass the DC resistance test, and the casing terminal will be discolored. This kind of fault should be dealt with in the case of external power failure, increase the contact surface between the casing and the conductor, and tighten the bolts. If it is in the lower part of the bushing (that is, inside the transformer body), the core should be lifted.