What are the causes of transformer winding deformation?

What are the causes of transformer winding deformation?

The main form of transformer winding deformation is irreversible deformation phenomena such as twisting, bulging, and displacement of the winding, among which common and typical forms are inter turn short circuits, main insulation discharge, or complete breakdown accompanied by insulation damage. In daily life, there are many reasons for transformer deformation, generally speaking, there are mainly the following:

1. The transformer winding is impacted by short-circuit fault current during operation

It is inevitable to be impacted by various short-circuit fault currents during operation. Especially in the case of close circuit and outlet faults, the winding will be subjected to a very large impact force from the short-circuit current, resulting in an increase in winding temperature and a weakening of the mechanical strength of the transformer related wires. The final transformer winding will deform or even be completely scrapped under the operation of electric power.

Generally speaking, there are two types of electric forces in transformers, one is radial (transverse) force, and the other is axial (longitudinal) force.

Once the transformer is subjected to current surges such as sudden short circuit faults during operation, each coil will generate a strong combination of radial and axial forces.



2. The transformer winding itself has limited bearing capacity

Due to the inherent defects of the transformer winding, i.e. limited bearing capacity, it cannot withstand the short-circuit current impact force caused by the transformer's short circuit well, resulting in the deformation of the winding. According to the analysis of 110KV power transformers in recent years, the biggest hidden danger of safe operation of transformers lies in the deformation of transformer windings. However, winding deformation is inevitable to a certain extent, so the inspection of transformer windings is particularly important.



3. There is a certain dead zone or operational failure in the protection system

Another reason for transformer winding deformation faults is the existence of a certain dead zone or action failure in the protection system, as the dead zone and failure can cause the transformer to withstand stable short-circuit current for a longer time, ultimately leading to winding deformation. According to data statistics, approximately 30% of transformer damage occurs due to delayed tripping when exposed to external short-circuit obstacles.



4. Transformer winding deformation caused by external force impact

Transformers are inevitably deformed due to external forces during transportation and installation, such as being violently impacted by machinery or other objects during installation.

EP Hipot Electric Co., Ltd.

2023.5.27