Dry-type transformer winding deformation

In the production of dry-type transformers, its internal structure is more complex, no matter which part of the failure will affect the operation stability of dry-type transformers, we need to do a good job in monitoring each component. Among them, dry-type transformer winding deformation is one of the important causes of dry-type transformer damage accidents, so what way do we have to judge whether dry-type transformer windings are deformed?　
Whether the dry-type transformer winding is deformed mainly has the following three ways to judge.
1) In order to correctly judge the deformation of the dry-type transformer, first measure the original data of winding deformation when the dry-type transformer leaves the factory and installs, leaving a "fingerprint" for later comparison. The test items are as complete as possible, such as short-circuit impedance value, special instruments and frequency response method.
2) When the winding short circuit accident, in addition to measuring the deformation, some conventional tests and special tests should be carried out, and a comprehensive analysis should be carried out in combination with the size of the short-circuit current and the length of the short-circuit time, and the deformation of the dry-type transformer winding should be judged.
3) When judging the deformation of dry-type transformer by frequency response method, in addition to whether the frequency response characteristics of the three-phase winding are consistent, it should also be based on the correlation coefficient R value between the three-phase waveforms drawn, and the R value is greater than 1.0, which means that the deformation is not obvious, and the R value is less than 1.0, which should attract attention.