Analysis of Transformer Winding Deformation

A typical amplitude frequency response characteristic curve of a transformer winding typically contains multiple distinct peaks and valleys. Experience and theoretical analysis indicate that the changes in the distribution position and quantity of peaks or valleys in the amplitude frequency response characteristic curve are important basis for analyzing transformer winding deformation.

Low frequency range of amplitude frequency response characteristic curve（1kHz~100kHz）A significant change in the position of the peak or valley of the winding usually indicates a change in the inductance of the winding, and there may be a short circuit between turns or between cakes. When the frequency is low, the capacitance impedance formed by the ground capacitance and inter cake capacitance of the winding is large, while the inductance impedance is small. If the inductance of the winding changes, it will cause a significant shift in the peak or valley position of the low-frequency part of its frequency response characteristic curve. For the vast majority of transformers, the low-frequency response characteristic curves of their three-phase windings should be very similar, and if there are differences, the cause should be identified in a timely manner.

In the frequency range of the amplitude frequency response characteristic curve（100kHz~600kHz）A significant change in the position of the peak or valley usually indicates local deformation phenomena such as winding distortion and bulging. The amplitude frequency response characteristic curve within this frequency range has many peaks and valleys, which can sensitively reflect the changes in winding distribution inductance and capacitance.

High frequency range of amplitude frequency response characteristic curve（>600kHz）A significant change in the peak or valley position of the winding usually indicates a change in the winding's capacitance to ground, which may result in overall coil displacement or lead displacement. When the frequency is high, the inductance of the winding is large and the capacitance is small. Due to the fact that the inter cake capacitance of the winding is much larger than the ground capacitance, the distribution of peaks and valleys is mainly affected by the ground capacitance.