Tank Vibration Analysis of an Extra-High-Voltage Transformer

In recent years, measurement of transformer vibration is being carried out as a means of detecting the looseness and deformation of its windings. Conventionally, the vibration components of even multiples of the power supply frequency (electrically generated vibration) were analyzed to diagnose the transformer. On the other hand, the natural vibrational frequencies of the winding structures represent their conditions, and the changes of these frequencies must be representing the changes in their pre-stress or displacement. We have measured the tank vibration of an extra-high-voltage transformer and investigated the dependence of load current, voltage, and temperature of the oil. As a result, although the electrically generated vibration has a complicated dependence, the winding's natural frequency is not affected by the current and voltage, and the influence of the oil temperature is not very large. It is considered that the natural vibrational frequencies of the windings are a suitable index for transformer diagnosis.