A Vibration Method for Identifying the Looseness of Windings for Large Power Transformers

摘要

The safe operation of large power transformers is very important for the electricity system, while the looseness of winding clamping pressure is one of the main failure reasons. To deal with this problem, a two-degree-of-freedom nonlinear mechanical model for one winding is proposed and analyzed to study the influence of clamping pressure looseness on the windings' vibration characteristics. The simulation of this model studies the influence of clamping pressure changes on the winding's natural frequency and its amplitude. Based on this study, the vibration method under swept frequency with constant current is put forward to identify the looseness of the windings. The experiments were conducted on one real large power transformer, which testifies that this method is effective by exactly identifying the windings' looseness.