Energy based contact burning diagnosis and Research of on-load tap changers

Contact burning is one of the main faults of transformer on-load tap changers (OLTC). If contact burning fault diagnosis is not timely, the decreasing contact area, increasing contact resistance and the increasing arc and heat during the witching processes will cause further burning. Researches on contact burning failure were done and a feature analysis method based on wavelet packet energy entropy of OLTC was proposed in this paper. After the comparison of the time domain vibration signal energy in the normal and fault conditions, the wavelet packet energy entropy was taken advantage to analysis the contact burning fault. Fault symptoms of OLTC were extracted by the simplified wavelet packet energy entropy. The contact burning fault can be determined by the symptoms and the results of the experiment show that this approach was feasible for the condition monitoring of OLTC.