Analysis on Vacuum Type On-load Tap-Changer about Abnormal Increase of Acetylene Content in Oil Chromatography

Taking an abnormal increase of acetylene content in oil chromatogram of 220kV transformer vacuum type on-load tap-changer as an example, the diagnosis method is introduced. In the case of no abnormality found in conventional DC resistance, voltage ratio and DC compound switching waveform test, the diverter switch of on-load tap-changer is inspected by hanging core. The full step switching waveform is acquired by DC power supply and oscilloscope, the abnormal situation of voltage waveform is analyzed, and the defect location is accurately judged by combining the disassembly inspection and the principle of switching steps. The results show that the interior resistance chip of the transition resistance has poor contact, overheating and low-energy discharge during the switching process cause the cracking of insulating oil to produce acetylene.