Test and Evolution Process Analysis of Vacuum Interrupter Failure of Vacuum Type On-load Tap Changer

The on-load tap changer (OL TC) is a precision electromechanical equipment with high reliability requirements. The vacuum type OL TCs are more and more widely used because of its strong arc extinguishing ability. However, in actual operation, the faults of vacuum type OL TC often occur due to the failure of vacuum interrupter in vacuum type OL TC. In this paper, the switching circuit principle of vacuum type OL TC and the vacuum interrupter failure test platform of OL TC were introduced firstly. A defect model of vacuum interrupter of vacuum type OL TC was made according to OL TC fault analysis experience. The failure switching test was carried out on the vacuum type OL TC with defect vacuum interrupter. The transient voltage and current changes during the switching process were analyzed, and the evolution process of tap changer from normal switching to switching fault was studied. The results show that the switching failure of vacuum type OL TC caused by the defect of vacuum interrupter was not sudden, but a gradual development process. Based on this conclusion, A solution for online monitoring and evaluation of switching performance of vacuum interrupter was proposed in the end of this paper.