Study on arcless switching experiments of hybrid on-load tap changer in transformers

The arc of traditional on-load tap changer in transformer during swithing period can significantly reduce contact's lifetime and accelerate the deterioration of transformer oil in switching process. In order to solve the above problems, this paper proposes a new principle of hybrid on-load tap changer, and the trial of the laboratory prototype model, using telescopic movement moving contacts to ensure switching sequence, mechanical components to achieve passive trigger of thyristor modules, assisting machinery with thyristor to achieve extinction in the process of switching. Establish a standard low-voltage switching test circuit, switching tests were under resistive load and inductive load conditions. Experimental results show that the process of switching thyristor in a trigger would be four times, twice during the current zero crossing off the natural, and twice turned off by bypass of mechanical switch. Experimental results validate shows the effectiveness of the hybrid arcless on-load tap switching method.