Research on Mechanism of over Current When Non-contact On-load Tap Changer Regulating Voltage

Automatic on-load voltage regulation of transformer is an effective method to stabilize load voltage. Mechanic contact tap changing is not adequate for distributing transformer because of its high cost and low capability. The paper presents the structure and automatic on-load voltage regulating principle of distributing transformer, which employs solid state relay as non contact automatic on-load voltage regulating tap changer. The generation mechanism and limiting measure of circular current that is occurred in the process of changing tap joint. By theoretical analysis and experimental verification, it is concluded that it has different occurring process of circular current when voltage is regulated to higher or lower value.