Reasonable control of voltage overrun time by using medium voltage no-load grade of transformer in guangxi electric power Zhou Hongyu (Hezhou Power Supply Bureau, Guangxi Hezhou 542800). Adjust the number of turns of the medium voltage side coil and lower the voltage on the medium voltage side by adjusting the no-load tap switch on the medium voltage side of the main transformer. After the voltage of the power supply side is high, when the voltage on the medium voltage side cannot be adjusted through the main transformer on-load adjusting gear and the drop-out capacitor, the number of turns of the medium voltage side coil can be adjusted by adjusting the no-load tap switch on the medium voltage side of the main transformer, so that the voltage on the medium voltage side can be effectively reduced, and the voltage can be controlled within the qualified range.