SVC (TND, TNS) series high-precision automatic AC voltage stabilized power supply is composed of contact auto-voltage regulator, servo motor, automatic control circuit and so on. When the grid voltage is unstable or the load changes, the automatic control circuit drives the servo motor according to the change of the output voltage, and adjusts the position of the carbon brush on the contact autovoltage regulator to adjust the output voltage to the rated value, and the output voltage is stable and Reliable, high efficiency, can work continuously for a long time. Especially in areas with large grid voltage fluctuations or large seasonal changes in grid voltage, satisfactory results can be obtained by using this machine. It is suitable for all kinds of loads such as instruments, meters, and household appliances to work normally. The product complies with: JB/T8749.7 standard.