Automatic Voltage Stabilizer (AVS) or called automatic voltage regulator (AVR) it is single phase and three phase high accuracy full-automatic power supply product, which is made up of servo motor, automatic control circuit ect.. When the power network voltage fluctuates or the load varies, automatic control circuit will send signal to drive the servo motor which can adjust the position of carton brush of automatic voltage stabilizer, then output voltage will be adjusted to rated value and get a steady state. It can be applied house large type electromechanical equipment, metal processing equipment, production line, construction device, elevator, medical equipment, equipment of light and textileindustry, air-condition, TV set, household appliance and lighting used for industry, agriculture, traffic, military, railroad, scientific culture, etc.