STAC single-phase high accuracy full-automatic AC voltage stabilizer is one kind of our dominant products, made up of contact auto voltage regulator, servo motor, automatic control circuit, etc. When the power network voltage fluctuates or the load varies, automaticsampling control circuit will send signal to drive the servo motor which can adjust the position of carbon brush of auto voltage regulator, then, the output voltage will be adjusted to rated value and get a steady state.