A servo-controlled system utilizes a closed-loop feedback mechanism to precisely regulate an output variable, such as voltage. In the context of Y S Engineering Solution, this technology is central to their servo voltage stabilizers. A servo motor and an electronic control circuit work together to sense any fluctuation in the input voltage. The control circuit then commands the servo motor to adjust the position of a variable transformer, instantly correcting the output voltage to a stable and desired level. This ensures that sensitive equipment is protected from damaging voltage sags, surges, or other power line anomalies, providing a consistent and reliable power supply.