The SERVO CONTROLLED VOLTAGE STABILIZER utilizes a motor driven variable auto transformer & a Buck\Boost transformer, which is connected between the incoming phase supply & the load. The primary winding of the Buck\Boost transformer is connected to the continuously Variable Auto Transformer in such a way that one lead of the winding is connected to a predetermined tap point of the auto transformer, depending on the position of the variable brush arm with respect to the fixed point the voltage applied to the primary winding has addition or subtraction on the supply voltage available on the secondary side.
The autotransformer is driven by an AC synchronous motor to achieve increase or decrease in output set voltage by rotating it in clockwise or anticlockwise direction depending on the input supply voltage.
An electronic control card continuously monitors the output voltage and the same is being compared against the set reference voltage to achieve the desired output voltage. The control card responds to the variation in input voltage in such a way that the motor in voltage correction doesn't overshoot in either direction. This method of correction in output voltage is free from generating waveform distortion & harmonics.