The Servo Stabilizer manufactured by Bluebird Power utilizes a motor driven variable auto transformer & a BuckBoost transformer, which is connected between the incoming phase supply & the load.

The primary winding of the BuckBoost 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