Servo Controlled Stabilizer

Method of operations
servo controlled voltage stabilizers maintain accurate output by feedback controllingm by servo motor. the input line is connected in series with the secondary winding of a buck boost transformer. The secondary will get additive or subtract voltage induced from its primary. When the input is low, the secondary will have additive voltage to give boosted output and vice versa. the primary of this buck – boost transformer is connected to the fixed tap and variable point of the variable transformer which is connected across the input supply. the position of the variable point with respect to the fixed tap point determines the amount of primary voltage and hence the secondary voltage of the transformer which becomes additive or subtract. Thus the input is boosted or bucked by the series connected secondary wiring corresponding to the position of the variable point of the variable transformer. the variable point is driven by a servo motor in the forward or reverse directions. the forward or reverse signals is given through a controller circuit which is energized by an output sensing transformer. the controller circuit will be giving forward or reverse signals to the motor till the ouiput is corrected to the required value. as sensed by the sensing transformer if the variation in the input voltage goes beyond the specified range. the brush arm of the variable transformer will be driven to either of the ends, thus unable to correct the output further. This however is likely to cause damage to the variacs, motor etc. To avoid the same limit switches are provided at both the ends of the variacs winding so that the brush arm on reaching the end will automatically cut off the supply to the motor and prevent further movement. if the variation in the input voltage revives to within the specified range, the supply to the motor comes into function automatically to set the output voltage to its specified level also when the limit