Abstract: A tap-changer transformer operated by the step-by-step principle in which its motor drive receives a signal to raise or lower the tap, has a voltage regulator in which the switching delay times and sensitivity values are freed matrix-like the respective tap changes. The actual voltage value of the transformer is compared with the preselected voltage setpoint and, based upon the control deviation, a value pair of delay and sensitivity are read out. This allows asymmetric response of the system as contrasted with the symmetrical response required by earlier systems.

Abstract: A motor-driven step switch for step transformers includes a drive motor connected to the step switch, display, input, and control units, a controller for actuating the drive unit in accordance with rotation direction, an information unit which obtains and transmits the step position and which is connected with the controller which delivers commands for controlling the drive motor and a switching operation, and an electrical connection between the controller and display, input, and control units. In accordance with this invention the information unit has a sensor for determining the absolute value of the actual position of the step switch, a nonvolatile memory unit for storing the position of the step switches with a range of step positions, and a unit for determining an end position of the step switch.