An on-load transformer tap changing system, for example for a power
transformer, wherein the secondary or primary of a transformer includes
at least one first tap and one second tap. A main connection circuit is
used for permanent connection of the first tap or the second tap to an
output terminal of the secondary or primary of the transformer. Secondary
connection circuits are each used to connect a tap temporarily and
directly to the output terminal of the secondary or primary of the
transformer. Each of the connection circuits includes one or more
insulated gate bipolar transistors. The system can be controlled without
zero current value transition detection in the secondary winding.