Contact arrangement for transformer stage selector - has fine and coarse windings controlled by switching stages to avoid voltage surges

摘要

The high voltage transformer with a wide operating range is designed to avoid the generation of large voltage surges through the contacts of the stage selector. The winding (51) of a three phase input is connected to a coarse winding (58) and a fine winding (60) has multiple pick-off points (61) that are in contact with the wiper (62) of a selector. A load switch (63) transmits the regulated voltage to output (64). Two switching stages (53,54) control the windings to minimise surges, operating in conjunction with auxiliary stages (55,59) to allow the coarse and fine winding voltages to be added or subtracted.