device for the feeding of a effektforbrukare from a vexelstromsnet with a overtonsfri strom

摘要

An arrangement for providing direct current to a consumer from a supply source of alternating current includes a transformer having its primary side connected to the a.c. supply source and the secondary side connected to a rectifier system from which the d.c. current is fed to the consumer. The secondary side of the transformer includes two windings each of which includes a tap that establishes two partial windings, and these partial windings are connected to a pair of full-wave rectifier bridges, the d.c. output sides of which are connected in series to feed the consumer. Each full-wave rectifier bridge includes both non-controllable valves and also controllable valves of the semi-conductor type such as thyristors, and control means are provided for selectively actuating the controllable valves in a step-like functional relation to the alternating current supply source such that different partial windings and combinations thereof are connected to the bridges to establish a step-like change in the transformation ratio of the transformer and hence also a step-like change in the voltage applied to the rectifier bridges.