Rectifier-circuit duty

The usual rectifier unit consists of a transformer with a number of rectifying elements connected to its secondary windings. The rectifying action may be resolved into two parts, namely, the circuit action which is determined by the transformer and the a-c and d-c circuits, and the unidirectional switching action which is performed by the rectifying elements. The circuit action is defined by the number, arrangement, and constants of the circuits connecting the a-c and d-c systems. The switching action consists of connecting the various secondary windings of the transformer to the load circuit at selected intervals during each cycle by means of mercury-arc rectifiers, metallic rectifiers, vacuum tubes, and other types of rectifying elements.