Alternating Current Rotary Transformer

—aA rotary transformer for changing alternating currents into direct currents, or direct currents into alternating. Alternating Current Transformer. a device used either to raise or lower the potential of an alternating current. It consists of an induction coil having a primary and secondary winding and aniron core. A primary current in the primary winding induces a secondary current in the secondary of either higher or lower potential according as the number of turns in the secondary is greater or le than the number in the primary. ‘Transformers which raise the potential of the primary current are called step-up transformers; those which lower it are called step-down transformers. The E. M. F. of the primary and secondary currents is proportional to the ratio of the number of turns in the two windings; thus, if the primary has ten, turns to one of the secondary the E. M. F of the secondary will be (approximately) one-tenth that of the primary.