Electrical Machine Exciter

a DC or AC generator that supplies the inductor in an electrical machine, thus creating in it an operating magnetic flux. Exciters were developed chiefly for synchronous machines, since they do not produce their own direct current, which is necessary for the inductor. Commutator-type DC generators with shunt or separate excitation from the pilot exciter are usually used as electrical machine exciters. In view of the increased power and the increase in the operating speed of control systems for synchronous machines, and also in the case of special machines (beginning in the 1950’s), electric machine exciters were introduced in which AC voltage is fed from the main machine (directly or through a transformer—that is, self-excitation) or from an auxiliary synchronous machine (separate excitation) to an ionic or semiconductor rectifier, which supplies the inductor of the main machine. Regulation is provided either in the power circuit of the exciter or by the action of the exciter on the exciter circuit. In another type of exciter an AC voltage from an auxiliary generator whose armature is on a common shaft with the inductor of the synchronous machine is fed to a rectifier mounted on the same shaft. The rectified voltage goes directly to the winding of the inductor. The principal advantages of such exciters are the absence of sliding contacts, increased reliability, and rapid response.