Electric Machines

Abstract

The function of all rotating electric machines is the conversion of one form of energy to another: mechanical into electrical energy in the case of generators; electrical into mechanical energy in the case of motors. The fundamental facts which make this conversion possible are first that an e.m.f. is induced in a moving conductor when it cuts the lines of force of a magnetic field, or when the number of lines of force cutting a circuit changes; and second, that a conductor carrying current is acted on by a mechanical force if it distorts the magnetic field in which it is placed. We see from the first consideration that an electric machine must consist essentially of two parts, namely that which produces the magnetic field, and that which carries the conductors in which the e.m.f.s are induced. It is obvious that there must be relative motion between these two parts.