Torque-Energy Relations in Induction Machines [includes discussion]

The laws of electromagnetic energy flow, through space and over wires, and of energy storage in magnetic and electric fields, are applied to an induction machine. This leads to a visualization of the machine as an array of magnetized air spaces in which intense and turbulent energy concentrations exist. The copper and iron structures of the machine that are apparent to the eye and to the touch are thus seen to be of secondary importance. Just as in a turbine the important thing is the flow of energy-containing gas or "fluid" through guided paths, so in an electric machine the important thing is the flow of energy through magnetized air spaces. A proper model of the machine therefore would be one formed by first immersing an induction motor in a plastic compound, and then dissolving out all the metal parts with acid, leaving a structure representing only the air and dielectric spaces. These concepts are useful in deriving equations for locking and synchronous crawling torques, and also for the magnetic noise-producing forces in induction machines.