The circuit theory and calculations of polyphase induction machines

The paper examines in a systematic manner the nature of the various circuits and circuit parameters of both wound-rotor and squirrel-cage induction machines. From these the basic voltage and torque equations are deduced. Substitute variables are then introduced to enable the equations to be made to depend on the speed rather than the position of the rotor, thus making the differential equations linear with constant coefficients for the important case of constant angular velocity of the rotor. In order that the theory formulated may be of value in practice, methods of evaluation of the various circuit parameters from the physical dimensions of the machine are developed. For these the existing methods available for conventional design constants have had to be considerably modified. The circuit parameters are computed for an actual machine and compared against test results.