The Revolving Field Theory of the Capacitor Motor

The paper presents an accurate theory of the split phase motor, both as regards starting and running performance. The general equations for an unbalanced two-phase motor are first derived, and the results are then applied to the special case of the capacitor motor. Evidence of the validity of the theory is given in the form of curves, comparing test results with calculations. The principal factors affecting practical capacitor motor design are discussed, and finally the performance characteristics of the motor are compared with those of repulsion-start induction motors. It is concluded that the capacitor motor has important advantages, which will justify its extensive use. The complete derivation of the theory is given in an appendix.