Extended cross-field theory of the tapped-winding capacitor motor, including iron loss and alternate connections

This paper presents an extension of the cross-field theory of the tapped-winding capacitor motor originally published by Puchstein and Lloyd (1935). It includes (1) the incorporation of separately-calculated iron losses by means of three separate resistors of variable value, two in the main-field axis and one in the auxiliary-field axis; and (2) the application of the basic theoretical model to a wide range of tapped-winding configurations by means of connection transformations. The theoretical model is nonlinear and requires an iterative solution. It is compared with test results on a fractional-kW motor, in which all the main trends are modelled with acceptable accuracy as the tap ratio changes.