Results are presented of an analysis of the steady-state operating mode of a powerful synchronous motor for single-phase supply; these results reveal a unique dependence between the constant component of the asynchronous torque due to the reverse synchronous field and the initial value of the asynchronous starting torque of the motor for three-phase supply. A method is developed on the basis of these results for the experimental investigation of the starting characteristics of powerful synchronous motors with asynchronous start.