Rectified single-phase power for traction motors

FOR YEARS attempts have been made to power locomotives by 25-cycle single-phase rectified voltage applied to d-c series motors. Early efforts were unsuccessful, mainly because of the faulty operation of the mercury-arc rectifiers. Continued research and development, however, made operation of d-c traction motors on mercury-arc rectifiers entirely feasible. The problem of such operation resolves itself into the problem of smoothing the undulating current sufficiently to avoid harmful effects on the motor.