A New Type of Single-phase Motor

This paper deals with the development of a constant speed a-c. motor for application to single-phase current. A description is given of the derivation of this new type of motor from the plain repulsion motor. The novel feature lies in the armature which consists of a combination of three elements, namely: a commutated winding, a squirrel cage of high reactance, and a commutating device consisting of shielding metal strips. It is shown that this motor in starting and acceleration possesses the characteristics of a series motor and when up to speed has the characteristics of a shunt motor. The changing over from the series to the shunt type is accomplished without the use of any automatic device, this change taking place due to the inherent qualities of the motor. An explanation is given of the high power-factor possessed by this motor and also an elementary theory of commutation, which has proved to be as good as that in a d-c. motor with commutating poles.