Single-phase squirrel-cage motor: With large starting torque and phase compensation

This paper describes a new single-phase motor which develops a large starting torque and operates with unity power factor. It outlines the manner in which the machine was developed, discusses the theory of its operation as well as the novel points to be considered in its design, and finally gives a number of test results obtained from motors of different sizes. The machine is of the squirrel cage type, but is also fitted with a commutator. Although the motor is often provided with a small centrifugal switch for closing the phase compensating circuit, it is shown that the failure of this switch to operate does not cripple the motor or materially change its characteristics, and that one or more of the commuted winding circuits may be interrupted without causing the machine to break down. Accidents of this description only affect the degree of compensation, the efficiency, or the overload capacity.