Line disturbance caused by special squirrel-cage and wound-rotor motors when starting elevators and hoists

The author examines the cause of line disturbances in starting hoists and elevator motors and draws comparison between the performance of wound-rotor motors and squirrel cage motors of a special design for elevator service. Diagrams are given showing graphically the current required for each type of motor to produce a given torque, and the method of control required by different types of motors is also considered. The performances of both types of motors at maximum, ordinary and light loads are compared.