Starting circuit with transformer for squirrel cage induction motor

摘要

A starting circuit with a transformer (1) for a squirrel cage induction motor (2) has contactors (4 to 7) to adjust a first starting stage of the motor. With these contactors at least a further starting stage can be adjusted and moreover, a stage for normal running can be adjusted. An electronic control device is provided for controlling the changeover between different stages according to a measured motor current. A converter device is provided to generate a voltage proportional to the measured current and the changeovers can be controlled according to this voltage. The transformer has two temperature sensors and temperature signals can be passed to the control unit for evaluation.