A good commutation, which is necessary to make effective the advantages which in theory characterizes y/- starting, must be made taking into consideration the rotation direction and the sequence of the wiring connections on the clamps of the motor passing from Y to - position. If the commutation occurs when residual magnetism of the rotor is in phase opposition with the magnetic field generated by the stator current, the current requirement could also be very high with values which could reach also 20 times a commutation not well calibrated affect not only the motor but also the behavior of the apparatus which constitute the coordination and cause inappropriate and unpredictable running.