Electrical Schematic – Motor Starting System – Part Winding Motor Starting

This system, not widely used in Europe, is quite common in the North American market (voltage of 230/460, a ratio of 1:2).

This type of motor has a stator winding divided into two parallel windings with six or twelve output terminals. It is equivalent to two “half motors” of equal
On starting, a single “half motor” is connected directly at full mains voltage strength, which divides the starting current and the torque approximately by two. The torque is however greater than it would be with a squirrel cage motor of equal power with star-delta starting.
At the end of the starting process, the second winding is connected to the mains. At this point, the current peak is low and brief, because the motor has not been cut off from the mains supply and only has a little slip.