Pole changing three=phase two layer winding for electromotor - has two sets of terminals and unsymmetrical winding group distribution to improve utilisation factors at low and high speeds

摘要

The winding is specif. applicable to a two-speed three-phase pole changing two layer winding with a pole pair ratio of 8:6 and employing 72 slots. The winding pitch is made to cover nine slot pitches, and the coils are distributed in 22 groups between the three phases. The winding has six terminals. The winding is thus distributed between the phases in unsymmetrical groups, but has the same number of coils per phase. The sequence of coils and coil groups follow a specified particular pattern. The arrangement gives a more favourable coil arrangement in the high speed connection and a winding factor some seven per cent higher than earlier designs with 24 coil groups and a winding pitch of 12 slots.