Ten Part-Winding Arrangements in Sample 4-Pole Induction Motor [includes discussion]

Using a 75-horsepower 4-pole 3-phase motor on which design and test data has previously been published,1 and without dividing the winding into segments smaller than its natural phase belts, it was determined that there are 10 possible different arrangements for half of the winding, each of which would be suitable for making the necessary connections to a part-winding starter composed of two line starters and a timing relay. To determine which of these arrangements would produce the more favorable characteristics of torque, line currents, and noise, tests were conducted on each and the results are presented. The winding pitch was then raised to a higher percentage than normally used and the effects of this variation on the test data and on some of the motor magnetomotive force waves are also given.