Mechanical Systems 373
Therefore, some starting method must be used for single-phase AC mo-
tors, since they are not self-starting.
Assume that we have a two-phase situation, as shown in Figure 14-
17B. We now have two sets of stator windings with one phase connected
to each set. Two-phase voltage is, of course, not produced by power com-
panies in the United States; however, this example will show the opera-
tional principle of a split-phase motor. As shown in the two-phase volt-
age-curve diagram, when one phase is at minimum value, the other is at
maximum.
At time interval t 1 , phase 1 is maximum while phase 2 is minimum.
Assume that the right stator pole becomes a north polarity, and the leftFigure 14-16. The split-phase induction motor: (A) Pictorial diagram, (8)
Schematic diagram