FIGURE 5.30 Basic 3-phase winding layout.
There are many winding line connections that can be used in three-phase drive systems. Figure 5.31 illustrates the various configurations. The half-wave wye is the simplest three-phase line configuration (Fig. 5.31a). It uses three power lines and one return line (four leads). The excitation is shown adjacent to the schematic in Fig. 5.31a. Only 33 percent (one lead) of the half-wave wye windings are energized at any time in operation. The second wye winding, the full-wave wye (Fig. 5.31b) has only three leads but 66 percent (two leads) of the windings are in operation simultaneously. The excitation scheme is shown to the right of the schematic.
The third major winding connection pattern is the delta, shown in Fig. 5.31c. It possesses the same excitation scheme as the full-wave wye. The delta winding configuration has been used more extensively than the wye in fractional-horsepower (