Fig. 1,525.—Vector diagram of pressures induced in the single phase multi-coil or distributed winding shown in diagram in fig. 1,524.
| Slots wound in series | Pressure across coils | Winding coefficient | Quantity of copper to produce same pressure |
|---|---|---|---|
| 1 | 1 | 1 | 1 |
| 2 | 1.93 | .97 | 1.03 |
| 3 | 2.73 | .91 | 1.10 |
| 4 | 3.34 | .84 | 1.19 |
| 5 | 3.72 | .74 | 1.35 |
| 6 | 3.86 | .64 | 1.56 |
Ques. What other advantage besides obtaining a sine wave is secured by distributing a coil?
Ans. There is less heating because of the better ventilation.
Fig. 1,526.—Developed diagram of a single phase monotooth or one slot bar winding; it is suitable only for operation at low voltage.
Single Phase Windings.—There are various kinds of single phase winding, such as, concentrated, distributed, hemitropic, etc. Fig. 1,527 shows the simple type of single phase winding. It is a "one slot" winding, that is, concentrated coils are used.
The armature has the same number of teeth as there are poles, the concentrated coils being arranged as shown. In designing such a winding, the machine, for example, may be required to generate, say, 3,000 volts, frequency 45, revolutions 900 per minute.