| πfZN | |||
| Emax | = | (1) | |
| 108 |
in which
- f = frequency;
- Z = number of inductors in series in any one magnetic circuit;
- N = magnetic flux, or total number of magnetic lines in one pole or in one magnetic circuit.
The maximum value of the pressure, as expressed in equation (1), occurs when θ = 90°.
Fig. 1,502.—Developed diagram of single phase partially distributed half coil winding for six pole alternator in two slot stamping, same as in fig. 1,501. In this arrangement the direction of rotation is not reversed. It is a question as to how far the coils of a single-phase armature may be spread with advantage. There is not much advantage in reducing the interior breadth of the coils below that of the pole face, nor in widening the exterior breadth beyond that of the pole pitch.
The virtual value of the volts is equal to the maximum value divided by √2, or multiplied by ½ √2, hence,
| ½ √2 × πfZN | 2.22fZN | ||||
| Evirt | = | = | (2) | ||
| 108 | 108 |
This is usually taken as the fundamental equation in designing alternators. It is, however, deduced on the assumptions that the distribution of the magnetic flux follows a sine law, and that the whole of the loops of active inductors in the armature circuit acts simultaneously, that is to say, the winding is concentrated.