Three-Phase AC Generator

What this figure shows. An armature core with six slots cut into its inner rim, spaced $60^{\circ}$ apart, carries six labelled conductors 1 through 6; the figure shows how conductors 1 and 4 are wired together in series to form coil 1, conductors 3 and 6 form coil 2, and conductors 5 and 2 form coil 3, with the rotating field magnet's N and S poles shown at their initial position at the centre. Because of how the six slots and three coils are arranged, the three resulting rectangular coils end up mechanically $120^{\circ}$ apart from one another around the core, which is exactly why the three alternating emfs they generate as the field magnet rotates come out with a …

What this figure shows. Three identical sine-wave curves, for $\varepsilon_1$, $\varepsilon_2$ and $\varepsilon_3$, are plotted together against the same time-angle axis marked in steps of $90^{\circ}$ from $0^{\circ}$ to $360^{\circ}$. The $\varepsilon_1$ curve for coil 1 begins its cycle at the origin O (t=0, when the field magnet is in its initial position relative to coil 1); the $\varepsilon_2$ curve for coil 2 is shifted to begin its cycle only after the field magnet has rotated a further $120^{\circ}$ (marked at point A); and the $\varepsilon_3$ curve for coil 3 begins its cycle only after a further $240^{\circ}$ of rotation (marked at point B) -- with dotted lines in the figure showing the tail end of each curve's previous cycle still completing as the next one begins. The figure is the direct graphical proof that a three-phase generator truly produces three separate, identical-amplitude sinuso …