Coil span

The coil span is the distance between one conductor of a certain phase and the corresponding return conductor.

The coil span can be given as a number of slot pitches, as a length, or as an angle.

Example: Below is the coil arrangement of phase U of a 4-pole 15-slot two-layer winding. The fundamental winding factor for this winding arrangement is 0.91.

Example of coil span

Fig. 1 Double-layer 4-pole 15-slot winding with a coil span of 3 slot pitches.

Assuming that the radius to the middle of the winding slot is $r$ = 100 mm, the coil span can be expressed as:

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