Fill factor (grooves)

In the coil winding technique, the ratio of the effective cross-sectional area of ​​the copper conductor to the theoretically maximum cross-sectional area of ​​the available winding window (eg in an electric motor, transformer or relay) is referred to as a filling factor

For a given geometry, a filling factor of 100% is applied to minimize copper losses. With round wire, the cross-section is not fully utilized and is therefore limited to a theoretical maximum of approx. 78% (≈ π / 4). Winding and wire insulation as well as wire insertion further degrade the filling factor. In the case of large machines and thick solid wires, rectangular profiled wires are used, filling factors up to over 90% being achieved. In the case of very thin wires, a completely regular layer structure can no longer be ensured (wire crossings, etc.), whereby the filling factor can drop below 50%. With RF strands with many thin single wires, the filling factor within the strand is already very poor, which also dramatically reduces the total fill factor. Single-level Edit source text

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