Induction-motor efficiency curve - peaks ~75 % load; drops sharply below 30 %.
Formula
$$ \eta(L) \approx \eta_n - k (L - 75)^2 $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $η_n$ | Nameplate efficiency | % | motor nameplate |
| $L$ | Load % | % | operating point |
Sources
- IEC 60034-30-1 IE classes.