Induction Motor: Torque-Speed Curve #
The torque-speed curve describes how torque varies with speed (or slip).
Key Points #
| Point | Condition | Torque | Speed |
|---|---|---|---|
| Starting | \(n=0, s=1\) | \(C_s\) (1.5-2.5× nominal) | 0 |
| Max torque | \(s = s_{max}\) | \(C_{max}\) (2-3× nominal) | Intermediate |
| Nominal | Normal load | \(C_n\) | \(n_n\) |
| No load | No load | ≈ 0 | ≈ \(n_s\) |
Stable vs Unstable Zone #
Right of max torque (stable): if load increases, motor slows → torque increases to compensate. Left of max torque (unstable): motor stalls if load exceeds \(C_{max}\).
Operating Point #
The intersection of motor curve and load curve determines the operating speed and torque.