NapkinCalc

AC Motors

Slip — why the rotor lags

continues from lesson 1 — values defined earlier in the course stay live here

If the rotor ever caught up with the field, no field lines would be cut, no current induced, no torque made. So it settles just below: the shortfall, as a fraction, is the slip. Loaded motors run at 1–5% slip.

nrotor=1740n_{rotor} = 1740 nameplate full-load speed (rpm)
sslip=nsync−nrotornsyncs_{slip} = \frac{n_{sync} - n_{rotor}}{n_{sync}} = 0.03330.0333 slip — typically 0.01 to 0.05
frotor=sslip⋅flinef_{rotor} = s_{slip} \cdot f_{line} = 22 frequency induced in the rotor (Hz)
✓ pass sslip<0.06s_{slip} < 0.06 healthy slip for a standard motor