AC induction motor calculator
Synchronous speed, slip, rotor frequency, shaft torque, three-phase input power and efficiency.
How it works
The stator's three phases build a field rotating at Ns = 120·f/poles. The rotor chases it, always a little behind — that lag is slip, s = (Ns−n)/Ns, and the rotor conductors see frequency f×s. Shaft torque is just power over angular speed, τ = 9.549·P/n — the same 9.549 that links Kv and Kt in the DC motor calculator, because it's nothing more than 60/2π.
Common questions
Torque comes from the rotor cutting field lines — which only happens when the rotor lags the rotating field. Run at exactly synchronous speed and the rotor sees zero relative field, zero induced current, zero torque. Slip isn't a defect; it's the mechanism. Typical full-load slip is 2–5%.
It's 60 seconds-per-minute × 2 poles-per-pole-pair. The field makes one electrical revolution per cycle, and p/2 pole pairs share the mechanical circle — so a 4-pole 60 Hz machine spins its field at 1800 rpm, a 2-pole at 3600.
A rotor spinning FASTER than the field: that's an induction generator. Wind turbines do exactly this. The same machine, same math — power simply flows the other way. (If you weren't expecting it, check your poles/frequency inputs.)