Free Motor Speed Calculator
Calculate the synchronous speed and estimated actual speed of an AC induction motor.
Actual Rotor Speed
1,455 RPM
Actual Rotor Speed vs Supply Frequency
AC Induction Motor Speed
The speed of an induction motor depends on the supply frequency, number of poles, and load-dependent slip.
Formulas
N_sync = 120 f / P (synchronous speed)
N_actual = N_sync (1 - s) (actual speed)
where f is the supply frequency in Hz, P is the number of poles, and s is the slip (as a decimal). Synchronous speed is the rotating magnetic field speed. The rotor always turns slightly slower.
Example Calculation
A 4-pole motor on 50 Hz supply with 3% slip at full load.
- 01Synchronous speed = 120 x 50 / 4 = 1500 RPM
- 02Actual speed = 1500 x (1 - 0.03) = 1455 RPM
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