Motor Speed Calculator
Calculate motor speed from frequency and poles, and estimate slip speed for induction motors. Fast, accurate, and easy-to-use motor RPM tool.
motor frequency calculator
Motor synchronous speed is given with the calculation Ns = 120f/P where f is frequency (Hz) and P is the poles. Reduced motor speed = (Ns) (1-slip).
Formula & Table Summary:
- Synchronous speed: Ns = 120 × f ÷ P
- Slip (%) = (Ns – N) ÷ Ns × 100
- Rotor speed: N = Ns × (1 – S)
Inputs: frequency, poles, slip. Outputs: synchronous speed, rotor speed, slip percentage.
synchronous speed calculator
This synchronous speed calculator figures out the synchronous speed of AC motors based on the supply frequency and poles. The calculation is Ns = 120 f / P, where f is the frequency (Hz ) and P is the poles. In the case of induction motors, there is a small difference between the actual speed of the rotor and the no-load speed owing to slip; this can be calculated using normal percentages of slip of a particular motor, or by entering actual RPM. The tool can assist engineers, electricians, and students in sizing motors, verifying design parameters, and debugging performance. The synchronous speed, the actual motor speed, and the slip percentage are calculated in one location. The calculator works with both 50 Hz and 60 Hz systems, and its pole count has a range of 2-12; thus, it is rather universal and may be used both in industry and in academia. A set of tables of data and formulas helps you find out the most common motor speeds easily and with no mistakes, quickly and without any confusion.
synchronous rpm
| Frequency (Hz) | Poles | Sync Speed | Slip % | Actual Speed |
|---|---|---|---|---|
| 50 | 2 | 3000 | 2 | 2940 |
| 50 | 4 | 1500 | 3 | 1455 |
| 60 | 2 | 3600 | 2 | 3528 |
| 60 | 4 | 1800 | 3 | 1746 |
Frequently Asked Questions - Motor Speed Calculator:
How do I calculate synchronous motor speed?
Use Ns = 120 × f / P, where f is Hz and P is poles.
What is slip in an induction motor?
Slip is the difference between synchronous and actual rotor speed, usually 1-6%.
How do I find motor speed from frequency?
Divide 120 × frequency by number of poles to get synchronous RPM.
What is the motor speed at 50 Hz, 4 poles?
Synchronous speed is 1500 RPM; actual speed ~1450 RPM.
Why is actual motor speed lower than synchronous?
Because induction motors need slip to induce rotor current for torque.
Can synchronous motors run at exact Ns?
Yes, synchronous motors rotate exactly at synchronous speed with no slip.
How do I calculate slip percentage?
Slip = (Ns - N) ÷ Ns × 100.
What is the speed of a 6-pole motor at 60 Hz?
Ns = 120×60/6 = 1200 RPM; actual speed ~1150 RPM.
Does slip increase with load?
Yes, as load increases, slip increases to provide more torque.
Why is motor speed important?
It determines torque, efficiency, and suitability for applications.
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