Calculated Results
Results appear here after submission and stay above the form.
Plotly Graph
Calculator Inputs
Enter shaft speed and electrical details. The tool returns mechanical frequency, electrical frequency, angular velocity, pulse rate, period, and optional slip.
Pole count should usually be an even number for AC machines. Reference frequency is used for synchronous speed and slip calculations.
Formula Used
fmech = RPM / 60
felec = (RPM × Poles) / 120
ω = 2π × RPM / 60
fpulse = (RPM × PPR) / 60
RPMsync = (120 × fref) / Poles
Slip % = ((RPMsync - RPMactual) / RPMsync) × 100
How to Use This Calculator
- Enter the measured or rated shaft speed in RPM.
- Input the machine pole count if electrical frequency matters.
- Add encoder pulses per revolution when pulse frequency is needed.
- Enter the reference electrical frequency to estimate synchronous speed and slip.
- Choose decimal precision and chart range for cleaner reporting.
- Press Convert RPM to Hz to display results above the form.
- Use CSV to export calculation history or PDF for a quick report.
Example Data Table
| Application | RPM | Poles | Mechanical Hz | Electrical Hz | Reference Hz | Synchronous RPM |
|---|---|---|---|---|---|---|
| Generator set | 1500 | 4 | 25.000 | 50.000 | 50 | 1500 |
| Induction motor | 1750 | 4 | 29.167 | 58.333 | 60 | 1800 |
| High-speed spindle | 3600 | 2 | 60.000 | 60.000 | 60 | 3600 |
| Six-pole blower motor | 980 | 6 | 16.333 | 49.000 | 50 | 1000 |
Frequently Asked Questions
1) What does RPM to Hz conversion mean?
It converts revolutions per minute into cycles per second. Mechanical frequency uses RPM divided by 60. Electrical frequency may also depend on the machine’s pole count.
2) Why can electrical frequency differ from mechanical frequency?
A rotating electrical machine can generate several electrical cycles during one shaft revolution. Pole count determines how many cycles appear for each revolution.
3) When do I need pole count?
Use pole count when converting RPM into electrical frequency for motors or generators. For simple shaft rotation frequency, divide RPM by 60 and ignore poles.
4) What is synchronous RPM?
Synchronous RPM is the ideal no-slip speed set by frequency and poles. It is calculated as 120 multiplied by frequency, then divided by pole count.
5) Why is slip useful?
Slip shows how far an induction motor runs below synchronous speed. It helps with troubleshooting load, torque behavior, overheating, and motor performance checks.
6) What does encoder PPR change?
Encoder pulses per revolution let you estimate pulse frequency from shaft speed. This is useful for sensor design, PLC inputs, counters, and control monitoring.
7) Can I use odd pole counts?
Most AC machines use even pole counts. The calculator will still compute a number, but practical electrical machines are usually built with even poles.
8) Is this converter suitable for generators and motors?
Yes. The same speed and pole relationships apply to both. Enter the actual RPM and pole count to estimate the related electrical frequency quickly.