Electric Motors
VFD Motor Speed Calculator
VFD Motor Speed converts the entered electrical measurements into estimated motor speed. Use it to the estimated motor speed calculation.
Enter values for estimated motor speed
Use one consistent electrical operating case for all fields.
How VFD Motor Speed works
The example applies speed ≈ base speed × frequency ratio. VFD Motor Speed uses Base speed, Frequency ratio to report Estimated motor speed.
With the loaded values, estimated motor speed evaluates to 1,029.00 rpm. Use separate cases for competing input values.
Inputs for VFD Motor Speed
Base speed and Frequency ratio belong to VFD Motor Speed. Keep source units with base speed. For motor current, use Motor Power Current Calculator.
Use the defaults to understand the output, then enter the real circuit or energy data.
- Base speed
- Example entry: 1470 rpm.
- Frequency ratio
- Example entry: 0.7.
Reading the VFD Motor Speed result
This output represents VFD Motor Speed.
Component selection requires more than the arithmetic result; verify margins, transients, and published ratings. Compare this result with Synchronous Motor Speed Calculator when synchronous speed is also needed.
Measurement and units
Motor nameplate data, duty, enclosure, starting method, load profile, and thermal limits govern final selection. Check prefixes on base speed.
Do not compare cases built from different unit prefixes or measurement locations.
Limits of this calculation
Slip and control mode affect actual speed.
Unlisted circuit behavior remains outside the computed result. Unentered effects remain outside VFD Motor Speed.
Questions about VFD Motor Speed
What does VFD Motor Speed calculate?
VFD Motor Speed reports estimated motor speed.
Can Base speed be zero?
For VFD Motor Speed, measure any zero base speed directly.