Monitoring VFD Power
- Thread starter ptonsparky
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ptonsparky
Tom
- Occupation
- EC - retired
| MOT RPM | @HZ | REV /HZ | TOTAL GEAR RED | RQD TORQUE IN FT/LB | RQD HP | RQD KW |
1765.0 | 60.0 | 29.4 | 1 | 74.39 | 25.00 | 18.5 |
1588.5 | 54.0 | 74.39 | 22.50 | 16.65 | ||
1500.3 | 51.0 | 74.39 | 21.25 | 15.72 | ||
1470.8 | 50.0 | 74.39 | 20.83 | 15.42 | ||
1176.7 | 40.0 | 74.39 | 16.67 | 12.33 |
Given line one is exact requirements. (We know it's not.)
The speed reductions via the VFD would give me the required HP at that RPM if torque is constant?
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Correct.
If torque is constant, then motor output power is simply proportional to speed.
Jon
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Current will vary based on load but can also vary with voltage too. The VFD is controlling both so generally current will follow torque, but only up to the full voltage available at the line side. If that dips, it can change things. So by using power instead of current, it is always a true representation of the actual load on the motor shaft. By reading power, and you will know the RPM from the drive, you can always calculate torque if you want it. But really, you are after the information on what the leg is capable of under the different product variations. Shift power tells you exactly that. Current is more indirect.
Last edited:
ptonsparky
Tom
- Occupation
- EC - retired
Power and torque seemed to travel hand in hand. Not too surprising. Power in the 90s and torque in the 90s.
ptonsparky
Tom
- Occupation
- EC - retired
What I ended up with:
Does what I want, so far.
Does what I want, so far.
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