Motor calculation
- Thread starter brianthejabroni2
- Start date
ptonsparky
Tom
- Occupation
- EC - retired
You need to look at the VFD instructions.
David Castor
Senior Member
- Location
- Washington, USA
- Occupation
- Electrical Engineer
The feeder to the VFD has to be sized based on the maximum rated input current to the VFD, not the motor. (125% of the rated VFD INPUT current)
ptonsparky
Tom
- Occupation
- EC - retired
The VFD will provide the motor over current protection.
Going to use this VFD as an example:
https://www.grainger.com/product/33M548?gucid=N:N:FPL:Free:GGL:CSM-1946:tew63h3:20501231
It's max output is 1170A, so you size wires based on 125% of that which is 1462.5A, you would use 4 sets of 500s
If VFD is soft start you can just use 1500A fuses, the VFD already usually has overload protection so you won't have to worry about overload.
https://www.grainger.com/product/33M548?gucid=N:N:FPL:Free:GGL:CSM-1946:tew63h3:20501231
It's max output is 1170A, so you size wires based on 125% of that which is 1462.5A, you would use 4 sets of 500s
If VFD is soft start you can just use 1500A fuses, the VFD already usually has overload protection so you won't have to worry about overload.