smoothops10
Member
- Location
- FL
- Occupation
- EE
Hey Guys, I would like to get some of your thoughts. It is a 2-parter question:
1) Looking at large 480VAC, 3PH, VFDs the input drive current rating is < motor FLC? - See attachment. What's the deal? I've tried to explain this by assuming a high pf on line side and lower pf on output but after doing the calcs this does not explain it. I've read on these forums someone claim the drive does not need to supply reactive power kvar on the output which explains the lower rating. I'm not sure I buy that.
2) I've ran a model in SKM to see what it says. As I had anticipated, load flow study still shows kVAR to motor but unexpected was that load side kVA is greater than line side kVA. What gives?
Fairly new to SKM so please excuse my ignorance if this is an obvious one.
3 attachments to illustrate my question.
Thanks
1) Looking at large 480VAC, 3PH, VFDs the input drive current rating is < motor FLC? - See attachment. What's the deal? I've tried to explain this by assuming a high pf on line side and lower pf on output but after doing the calcs this does not explain it. I've read on these forums someone claim the drive does not need to supply reactive power kvar on the output which explains the lower rating. I'm not sure I buy that.
2) I've ran a model in SKM to see what it says. As I had anticipated, load flow study still shows kVAR to motor but unexpected was that load side kVA is greater than line side kVA. What gives?
Fairly new to SKM so please excuse my ignorance if this is an obvious one.
3 attachments to illustrate my question.
Thanks