Suggest Best VFD to Vary RPM (Max 985/Min) for a 75KW 3 Phase Motor

Any VFD will perform this task, it is the most basic of applications for a VFD. What brand to use is, in my opinion, more related to who provides the best LOCAL service to you wherever you are. Nobody makes absolute garbage, otherwise they would not survive. But some people sell them very cheap because they make very little investment in providing local support for the users. That is the only non-sustainable aspect of the transaction, so using cheap remote suppliers with minimal support will ultimately harm you.

Thanks for the suggestion. As we are very close to ABB we will go for VFD of ABB. As you rightly said after sales is the criteria. How to decide the rating and model? AS In our application the capacity is not fully utilised. Hence is it possible to have a constant 30% speed reduction through out (with a speed controller) as well as to have a VFD to vary it further depending on load requirement. Or is it better to configure it on the VFD for both purposes. The motor is not required to run at the maximum rpm of 985 at all. ie the frequency may be upto 30HZ continuous for 12 hours.

The VFD must be sized for the motor it is intended to control. The reduction in load does not significantly reduce the demands put upon the VFD. But likewise there is seldom any reason to over size a VFD either. Just keep it simple.

The motor descriptin plate reads as 124A and 75KW, and as it is only a blower application, Can a 55KW VFD (of ABB) be used which gives a max 125A. Our application goes only upto 90A on full load. The supplier says this is fine, but will the motor or the VFD be at risk? though the VFD will be at warranty and the supplier will have a point to say that the motor was an old one hence the insulation may be the cause of failure if at all it fails. Please give me a reply. I think the point of doubt is clear