From : Mr.M. S. Nimbalkar.

We have again checked with our supplier of screw pump.  They have recommended to use VFD only for the speed variation and not to use VFD which gives torque variation.  VFD for torque variation can malfunction the pump. Hence they have strongly recommended to use VFD only for speed variation.   In view of this, kindly give us the permission to use VFD model ACS 350 for the screw pump.