I changed an old Mitsubishi VFD for a Yaskawa F7 (keep the same ac motor). I had to adjust the speed, accel and decel parameters to keep the machine running like previously (with the old Mitsubishi).

Why do I had to change these parameters? We still have the same motor?

Thanks.

 

The things that come to mind are kind of obvious, and not knowing everything about your exact models... but here goes.

1) The units in the drives are different
2) They use different parameters for scaling, i.e. one drive uses max speed (which can be different than the base speed per the application), the other drive uses base speed.
3) Motor parameters may not be entered correctly.

B