VFD conversion on an Enco 100-1525 (baby BP clone - 1991). This was a tricky one because the motor was a 2/8 pole motor rather than 2/4 pole. The speed change between ranges was 4 to 1. With a 2/1 range motor you can usually just wire the motor on the high range and use the VFD for speed control and not worry much about about low speed torque. With this motor that wasn't possible so I had to allow for switching the motor between ranges to get the full range and torque. Normally it's not kosher to put switches between the VFD and motor, but the Hitachi VFD had program settings for two motors and conveniently also had had a programable relay output that I used to drive three contactors. It's all set so that the contactors cannot switch while the motor is running. If I try to to switch ranges with the machine running, it ignores me and waits until the motor spins down before switching over. There is also an indicator light that says when high-speed is actually on. I thought I was going to need some logic for this, but the VFD handled it all.