Quote Originally Posted by Jonathan View Post
What have you currently got the ramp up/down (PD14,PD15) times set to? I don't remember exactly (will check), but I set mine to no more than a couple of seconds and it's fine. If the acceleration is set too high the DC bus voltage in the VFD will get too high, and the inverter will cut out for protection so it's very unlikely to break anything. Try changing it gradually...
On a machine with gearing etc, like a lathe, it's not sensible to set the ramp up time to something very high, since it would just wearing out the gearbox unnecessarily.
How will accelerating too fast cause the DC bus to go overvoltage?

Also, how is accelerating a geared machine too quickly with a VFD any different from turning the motor on with a switch?