Quote Originally Posted by JAZZCNC View Post
Do not rely on the OV protection of these drives, they will not save you from more than just a few volts. So if you get a spike then they will fry them.
They are good drives provided you leave a good safety margin.

You need to leave at least a 10% safety margin on the voltage and I wouldn't run much above 60Vac with 70Vac Max.

Regards the Transformer I use 750Va with these drives without any issues. I wouldn't go above 750Va because you will get troubles from inrush.

Do NOT use a regulated PSU like as been suggested by one member as it could cause you troubles with voltage clamping.
Now this gets fun! So, given that I want steppers around 4Nm. They usually (based on my google searches) come rated at 4-5A and 2-3mH inductance meaning total drawn amps are in the range of (Atot_= 2/3*pcs*Arated) 10.5-13.5Atot and Vmax (=32*√mH) 45-56V.. Now based on what I've picked up in this discussion I want to give my drives as much voltage as possible (minding 10% safety margin) and restrict the PSU to 750VA due to inrush. Say I supply 60V to 70Vmax drives, that means the 750VA PSU supplies 12.5A of current i.e. steppers should be rated at 4.5A (~12Atot) or lower in order to get max performance out of them (naturally I could have higher rated steppers, but that would be wasted monies, correct?). Am I correct in this logic?

Moreover, is the performance of the steppers linearly related to the current supplied or is there some leverage at play, i.e. say I supply a stepper with 4.5A, now will a 5A (arbitrarily chosen) rated stepper perform equally well as a 4.5A rated stepper would?