Basic VFD questions

[m_c]

The frequency is the maximum frequency the VFD can deliver. You don't have to use the maximum frequency of the VFD.

What you need to know, is what the maximum frequency is for the lathe, so you can then set that in the new VFD.
However, if the Easiturn is anything like my old Cyclone, then they're using a VFD rated motor, that is designed to operate above the usual rated 50Hz,and IIRC the current ratings were not the same as a typical induction motor.

Ideally, you'd want to get write down all the settings from the KEB, but I know with mine, it had a PIN set, which I could never get past.

[JohnHaine]

A lot of Denford machines actually use DC motors; and "KB Electronics" make DC drive controllers. One of their controllers might have a maximum mains frequency limit of 130Hz, so just to check that your lathe does use an induction motor and VFD? The electrical drawings seem to confirm that but just to be sure.

Assuming that it is a VFD, then just setting the max frequency of the new one to 130Hz shouldn't go far wrong. Or you should be able to work backwards if you know the maximum lathe spindle speed and any pulley ratios and how many poles the motor has. Look at the motor spec plate, if it says 50 Hz and ~2800 rpm it's 2 pole, or 1490rpm it's 4 pole.

The other possible gotcha is if the motor is star connected and expects to see a 415V supply, since the vast majority of the lower end VFDs only give a max voltage of 240V. I doubt your motor is 415V but worth checking. If it is it will still run on a 240V VFD but won't give the same maximum power.

I assume that you know the Denfordata site?

https://www.denfordata.com/bb/viewforum.php?f=34