Hi all,
I’m currently looking at ebay VFD inverter drives for a machine restoration project. I think I need some help with understanding the basics.
Firstly, I’d like to run an old 60s Hoover 240V, 3ph, 3/4hp 1425rpm motor, using a single phase supply. It’s a rather hefty drilling machine which will probably only see light, infrequent use and <10mins of duty at a time.
3/4hp is approx 0.56KW, how much headroom should one allow in this figure?
Secondly, it would be nice to also provide some degree of speed control to my lathe motor (240V, single phase, 3/4hp, 1425rpm, capacitor start w/ centrifugal switch) using the same VFD (not at the same time, obviously). Would I choose a VFD with 3 times the rated power of this motor and run it off a single phase? Or do I need a dedicated VFD with single phase output? Another option is to swap the motors over. I believe this would be possible as the spindles are the same diameter (although I haven’t checked the keyways yet). If I did this, then I wouldn’t need to worry about the single phase motor at all, as the drilling machine has the usual step pulleys plus a back gear for low speed.
Thirdly, should I be looking at used ‘quality brand’ units, or are the cheapo Chinese VFDs good enough for hobby use?