Upgrading to VFD: questions inside.
I have a 220vAC 1hp 1phase motor on my benchtop mill. I want to go to VFD.
Breakout board is a PMDX 131 and I know I'll need the PMDX-106 driver. This will control the VFD drive and subsequently, the motor.
When I size my motor, should I stay with 1hp or is there a difference between 1 and 3 phase as far as power/torque requirements.
I'm also thinking of going with belt drive since the gears I have are noisy.
Any insight would be great.
Also, the motor mounts with the spindle facing down..what do you call this type of mount? Will I need a specific motor type to achieve this orientation? Most I've seen have the mounts on the side, this will not work.
Once again, thanks for all your help,
VFD's made now can often be run single phase. The motor HP is a factor of speed and torque and 1 HP is 1 HP. If the speed on the motor you now have and the speed of the motor you intend to run at three phase is the same you'll be all set as far as the motor is concerened. What you may want to consider is the size of the drive you choose if you are running it with a single phase power source. The drive should be double the capacity of the motor if this is in fact the case. Inverters make a large dc supply and remanufacture the three phase with this. The main job of these devices is to bring the voltage and the frequency up and down proportionetly to give you the speed contol it has to offer. When the three phase go into the drive it firsts see a three phase rectifier to make the bulk dc supply. The the filter capacitors act as real short term batteries to keep the dc available while the ac dips below it's peak voltage. When you run these single phase this time the capacitors need to source the power is lenghtened and a 1 HP drive is unable to supply the needed power. By multiplying the drive size by two, there is enough to carry it through. (technically 1.73 is the multiplyer) the square root of three. Good luck and I hope this is of use to you.
Lots of good info.
Unfortunately I cannot find a single-phase VFD above 1.5hp rating. According to your data, I need a 1.73hp minimum, so I'm back to looking at a single -phase in three-phase out 2hp VFD with a 1 hp motor 3 phase motor. Is this correct?
Last edited by DR; 10-26-2007 at 09:45 AM.
I'd suggest a sensorless vector drive for the superior performance at lower RPM, it's really pretty close in torque to a DC drive. I have a Hitachi SJ100 on my Lagun and it's got great performance, I leave the belt on the step sheaves about midpoint and the VFD display programmed to display the spindle RPM so I can simply dial up the spindle as I like.
I'll second "rkepler" on the sensorless vector drive. I've got one on my 10EE, and it has great performance. I did have to add an external bank of braking resistors to stop the spindle in under 2 seconds.