On 7 January 2016 at 23:20, John Kasunich <[email protected]> wrote: >> I am sure you are right, but that wasn't my point. 240V single-phase >> VFDs largely top-out at 3HP. > > Doesn't need to be single phase input. > > A single-phase input VFD has modestly up-rated diodes and caps to > handle the higher peak currents and ripple current that comes with > a single phase operation.
Clearly there is a lot more to this VFD thing than I thought. I got a 4hp Huangyang VFD from that eBay. Communicating with it via RS485 turned out to be very easy with the hy_vfd HAL component. This evening I connected it to the lathe, and found that the lathe would turn at very low speeds, but then it was acting like the clutches were not working. But it had all worked OK before, and nothing had changed but the VFD. So I fitted the castor-frame to the lathe, and rolled it away from the wall so that I could see the motor shaft. Very bizarrely the motor was running weakly at low speed requests, then getting even weaker at higher speed requests, and basically stopping at a VFD-displayed 50Hz and 3.5A. Well, at least it wasn't a clutch problem.. So, I reset the VFD to factory settings, and tried running from the operator panel. Lo and behold it all worked fine, and at 100Hz I get the full 3000rpm spindle speed that the lathe is rated for. Oddly, the display at 50Hz / 1440 rpm _still_ only says 3.5A. Setting it back to RS485 didn't bring back the wierd behaviour, it was running happily at 3000 rpm in high range and seemed to make decent torque down to 80rpm in low range. So, I have no idea what was wrong at first, but maybe it got unhappy being powered up with no motor when I was setting up RS485. I am also very baffled why the same motor would trip out a 3hp VFD at 12A and 1500 rpm but run at 3000 rpm at 3.5A with a 4hp VFD. -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1916 ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
