On Mon, 14 Jun 2021 at 23:36, Gregg Eshelman via Emc-users <emc-users@lists.sourceforge.net> wrote: > > The motor is in a Hardinge UM mill, less than 1 horsepower. It cannot be > switched to 220V. Any way to get it running off 220 volts, three or single > phase, without breaking a few banks?
Yes. Find a significantly over-rated 440V VFD. Re-configure the input stage as a Delon doubler rather than a simple rectifier / smoothing cap setup. https://en.wikipedia.org/wiki/Voltage_doubler Feed the output into the same place as the original version that the input stage went. You need an over-rated VFD just because doing this needs much bigger caps. It's likely to work better on 3-phase because ripple will be lower but 5 seconds of googling didn't find a 3-phase doubler circuit. It is possible to buy doubling inverters, but rarely cheaply on the second-hand market. Also note that many VFDs allow connecting the DC busses of several VFDs together, so you could feed your doubled voltage in there, and retain the original input caps purely for smoothing. (Or, in fact, you could feed your doubled voltage in via the single-phase inputs, with the caveat that you are now rather over-driving one of the input diodes as it is doing the work of 6.) -- 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, 1912 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
