Kirk Wallace wrote: > On Thu, 2008-07-03 at 21:08 -0400, John Kasunich wrote: > ... snip > >>capacitor, you can run on single phase. There will be significantly >>more ripple voltage on the capacitor (which may affect downstream >>circuitry), and significantly more ripple current through the capacitor >>(which may increase heating and shorten its life). Reducing the load >>will reduce both of those effects... if you are running at half the >>design load or less you should be perfectly OK. > > > I was wondering if one could rectify and filter the single phase voltage > and feed this into the VFD. Maybe with DC on R, S and T or L1, L2 and DC > on R, S and T, respectively. This might allow the VFD to run at its > rated performance. > Most modern VFDs of up to 5 Hp or more, now have adequate capacitor banks to run fairly well on single phase, especially since they often are required to run on 208 V 3-phase, and the 240 V mains give it more voltage to work with.
If you are going to run a compressor or other machine that runs right up to the rating of the drive, then you need to up-size the drive for single phase operation. I think Igor Chudov on the rec.crafts.metalworking group ran into an older VFD that had a TINY capacitor in it, and wouldn't work at all on single phase, and he had to add external capacitors. Most VFDs that will work on single phase will also work on DC, in fact some of them interconnect the DC bus to share capacitors and exchange recovered energy from braking. But, some VFDs have charge-up circuits that reduce the inrush surge at turn-on, and may be damaged by DC (like they use an SCR to engage an AC contactor). > Another option might be running the VFD on a rotary converter. > This seems like towing your car with V8 and automatic transmission by a pair of horses, waving your buggy whip out the side window. > Jon ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
