On Sat, 2009-06-27 at 17:23 +0100, Andy Pugh wrote: > 2009/6/27 Ray Henry <rehe...@copper.net>: > > > My first choice would be a rotary phase converter if you don't have > > three phase. > > I built one once, I would never consider doing it again. eBay is full > of solid-state 3-phase converters that do a better job, in less space, > with less fuss. >
My rotary was easy to build and works well, but I don't use it much anymore. I used valve springs as feet so it is pretty quiet. I don't like that the phase timing is 0, 90, 180, but it seems to work. I am pretty leery of the static converters, but I suppose it could be considered a rotary converter if you have one unloaded motor on the circuit somewhere. The ebay solid state setup like this one: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260434019480 is new to me. It looks like a enhanced rotary, hopefully fixing the phase timing. Oops, I just read another ad, which seems to indicate that only the the converted phase voltage is controlled. I have seen a link that explains how to use a three phase induction motor as a generator. The trick is to pulse the stator to build an initial field in the rotor. An engine or single phase motor is needed to drive the "generator". The other problem I have with most converters is that most of the time they sit running at idle which wastes energy. Another thought comes to mind about using a VFD as a phase converter. All of the manuals I have read indicate that the VFD output should not have a switched load, so it seems to me that one could not use a VFD between the single phase mains and a machine. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
