On Tue, 2011-03-08 at 09:16 -0800, dave wrote: > On Mon, 2011-03-07 at 22:03 -0800, Clint Washburn wrote: > > I am in the process of converting my 1978 Hitachi Seiki CNC lathe to EMC. > > It currently has a 7.5 KW dc motor that used to be powered by FUJI SCR > > drive. My first problem my house does not have 3 phase power. I am having ... snip > Just to be totally contrary if the dc motor is working fine then use a > rotary single phase to three phase converter. Lots of stuff on the web > about how to make one. It won't be perfect but probably good enough to > power the fuji controller. I used a 5 hp homebuilt for several years > before upgrading to a 30 Hp commercial job to power the Mazak. > The commercial one is much better balanced but the other was adequate. > > By OK I mean it balance to about 240, 240, 220 for the homebuilt. > The commercial is within 5 v.
I use a home made rotary converter for one of my lathes. This lathe is not as convenient to use as the lathes with VFD's. It's kind of a pain to worry about turning the converter on only when I need to use the lathe, so I tend to not use the lathe unless I have to. Having a remote start might fix this. Another thing is that for all static and rotary converters I have seen, the single phase is passed right through and the converter creates a 90 (or 270) degree phase, so you get 0, 90 and 180 degrees instead of 0, 120 and 240 degrees. A three phase motor should run more smoothly with evenly spaced phases, but on the other hand, I haven't noticed any problem with my lathe that uses the converter. Before I had any VFD's, I was thinking about making a three phase generator. I only have 50Amps feeding the shop, so I have to be very careful how I use power. My 300Amp welder needs 150Amps of 240VAC (36kW). Having a 30 or 40kW generator might fix the problem. For those with plenty of single phase amperage, the generator could be run with a single phase motor. Power factor may play a roll with these issues. I don't know much about the subject, but the Pro's seem to worry about it. For the Hitachi lathe, I would tend to figure out what the SCR drive needs and leave it in place. SCR's need zero Volt crossing to trigger, so some sort of AC seems to be needed, unless the drive converts the input to DC and then creates its own AC from that. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ What You Don't Know About Data Connectivity CAN Hurt You This paper provides an overview of data connectivity, details its effect on application quality, and explores various alternative solutions. http://p.sf.net/sfu/progress-d2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
