On Tue, Mar 8, 2011 at 1:12 PM, Kirk Wallace <kwall...@wallacecompany.com>wrote:
> 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. > > This is not true, phases are evenly spaced on mine. I use run capacitors. My voltages are very close to each other L1-L2, L1-L3, L2-L3. i > 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 > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
