Are there any VFD's you recommend that would support such a motor? -----Original Message----- From: Kirk Wallace [mailto:kwall...@wallacecompany.com] Sent: Tuesday, March 08, 2011 12:00 AM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Single Phase Lathe spindle motor question
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 > to work around this issue with my whole retrofit. I wish to convert this to > a 3 phase AC spindle. What VFD's are people having success with as a > spindle drive with single phase power? Is it realistic to have a 10 hp 3 > phase spindle on single phase power? or will I have to go with a spindle > motor closer to around 7.5hp instead? What is everyone's input on this? > > Clint Washburn I have VFD's on all of my machines except one, but only 3HP max. I am not an expert on VFD's, but it is my understanding that the basic issue with running single phase into a three phase VFD is that the input is run through a rectifier that converts the AC in a very wavy DC. This DC then goes into a bank of capacitors that are there to smooth the wavy DC to get smooth DC. DC from single phase is much more wavy, and has periods of zero Volts and full Volts at 60 Hz (in normal places :). On the other hand, three phase always has a phase that has fairly high voltage, so the rectified DC is ripply rather than wavy. For single phase, there will be much more current going in and out of the capacitors, which is not good for them. Current heats and ages the capacitors, so they can die early. The rectifiers work a lot harder too. To get around this, if you use a VFD that is current rated 1.5 or more times higher than your maximum load, the VFD won't be worked hard enough to heat up and break down. So use a larger VFD, fed with an over sized mains connection. Another approach might be to use some form of phase converter to help smooth the single phase mains before it gets to your VFD, but I haven't gotten beyond the thinking stage on that one. I suppose one could actually feed DC into the VFD power input, and it should work fine. The problem with the bigger VFD's is that generally, the factory doesn't fill them with smoke, but they need to fill them with sparks and fire. -- 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 __________ Information from ESET NOD32 Antivirus, version of virus signature database 5937 (20110308) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 5937 (20110308) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
