On Wednesday, April 06, 2011 04:02:33 PM andy pugh did opine: > And now the cap sizing. > If I say that I can put up with 10% ripple at max rated current (7.5A > for the motors) on a nominal 300V then I end up with > C = 7.5A X 10mS / 30V = 2500uF. > > Eeek! > Understatement Andy, it will weld relays closed with the inrush unless surge limited. And for 60hz power, your 10ms would be 8.33333333333 for a full wave bridge.
> http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getPro > duct&R=5436785 > > Is the cheapest that is even close. > > A thread on CNCzone said 20,000uF per amp, but I decided to ignore that. It might be pretty close, my 28volt supply is a pi section, with 175k uf on both sides of a small choke. Its running pretty close to 10 amps when the A(B/C) table is plugged in. I did use it for EDM at the same time, but 28 volts was slow, so I built an 80 volt supply for that, works very well but wear your rifle range muffs, it is painfully noisy. But it pokes an 8mm hole in the web of a 10" table saw blade in 3 or 4 minutes. Clean, no burrs. Why? So I can mount it on the A(B/C) table and sharpen it with a dremel diamond wheel. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> <http://www.cantrip.org/gatto.html> <Overfiend> this is the New Overfiend, preacher of Love and Tolerance ------------------------------------------------------------------------------ Xperia(TM) PLAY It's a major breakthrough. An authentic gaming smartphone on the nation's most reliable network. And it wants your games. http://p.sf.net/sfu/verizon-sfdev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
