Yes, you are probably right, I will look for a local professional guy to come and get things going. At least I have an idea of what is happening...
Thanks for the advice On Fri, Nov 11, 2011 at 10:54 AM, gene heskett <ghesk...@wdtv.com> wrote: > On Friday, November 11, 2011 11:28:02 AM Peter Blodow did opine: > > > Brian, > > looking at your questions I get the feeling that you are a bloody > > beginner as far as power electricity is concerned. I get the scares > > imagining what you could possibly do to yourself and others, > > experimenting with your mains supply. It would be much safer for you and > > would calm my nerves (and apoparently other's, too) if you'd call a > > local electrician to wire the basic supply of your machinery or what you > > have. It's worth your life's value. Please get yourself some sound > > advice! This is not electronics where a fault only results in a burned > > up transistor or so. > > I've been following this thread, debating if I should jump in, but now that > Peter has said it, I concur heartily with his advice. > > Its easy enough to be crispy critter'd around mains power, I've damned near > done it to myself at least 3 times in my work around tv stations where we > may be the local power companies largest customer. 2nd degree burns on both > arms & the at the instant bare chest, will take ALL the starch out of you > for a few days, and likely lay you up with the shingles for a month or > more. Been there, done that, it will totally redefine your personal pain > threshold, upwards. No one needs that but somehow I kicked loose and > survived. > > Simply put Brian, if you need to ask these questions, then get a licensed > pro who is intimately familiar with the local codes and let him do it. We > aren't there and in some cases in this thread are trying to be helpful with > inadequate information and almost zero knowledge of local codes. > > Old buildings with grandfathered in electrical supplies can be legal, and > lethal. > > > To make it clear: grounding is the up and down of electrical power > > application. Imagine only a little high resistance insulation fault in > > the primary of your local high voltage transfomer - if the secondary > > would not be grounded in some way, in this case you could easily > > experience 10 or 20 kV on your home outlet.... In case the secondary is > > ground referenced by connecting the center tap of the secondary windings > > to ground, this fault might not even be noticed! Floating potentials are > > a highly dangerous thing, never leave any circuit unreferenced to > > ground! > > > > Peter Blodow > > > > Brian May schrieb: > > > Sent from my iPod > > > > > > On Nov 10, 2011, at 10:30 PM, Dave <e...@dc9.tzo.com> wrote: > > >> Usually bigger 3 phase machines being fed with 480 volts or so will > > >> only have the 3 phases run to the machine without a neutral wire. > > >> > > >> The reason being that Line to Neutral on a 480 volt system is 277 > > >> volts and that is not very useful for anything other than lighting. > > >> > > >> To get 120 VAC, two of the phases will be tapped (480 volts) and that > > >> will be run to a step down transformer. > > >> One the secondary side of the transformer, one leg of the > > >> transformer will be declared the hot line, and the other leg will be > > >> declared the neutral. > > >> The neutral will be bonded to the ground close to the transformer. > > >> The hot line is fused. That will establish a proper 120 VAC > > >> circuit off the 3 phase input power. > > > > > > What is meant by "bonded to the ground"? Does that mean connecting > > > the nuetral leg of the transformer to the ground? If so, why use the > > > transformer at all when i can just go from a leg to ground? > > > > > >> You could run a separate single phase feed into the existing 3 phase > > >> power panel, but then you would have power being fed into one panel > > >> from two different sources and that gets tricky from a safety > > >> standpoint. I try and avoid doing that whenever possible. > > >> Generally when you pull the disconnect switch on a machine panel you > > >> want to kill all power in the panel for safety. > > >> > > >> A lot of machine builders are now avoiding 120 volt power system in > > >> their machines entirely. They do that by using DC power supplies > > >> that can accept high voltage input power directly. > > >> > > >> You can buy 3 phase input power supplies that will accept up to 600 > > >> VAC and produce 24 VDC. Most of the big power supply makers sell > > >> them. > > >> > > >> Dave > > >> > > >> On 11/10/2011 10:27 PM, Brian May wrote: > > >>> Ok that makes sense. > > >>> > > >>> Just out of curiosity, How do other machines do it. Our other cnc > > >>> machines only have the 3 lines and earth ground running into > > >>> them... > > >>> > > >>> Sent from my iPod > > >>> > > >>> On Nov 10, 2011, at 9:01 PM, Brian Mihulka<bmihu...@hulkster.net> > wrote: > > >>>> On 11/10/2011 08:50 PM, Brian May wrote: > > >>>>> This is probably an easy question for alot af the people on the > > >>>>> list. > > >>>>> > > >>>>> I have 3 phase power going to my vfd on my machine. I want to the > > >>>>> use that same power to power all the 120 single phase components. > > >>>>> (the dc power supply for the steppers and varios other motors. ). > > >>>>> This way i only need 1 plug > > >>>>> > > >>>>> I have been reading and people say i can go from 1 leg to a > > >>>>> nuetral or leg to leg. I do not have a nuetral line so my > > >>>>> question is will it be ok to go from leg to leg for the 120 > > >>>>> single phase? Or is there some other component i need? > > >>>>> > > >>>>> Thanks > > >>>>> Brian > > >>>>> > > >>>>> Sent from my iPod > > >>>>> ------------------------------------------------------------------ > > >>>>> ------------ RSA(R) Conference 2012 > > >>>>> Save $700 by Nov 18 > > >>>>> Register now > > >>>>> http://p.sf.net/sfu/rsa-sfdev2dev1 > > >>>>> _______________________________________________ > > >>>>> Emc-users mailing list > > >>>>> Emc-users@lists.sourceforge.net > > >>>>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >>>> > > >>>> If its 3 phase 208, one leg to any other leg will give you 208. > > >>>> You have to have the neutral to get 120 from any leg. You should > > >>>> get 120 from any leg to ground but it wouldn't be up to code. > > >>>> > > >>>> Brian > > >>>> > > >>>> ------------------------------------------------------------------- > > >>>> ----------- RSA(R) Conference 2012 > > >>>> Save $700 by Nov 18 > > >>>> Register now > > >>>> http://p.sf.net/sfu/rsa-sfdev2dev1 > > >>>> _______________________________________________ > > >>>> Emc-users mailing list > > >>>> Emc-users@lists.sourceforge.net > > >>>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >>> > > >>> -------------------------------------------------------------------- > > >>> ---------- RSA(R) Conference 2012 > > >>> Save $700 by Nov 18 > > >>> Register now > > >>> http://p.sf.net/sfu/rsa-sfdev2dev1 > > >>> _______________________________________________ > > >>> Emc-users mailing list > > >>> Emc-users@lists.sourceforge.net > > >>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >> > > >> --------------------------------------------------------------------- > > >> --------- RSA(R) Conference 2012 > > >> Save $700 by Nov 18 > > >> Register now > > >> http://p.sf.net/sfu/rsa-sfdev2dev1 > > >> _______________________________________________ > > >> Emc-users mailing list > > >> Emc-users@lists.sourceforge.net > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > ---------------------------------------------------------------------- > > > -------- RSA(R) Conference 2012 > > > Save $700 by Nov 18 > > > Register now > > > http://p.sf.net/sfu/rsa-sfdev2dev1 > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > ------------------------------------------------------------------------ > > ------ RSA(R) Conference 2012 > > Save $700 by Nov 18 > > Register now > > http://p.sf.net/sfu/rsa-sfdev2dev1 > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > 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) > My web page: <http://coyoteden.dyndns-free.com:85/gene> > They call them "squares" because it's the most complicated shape they can > deal with. > > > ------------------------------------------------------------------------------ > RSA(R) Conference 2012 > Save $700 by Nov 18 > Register now > http://p.sf.net/sfu/rsa-sfdev2dev1 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Brian May 506.8862.9162 (Cell) 506.2293.6375 (Office) ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
