Brian, if you use two legs of your incoming mains for a single phase supply, you will have two hot wires in these appliances plus an uncommon voltage. Using one hot leg plus neutral you will have a much safer supply with an usual voltage (for the US). Two hot legs means all switches must be double pole, and you have a 100% chance to die if you should accicentally touch parts of the circuit instead of 50%.
Here in Germany, all electrical supply, home and industry, is done with three phase current plus neutral. For single phase use, like for apartments, the three phases are split up and each apartment or room gets one hot leg plus neutral (plus protective earth). Motor supplies may be built without a neutral wire because the windings can be switched in star or delta (triangle) way without needing a neutral wire in either case. If you need power for single phase devices, say, a control box or control computer, a transformer can be used to generate the usual 120 volts (US). The disadvantage is that these transformers have limited power capacity whereas a direct single mains supply has (almost) no limitations. The voltage between the outer legs is equal to: voltage between one leg and neutral times square root of three (about 1.7). If you want to do yourself something good make the investment into a fourth wire for neutral and you will be on the safe side at the least cost. In Germany (and most european countries, i think), any electrician installing a three phase supply without neutral and protective earth would be kicked out of business by law for life time instantly. Peter Blodow Brian May schrieb: > Yes everything at our shop is wired off 3 phase. But our box has a nuetral. > So it goes from leg to nuetral. However my machine only has 4 lines - the 3 > legs of power and an earth ground. So i guess my question is do i need the > nuetral? > > Sent from my iPod > > On Nov 10, 2011, at 8:59 PM, Eric Keller <eekel...@psu.edu> wrote: > > >> the lights and most outlets here at work are single phase wired off of 3 >> phase. >> >> On Thu, Nov 10, 2011 at 9:50 PM, Brian May <bri...@diezorlich.com> 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 >>> >>> >> ------------------------------------------------------------------------------ >> 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
