On Sunday 27 December 2015 18:21:33 John Thornton wrote: > The VFD filter has no place to connect a neutral... only hots and > ground. > Goody. But if it works, hey!
> On 12/27/2015 5:10 PM, Gene Heskett wrote: > > On Sunday 27 December 2015 17:07:15 John Thornton wrote: > >> I've built a bunch of automation machines for Briggs and Stratton > >> and they never pull a neutral only 3 240v hots and a ground. We > >> always have a control transformer for the 120v stuff... I have the > >> same here now. > > > > After an hours searching thru it, and its the 1996 issue, a 240 volt > > single phase line w/o a neutral is legal if it goes only to that > > machine AND the machine was designed for that power configuration, > > eg is designed to run on 240 for everything. > > > > IOW if it goes anyplace else in the building besides that machine, > > it has to have a neutral too. And of coarse grounded is a given. > > > > So in your case, you can utilize a 240-120 stepdown that is NOT an > > autoformer. And from whats been said, that is what you are doing. > > > > However, speaking as a C.E.T., not having the neutral so that the > > filters you are installing can ship their noise back up that > > separate circuit, effectively isolated from what is supposed to be a > > nice quiet ground, does seem like it would put a lot of the absorbed > > noises into the grounding system. And unless putting the filters in > > fixes it, making me just a worry wart, I believe this may be much of > > your noise problem. > > > > Since we've come 19 years into the future since my copy of the NEC > > was put to bed & sold, with more efficient (and more noise > > sensitive) ways to do things now, I'd expect that a current copy of > > the NEC would more than likely have some additions designed to head > > off problems like this. > > > > Unfortunately a current copy is now at or somewhat north of a 120 > > dollar bill. > > > >> On 12/27/2015 3:52 PM, Gene Heskett wrote: > >>> On Sunday 27 December 2015 16:17:20 John Thornton wrote: > >>>> well there is no neutral because it's a 240vac circuit only... > >>> > >>> The only reason there is not a neutral is that the wire was never > >>> pulled. And I am not sure that missing neutral is NEC kosher. My > >>> copy is now 17 years old, so I think I'd check a newer one to be > >>> sure. With it, you wouldn't need the stepdown and isolation > >>> tranny because you would then have a pair of 120 circuits > >>> available in the machine. But those loads MUST return on the > >>> neutral, they cannot use the static ground. > >>> > >>>> On 12/27/2015 12:16 PM, Bruce Layne wrote: > >>>>> On 12/26/2015 06:51 PM, John Thornton wrote: > >>>>>> There is no neutral in the machine, only L1 L2 and GND. The > >>>>>> Neutral for the house is bonded to ground at the panels. > >>>>> > >>>>> Electrician's Joke: > >>>>> > >>>>> Q: What's the difference between neutral and ground? > >>>>> A: About six inches. > >>>>> > >>>>> There's a very good reason the return current is carried on the > >>>>> neutral and the ground should not carry any current in normal > >>>>> circumstances, but we do need to understand that electrons don't > >>>>> care about our conventions. They're just as happy returning via > >>>>> the ground wire. They don't know that the green wire is off > >>>>> limits for all but emergency traffic. > >>>>> > >>>>> The concept of ground/neutral functional equivalence is also a > >>>>> real life saver for anyone who might otherwise consider standing > >>>>> barefoot on a basement floor while hot wiring any line powered > >>>>> AC circuit. > >>> > >>> Cheers, Gene Heskett > >> > >> ------------------------------------------------------------------- > >>--- -------- _______________________________________________ > >> Emc-users mailing list > >> Emc-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > Cheers, Gene Heskett > > ---------------------------------------------------------------------- >-------- _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
