gene heskett wrote: > On Monday, May 28, 2012 01:43:30 PM Jon Elson did opine: > > >> >> First, you should forget the mains neutral. This terminal has no >> meaning for the generated >> 3-phase system, and just causes confusion. If the motor has a center >> tap, you can use >> that as the reference for the 3 phases. But, on John Thornton's machine >> he is trying >> to power a big DC supply, so there is no reference available, unless he >> can get it >> from his idler motor. >> >> Jon >> > > True, but that point can be lethally hot to ground in operation. Hence the > isolation transformer need. > Right, what may be needed (although I am not convinced) would be a transformer where the WYE secondary's center point can be tied to the safety ground, creating a new neutral specific to the 3-phase system.
But, I am still not convinced that a transformer will help the problem. If some sensing circuit is detecting the odd line voltages from the neutral, then it probably should be tripping all the time, or not even allowing the machine to power on. If the problem is improper SCR firing due to poor voltage/phase balance, the transformer is not likely to help much. (A delta-wye transformer may redistribute the imbalance, so that might help, but a 7.5+ KVA transformer will be fairly big. I think it should be possible to improve the balance of this phase converter and I think that will cure the problem. Jon ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
