On Tue, 2011-09-06 at 17:57 +0100, andy pugh wrote: > On 6 September 2011 17:15, Peter Blodow <p.blo...@dreki.de> wrote: > > > - Think about the effects that plugging the mains plug 180 degrees > > turned over could have, don't rely on wires having seemingly no > > potential in one case! > > This isn't possible with UK wiring. > Also, UK 240V single phase is neutral + live, with neutral sitting at > a few volts relative to earth, it isn't the US-style 2-phase 240V.
Just picking knits, but I believe US 240Vac is not considered two phase. The two 120Vac legs that are referenced to neutral, might in some way be considered two phases, but 240Vac is a single sine wave between L1 and L2. As far as I know, neutral has no part in it, so can't be considered in 240Vac's description. Being a center tap, neutral could be used with L1 or L2 as a source for single phase 120Vac. I think wikipedia mentions that very early US mains power systems offered a true two phase power with 90 degree phase shift between L1 and L2 for industrial motor starting, but capacitor starting and three phase replaced it. http://en.wikipedia.org/wiki/Two-phase_electric_power > > - Be aware of the fact that ordinary switches, relay contacts, fuses > > etc. can switch off much less DC voltage than in the AC case > > The only switching on the DC side is an NC relay which connects a > resistor across the capacitors when the mains power disappears. That > breaks at 0V before the power is directed to the rectifier. > > > Have you > > considered using a 1:1 transformer? > > Yes, but I can't find one. (or not one rated at 15A / 240V anyway) I wonder if an old welder transformer could be used? You might be able to make one using one or more Antek cores: http://www.antekinc.com/index.php I reused the transformers out of my Hardinge lathe, one of them is about 80 pounds or 36? kilos. I would think many old surplus industrial or main frame computer racks would have a very large mains transformer or two. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Special Offer -- Download ArcSight Logger for FREE! Finally, a world-class log management solution at an even better price-free! And you'll get a free "Love Thy Logs" t-shirt when you download Logger. Secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsisghtdev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
