Andy, looks like a neatly made power box. Rectifying AC line power without potential insulation, however, is unusual and bears some risks.
- Be aware that both of your DC lines will have potential to ground, none can be grounded. - Be sure that every metallic enclosure that is powered by this device will be properly connected to protective earth (PE) and none of the motor's leads will be near earth! - Be sure that the drives and motors have sufficient high voltage protection to ground, check technical specs. - You can't connect the control circuitry, which will be ground referenced in most cases (zero of the 5 V supply connected to the metal parts and PE) without an optical or other insulator which makes things more complicated than usual. - 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! - Be aware of the fact that ordinary switches, relay contacts, fuses etc. can switch off much less DC voltage than in the AC case. A DC arc, several inches long, will be stationary at as little as 110 volts DC in some cases. And it creates a lot of heat... In the good old DC times we used to have spring loaded, fast acting switches with wide gaps between the contacts, remember? - Honestly: You must be a much braver man than I because I myself wouldn't dare using that box knowing that I'm too much used to the way of thinking that one leg will always have zero volts.... Have you considered using a 1:1 transformer? Good luck! Peter andy pugh schrieb: > I have made a servo PSU. It simply rectifies mains voltage to give me 325V DC. > https://picasaweb.google.com/lh/photo/HdNJXBD5wPqDUi9E8C46HQ?feat=directlink > https://picasaweb.google.com/lh/photo/dTcU2i7GYh53xSrqjh--BQ?feat=directlink > There is a bit of extra componentry in the box to discharge the caps > on power-off and to switch in a resistor for soft start, but basically > it is just a rectifier and some caps. > > I am a bit puzzled about the status of my -V. > I guess that my 0V will be a few volts away from neutral, which is a > few volts from earth. Should there be an explicit connection between > my DC- and earth, machine 0V, mains neutral, none of the above? > > I think perhaps I should have a 1:1 transformer to float the DC, which > would then allow such a connection. > > ------------------------------------------------------------------------------ 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
