On Mon, 2011-03-14 at 22:55 +0100, Peter Blodow wrote: > Kirk, > > "Neutral" is not to be considered. You have two wires coming from the > supplier. Adding a capacitor makes three of them. The two mains lines > are 180 degrees apart by definition. The capacitor makes a third phase > 90 degrees between them. Connect your motor, and it will be running, > regardless of which line is grounded. > > Peter Blodow
Sort of. Your description above I believe matches my diagram showing the starting mode, or the middle picture: http://www.wallacecompany.com/machine_shop/EMC2/three_phase_converter-1a.png In my original argument, I stated I thought L1 and L2 from the mains are 180 degrees apart, because if you scope L1, you get a sine wave. If you scope L2, you get a sine wave that is shifted 180 degrees from the L1 sine wave. The problem is that the scope uses ground or neutral as the reference for the L1 and L2 voltage. but the neutral is not used in the circuit so the 180 degrees doesn't apply or add to the understanding of how the circuit works. The only thing we know is that there is a single 240 Volt sine wave when L1 is referenced to L2 or vis versa and this single wave is connected across a single phase on the converter motor. Once I drew this single phase wave on the A and B converter motor terminals, everything else flowed from that. The only time 180 degrees came to mind from developing this diagram was in considering the unconnected C terminal relative to A and B. C looks like a transformer center tap relative to A and B, so there should be a sine wave between L1 (A) and and C that is 180 degrees from L2 (B) and C. To me so far, this doesn't add anything to the understanding of the converter. My converter does have a pair of running capacitors and sometime I may try to apply the start capacitor logic to these to try to figure out how they work. My guess is that they store energy during the motor period and release it during the generating period of each shaft rotation, but I can't prove it, yet. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
