Right now the 10hp RPC is adjusted with the caps without a load to give me A-B=244, A-C=253, B-C=253. As I understand it that is about as good as you can expect from a RPC. I still need to check it under load and perhaps the idea from the past about having an Ardunio or something switch in some more caps when the load increases has some merit.
John On 5/29/2012 10:24 PM, gene heskett wrote: > On Tuesday, May 29, 2012 11:04:48 PM Jon Elson did opine: > >> John Thornton wrote: >>> Where should the 208v be? The mains are 244vac. >> If you measure from the mains neutral (which is NOT the center point >> of the 3-phase system) to the generated leg, it should be about 208 >> Volts. >> >> The three-phase system is an equilateral triangle, with each side 240 V. >> The neutral is the center of the bottom side, the 240 V mains are >> the left and right corner of the bottom. The generated line is the top >> of the triangle. >> So, if you cut it in half vertically, you have two 30/60/90 degree >> triangles, >> with the 90 degree angles against each other. The left and right >> sides of the big triangle are also 240 V. So, the hypotenuse of the >> 30/60/90 triangles are 240, the base is 120. sin (60) * 240 = >> 207.8 >> >> So, that's where the 208 comes from. If your mains are actually >> 244 V, then neutral to L3 would be 211.3 V. >> >> But, you really should not be measuring from the mains neutral, as >> that is not germane to the 3-phase system. Just measure from each >> line to another. You should get 240 on each one. > Neglecting ohmic losses, if all 3 phases read within 2 or 3 %, A/B, B/C, > C/A, then the generated phases absolutely have to be within 10 degrees of > 120 degrees when referenced to either of the other combo's. > > So basically, adjust the capacitor sizes, under load, so that the A/C > voltage is very close to the B/C voltage, and the phases have to be "close > enough for the girls we go with." Larger capacitors, ISTR tend to reduce > the load sensitivity, but there could well be a way to overdo that. > >> I have not >> derived the math on this, but I am pretty sure that it is impossible to >> have 240 V from each line to another and have the phase angles >> wrong. So, if the voltages read balanced, the phase angles ALSO >> have to be correct. > Yes. >> 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 > > Cheers, Gene ------------------------------------------------------------------------------ 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
