On Sunday, May 27, 2012 04:11:18 PM Dave Caroline did opine: > On Sun, May 27, 2012 at 6:45 PM, andy pugh <bodge...@gmail.com> wrote: > > On 27 May 2012 17:59, John Thornton <bjt...@gmail.com> wrote: > >> I did manage to get two traces last night with a kick start from your > >> instructions and lots of help from the IRC > > > > One thing that occurred to me is that phase balance on the drive-side > > of the reactor is possibly more important than phase-balance on the > > convertor side. > > Until he motor generates, the current design has two phases at 180 deg > with the poor relation in between > > Dave Caroline
Not entirely true Dave, that is what the capacitors attempt do do, is to form that 3rd leg with a reasonable imitation of the correct phase. The key to making it work well is to hook the load up delta, because when its hooked up wye style, the voltages on that 3rd leg, when measured to ground, are as wild as some of the measurements posted here already. I'd think, since this is a somewhat ferro-resonant way of doing it, that it is also quite dependent on the load, since most are designed with a direct 3 phase motor as a load. Put the full wave bridges load on it, where the rectifier diodes only conduct for the top 10% of the output waveforms voltage, loading only the tips of the waveform with a load that is easily 400% or more of what a resistive load would draw, but only during the peak developed voltage and its no surprise that tuning becomes super critical. Not having a schematic of those power supplies makes it highly subject to a lot of WAGuessing. If that was carried to its logical conclusion, I would look at the possibility of converting each phases rectification system from what is 99% likely a capacitative input filtering scheme to an inductive input filtering scheme, which would spread the load over considerably more of the waveform. Unforch that would also reduce the output voltage to approximately the RMS value of the input voltage where now it is nearly the peak to peak value. Now, here John, is another thought if my train of thought follows and this thing is hooked up delta on the outside, but is 3 individual loads to ground inside the kit, and which I can see objecting to the over voltages the phase converter generates,you might be very pleased with how it works IF you interpose a 3 phase transformer between your phase converter output and the supply to this kit. Hook the input side up as a delta load, ignoring the center of the wye this idler motor has AND the center of the primary side wye (other than making sure, if it has individual bolts per phase, that they are connected together). Then ground to the machines neutral and effectively to ground, the center of the wye of this 3 phase 1/1 transformers secondary, and feed your kit with the outside 3 corners of the wye. That should go a long ways to restore the "to ground" voltage balances. The transformer will of course need to be rated at about 125% of the kits actual load. And not having researched it, I'd have no clue as to the ready availability of such a beast. Doing a google search, I came across this: <http://www.elec-toolbox.com/usefulinfo/xfmr-3ph.htm> which might make it a bit clearer than my word pictures. Cheers, Gene. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> Work Hard. Rock Hard. Eat Hard. Sleep Hard. Grow Big. Wear Glasses If You Need 'Em. -- The Webb Wilder Credo ------------------------------------------------------------------------------ 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
