On Monday, March 14, 2011 10:50:03 AM John Thornton did opine: > Is it not amazing that the hillbillies from backwoods Missouri with a > 3rd grade education can make a rotary phase converter without all the > math... > > Interesting discussion. > Interesting indeed John. I have stayed out of it largely because the convoluted reasoning used to arrive at the conclusions does not agree with my personal experience. And FWIW, my formal education stops at the 8th grade. But I also have not stopped learning...
If I read it right, it is being said that perhaps a capacitor of the correct value to create a usable phase lead, from L1 or L2 to L3, will start a 3 phase motor on single phase power, direction of the rotation dependent on which 2 the capacitor is connected to. This I can believe as that is how the common 1/4 horse capacitor start motor starts, and then runs with the capacitor disconnected. This of course doesn't give huge amounts of starting torque, but is generally sufficient. Where it falls apart in my experience is when a real 3 phase motor is substituted, then there is a third winding to deal with, but I don't have the math background to analyze it properly. What I do know is that a running 3 phase motor, in this case a 15 horse motor pulling a water pump delivering about 110 GPM to a pair of 4KM100LA klystrons, will, when finding one phase in a delta connection opened, in this case by a failing contact in a Heinman circuit breaker, will slow and stop in about 1 second. This leaves one winding with power still on it, drawing LRA currents, (and you can hear that saturated iron hum for about 500 feet!) which should open the circuit breaker forthwith, but it was not fast enough (and GE did not have logic to detect a pump failure other than low flow sensors which it turned out were too slow). When the post mortem was done, that manually controlled breaker was still closed, but because the coolant flow stopped, there was a hole burned through the bottom of the klystrons beam collector funnel where 96% of this coolant is sent, burned by the electron beam of the tube, which was a bit more than 19.7KV x 5.6 Amps, just about 110KW of power that water/glycol mix was supposed to be carrying away. That allowed the coolant and its steam, into the vacuum of the tube, that caused the whole beam supply to be crow barred and the 1200 amp rated building entrance breaker opened (but I assume the overcurrent sensors in the GE AK-225 beam power breaker also opened, but its state was not preserved for the 'autopsy' as it had undervoltage protection which would have opened it when the entrance breaker cleared, and was probably probably being cleared by the transmitters own excessive beam currant logic at about the same time. The 2nd tube, normally a tired visual being finished by using it for the much lower powered aural, survived. Those things were about $150k each. So my personal experience says if they wanna try it, fine, just do it with their own money paying for the failures. I personally think they will be "interesting", with expensive adjectives. :( -- 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) <http://tinyurl.com/ddg5bz> <http://www.cantrip.org/gatto.html> My idea of roughing it turning the air conditioner too low. ------------------------------------------------------------------------------ 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
