Your thread title says 6 phase secondary. 9 secondary windings do not correlate with a 6 phase output. You can get 60 degrees separation utilizing a dual delta to wye configuration because it has an inherent 30-degree phase shift.
6 phase forked star secondary wound transformer
- Thread starter RogerRoger25
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RogerRoger25
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FWIW, the primary phasor diagram does not correlate with the primary winding depiction.This is the phasor diagram;
Your secondary winding voltages will be VPRI·SEC
RI turns ratio. The magnitudes of Vhn, Vgn, and Vin, i.e. the short phasors, correspond to the calculated result. The remaining six will have a magnitude that is 1.732 times that magnitude. The angles will be as depicted (0° being to hard right).Looking at it again, a couple secondary phasors do not correlate properly with the depicted winding configuration. Here is a corrected diagram...
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Smart$, I think that you have linked to a Google-based image that is not visible to other users.
Can't login to my photobucket account. It keeps rejecting my username.
This any better?
FWIW, looking at the diagram even yet another time. The polarity dots on the secondary windings seem to indicate the secondary phasors are pointed the opposite direction of where they should. Can anyone confirm?
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There are six line to neutral terminals.
At the point I wrote that I was not aware he was wanting to use the triple-wye secondary...
No problem.
I just don't know what it would be used for. I have the J&P transformer book. It's 800 pages and no mention of such an arrangement. It looks like three zig-zags connected together. I'd be interested to hear if anyone can cite an actual application where one has been installed. And why.
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I'm pretty sure saw it used once a long time ago as a way to have one large main transformer feeding multiple low voltage three and single phase loads to large IBM main frame computers (back in the day). Old IBM main frames used to use 415V 3 phase for the computer power supplies and 240V single phase for the fans and coolant pumps inside. So looking at those vectors, the large vectors would give you 2 sets of 3 phase 415V: a, c, e and f, b, d, then 3 connections for 240V single phase loads: h-n, g-n and i-n. I can imagine they did that for better balancing of the loads?
The thing is, computers aren't built that way any more and those that were are museum pieces now, so it's highly unlikely that anyone uses this any longer. The only reason I saw it at all was because I helped scrap an old IBM mainframe computer from a hospital in the late 70s and that transformer was fascinating to me, so I looked it up. I never actually knew the voltages at the time, it was already apart when I saw it, but I learned years later that IBM had used 415V for the power, and I knew from that scrapping job that all the fans and pumps were 240V single phase, because we used them for different things, so I'm putting 2 and 2 together as to what was going on. Seeing this diagram now that I know more made me realize that's what I had seen.
The transformer was I think around 150kVA, which if you think about the fact that my iPhone probably has as much computing power as that beast did back then, is pretty amazing. We stripped it for the copper, I think we got something like $25 for it at the time... We stripped out all the PC boards and sent them to a refiner, got back a little over 8 ounces of gold, but as I recall, we had just gone off of the gold standard a few years earlier and got something like $120/oz. Wish I had just kept it...
The thing is, computers aren't built that way any more and those that were are museum pieces now, so it's highly unlikely that anyone uses this any longer. The only reason I saw it at all was because I helped scrap an old IBM mainframe computer from a hospital in the late 70s and that transformer was fascinating to me, so I looked it up. I never actually knew the voltages at the time, it was already apart when I saw it, but I learned years later that IBM had used 415V for the power, and I knew from that scrapping job that all the fans and pumps were 240V single phase, because we used them for different things, so I'm putting 2 and 2 together as to what was going on. Seeing this diagram now that I know more made me realize that's what I had seen.
The transformer was I think around 150kVA, which if you think about the fact that my iPhone probably has as much computing power as that beast did back then, is pretty amazing. We stripped it for the copper, I think we got something like $25 for it at the time... We stripped out all the PC boards and sent them to a refiner, got back a little over 8 ounces of gold, but as I recall, we had just gone off of the gold standard a few years earlier and got something like $120/oz. Wish I had just kept it...
Odd thing for an exam question though..........
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No argument from me on that, but I feel that sometimes people toss really oddball things into exams just to make sure nobody gets 100%... :dunce:
Yes, the 100% thing.
That takes me back to a very long time ago.
Mods be kind.
I already got unreasonably admonished by a mod for saying I had 50 years experience despite that being the truth, but this was from an exam 54 years ago and it stuck in my mind.
The question was about energy and I gave the correct numerical answer but I called it Joules. A
ccording to the professor, should have been J. Rather like we label volts as V.
My otherwise 100% was deducted by two points for that gross error of incompetence.
My pal Al said the same thing you did. They don't want to give out 100% scores.
Trivial, I know.
And life moves on.
It's now gone 07:00 here so I'll just walk the black and white brute for a few miles and observe the wonders of nature in spring.
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Years ago I went to PLC training at Allen Bradley in Milwaukee. On the final; exam, the last question was
No matter what answer you gave, they would mark it wrong for one of a dozen possible reasonings; if you said "The US", the answer was "No, in North America"; if you said "North America", they said "No, the world"; if you said "The world", they said "No, the solar system"; etc. etc. etc., meaning it's entire existence on the exam was so that nobody got 100%. Also if your co-workers clued you in before attending, they couldn't give you the correct answer in advance either. I hear they no longer do that simply because their clock is now only the largest 4 faced clock in North America, there are bigger ones elsewhere, even on this planet.
No matter what answer you gave, they would mark it wrong for one of a dozen possible reasonings; if you said "The US", the answer was "No, in North America"; if you said "North America", they said "No, the world"; if you said "The world", they said "No, the solar system"; etc. etc. etc., meaning it's entire existence on the exam was so that nobody got 100%. Also if your co-workers clued you in before attending, they couldn't give you the correct answer in advance either. I hear they no longer do that simply because their clock is now only the largest 4 faced clock in North America, there are bigger ones elsewhere, even on this planet.
Takes me back to school days.............
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