Question on 3 wire Delta connected winding
- Thread starter Rob2019
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- Location
- Illinois
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- retired electrician
That would work like a 240/120 high leg delta. The voltage would be (370/2) * sq rt 3
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Pythagorean's theorem.
Side C = Line-Line voltage (Vll)
Side A = Line-center tap voltage (1/2 x Vll)
Solve for Side B
- Location
- San Francisco Bay Area, CA, USA
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- Electrical Engineer
Why would there be a center tap on one winding in a 3 wire delta system?
And where are you seeing a 370V delta system in the first place?
And where are you seeing a 370V delta system in the first place?
- Location
- San Francisco Bay Area, CA, USA
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- Electrical Engineer
And by the way, you cannot attach just any file, you can only attach images, such as .jpg, .gif, .png etc.
kwired
Electron manager
- Location
- NE Nebraska
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- EC
Well if you are actually utilizing the center tap of said winding you now have a three phase 4 wire delta system. Pole pig transformer banks often have center tap on every pig in a delta configuration, but they either corner ground one corner or ground only one midpoint and leave the others floating.
flashlight
Senior Member
- Location
- NY, NY
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- Electrician, semi-retired
As an interested grunt on the secondary side of all this, I really appreciate your guys explanations of what's happening at the primary.
Thank you sir!
Can't you also multiply 370v ph-ph x .866, to find the same.fir a center tapped delta. That is how I was taught. The .866 is the teaser tap on a scott T xfrmr true 2 phase 4 w setup, and also inversely the relation of a high leg to ground verus the phase to phase on a center tapped delta system, or a 4w delta.( why the smoke comes out when you use the bastard leg, for outlets) Which is always half voltage p-N or G if it's truly 4 wire delta on the other two legs. On tthe third is your bastard leg. Had lots of both the first place I worked. One system there supplying 120v outlets from a 4w delta and small motors at 240v 3 phase, one supplying 2 phase 4 wire motors from the turn of last century. The old guy that held my hand there learning the systems Also taught me in the few places we had 2 phase, 3 wire that the proverbial B phase carried the sum of currents and was larger by 1.414x, which also is the multiplier for 45* offsets. He was 76 I was 18. I wish he was still live. Would love to pick that brain.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
.866 is SQRT3 divided by 2, so yes.
Formula is basically half line to line volts times SQRT 3 - if you draw the delta out that is what you would be measuring, mid way point of one side to the opposite corner.
In 19 years doing this, that was never explained so easily. Everyone should know 120/208/240 from a 4w Delta. Never put the 208/120 part together. Never had it explained so succinctly. The oddball systems we had, was a simple way for me to remember. Thank you! Working aboard ships now, and everything is a delta, and ungrounded, even the 120v outlet for a phone charger. A Wye system is incredibly foreign. Now. Even the 4160 stuff is an ungrounded delta, a real oddball. 2 things I do remember. Don't get in series with a 277v neutral, and 277 is miserable to get whacked from
grich
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