Talk:Y-Δ transform

(No section)

This seems to read more like a how-to than a proper encyclopedic article on the subject.

---

The following old comments seem no longer applicable. --SlothMcCarty (talk) 05:05, 2 December 2011 (UTC)

---

I wonder if this ought to be written as Wye-Delta rather than Wye-delta, because for obvious reasons the letter Δ needs to be a capital? Michael Hardy 21:32, 18 Sep 2004 (UTC)

---

This article is mixing in "Y-delta" starting of motors - that technique should be moved to the induction motor article. --Wtshymanski 03:51, 14 Jan 2005 (UTC)

---

The formula is WRONG, the pictures name the resistance Rac, Rab, Rbc, Ra, Rb, Rc and the formula is written in terms of R1, R2,R3,Ra,Rb,Rc. See http://en.wikipedia.org/wiki/Analysis_of_resistive_circuits in the delta to wye part for show is should be. Someone please edit it. I only know the basics of wikiditing.

Suggestions

Here are a few suggestions:

1. The article could give an example of a bridge circuit that can't be broken down into parallel and series parts unless the Y-delta transformation is used. Otherwise it's not clear from the article why the transformation is useful.
2. The transformation can be derived from the condition that the resistances of the two circuits are equal when voltages are applied to any two terminals, and the third is left floating. However, it's not trivially obvious that this also makes them completely equivalent in all other cases, e.g., where no terminal is floating. I'm not a big fan of mathematical proofs in WP articles, but the logic could be made more clear without giving the actual proofs.
3. Can the Y-delta transformation be used to break *any* network of resistors into series and parallel parts?

--Bcrowell 16:47, 26 September 2005 (UTC)

As for #1, agreed and done. --SlothMcCarty (talk) 11:34, 2 December 2011 (UTC)

If someone would care to transcribe the Anderson Bridge circuit [[1]], it is an excelent example of where a Delta-star transform helps its analysis. The bridge allows measurement of inductors and capacitors but requiring only variable resistors in the bridge itself. The problem with analysis is that the bridge doesn't quite resemble a conventional bridge as the detector is not connected to a corner. However performing a delta-star transform on the delta formed by P, r and C (in the referenced diagram), converts the bridge into a conventional bridge circuit, although the detector does have an impedance in series with it - but as the detector current is zero at balance, it conveniently disappears. 109.153.242.10 (talk) 16:57, 25 January 2012 (UTC)

30 degree phase shift

Can someone explain why there is a 30 degree phase shift between delta-wye and wye-delta transformer configurations. I've check numerous sites, but all the sites say is that there is a phase shift of either +30 or -30 degrees.

If a transformer has DELTA in primary and both STAR & DELTA in secondary so what will be the phase difference in secondary between STAR and DELTA.

Balance

I’ve tried to clean up the article a bit. Since I did not understand the intent of the statement

Balanced System: $R_{\Delta }=3\times R_{y}$

I’ve moved it here. Can somebody put it back in context or explain it? —xyzzy_n 01:12, 14 January 2007 (UTC)

practical usage

I do not agree with BCrowell above

I agree assuming a node is at zero potential is not feasable but that is not done here. The voltages of the nodes are never preserved (note that there is one more node in the graph) only the currents coming in and out of the nodes are preserved. This seems to imply superimposing the 3 cases

(assume the inputs at nodes N1 ,N2,N3 are current sources and not voltage sources)

1. we have N1

2. we have N2

3. we have N3

in each of these cases, we have to compute the current leaving each node w.r.t "a zero reference (that we add in the graph)" being equivalent.

so in other words

we would have between N1 and N2

N1-N2=Ib.Rb

N2-N3=Ic.Rc

N3-N1=Ia.Ra

hence between N1 and N2 we have 2 effective circuits

N1-N2=Ib.Rb

and

N2-N1=IcRc+IaRa

because we assume N3 is non existent (nonzero but non existent) we can assume it is parallel to the 1st and hence Ic=Ia

Likewise for the other 2 cases

So in other words we are superimposing the 3 conditions to find the equivalent (assume the inputs at nodes N1 ,N2,N3 are current sources and not voltage sources)

-Alok 06:11, 20 January 2010 (UTC)

Improve symmetry of transformation equations

I would like to see the diagram modified slightly in order to make the equations simpler and more elegant in my view. A non-exhaustive perusal of talk entries indicates that this topic is not covered. I would have liked to demonstrate the changes, but I could not figure out how to edit mathematical Wikipedia expressions.

I refer to the left hand (delta) portion of the article's main diagram. Using my representation for subscripted symbols, I would replace Rc, Ra, and Rb by Ra, Rb, and Rc respectively. Doing so will associate the first three letters of the alphabet, abc, with the first three natural numbers, 123 in order. This will correspond to node order numbers. That will remove one source of confusion when trying to follow the details. There will be more symmetry to the transformation equations. —Preceding unsigned comment added by PEBill (talk • contribs) 23:10, 10 September 2010 (UTC)

I agree. Dauto (talk) 15:14, 13 February 2011 (UTC)

Done. I would appreciate someone checking my work. --SlothMcCarty (talk) 05:00, 2 December 2011 (UTC)

Topic is backwards

The topic of the article is backwards vs. what you write in the article!

The topic says: "Y-Δ transform", where the first character is pronounced "Star" and the second one "Delta", but the article talks about "Delta Star transform".

Seems like some other languages they've got this already right, but how come it's still backwards here?!

Please fix to avoid more confusion or explain yourself in the article. Thanks!

188.238.22.14 (talk) 19:26, 14 September 2013 (UTC)