# First online complex Delta-Star or Delta-Y Transformation Calculatoris ready

Discussion in 'Electrical Engineering' started by Patrick Chung, Oct 10, 2013.

2. ### Don KellyGuest

1)hopefully not for someone taking circuit theory where 3) is more useful
2)not really -it is one of the network theorems that is sometimes useful
3)absolutely true.
4)sure
5)yes- J or APL also work well

But- it is pretty!

4. ### J.B. WoodGuest

Hello, and I probably overreacted a bit. What is new I guess is the
convenience of an online calculator. My apologies to the ng and the OP.
Sincerely,

5. ### Don KellyGuest

However- how often have you needed such a calculator? Also, if so, how
often would you either look it up or work it out from scratch as I have
often done simply because I either forgot or was too lazy to look it up?
It is not a teaching tool.

I have dealt with a lot of circuit analysis over the last 60 years but
over this time, my use of star delta transformations has declined
considerably as
(a)I am looking for complete circuit solutions
(b)If I am trying to reduce a circuit to a thevenin model--why bother
when there are more powerful methods such as Z-bus which take advantage
of the computer.
(c) In relatively few cases I want to use this for its own sake.

Admittedly this calculator may be useful as part of a set of tools
-provided that set was all in one place and results could be saved and
applied elsewhere. To some extent a language such as APL or J then
allows considerable freedom along with the use of pre-defined
transformations such as the delta-wye. As an aside, in J, the delta-wye
transform and the y-delta transform each take one short relatively
readable line. As with Patrick, I am sure that I learned more about

6. ### Don KellyGuest

This is interesting -you have hit a core of the problem. Going from A
(Z12) B (Z23c) C (Z31) to a b c or z1n z2bn z3n works nicely -i.e going
delta to wye. However there may be a problem going the other way- to
deal with this one must say Z12 =A =(z1n*z2n +z1n*z3n+z2n*z3n)/ z3n or
(ab+ac+bc)/c
The problem is that the numbers are right but as you have indicated A
and a do not touch. There is a rotation which is a problem of
nomenclature - what is fixed is the terminals 1, 2,3 and we are dealing
with Z12 etc or z1n etc (n being a 4th or neutral terminal not present
in the delta).

7. ### Don KellyGuest

You are right- One does need double subscripts to deal with this
properly. You know what is going on and the format and have put the clue
in considering the "one and only resistor in the wye that is not
touching" You use, properly a double subscript notation. Dealing with an
idiot box, inputis of the form a b c where awhat is referred to may be
Zab,Zbc, Zca or in the reverse case Zan,Zbn, Zcn. Check it out regarding
the preservation of the terminals A B C.

As to the need for the transformation- I agree- use Kirchoff.
From my viewpoint as it appears is yours, use of I =YV (mesh) is
better than V-ZI (loop) simply because in most cases it results in
fewer simultaneous equations and is generally better for computer
modelling because once a choice of reference bus is made (in power
systems it is easy), the rest can be automated. It is messier with loop
methods as there are so many choices.