Python in Electrical Engineering: Converting between Y and Delta impedances

Given the branch impedances in delta configuration, what is the equivalent circuit impedance if connected in a Y configuration? the folowing short Python codes ease the conversion between Y and Delta impedances.

"""
file       deltay.py
author     Ernesto P. Adorio, Ph.D.
           UPDEPP (U.P. at Clarkfield)
desc       translate delta impedances to Y impedances.
version    0.0.1    04.21.2011
"""



def delta2yZ(Zab ,Zbc, Zca):
    """
    translate delta impedances to Y impedances.
    Arguments
       Zab, Zbc, Zca - complex impedances of Deta connection.
    Output
       Za, Zb, Zc - equivalent Y connection impedances to commom point.
    """
    denom = Zab + Zbc + Zca
    return (Zca * Zab/denom,Zab* Zbc/denom, Zbc * Zca/ denom)

def y2deltaZ(Za, Zb, Zc):
    """
    translate Y impedances to delta impedances.
    Arguments
       Za, Zb, Zc - complex Y connected impedances 
    Output
       Zab, Zbc, Zca - equivalent delta connection branch impedances.
    """
    num = Za*Zb + Zb*Zc + Zc* Za
    return (num/ Zc, num / Za, num/Zb)

We will continue this with an example later.

Exercise: State the formulas used by the above routines y2deltaZ(), delta2yZ() routines. It is so easy to write the functions that we did not bother to write the documentation for this first version, but we will later!