The Parallel Equivalent Of Series Impedance:

For equivalence of the two circuits (a) and (b), Y of Fig.(a) must equal Y of Fig (b)

Therefore Y=1/ (R_S+ jX_S) = 1/R_P +1/jX_P.

i.e. R_S/ (R_S²+X_S²) – jXS /(R_S²+X_S²)=1/R_P – j/X_P

Fig(A)

Ť EquivalentCircuits ť

Fig(B)

R_S/ (R_S²+X_S²) is called Conductance of the series impedance Z_S and is denoted by symbol g.
X_S/ (R_S²+X_S²) is called the Susceptance of the series impedance Z_S and is denoted by the symbol b.