In the context of modeling and analysis of electrical networks, the self admittances of a transformer can be thought of as the device’s impact on the diagonal elements of of the nodal admittance matrix Ybus.

Considering the self admittance of the transformer’s primary, Equation 17 states

 $\mathbf{Y_{pp}}=\frac{\mathbf{Y_{L}+Y_{M}}}{a^{2}}$ (26)

Expressing the complex equation in rectangular form and making the substitution defined in Equation 25

 $\mathbf{Y_{pp}}=t^{2}(g_{L}+g_{M})+jt^{2}(b_{L}+b_{M})$ (27)

When the magnetizing admittance is ignored, Equation 27 reduces to

 $\mathbf{Y_{pp}}=t^{2}{g_{L}}+jt^{2}{b_{L}}$ (28)

 $\mathbf{Y_{ss}=Y_{L}}$ (29)
 $\mathbf{Y_{ss}}=g_{L}+jb_{L}$ (30)