A transmission line having a length of more than 80 kms but less than 250 kms is considered as a medium transmission line. The parameters (Resistance, Inductance, and Capacitance) are distributed uniformly along the line. For a medium transmission line, charging current is appreciable and due to the length of the line the shunt admittance plays a significant role in the calculation of the effective parameters of the line.

The shunt admittance and series impedance are considered as a lumped parameter of the medium transmission line. The medium transmission line is shown below in the diagram.

Many localized capacitance models have been used to make approximate line performance calculations. The following models are commonly used.