Editing Electric power transmission (section)

===Medium line===
The medium line approximation is used for lines running between {{cvt|80 and 250|km}}. The series impedance and the shunt (current leak) conductance are considered, placing half of the shunt conductance at each end of the line. This circuit is often referred to as a ''nominal [[Pi (letter)|''π'' (pi)]]'' circuit because of the shape (''π'') that is taken on when leak conductance is placed on both sides of the circuit diagram. The analysis of the medium line produces:

:<math>
\begin{align}
A &= D = 1 + \frac{G Z}{2} \text{ per unit}\\
B &= Z\Omega\\
C &= G \Big( 1 + \frac{G Z}{4}\Big)S
\end{align}
</math>

Counterintuitive behaviors of medium-length transmission lines:

* voltage rise at no load or small current ([[Ferranti effect]])
* receiving-end current can exceed sending-end current