Shunt Admittances

Shunt admittances play a crucial role in the analysis of transmission lines, particularly for three-phase systems with neutral conductors. When a uniformly charged conductor is positioned above the Earth, it induces an equal but opposite charge on its surface. This interaction creates electric field lines between the conductor and the Earth.

Consider a uniformly charged conductor above Earth. It induces an equal negative charge on Earth, creating electric field lines.

Earth's effect is modeled using an image conductor, identical but beneath the original, keeping the electric field and voltage constant.

For three-phase lines with neutral conductors, separate image condu...