In power system analysis, the earth's presence beneath overhead transmission conductors alters the electric field distribution and therefore the line's shunt capacitance, an effect modeled using the method of images (replacing the ground's equipotential boundary with a fictitious oppositely-charged mirror conductor at equal depth below the surface). The theory extends this earth-effect capacitance calculation from single-phase to three-phase and multi-conductor (with overhead ground wires) systems, and separately derives the mutual series-impedance and shunt-admittance coupling between the two circuits of a double-circuit transmission line sharing a common tower.
In power system analysis, the earth's presence beneath overhead transmission conductors alters the electric field distribution and therefore the line's shunt capacitance, an effect modeled using the …