2. Reduction of and [] matrices to phase conductors only

The installation of guard wires has the effect of slightly modifying the parameters of a power line:

• phase conductor capacities are slightly increased (by less than 3%);

• correlatively, inductances are reduced under the influence of currents induced in the ground wires by phase currents.

In addition, the Joule losses dissipated by these induced currents result in an apparent increase in phase conductor resistance.

In most cases, we can neglect the guard wires and simply write matrices whose order corresponds to the number of phase conductors.