Abstract
In a ground wire associated with an overhead transmission line, 5_??_10% of the current in a phase conductor usually flows due to the magnetic induction effect, and it brings some amount of power loss.
In this paper, we propose a new reduction method of power loss in the ground wire. The current induced in the ground wire is effectively reduced by sectionalization of the ground wire every around 1 km along the power line. Thus, the total power loss also decreases so much.
A computer program was developed in this process to calculate the exact current distribution in each section of the ground wire.
We carried out field test on two different transmission lines in service to verify actual reduction of power loss by the proposed method. The ground wires were sectionalized prior to the test.
The total power loss produced in the sectionalized ground wires were reduced to about one tenth in the original conventional arrangement. The observed current distribution agreed well with those estimated by the developed program.
The sectionalized ground wire is grounded through all towers included in each section and, thus, the electrostatic shield effect to avoid lightning stroke to the conductors is never lost. The electromagnetic shield effect for adjacent communication lines is also effective.
Finally it is shown from economical viewpoint that the saved kWh-cost due to the proposed sectionalization of the ground wire is much higher than the cost to realize the necessary improvement on the ground wire arrangement.
