Large Scale Earth Resistivity Experiment in New Zealand

Abstract

IN 1965 a high voltage d.c. line, 580 km long, began operation, bringing power from the Benmore hydroelectric power station in the South Island of New Zealand to the Haywards terminal in the North Island (Fig. 1). Initially, the return path of the current was through the ground from which an approximately dipole pattern of potential might be expected on the Earth's surface. This potential would not in general be separable from other ground potentials of natural or artificial origin. Load changes in the Benmore–Haywards system are, however, carried out in steps of 20 MW, or 80 amp in line current. The consequent abrupt changes in ground potential can be observed for considerable distances from the electrodes provided there is no great telluric activity at the time.