A Voltage Gradient Meter

EARLY IN the studies now in progress on the Tidd 500-kv test lines at Brilliant, Ohio, it was thought that the voltage gradient at the earth's surface might have an important effect on corona and radio influence. Since the phase conductors on a grounded-neutral transmission system are grounded for d-c potentials through the transformers, the earth's electric gradient induces a static charge on these conductors of such polarity and magnitude as to nullify exactly the potential which would exist in space if the conductors were not present. The presence of this induced static charge establishes a gradient on the surface of the conductors which theoretically is superimposed upon the gradient produced by the applied alternating voltage, and thus it may alter the corona and radio influence performance of the line. It was decided to include an investigation of these effects in the Tidd test program.