Electric Fields and Ion Currents of a ±400 kV HVDC Test Line

In a continuing program to characterize the electrical environment in the vicinity of high voltage dc transmission lines, the ground level electric fields and ion current densities produced by a bipolar test line with a 2 x 3.82cm conductor bundle energized at ±400 kV have been measured at the High Voltage Transmission Research Facility in Lenox, MA (Project UHV). The results reported are for six different combinations of pole spacing and minimum height above ground. The conductor bundle is similar to the conductor bundle used on the CPA-UPA HVDC transmission line in North Dakota and Minnesota. Measurements were made over a six month period from June to December, 1981. Data is reported for different weather conditions; Fair weather, Fog, Rain, Frost and Snow. A seasonal dependence is observed for the Fair weather electric fields and ion current densities. The effect of pole spacing and line height is discussed.