High Altitude Effect on Corona Inception Voltages of DC Power Transmission Conductors Based on the Mobile Corona Cage

In order to investigate the high altitude effect on dc corona inception voltage of power transmission lines, a mobile corona cage test system was constructed. The experiments were carried in Wuhan, Xining, Geermu, and Nachitai, respectively. Photons released as a result of corona discharge on the conductors were detected by the ultraviolet image detector. Both positive and negative corona inception voltages could be acquired by the "tangent method" based on the measured data. The approximate linear altitude correction formulas were suggested.