Abstract: The vertical DC grounding electrode forming an elliptical ring occupies a relative small land and has strong topography adaptability, which makes it worth to be widely applied. However, the nonuniformity of current releasing density caused by elliptical ring arrangement becomes a problem worth to be studied further. This paper carried out the analyses and comparison how those parameters of grounding electrode shape affect the electrode releasing characteristics. The shape parameters include ellipticity, circumference of pole ring, electrode length, electrode separation and the number of electrodes. The results show that the nonuniformity of current releasing density would be more significant on condition that with a higher ellipticity value, longer electrode length, shorter electrode separation and smaller electrodes number, moreover, the main factors by importance are in sequence of ellipticity, electrode length and separation distance, electrode number. The vertical grounding electrode should be arranged considering the nonuniformity of current releasing density between electrodes and that on a single electrode, so as to control the maximum error index of current releasing density at any point on the electrode.

Key words: DC vertical earthing electrode, elliptical ring, current releasing density, error index