Measurements of Ground Impedances of Deeply-driven Ground Rods

초록

The evaluation of the measurement errors due to earth mutual resistances recommended from IEEE std. 81.2 doesn't be applied to the deeply-driven ground rod. When measuring the ground impedance using the high frequency test currents, there is a need to evaluate the earth mutual resistances and AC mutual coupling for the vertically installed ground rods. In this paper, the errors due to the earth mutual resistances and AC mutual coupling are measured and simulated for the ratio of the distance to potential electrode to the length of ground rod (D/L). The error rates due to the earth mutual resistances are decreased with increasing the length of the ground rod at the same ratio D/L. It is recommended that the distance from the ground rod being measured to the current and the potential auxiliary electrodes is shortened to the length of the ground rods so that, the earth mutual resistances are compensated for. The obtuse angled arrangements of the current and the potential auxiliary electrodes are reasonable for reducing the AC mutual coupling effect.