Presumption manner null of the grounding resistance which corresponds to the embedding depth of the cylindrical earthed electrode

摘要

PURPOSE: To determine the burial depth of a bar-shaped ground electrode by calculating a potential difference/current ratio at each point using Wenner's our-electrode method while varying in steps the interval between electrodes, and obtaining an estimated resistance value through the multiplication of each value by a constant determined by the diameter of the bar-shaped ground electrode, and estimating this value to be the ground resistance of the ground electrode buried to a depth matching the electrode-to-electrode interval. ;CONSTITUTION: Four point electrodes C₁, P₁, P₂, C₂ are arranged on a straight line on the surface of the ground at intervals a, and a direct current l is passed between the electrodes C₁, C₂ to measure a potential difference V between the electrodes P₁, P₂. When the diameter and length of a bar-shaped ground electrode are D and L, respectively, the distance between the upper end of the ground electrode and the surface of the ground is t and the length of the ground electrode corresponding to a hemispherical electrode having a diameter of 1m is L₁, then a=l+t so that the ground resistance R of the ground electrode is R = (1/1.41) (L₁+t) (V/I)=C(V/I), the constant C determined by the diameter D. Therefore, the interval a is varied in steps to calculate V/I at each point, and the value of V/I is multiplied by the constant C to obtain an estimated resistance value, and this value can be estimated to be ground resistance when the ground electrode is buried to a depth matching the interval a.;COPYRIGHT: (C)1996,JPO