| 摘要 |
PROBLEM TO BE SOLVED: To achieve measurement of grounding resistance at a point at which high ground potential is generated, while avoiding inaccurate measurement of the grounding resistance.SOLUTION: A constant current source 2 can supply a measurement current I with a plurality of current values I1. A processing unit 8 calculates a grounding resistance value Re of a grounding electrode E from a measuring current I of a current value I1 in such a manner that: a peak value Ve1 of an AC voltage Vep, measured by a voltage meter 3 when the measuring current I is in a halt state, is measured as a voltage value of a ground voltage Ve; a current value of the measuring current I is set to one current value I1 on the low side among the plurality of current values I1, and temporary grounding values Re, Rp and Rc for the grounding electrode E, auxiliary grounding electrodes P and C respectively, are calculated; on the basis of the respective temporary grounding resistance values Re, Rp and Rc, the peak value Ve1 and a maximum output voltage value Vmax of the constant current source 2, the current value I1 is determined of which a total voltage value of a peak voltage value generated from the respective grounding resistances Re and Rp ((Re+Rp)×I1×√2) and the peak value Ve1 becomes less than the voltage value Vmax and also nearest thereto. |
