| 摘要 |
PURPOSE:To measure by direct reading the ground resistance of a DC circuit with simple circuit constitution, by connecting positive pole and negative pole side lines by a switch and a variable resistance, forming a bridge together with the ground resistance, and measuring the ground resistance. CONSTITUTION:Between a positive pole side DC line l1 and a negative pole side DC line l2, a switch SW1 of a ground resistance measuring device 1, a variable resistance VR by which the respective resistances of the lines l1, l2 attain R1 and R2, and a switch SW2 are connected. When these switches SW1, SW2 are turned on, and a bridge circuit formed by the switches SW1, SW2, the resistances R1, R2, and the each ground resistances RP, RN of the line l1, l2 is balanced through the resistance VR, the resistances R1, R2, RP and RN satisfy the condition of an expression. When only the switch SW2 is turned on in this balanced state, a current IP flowing to an ammeter M becomes IP=E/(R1+R2+ RP) based on the condition of the expression, and attains to a value corresponding to the resistance RP. With respect to a resistance R0, too, it is measured in the same way, and the ground resistance of a DC circuit can be measured by direct reading with simple circuit constitution.
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