Owner's manual

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5. Measurement principle
This instrument can measure the earth resistance to earth in multi-earthed system.
Let's regard earth resistance under test as Rx, and the other earth resistances as
R
1 , R 2 , … Rn.
Of these earth resistances, R 1 , R 2 , … Rn can be considered that they are
connected in parallel.
And can be regarded as a combined resistance Rs. The Rs can be regarded small
enough against Rx since a combined resistance cons
ists of several resistances.
Following is an equivalent circuit diagram of this circuit.
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