KYORITSU 4106 - Manual (Page 28)

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9. Measurement Method
# DANGER
● No voltage should be applied between the measuring terminals at earth
resistance measurements.
9-1 Earth Resistance Measurement
# CAUTION
● The measured results may be influenced by induction if measure-ments
are made with the Test Leads twisted or in touch with each other.
When connecting the Probes, they should be separated.
Note) When measuring multi-earthed system such as interconnected towers
and electrical poles with this instrument, the measured results
smaller than the values of single-earthed system are obtained since
these earth resistance can be considered that they are connected
in parallel. Let’s regard earth resistance under test as Rx, and the
other earth resistances as R1, R2, •••Rn.
Of these earth resistances, R1, R2, •••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 it is a combined
resistance consists of several resistances. So the measured values
obtained by using this instrument will be quite small since Rs values are
measured actually. To measure earth resistances of multi-earthed system, a
use of our Digital Earth Clamp MODEL4200 is recommended.