Hioki FT3151, Instruction Manual

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26
Measuring Earth Resistance Precisely
(Precise Measurement, 3-Pole Measurement Method)
Measurement of large-scale earthing electrodes
When measuring a large-scale earthing electrode such as a mesh earthing
electrode, ring earthing electrode, or earthing electrode provided by a large
building structure, it cannot be accurately measured because the H(C)
electrode and S(P) electrode come inside the earth resistance area of E
electrode.
If long cables are used to avoid the H(C) electrode and S(P) electrode
getting inside the earth resistance area, accurate measurement cannot be
carried out because it is significantly affected by noise.
In general, measurement of large-scale earthing electrode requires
a large measurement current of approximately 20 A. Use measuring
instrument designed for measuring large-scale earthing electrodes for this
measurement. (No measuring instrument is available for this purpose from
Hioki)
Connecting measurement cables
WARNING
• The maximum rated voltage between input terminals
and the ground is as follows:
(CAT II): 300 V rms
Attempting to measure voltages exceeding this
level with respect to ground could damage the
instrument and result in personal injury.
• To avoid an electric shock, do not short-circuit live
lines with each other by contacting the test leads to
them.