Hioki FT3151 - Page 98

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Measuring Earth Resistance Simply
(Simplied Measurement, 2-Pole Measurement Method)
CAUTION
Use the optional L9787 Test Lead for simplied
measurement for safety. Connecting the L9841, L9842-11,
L9842-22, L9843-51 and L9843-52 Measurement Cable to
a commercial power supply may cause electric shock.
What is simplied measurement method (2-pole method)?
Simplied measurement method (2-pole method) is a measurement
method to check the earth resistance of the equipment earthing with an
earth system called TT method.
If auxiliary earthing rods cannot be inserted, the earth resistance is
obtained with use of an existing low earthing resistor as an auxiliary
electrode.
In this method, the measured value is the sum of the earth resistances of
the measuring object and existing earthing resistor (Rx+Ro), according
to the measurement principle. Thus, the earth resistance of the existing
earthing resistor needs to be lower than that of the earthing electrode of the
measuring object.
When using the simplied measurement method, the resistance of the
existing earthing body is added to the measurement result.
Apply the 3-pole method to measure an earth resistance of 10
Ω
or less.