Sofamel IER-4000 Manual De Instrucciones página 42

(2) Measurement of earth voltage
Earth voltage measurement should be done before measurement of earth resistance to check
the amount of earth voltage, as voltage more than 10 V is likely to cause larger error in the
measurement of earth resistance. In this case, cut the measured object from the power supply
and wait until the earth voltage drop for another measurement.
(3) Measurement of earth resistance
Rotate the switch to 2 POL position, press down the key of MEASURE to start the measure-
ment, with the key LED turned on and glittering. When the measurement comes to the end
automatically, the buzzer will give a sound, the key LED will go off and the data will be held
automatically.
Attention: >LIMIT4000Ω displayed on LCD warns that the auxiliary earth resistance of the auxiliary
earth rods is so high that the current can not flow across the meter. Check if the test leads become
loose and the amount of the earth resistance of the auxiliary earth rods
(4) Value measured
Re, value of the earth resistance measured by Bi-pole method, equals the sum of re, the earth
resistance of earth rods, and RX, the real earth resistance of the object measured; therefore,
RX=Re-re, meaning that the real resistance of the object measured equals Re minus re.
Operation Instruction
42