Measurement Of Earth Resistance - IDEAL 61-920 Mode D'emploi

7.3 Measurement of earth resistance

• Follow the procedure described in "7-1 Normal measurement of current" and measure the
current flowing on the earthed wire prior to the measurement of earth resistance. If "
is displayed in the upper right of the LCD, it means there is too much interference to obtain
an accurate reading. To avoid such inaccuracies, reduce the current flowing on the ground
wire by turning off the device causing this current to flow.
• Measurements cannot be made for multi-ground systems or when the ground resistance
under test is smaller than the other ground resistances.
• If the jaws of the instrument are not properly closed, the "
Close the transformer jaws properly to continue with the measurement.
• The response time is about 7 seconds on the earth resistance function. Note the reading after
it becomes stable.
• Measurement procedure
- Press the Function button
- Confirm that the displayed unit of measure is " Ω " and " MEM " is not displayed in the
upper left corner of the LCD.
- Press the lever to open the transformer jaws and close them around the ground wire
under test.
- The measured resistance value is displayed on the LCD.
<Noise check function>
When in the earth resistance function, the "
following scenarios, noise can affect the measurement accuracy:
1. The current flowing on the ground wire is exceeding the following values:
Range of Earth Resistance Function
20Ω
200Ω / 1200Ω
2 The current flowing on the ground wire includes a harmonic waveform.
<Jaws check function>
The " " symbol is displayed when the transformer jaws of the instrument are not properly closed.
Measurement is stopped while this symbol is displayed on the LCD.
CAUTION
" mark will be displayed.
and select the Earth resistance function.
" symbol is displayed on the LCD. Under the
Allowable current value
2A or less
400mA or less
14
Earth resistance measurement of a pole grounding electrode.
"
Earth resistance measurement of a ground electrode in a street lighting system.
Earth resistance measurement of a grounding electrode in a lighting protection
system.
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