KYORITSU 4202 - Manual (Page 14)

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# CAUTION
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.
In case that the " " symbol is displayed at the upper right of the
LCD, it means that a great error would be included in the measured result.
To avoid such inaccurate measurement, reduce the current flowing on the
earthed wire by turning off the device from which current is applied to the
earthed line under test.
Measurement cannot be made for the earth without multi-earthing system or
when the earth resistance under test is smaller than the other earth resistances.
To avoid inaccurate reading may be taken, never make a measurement for
the same earth system with multiple units of this instruments.
The " " symbol may be displayed during a measurement of earth
resistance. It indicates that the jaws of the instrument are not properly
closed. Measurement is being stopped while this symbol is displayed on the
LCD. Close the Transformer jaws properly to re-start the measurement.
Response time at Earth resistance function is about 7 seconds. It takes
awhile until the readings become stable.
7-3 Measurement of earth resistance
Measurement procedure
* Press the Function button and select the Earth resistance function.
* Confirm the displayed unit is " Ω ", and " MEM " is not displayed at the upper
left on the LCD.
* Press the trigger to open the Transformer jaws, and close them over the
earthed wire under test.
* Measured resistance value is displayed on the LCD.
<Noise check function>
At the Earth resistance function, the " " symbol is displayed on the LCD in
the following cases which may effect on a measurement.
* The current flowing on the earthed wire is exceeding the following value.
Range of Earth resistance function Allowable current value
20Ω 2A or less
200Ω/600Ω/1200Ω 400mA or less
* The current flowing on the earthed wire includes a harmonic wave which
effects on the measurement.
<Jaws check function>
The " " symbol is displayed when the Transformer jaws of the instrument are
not properly closed.
Measurement will be stopped when this symbol appears on the LCD.