Earth/Ground Tester
Description of Functions
9
Measurement of Earthing Resistance (R
E
)
The earthing resistance is determined by a 3- or 4-pole current and voltage
measurement. The measuring voltage is a square pulse AC voltage with 48 /
20 V and a frequency of 94, 105, 111 or 128 Hz. The frequency can be selected
manually or automatically (AFC).
Selective Measurement of Earthing Resistance (R
E
A
)
Measurement of a single earth electrode in a mesh operated (parallel) earthing
system. The current flowing through the single earth electrode is measured
with an external current transformer.
Resistance Measurement (R~)
The resistance is determined by a 2 pole current and voltage measurement. The
measuring voltage is a square pulse AC voltage with 20 V and a frequency of
94, 105, 111 or 128 Hz. The frequency can be selected manually or automati-
cally (AFC).
Low Resistance Measurement (RF)
The resistance is determined by DC current and voltage measurement. 2- as
well as 4-pole measurement is possible. The short circuit current is > 200 mA.
The resistance of both current directions is measured and stored.
Checking for Correct Measuring Connection
The processor checks if the measuring lead is properly connected according to
the selected function via isolated, two piece contacts, inside of each 4 mm (ba-
nana) input socket, in combination with detection circuitry. A wrong or miss-
ing connection is indicated by an optical or acoustical signal.
Beeper
The built in beeper has two functions:
1. Giving messages if set limit values are exceeded.
2. Indicating dangerous conditions or maloperation.
Controlling is done by means of the microprocessor.
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