Three Pole-Measurement Of The Earth Resistance - TESTBOY TV 441 Bedienungsanleitung

(3) Measuring the earth resistance
Turn the rotary switch to 2POL and press the MEASURE button. The button illuminates during the active
measurement. A signal tone sounds after the measurement has come to an end and the LED extinguishes.
The data are displayed automatically.
Caution:
If > LIMIT 4000 Ω is displayed on the LCD, this means that the auxiliary resistance of the auxiliary earthing rod is
so high that the current cannot flow through the measuring instrument. Check whether the test leads have
disconnected and the level of the earth resistance of the auxiliary earthing rod.
(4) Measured value
Re, the value of the earth resistance measured with the two-pole procedure corresponds to the sum of re, the earth
resistance of the earthing rod, and RX, the actual earth resistance of the measured object. Thus RX = Re - re, the
actual resistance of the mass object corresponds to Re minus re.

Three pole-measurement of the earth resistance

The measuring instrument uses the voltage drop procedure for measurement. The earth resistance RX is
determined by allowing the nominal current I to flow between the measurement object E (the earthing rods) and the
current pole C and then measuring V, the voltage difference between E and the voltage pole P.
(1) Connect the test leads to the measuring instrument in the following fashion
Place the auxiliary earthing rods P and C deep in the soil in a perpendicular manner with a clearance of 5 to
10 metres. Connect the test leads (black, red and green) from the connections E, P and C with the measurement
object and connects with the auxiliary earthing rods P and C.
Caution:
The ground around the auxiliary earthing rod must be damp Dampen any dry loam, sand or grit before the
measurement. Should the floor surface be cement, place the auxiliary earthing rod on the floor, wetten it and
cover with a damp cloth.
(2) Measuring the earth voltage
Before measuring the earth resistance, it is first necessary to measure any earth voltage present, as voltages
over 10 V can cause serious errors in the measurement of the earth resistance. In this case, disconnect the
measurement object from the power supply and wait until the earth voltage falls.
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Testboy TV 441
Operation
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