AEMC 4620 User Manual

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AEMC 4620 User Manual Manual pdf 11 page image

Digital Ground Resistance Tester Model 4620 and 4630 92.3 Fault Indicator LEDsThe three indicators confirm that the correct measurement is being taken,if none of them are lit.2.3.1 X-Z FaultThis LED signals that the voltage between terminals X and Z exceeds 30Vpeak.There are four possible causes:• the resistance of the current circuit between X and Z is too high• interference voltage in the current circuit is too high• the fuse is blown• the circuit is open (lead not connected)2.3.2 Xv-Y High ResistanceThis LED signals that the resistance in the voltage circuit (between Xv andY or X and Y) is too high (approx 50kΩ) or that the circuit may be open.• Flashing will continue throughout the measurement, even if theresistance drops below the threshold (e.g. after reconnectingor lowering auxiliary rod resistance). In this case, you mustrelease the push-button and press again after the fault has beencorrected.• Occasionally, a stray voltage above 4.5V may also set off thislight.• Check the leads for a possible solution.2.3.3 Xv-Y High NoiseThis LED signals the presence of excessive electrical noise (13V peakapprox) in the voltage circuit (between Xv and Y or X and Y).• One remedy is to use shielded leads from the instrument to theauxiliary electrodes.• Connect all the shields to the rod under test.