AEMC 4620 User Manual

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AEMC 4620 User Manual Manual pdf 12 page image

10 Digital Ground Resistance Tester Model 4620 and 46302.4 BuzzerThe Models 4620 and 4630 feature a buzzer, which will sound when theterminals of the tester are connected to a voltage source. The soundvolume is proportional to the voltage up to 30V approximately, thenbecomes stable.2.5 Over-range IndicationOver-range is indicated when the display reads 1, or when the display isblinking and the indicator is lit.2.6 Fault LED Indication – Tips and SolutionsThe LED indicators show excessive electrode resistance and excessivetransient noise and/or stray current.In the event of an incorrect measurement indication:• Improve the quality of the connection to earth of auxiliary groundelectrodes Y and Z. Z is the most likely source of problems causedby excessive electrode resistance.• Check connections for continuity between leads and electrodes.• Be sure that electrodes are properly inserted; they should beburied as much as possible.• If high electrode resistance still exists after properly inserting aux-iliary electrodes into the earth, try pouring water on and aroundthe auxiliary electrodes. This will improve their electrical connec-tion to earth.• If stray currents are suspected, one solution to reduce their influ-ence is to move both Y and Z electrodes in an arc relative to the Xelectrode (try, e.g. a 90° shift), and test again.• Display of 0.00: Xv and Y are short-circuited.• Display of <0: X and Z or Xv and Y rods are reversed.NOTE: Accuracy may be affected by auxiliary ground rod (Ry, Rz) resistancelevels and by stray signal levels (earth currents).