AEMC 3640 User Manual

Digital Ground Resistance Tester Model 3640 and 4610 92.4 Over-range IndicationOver-range is indicated when the display reads 1, or when the display isblinking and the indicator is lit.2.5 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).