Over-Range Indication; Fault Led Indication - Tips And Solutions - AEMC 3640 User Manual

2.4

Over-range Indication

Over-range is indicated when the display reads 1, or when the display is
blinking and the indicator is lit.
2.5 Fault LED Indication – Tips and Solutions
The LED indicators show excessive electrode resistance and excessive
transient noise and/or stray current.
In the event of an incorrect measurement indication:
• Improve the quality of the connection to earth of auxiliary ground
electrodes Y and Z. Z is the most likely source of problems caused
by excessive electrode resistance.
• Check connections for continuity between leads and electrodes.
• Be sure that electrodes are properly inserted; they should be
buried as much as possible.
• If high electrode resistance still exists after properly inserting aux-
iliary electrodes into the earth, try pouring water on and around
the 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 X
electrode (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) resistance
levels and by stray signal levels (earth currents).
Digital Ground Resistance Tester Model 3640 and 4610
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