UTM-00339 | Rev 19
Page 251 of 253
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When an individual string of detonators is tested with a Tagger, the leakage reading is within specification,
however, when all strings are connected together, the leakage value is outside the acceptable limit indicating that
the accumulative leakage value is now outside acceptable parameters. The sum of the leakage on all the strings is
greater than the acceptable level.
Damaged surface harness wire insulation and/or detonators cables cause resistance between the surface harness
wires when lying in an electrically conductive material which results in high leakage.
The best way of resolving this problem is by conducting a binary search as follows.
Divide the blast in half, cut the surface harness at mid-point.
Connect DigiShot
®
Plus Tagger and check the rear half of the installation for leakage, Tagger displays satisfactory
leakage.
Connect DigiShot
®
Plus Tagger and check front half of the installation for leakage, Tagger displays satisfactory
leakage.
Reconnect the break in the surface wire / bus and retest surface harness, DigiShot
®
Plus Tagger displays high
leakage indicating fault present.
Return to mid-point break, remove joint in surface harness.
Re-join the surface harness wire by crossing over the wires, yellow wire to green and green wire to yellow. High
leakage is reduced because the exposed wires A and B are now on the same line.
Ensure all wires are correctly insulated with tape to prevent further leakage problems.
Test surface harness wire to ensure leakage is within acceptable limits.
If high leakage is still present, split the blast onto separate channels in the middle of the blast.
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