RD4000 Locating System User Manual
Page 42
Take readings at the survey intervals determined by the reference reading. To locate the cable during a
FaultFind survey, press the peak/null antenna button once and the receiver will switch to 8kHz null mode.
Locate the cable using the normal null mode technique. Press the peak/null antenna button again to return to
FaultFind mode.
As a fault is approached the FaultFind direction arrow will
lock on to the fault signal and point forward and the dB
readings will increase. When the fault is passed the arrow
will point back towards the transmitter. Take readings at
smaller survey intervals to determine the exact point of
the fault.
When the A-frame is directly over the fault the dB reading
will drop as shown opposite.
Note: The values given are for illustration purposes only and
may not be the same as those obtained in other situations.
To pinpoint the fault, turn the A-frame 90
0
to the cable
and FaultFind until the exact point is found where the
arrow direction changes. The centre line of the A-frame is
now directly over the fault.
Mark the ground to show the position of the fault. Find the maximum dB reading in front of the fault by pushing
the A-frame into the ground at small intervals. Note the dB reading. If the reading is approximately the same as
the reference reading, you can assume that there is only one fault. If the reading is less than the reference
reading, keep surveying the cable for other faults.
Replace the bonds between the sheath and ground at each end of the line once the faultfinding survey has
been completed.
Tip.
If the cable runs under a road, use the equipment as
normal on the road surface as it can sometimes detect
signals when working on blacktop, concrete, or paved
surfaces. If necessary, try wetting the road surface.
Pouring a very small amount of water around the bottom of
the A-frame spikes before each FaultFind will
generally ensure a good ground connection.
Tip.
If the cable runs under a paved surface, the fault can often be pinpointed by fault finding in the grass/soil
adjacent to the paving. Reduce the distance between placing the A-frame spikes in the ground to allow for the
increased distance to the actual fault position.
dB
20
40
60
80
80
60
40
40
20
0
Road
Path
Soil
Fault
line
