© 2014 Radiodetection Ltd
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6.3.2 About current measurements
The transmitter applies a signal or current onto a target
line. The current decreases in strength as the distance
from the transmitter increases. This rate of decrease
depends on the type of line and on soil conditions.
Regardless of the type of line and the frequency being
used the rate of decrease should be regular with no
sudden drops or changes. Any sudden or abrupt current
change indicates that the line or its condition has
changed.
In congested areas, where there is more than one line,
the locator may sometimes detect a stronger signal from
an adjacent line to which the signal has coupled or
shares common grounding because it is nearer the
surface. Although current measurement compensates
for depth, signal response will be less as the depth
increases.
The line with the highest current measurement, rather
than the line giving the strongest response, is the target
line to which the transmitter signal has been connected.
Measuring current provides useful information about the
position of bends and intersections. Measuring current
after a tee will indicate the main line that pulls more
current along its greater length.
Figures 6.4
– 6.6 Taking current readings
6.3.3 Applying a transmitter signal
The transmitter signal can be connected, clamped or
induced to the target line in the same way as the signal
for line tracing is applied.
WARNING! Direct connection to live conductors is
POTENTIALLY LETHAL. Direct connections to live
conductors should be attempted by fully qualified personnel
only using the relevant products that allow connections to
energized lines.
6.3.4 Signal current measurements
Pinpoint the line and confirm the accuracy of the peak
pinpoint with a null pinpoint. Check the locator is directly
over the line, with the antennae at right angles to it and
vertical.
The locator will automatically estimate and display
depth on the LCD.
A signal coupled to a nearby line may distort the
accuracy of the measurement. If the accuracy of the
Figure 9.3 current readings
Figure 6.3 Current readings
Summary of Contents for rd7000+
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