Operating Tips For Active Line Tracing - RIDGID SeekTech SR-20 Manuel De L'opérateur

SeekTech SR-20
Rechecking the Measured Depth and position periodi-
cally during the excavation process can help avoid dam-
age to a target utility and may identify additional utility
signals that were not noticed prior to excavation.
When line tracing, it is important to remember that tees,
curves, other conductors in the vicinity, and nearby
masses of metal can add distortion to the field, requiring
closer scrutiny of the data to determine the true path of the
target utility.
Clarifying the situation can be done by assessing
whether the distortion is due to a poor signal that needs
to be improved, a local interference such as a near-by
car, or a tee or turn in the line.
(See below for tips on improving the signal.)
Circling the last location of a clear signal at a distance of
about 20 feet (6.5 m) can clarify if the distortion is com-
ing from a local turn or tee in the line, and enable the op-
erator to again pick up the line nearby.
If the signal is clear, the SR-20 will often show a straight
signal line with very little distortion right up to a 90-degree
tee, show a small amount of distortion as it follows
around the curve, and then show a clear signal again as
it resumes its travel after the tee.

Operating Tips for Active Line Tracing

The SR-20 quickly identifies distorted fields. If the guid-
ance arrows are centered on the screen, and the Trace
Line is not centered (or if the Proximity Signal number
and Signal Strength are not maximized where the Trace
Line centers), then distortion is creating a complex non-
circular field.
To improve the tracing circuit:
a) Try changing the frequency.
b) Move the ground stake position. Use a larger ground
contact surface (e.g., a shovel blade)
c) Make sure that the line is not commonly bonded to an-
other utility. (Undo common bonds only if safe to do so).
d) Move the transmitter to a different point on the line, if
possible.
If the Tracing Line will not center or if it moves across the
screen erratically, then the SR-20 may not be receiving
a clear signal. The Measured Depth and the Proximity
Signal may also be unstable under these circumstances.
a) Check the transmitter to be sure that it is operating and
well grounded. Good connection and good ground-
ing can overcome low current problems.
b) Test the circuit by pointing the lower antenna at either
transmitter lead.
14
c) Check that the SR-20 and transmitter are operating on
the same frequency.
d) Try different frequencies, starting with the lowest, until
the line can be picked up dependably. Using lower
frequencies can overcome bleedover problems.
e) Re-locate the ground connection for a better circuit.
Ensure there is enough contact (ground stake is suf-
ficiently deep) especially in dryer soils.
f) In extremely dry soil, wetting the area around the
ground stake will improve the circuit. Be aware the
moisture will dissipate and evaporate, reducing the
quality of the circuit over time.
Using the numeric Signal Angle Indicator is another
way to check for distorted signals.
Figure 23 – Checking for Distortion
Move the SR-20 to either side of the traced line until the
numeric Signal Angle indicator reads 45 degrees. Be
sure to keep the lower antenna node at the same height,
and the locator mast vertical. If there is little or no dis-
tortion the traced line should be in the middle and the
distance to each 45 degree point should be approxi-
mately the same on either side. If the signal is undis-
torted, then the distance from the line center to the 45°
point is approximately equal to the depth.
Another variation of this technique is to move the same
distance to the right and left of the traced line, say 24
inches (60 cm) and check that the Signal Strength read-
ings are similar or that the Signal Angles are similar.
Ridge Tool Company
= Same Distance
45°
° °
Energized Pipe
45°