© 2022 Radiodetection Ltd
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Section 5 - Locating cables and pipes
This section introduces the principals and techniques of locating buried cable and pipe utilities with the RD7200
system. For more information on the theory of cable and pipe location, refer to
The theory of buried cable and pipe
location
which is available to download from
5.1 Frequencies
The RD7200 locator supports a range of active and
passive frequencies.
For a complete list of supported frequencies, refer to the
RD7200 Locator Specification datasheet.
Passive frequencies
Passive frequency detection takes advantage of signals
that may be present on buried metallic conductors.
Dependent on the model, RD7200 locators support up to
three types of passive frequencies:
Power
,
Radio and
CPS
signals.
You can detect these frequencies without the aid of a
transmitter if they are present on the utility you are
surveying.
Power Filters™
The RD7200 locator allow you to take advantage of the
harmonic signals found on power networks.
When strong or interfering power signals are present,
accurate tracing of a target cable can be challenging.
Power Filters™ allow you to establish if a single large
power signal comes from one source or from the
presence of multiple cables. The different harmonic
characteristics of the detected lines can then be used to
trace and mark their route.
Once in Power Mode, press the key to switch out of
Radiodetection’s sensitive Power Mode and scroll
through the five individual Power Filters.
The use of an individual Power Filter harmonic can also
allow you to locate power lines in situations where the
total signal would otherwise be too large.
Active frequencies
Active frequencies are applied to a buried conductor
using the transmitter. The transmitter can apply a signal
using three methods:
Direct Connection
In Direct Connection, you connect the transmitter output
directly to the utility. The transmitter will then apply a
discrete signal which you can locate using the locator.
This is the preferred method of applying a transmitter
signal to a utility and in the majority of applications will
apply a stronger signal to the utility, which may increase
the locate distance.
To directly connect to a non-energized conductive utility:
1 Switch the transmitter off
2 Connect the Direct Connection lead into the
transmitter accessory socket
3 Clip the red connection lead to the utility ensuring
that the area around the connection is clean and that
a positive connection is achieved
4 Clip the black connection lead as far away as
possible and at 90° to the ground stake or suitable
ground point nearby ensuring that a positive
connection is achieved
5 Switch the transmitter On
6 The display will show the Direct Connection lead
connected icon
Figure 5.1 Direct Connection lead icon
For more information about other signal connection
accessories, refer to Section 8.
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.
WARNING! The transmitter is capable of outputting
potentially lethal voltages. Take care when handling the
terminals, connection leads and ground stake, notify other
technicians working on the line of the hazard and guard
exposed conductors to prevent accidental contact.
WARNING! Ensure the TX transmitter is switched OFF
before making a connection and before disconnection of the
direct connection lead to a service.
Induction
In this mode of operation the transmitter is placed on the
ground over or near the survey area. If a Direct
Connection lead or signal clamp is not plugged into the
transmitter, it will automatically go into induction mode.
In this mode, only frequencies applicable for induction
mode will be made available as the key is pressed.
Once activated the transmitter will induce the signal
indiscriminately to any nearby buried conductors.
