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78-8130-6150-0 Rev G 25
and metal pipes), but would require increased sweep distance separation between the
transmitter and receiver.
Note: If nothing is plugged into the Output Jack [T-6] of the transmitter, the
transmitter will automatically turn on the internal antennae, and the last frequency
used (8 kHz (12 Watt transmitter only), 33 kHz or 200 kHz) will broadcast in induction
mode.
The induction frequency can be changed by pressing the Frequency button on the
transmitter. For best results, the receiver should be at least 25 feet (7.6 m) away from
the transmitter to begin tracing the target path and have the gain set between 78-84%
when starting the sweep. This is used to establish a baseline gain threshold prior to
starting a sweep. When crossing a target pipe or cable, the bar graph will close and
the signal strength and audio response will increase. Attempting to trace the target
close to the transmitter may lead to false indications due to the receiver detecting the
large magnetic field radiating from the transmitter.
B. Sweeping (Active) Induction Mode Locating
Sweeping an area with the 3M
™
Dynatel
™
Locator 2200M Series allows the location of
multiple metallic cables and pipes buried in an area without direct connect or coupler
access to the cable or pipe. This approach is effective before any excavation takes place.
Note that when specific buried objects need to be identified, it's important to use the
direct connect or coupler method for applying the signal. This will help limit the applied
locate signal to a specific facility that provides more position and depth accuracy along
with an effective identification. There are two main types of “no access” or “blind”
Induction Sweeps;
Passive Sweeps: These require only the use of the Receiver with passive frequency
detection capability. This method uses existing external signal sources, such as 60 Hz/50
Hz for electric power, 15 kHz to approximately 30 kHz for low frequency radio signals,
120 Hz / 100 Hz CPS impressed current Cathodic Protection signals and the less
commonly occurring CATV signal of 31.25 kHz NTSC with CRT TV turned on.
Active Sweeps: These require both the Receiver and Transmitter with Induction
capability. This method refers to using a 3M Dynatel transmitter as the signal source
through induction, instead of relying on passive frequencies that may exist on the
buried conductor or metal pipe. Active Induction allows for detecting buried cables
and metal pipes in the absence of passive signals and at deep depths and short sections.
3M Dynatel transmitters provide a choice of induction frequencies and output power
levels. Higher induction output power levels are needed for detecting deeper depths and
longer ranges. The 2200M Series 3 Watt transmitters provides two induction frequencies:
33 kHz and 200 kHz. The 12 Watt transmitter provides three induction frequencies: 8
kHz, 33 kHz and 200 kHz. The 200 kHz frequency is commonly used for deeper cables/
pipes and the lower frequencies are used to give longer locate distances. The 8 kHz (low
frequency) induction helps in locating shallow facilities, such as risers.
C. Passive Sweeps
Select Special (single) Peak (Spl Pk) mode on the receiver and then select the frequency
(source; for example, power, LF, etc.) to be traced. Passive sweeps at power frequency
will detect buried power cables and conductors carrying 60 Hz/50 Hz power signal in the