3M CablePipeFault Locator 25502573 Series User Manual

							78-9000-0192-2 Rev D 21
6. Locating Buried Cables And Pipes
A.  Transmitter Connections
Perform a battery test. Use one of the following three methods to produce a trace signal 
on the target pipe or cable.
1. Direct Connect Method
! WARNING
This WARNING applies to the use of the Direct Connect Cables and the Transmitter.
To avoid potential shock, or electrically damaging the Transmitter, when setting up the 
Transmitter to locate using the Direct Connect method, follow these basic steps;
•    ALWAYS plug the Direct Connect Cable into the Transmitter Output Jack [T-6] BEFORE 
connecting the leads to the cable/pipe to be located and the ground rod.
  – Connect the red lead to the cable/pipe. 
  – Connect the black lead to ground rod.
A POTENTIAL FOR ELECTRICAL SHOCK, AND/OR TRANSMITTER ELECTRICAL DAMAGE, EXISTS 
WHEN USING THE DIRECT CONNECT CABLE ON CABLES ENERGIZED WITH ELECTRICAL POWER 
IF THE ABOVE INSTRUCTIONS ARE NOT FOLLOWED. USE APPROPRIATE SAFETY PROCEDURES.
CHECK VOLTAGE BEFORE CONNECTING TRANSMITTER. VOLTAGE HIGHER THAN 240 VOLTS WILL 
DAMAGE EQUIPMENT. FOLLOW STANDARD PROCEDURES FOR REDUCING THE VOLTAGE.
•  Plug the direct connect cable into the Output Jack [T-6] of the transmitter. Connect 
the black clip to the ground rod. Place the ground rod in the earth perpendicular to 
the suspected cable/pipe path. If necessary, extend the black lead with the Ground 
Extension Cable (#9043 available separately).
• Remove the ground bonding and attach the red clip to the shield of the cable, pipe, 
or target conductor. (If locating power cables, the red clip can be attached to the 
transformer cabinet, or the meter box). Metal contact must be made between the red 
clip and the transformer cabinet or meter box. If painted, some paint will need to be 
removed/scraped off to allow metal-to-metal contact.
•  Turn the transmitter on by pressing Ohms  [T-2]. The continuity of the circuit will be 
measured. The results are displayed on the Digital Display [T-4] in ohms and as an 
audible  tone. 
						

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− If the continuity of the circuit is very good (the reading on the display is less than 
3K Ω. and a solid tone from the transmitter is heard) all frequencies can be used to 
locate. Always use the lowest frequency available (for example, 577 Hz). Lower 
frequencies are less likely to ‘bleed over’ to other cables in the same area, and are 
very good for tracing over long distances.
 
− If the circuit reads more than 3K Ω., but less than lOK Ω (indicated by a beeping 
tone from the transmitter) it will be necessary to use a higher frequency than 
577 Hz in order to locate the cable/pipe.
 
− If the circuit reads more than lOK Ω., it will be necessary to use an RF signal such 
as 33 kHz, 82 kHz or 200 kHz.
 
− If there is no tone and the transmitter indicates that there is an open circuit (OL 
in the display) this could be an indication of a poor ground, or an open-ended 
cable or pipe. Use one of the higher frequencies available, at high or maximum 
output power level. If it is an open-ended cable or pipe, the receiver's response will 
decrease suddenly at the site of the clear or severed end.
Note: In the ohms mode, the transmitter can detect voltage as well as ohms. If a low 
voltage is detected, the Digital Display [T-4] will alternate between displaying ohms 
and volts. When displaying ohms, the flag over the Ω symbol will be visible. When 
displaying volts, the flag over the ‘V’ will be visible. When the voltage magnitude 
is sufficient to impair the accuracy of the ohms measurement, only voltage will be 
displayed. If the voltage is AC, a sine wave will be visible on the Digital Display [T-4]. 
If a high AC voltage is detected, a rapid beeping tone will be heard.
•  Press  Trace [T-3] repeatedly until the desired frequency appears on the display. Note 
that the number that flashes alternately with the selected frequency is called the 
relative current. This number can be useful in identifying the target cable/pipe and 
is discussed more in 8. Depth and Current Estimate  and 10. Locating in Directional 
Peak Mode.
•  Press  Output Level  [T-5] to select high, or maximum, output power level for longer 
tracing distances or deep pipe/cable. 
						

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2. 3M™ Dyna-Coupler Method
! WARNING
This WARNING applies to the following 3M Dyna-Couplers;
• 3" (75 mm) - Part number 3001
• 4.5" (114 mm) - Part number 4001
• 6" (150 mm) - Part number 1196
•    All accessory kits containing any of the listed Dyna-Couplers - Part numbers 3019, 4519, 
1196/C
A potential for electrical shock exists when using the Dyna-Coupler on c\
ables energized with 
electrical power. Use appropriate safety procedures.
DO NOT USE ON CABLES CARRYING IN EXCESS OF 600 VOLTS RMS.
 
Use a ground extension cable, 
or wire, and ground rod set-up 
between a target pipe/cable and 
a gas meter valve/box, or cable/
electrical meter box. This will isolate 
the locate signal to the target pipe/
cable section below the meter/box, 
between the grounding points. This 
provides a good return path for the 
tracing signal. Insulating coupling 
above a gas meter valve on a pipe 
will isolate the returning signal from 
ground and may make locating 
more difficult.
•  Connect the 3M Dyna-Coupler to the transmitter  Output Jack [T-6] using the coupler 
cable  (9011).
•  Clamp the 3M Dyna-Coupler around the cable or pipe, below any bonds, just before it 
enters the earth.  The jaws of the coupler must fully close.
•  Press  Trace  [T-3] to turn on the transmitter. Press again to select 8 kHz, 33 kHz, 
82 kHz or 200 kHz.
Note: When using a 3M Dyna-Coupler, always select high, or maximum, output power 
level by pressing Output Level [T-5] key on the transmitter. 
						

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3. Induction Method
If you cannot make a direct connection, or use the 3M™ Dyna-Coupler clamp to apply a 
locating signal on the target, use the induction method. When nothing is plugged into the 
Output Jack [T-6] of the transmitter the unit will be placed into induction mode when it 
is turned on. This method uses the internal coil of the transmitter to generate a magnetic 
field. This is the least preferred method of applying a signal on a target conductor 
because it can easily be picked up by other non-target conductors in the area. However, 
it is the preferred method of applying a signal to multiple cables/pipes in the same trench 
and for the “two-person sweeping” application.
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 2500 Series transmitters provide four induction frequencies: 
8 kHz, 33 kHz, 82 kHz and 200 kHz and three output power settings up to 12W. The 
82 kHz and 200 kHz frequencies are 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.
The following sections review Non-sweeping and Sweeping (Area) methods\
 used 
with the Induction Mode. The Non-Sweeping method is utilized when a specific target 
requires path tracing. The transmitter remains stationary in-line over the target and the 
path is traced. The Sweeping method is utilized when a designated area needs to be 
swept for non-specific targets, for example, all the buried pipes or conductors in the 
designated area. Several sweeping methods will be reviewed.
A. Non-Sweeping(Passive) Induction Mode Locating
•  Position the transmitter over the target facility, with the hinge of the transmitter over 
and in line with the cable/pipe path. Remove any cables from the Output Jack [T-6].
 
− Align the Induction Direction arrows on the transmitter with the target conductor.
•  Turn on the transmitter, select the frequency and select high output or maximum 
output power level for best signal-to-noise ratio.
•  Trace the signal path with the receiver using the Induction Peak (Ind Pk) mode.
The Induction Peak (Ind Pk) mode of the receiver is a mode in which the upper antenna 
of the receiver is tuned to minimize distortion from the magnetic field of the transmitter.
Use Induction Peak (Ind Pk) mode when sweeping distance between the transmitter and 
receiver is 25–60 feet (7.6–20 m). Beyond 60 feet (20 m) you can also use the Special 
(single) Peak (Spl Pk) or Directional Peak (Dir Pk) modes. Special (single) Peak (Spl 
Pk) can be used for maximum detection depth and range (needed for deep conductors 
and metal pipes), but would require increased sweep distance separation between the 
transmitter and receiver. 
						

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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, 33 kHz, 82 kHz or 200 kHz) will broadcast in induction mode.
The induction frequency can be changed by pressing the Trace [T-3] (Frequency [T-3] 
on 2550) 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, ha\
ve the gain 
set between 78-84% and have the receiver in Induction Peak (Ind Pk) mode when 
starting the sweep. 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 2500 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 for 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 sec\
tions. 
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 2500 Series transmitters provide four induction frequencies: 8 
kHz, 33 kHz, 82 kHz and 200 kHz and three output power settings up to 12W. The 82 
kHz and 200 kHz frequencies are commonly used for deeper cables/pipes and the lower 
frequencies are used to give longer locate  distances.
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 
ground. Other passive sources exist, such as Cathodic Protection, LF and CATV cable 
(with NTSC TV CRT turned on). 
						

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Walk in a grid pattern over the sweep area holding the receiver as shown in the 
following illustration. Stop when there is a response increase, locate the position of the 
maximum signal, follow the conductor path all the way out of the sweep area while 
putting location marks on the ground. Resume the sweep until another cable or pipe is 
detected, or the whole area is completely swept. Switch to another available passive 
frequency in the receiver and sweep again.
D. One-person Active Induction Mode Sweeps
One-person active induction mode sweeps require that the transmitter be set on the 
ground over the suspected path of the buried infrastructure. The receiver is used to 
detect signals induced by the transmitter on buried long conductors. Proper placement 
and orientation is key to maximize the induced signal in the buried cable or metallic 
pipe enough to be detectable by the receiver along each path in the swept area. (Note 
that no signal is induced onto a conductor whose path is perpendicular to the Induction 
Direction indication.)
• Place the transmitter in the upright (bottom on ground) position for directional 
optimization when aligned with the Induction Direction shown on the label on the 
transmitter.
•  Tip the transmitter over towards the front, and lay it on it's front surface, for multi-
directional wide area induction. (Note that no signal is induced onto a conductor 
whose path is directly under the transmitter).
•  Remove anything plugged into the Output Jack [T-6] (this will place unit in Induction 
Mode), select highest available frequency (200 kHz) and highest output power level.
•  Select the Induction Peak (Ind Pk) mode and 200 kHz frequency on the receiver\
. 
When in close proximity to the transmitter in induction mode, there is a direct signal 
from the induction antenna in the transmitter to the receiver through the air. Induction 
Peak (Ind Pk) mode is a newly added locate mode for use in closer proximity to a 
transmitter in Induction mode (
						

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E. Two-person Active Induction Mode Sweeps
In two-person active induction mode sweeps, one person holds the transmitter and 
the other holds the receiver while walking together in a sweep pattern detecting long 
conductors in the ground when crossed by transmitter and receiver positions and 
orientation, as shown below:
Transmitter Set-up
• Remove anything plugged into the Output Jack [T-6] (this will place unit in Induction 
Mode), select high frequency (200 kHz), or medium frequency (33 kHz or 82 kHz), 
and highest output power level.
•  Hold the transmitter with the lid facing up and align it with the Induction Direction 
arrow label, as shown on the transmitter, with the receiver
Receiver Set-up
•  Set the receiver to the same frequency as the transmitter.
•  Select the Induction Peak (Ind Pk) mode, and press the Gain [3] (+ or -) key until the 
Bar Graph [11] ([10] for 2550 locator) is just visible.
Sweeping
•  Sweeping can be done at close distances between the transmitter and receiver.
•  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. 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.
•  Induction Peak (Ind Pk) mode cancels the air signal coming directly from the 
transmitter induction antenna to the receiver. Increasing the sweep distance between 
the transmitter and receiver reduces the direct air signal and allows for sensing deeper 
conductors and sections of metal pipes. Use Induction Peak (Ind Pk) mode when 
sweeping distance between the transmitter and receiver is 25–60 feet (7.6–20 m). 
Beyond 60 feet (20 m) you can also use the Trace View (T-view), Special (single) 
Peak (Spl Pk) or Directional Peak (Dir Pk) modes.
•  Special (single) Peak (Spl Pk) can be used for maximum detection depth and range 
(needed for deep conductors and metal pipes), but would require increased sweep 
distance separation between the transmitter and receiver. 
						

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7. Receiver Locating Trace Modes
A.  Trace View (T-View)
TRACE [2]
Trace View mode, or T-View, provides an intuitive mapping display showing the utility 
path utilizing a dynamic directional arrows and path indication line. This combination 
provides an excellent visual representation of the utility path and directional assistance 
to assist in pinpointing the target.
Several displays may be seen when using Trace View:
Display 1.  When the receiver is outside of the detectable locating signal range, the 
display will show a solid circle inside of a dotted circle. At times it may 
show the dynamic directional arrow shown in Display 2 and/or the image 
in Display 4 below. The images may flash alternately indicating that the 
receiver is out of detectable locating signal range. See following example;
Display 2. When the receiver is within the detectable locating signal on the target, a 
steady target line will appear on the receiver display representing the target. 
The dynamic directional display arrows will guide the operator towards the 
target. The receiver volume and the signal strength increase as the target is 
approached. See following examples;
Left of Target Path
Right of Target Path 
						

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Display 3. As the receiver antenna crosses the target, the receiver volume increases to 
a maximum, the signal strength will be at its maximum and the directional 
arrow will become a straight line that is closely lined up with the target line 
on the display. See following examples;
On Target Path
Display 4. A circle consisting of two arrows appears when the orientation of the receiver 
is not at the optimum position in relation to the target. The arrows indicate 
that the receiver should be twisted to obtain the optimum position. See 
following examples;
Twist Receiver
B. Special Peak (Spl Pk)
TRACE [2] + Mode [SK] + Spl Pk [SK Toggle] or 
Menu/OK [5] + Cable/Pipe [SK] + Mode [SK] + Spl Pk [SK Toggle]
Special Peak mode turns on only the peak antenna closest to the ground. Special Peak 
Mode is used in applications such as very deep cables or pipes, or when the signal is too 
weak for Directional Peak (Dir Pk) or Trace View (T-View) mode tracing.
Left or Right of Target PathDirectly Over Target Path
C. Induction Peak (Ind Pk)
TRACE [2] + Mode [SK] + Ind Pk [SK Toggle] 
or Menu/OK [5] + Cable/Pipe [SK] + Mode [SK] + Ind Pk [SK Toggle]
If you cannot make a direct connection, or use the 3M
™ Dyna-Coupler clamp to apply 
a locating signal on the target, use the induction method. This method uses the internal 
coil of the transmitter to generate a magnetic field. 
						

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The Induction Peak mode of the receiver is a mode in which the upper antenna of the 
receiver is tuned to minimize distortion from the magnetic field of the transmitter.
Left or Right of Target PathDirectly Over Target Path
D. Directional Peak (Dir Pk)
TRACE [2] + Mode [SK] + Dir Pk [SK Toggle] 
or Menu/OK [5] + Cable/Pipe [SK] + Mode [SK] + Dir Pk [SK Toggle]
In Directional Peak mode, four peak antennas are used to analyze the magnetic field 
pattern. The bar graph indicates signal strength and the directional arrows sense the 
edges of the magnetic field. The left/right arrows will indicate the direction to the nearest 
cable/pipe that is in-line with the receiver handle.
As the antenna crosses the cable or pipe, the receiver speaker volume increases to a 
maximum, the Bar Graph [1l] ([10] for 2550 locator) fills from both sides toward the 
middle, and the numeric  Signal Strength [9] ([8] for 2550 locator) increases. As the 
antenna moves off the target path, the speaker volume decreases and the Bar Graph [1l] 
([10] for 2550 locator) opens. Use the Bar Graph [1l] ([10] for 2550 locator) and the 
numeric  Signal Strength [9] ([8] for 2550 locator) to locate the exact target path.
Left of Target PathDirectly Over Target PathRight of Target Path
Once the target path has been located, the arrows at the top of the display will indicate 
the location of the target path in relationship to the receiver handle.
Note: When field distortion (due to congestion) is affecting the receiver, the left/right 
arrows may not coincide with the bar graph. Use the maximum numerical Signal 
Strength [9] ([8] for 2550 locator) to target the cable or pipe.