Radiodetection
PCM
Pipeline Current Mapper
PCM+
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Radiodetection
PCM
The PCM can….
• Find contacts with other structures
• Evaluate Pipe Coating for defects
• Perform periodic Pipeline surveys
• Find defective Insulation joints
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Radiodetection
PCM
What is different about PCM
• High output power Transmitter
• Low Frequency signal
• Current Direction of applied signal
• Data logging of current measurements
• A Frame pinpointing of coating holidays3
Radiodetection
PCM
Benefits of low frequency
t
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4
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Radiodetection
PCM
Benefits of low frequency
1
A
(
4
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)
1
A
(
1
K
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)
69600mmAA
4
0
m
A
4
0
0
m
A
9
0
0
m
A
2
0
0
m
A
40m6A0mA
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a
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Radiodetection
PCM
The Transmitter utilises..
• High output power (150W)
• Very low frequency
• This helps to….
increase range
reduce coupling to other
services
reduce field distortion
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Radiodetection
PCM
The Transmitter
• Can be powered
from…
110/240Vac
The D.C output of a
rectifier (20 to 50vD.C)
External Automotive
batteries (24v to 48V)
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Radiodetection
PCM
PCM Receiver provides..
• Pipe location and
depth
• Current measurement
of survey current
• Stores up to 999
readings for download
to a PC or PDA
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Radiodetection
PCM
Transmitter connection
• Typical rectifier
installation.
• Provides a perfect
pipe connection
point
• Anode provides
perfect ground
connection point
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Radiodetection
PCM
Transmitter Connection
• Disconnect the
rectifier output from
both pipe and
Anode
• Connect the PCM
transmitter in place
of the rectifier
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Radiodetection
PCM
Setting the Transmitter
• Three output settings
4Hz and 98Hz
4Hz, 8Hz and 98Hz
4Hz, 8Hz and 512Hz
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Radiodetection
PCM
Setting the Transmitter
• Set Current switch
to desired current
• The PCM
transmitter is a
constant current
source, this
ensures stable
survey readings.
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Radiodetection
PCM
Taking current reading
• Ensure both PCM
receiver is set to the
same frequency as
the Transmitter
• Pinpoint the pipe in
the peak Mode
100
%95
%
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Radiodetection
PCM
Taking Current Readings
• Hold the
Receiver Steady
on the ground,
press and hold
the PCM Key.
• Current is
displayed after
approximately 3
seconds
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Radiodetection
PCM
PCM current v Line Drops
L IN EA R
C
A MP S
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1
1
1
0
0
0
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0
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3
5
7
9
2
4
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LOC A TION
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Radiodetection
PCM
Current Direction
• This tells you in which direction the
Current is flowing
– Aids fault analysis
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Radiodetection
PCM
Datalogging
• 999 readings can be stored
• Stored readings can be
reviewed on PCM+ or
downloaded to PC
• Downloaded files are in text
format and can be displayed
using Excel or 123
speadsheets
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Radiodetection
PCM
Pinpointing Coating Defects
• For accurate
coating defect
location use the
A Frame
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Radiodetection
PCM
Finding Coating Defects
A
F
r
a
m
e
T
r
a
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s
m
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Radiodetection
PCM
Case Histories
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Radiodetection
PCM
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Radiodetection
PCM
Defects found by PCM
Cut away ready for repair
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Radiodetection
PCM
Close up view of cutaway
showing area of metal loss
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Radiodetection
PCM
Cables in contact with pipe
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Radiodetection
PCM
Sheet pile in contact with pipe
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Current Attenuation
Graph
Actual PCM Results
3 steps are different
looking in mA but
nearly identical in dB
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•
•
•
•
•
AC
Voltage
Gradient
Can be part of Current tools
Becoming very popular
Extreme sensitivity
Rejection of interference
Very accurate location of faults
– typically better then 6"
• Sometimes part of Current Attenuation equipment
• This method deserves to be considered as a solid
tool for integrity and the ECDA process.
ACVG in Operation
• Both signal
strength and
direction arrows
lead user to
holiday.
• Fault value is
proportional to
holiday size and
soil resistivity.
Pool of Potential
Is AC, but at any instant in time, there is a direction.
ACVG Receiver Theory
ACVG Tuning
• Older systems used a simple DMM
– Does not tune to any one frequency
– 60 Hz, cable earth faults, telecom noise
Rx’d
• Very tight tuning in the signal generator
and receiver effectively increases
sensitivity as it ignores current from
other sources
– SNR improves
• In this case the next fault was quite close (20-30m) which is
why the left side of graph climbs quickly.
• Other cases may show 100s of meters of signal at 30 and
under..
Dig Pictures