
Leaders in Pipelin
e Survey Systems
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SYSTEM MANUAL Version 6.03i
7
1. OUTLINE OF THE C-SCAN SYSTEM
The main elements of the C-SCAN Pipeline Coating Evaluation System are the Signal
Generator and the Detector Unit.
The Signal Generator is connected to the pipeline and to an appropriate ground point, and
generates a constant AC signal which passes along the pipeline, this in turn produces an
electromagnetic field which radiates from the pipeline.
The Detector Unit measures the strength of this electromagnetic field radiating from the
pipeline and uses it to determine the location and depth of the pipe, along with the residual
current remaining on the pipeline at the observation point. This data is stored in the
memory of the Detector Unit’s computer and is used to compute and store attenuation
rates between any two given observation points. The complete record of the survey (with
time, date & GPS positioning) may be downloaded and printed out at the end of the survey
to provide a permanent record.
1.1. Signal Generator
The C-SCAN Signal Generator is a self-contained unit producing a computer controlled AC
signal current with a frequency of 937.5 Hz.
Fig. 1.1 – Signal Generator
The output from the Signal Generator is a sine wave signal at a frequency of 937.5Hz, with
a nominal maximum voltage of 60V p-p (18V RMS). The maximum current obtainable is
1.5A (1500mA). The RMS value of the current being produced is displayed on the LCD on
the control panel, expressed in mA. The actual level of current produced is set by the
Surveyor using the instrument’s controls. Once set, this current level will be maintained at
a constant level (despite any transient changes in soil resistivity) until the batteries are
exhausted. In tests, the unit, when fully charged, has maintained a constant output of
600mA for up to 8 hours continuous operation when using the internal batteries. Use of an
external 12-18 volt supply can extend this time indefinitely.
Automatic
pressure relief
valve
Auxiliary Power
socket for charger
or external 12 volt
supply
PIPE connector -
connects
generator to
pipeline
GROUND
connector -
connects
generator to
suitable earth
Battery ISOLATOR switch
- used when storing or in
transit