Operation; Principles Of Operation; Accuracy And Velocity Of Propagation (Vp); Getting Started - Chauvin Arnoux CA 7026 Manual De Instrucciones

4. OPERATION

4.1

Principles of Operation

The Fault Mapper Pro™ works by measuring the time taken for a signal to travel to the far
end of the cable under test, or to an intermediate fault, and return. The velocity at which the
signal travels Vp (Velocity of Propagation) will depend on the characteristics of the cable.
Based on the selected Vp and the measured travel time of the test pulse, the Fault Mapper
Pro™ calculates and displays impedance anomalies and their distances along the cable.
4.2

Accuracy and Velocity of Propagation (Vp)

The Fault Mapper Pro™ measures distances to faults and cable lengths to an accuracy of
±1%. This measurement accuracy is based upon the correct value of Vp being used for the
cable under test, and homogeneity of the Vp along the cable length.
If the Vp is set incorrectly by the operator, or the Vp varies along the length of the cable, then
additional errors will be incurred and the measurement accuracy will be affected.
See § 4.7 for setting the Vp.
NOTE: The Vp is less well defined with unshielded multi-conductor cable, including power
cable, and is lower when a cable is tightly wound on a drum than when it is installed in a
linear fashion.
Correct measurement of fault distances is also dependent on the cursor being positioned
accurately by the operator. When locating faults with the Fault Mapper Pro™ the cursor
should be positioned at the beginning of the feature on the cable waveform as shown
below.
Vp=72% Z=100W
621ft
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4.3

Getting Started

The instrument is switched on and off using the green power button
right side of the front panel. When the unit is first switched on it will display the opening
screen giving the software version, the currently selected Vp (Velocity of Propagation),
cable impedance and battery status indicator.
CHAUVIN ARNOUX
Fault Mapper Pro V1.0
Vp=70% Z=100W
4.4

Set-up Mode

Hold down the TDR/ button, then press the TEST/
> Vp=72%
Z=100Ω
Feet
Contrast
• Vp can be set in the range 1% to 99% (see § 4.8)
• Z, the cable impedance, can be set to 50, 75 or 100W
• Measurement units can be set to Feet or Meters
• The display contrast can adjusted
Press the TEST/ button to move the line selector (>) down the screen.
Press the Vp and Vp buttons to change the setting of the line selected.
Press the TDR/ button again to save changes and exit set-up mode.
When the Fault Mapper is turned off, it will remember the current set-up
parameters.
This feature is useful in the situation where the operator is performing many
tests on the same type of cable.
I
, found on the lower
button to enter set-up mode.
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