Operating Instructions
Faults that are a long distance from the CT100 will show shallow reflections that are very long
because the length of cable attenuates the high frequencies necessary for precise fault
localization and characterization (Figure 11). Position the active cursor at the beginning of the
reflection where it first deviates from the straight line trace of the cable.
Faults with reactive components such as capacitance and inductance appear as either
transient dips or exponential curves above or below the characteristic impedance of the cable
depending on whether they are parallel with the conductor or represent a fault to ground.
Faults that are not opens and shorts may not appear at the end of the trace after pressing the
AUTOFIT
button, but can appear anywhere along its length.
Any fault is likely to reduce the pulse strength and change the pulse velocity. The accuracy of
distance measurement of a fault that appears beyond another fault is reduced.
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Mohr CT100 / CT100HF Operator's Manual
Figure 11: An open cable fault at 1000 ft demonstrates a long,
shallow reflected rise caused by cable attenuation of high
frequency components of the step pulse.
