Fault Location Mode
22
Data Points
Increasing the number of data points increases the measurable distance (401
points results in twice the distance of 201 points, and 801 points results in four
times the distance of 201 points). When changing the number of data points
measured, the software automatically recomputes the new maximum
measurable distance. If a maximum distance is entered manually, be sure to
select the data points before entering the max distance. Changing data points
does not turn calibration off.
Note:
Changing data points does not turn calibration off.
Frequency Span
The larger the frequency span, the shorter the measurable distance. Narrowing
the frequency span increases the measurable distance.
Velocity of Propagation
The velocity of propagation (Vp) is a characteristic of the cable and is expressed
as a percentage. Consult the cable manufacturer's specifications to get the
velocity of propagation value for the cable being used.
Calculating the Frequency Span
T
1
F
--------
N
1
–
F
max
F
min
–
-------------------------------
=
=
DTF
max
C V
p
T
2
----------------------------
C V
p
N
1
–
2
F
max
F
min
–
-------------------------------------------
=
=
Note:
N = Test points
F
min
= Start frequency
F
max
= End frequency
This max distance value can be recalculated as the max distance
for the DTF test.
Note:
C = Speed of light
Vp = Velocity of Propagation (cable)
Example -
For a cable with a dielectric constant of 1, the velocity
percentage is 100% and 201 data points are chosen, then the Site-
Hawk Analyzer should be set to a frequency span of 0.1 MHz
(85MHz to 85.1MHz). The maximum distance of fault will be
299,792.458 meters.
