Fluke Networks TS100 Mode D'emploi page 19

A: Not for any of the testing functions. However, when
you connect the tester to a cable, if you connect the red
lead first, an invalid reading may be displayed until the
full connection is made with both leads. The tester's
TDR technology requires both leads be connected to
the wire pair or cable in order to determine its length.
While using only one of the leads is useful in tracing
cable position with the injected tone, both leads are
required to make valid length measurements.
Q: What does the low battery indicator really indicate?
A: The LED comes on (flashes) when the battery
voltage falls below 4.1 volts, indicating that you should
replace the batteries. While the tester will continue to
operate for at least 1 hour below this voltage, some
readings may be less accurate.
Q: I tested an orange outdoor 25 foot (8 meter)
extension cord and the display read 19 feet (6 meters).
Is the tester broken?
A: No. The accuracy of the reading is dependent on the
setting of the VOP. While the nominal setting for
general testing is -66-, the VOP for that kind of cable is
-56-. To improve the accuracy of length measurements
for that or any cable, change the VOP as shown in the
instructions in the Velocity of Propagation section.
Q: Why does the length reading sometimes change a
small amount when I open and short the far end of a
test cable?
A: There are two causes. The first is that this is a
characteristic of the measurement technique used in
almost all low and medium cost cable length test tools.
In the case of the TS100 Cable Fault Finder, the variance
occurs in only a few cable types and both readings are
within the specified accuracy of the instrument. The
second cause occurs when the cable is coiled, as in a
box or on a spool. The magnetic field caused by the
TDR signal itself couples across to other parts of the
cable and changes the characteristics of the reflections.
Frequently Asked Questions
Q: Why, on some cables, does the number displayed
jump between 2 or 3 different values?
A: As the TDR signal travels down a cable, it loses some
of its strength. At some point, the noise on the cable
has an amplitude similar to the reduced strength TDR
signal and will influence the measurement results. The
tester's software filters out many of the noise related
variations in the displayed length, but some variations
do get through.
Q: I accidentally cracked the plastic housing, does this
affect the moisture protection of the components?
A: Not at all. The component protection is provided by
a coating on the components and Printed Circuit Board
(PCB).
However, if sufficient plastic is missing then a possible
shock hazard exists. You should not use the tester until
the plastic is repaired or replaced.
Q: Can this tester measure the length of single
conductor wires like THHN?
A: No. All TS100 measurements must be made on TWO
conductors from the SAME END of a cable.
Q: If I touch the bare metal of the wires or clip leads,
will the measurement be affected?
A: After BOTH clips are connected, measurement
results will ordinarily not be affected if inappropriate
human contact is made with the input connectors.
Under moist conditions, if a large surface area of cable
is in contact with moist skin, some readings may be
affected.
Q: On multi-conductor cables with a short between
two of the conductors, I sometimes read an "open" at
twice the known length of the cable.
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