Fluke TS53 PRO, Руководство пользователя, Страница: 32 / 38

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TS54TDR/TS53 PRO Test Sets
Users Guide
Frequently Asked Questions
Q: How do I calibrate the test set?
A: The test set does not need calibration.
Q: Why are length measurements sometimes incorrect?
A: The accuracy of the length measurement depends
on the VOP value. For accurate measurements, the VOP
must be correct for the cable that you measure. See
"VOP Variations" on page 27.
Q: Can this test set measure the length of single-
conductor wires such as THHN?
A: No. The test set measures the length of only cables
that have two conductors, and you must connect the
test leads to the conductors at the same end of the
cable.
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.
A: If the cable has more than two conductors, and a
short exists at the far end between one of the
conductors you are connected to and a conductor you
are not connected to, the displayed length will be the
sum of the lengths of the conductors joined by the
short.
Q: When testing a set of wires that go into a conduit, I
sometimes get a reading of 0 or 1. Why?
A: If there is more than a foot or so of wires that are
physically separated before they enter the close
confinement of the conduit, this will look to the test set
like an open at the start of the cable. Remember that
TS54 reports the FIRST failure that it finds. Try bringing
the two wires of the pair closer together for the path
from the TS54 to the entry to the conduit.
Q: How does the test set react to a speaker or a
transformer at the end of a cable?
A: A speaker or a transformer is a large coil of wire. This
usually causes the length reading to be larger than that
of the cable alone. A moderate power speaker adds
500 feet (150 meters) to the length reading. Some
combinations of speakers and transformers connected
to the cable can make the test set give incorrect results,
such as a length reading that is too long or too short.
Table 4. VOP Values for Other Cables
VOP Cable Type
68
Twisted Pair, Gel Filled 19 AWG
64
Twisted Pair, Gel Filled 22 AWG
62
Twisted Pair, Gel Filled 24 AWG
60
Twisted Pair, Gel Filled 26 AWG
68
Twisted Pair, Paper 22 AWG
66
Twisted Pair, Paper 24 AWG
65
Twisted Pair, Paper 26 AWG
72
Twisted Pair, PIC 19 AWG
67
Twisted Pair, PIC 22 AWG
66
Twisted Pair, PIC 24 AWG
64
Twisted Pair, PIC 26 AWG