9 Capacitance measurement (C)
ARGUS Copper Box
49
9.1 Calculating line length
Every telecommunication cable has a certain loop resistance and operating capacitance
per unit of length. As the type of cable laid is generally known, this value too is known. The
values are design-related and relatively constant, as the cables are laid in the earth and
subject to relatively minor temperature and humidity effects. However, a typical subscriber
line can consist of multiple segments. In these segments, the wire cross-sections, and thus
the technical specifications, can vary.
This can only be determined for a measurement between the Tip- and Ring-wires. The
measurements with respect to Ground can be subject to random influences and thus can-
not be specified with a general capacitance or resistance value per unit of length. The line
length calculations can then be compared with the line length, which is generally also
known, thus providing information about faults. Using the calculated value, you can roughly
compare the line lengths and conduct further fault-finding (e.g. with a TDR) in the event of
discrepancies.
A wire type must be selected to enable calculation of the line length using a C or R
measurement. See page 30 for these and further settings.
The wire type can be selected and configured during or after the measurement.
Starting capacitance measurement.
ARGUS in the status display.
In this example, capacitance measure-
ment is carried out with a measuring
frequency of 8 Hz and the values stored
for wire type 1.
It is important to select a cable type (see
page 31), the default is „No cable type“.
<Menu>
Opens the Copper Box
<Start>
Starts capacitance
measurement.
