User’s manual
Theory
Time domain reflectometers (TDR) are electronic instruments used for locating faults
in transmission lines.
A
short electrical pulse
is sent over
the line, and then a reflected pulse is
observed. By knowing the delay between
two pulses, the speed of light and the
cable velocity factor, the
DTF
(distance-
to-fault) is calculated. The amplitude and
the shape of the reflected pulse give the
operator idea about the nature of the
fault.
Instead of a shor t pulse, a “
step
” function
may be sent over the cable.
32
Annex 5
TDR mode
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