technoac TDR-TA3.3T, Руководство пользователя

Страница: 18 / 25

Cable fault locator
TDR-TA3.3T
________________________________________________________________________
________________________________________________________________________
18
6.6 Measurement of the distance to the researched line irregularity
6.6.1 The distance to the researched line irregularity to be measured according to the
method in issue 5.4.
6.6.2 The type of irregularity of the researched line to be defined according to the Table 2
and issue 2 of a given User Manual.
6.7 The analysis of typical irregularities of the researched line
THE COMMENT to the pictures 6-1
– 6-4: the researched line is sketchily shown at
the top of the picture, a waveform of this line is shown at the bottom part of the picture.
6.7.1 Distance definition to sockets, joints and breaks
Picture 6-1 Sockets, joints, breaks
Reflection from irregularity that distinguishes the cables joint is expressed in a
positive polarity response. The quality of a cable splice should be evaluated by the
reflected response magnitude. The domain reflectometer allows the user to distinguish
several discrete irregularities. The cursor position 1 depicts the reflected pulse of positive
polarity that denotes the connection in a cable line. The connection in the cursor position 2
was done worse than the previous connection. The reflected pulse in the cursor position 3
denotes the break (end) of the cable line.
6.7.2 The determination of distance to short circuit between the cable cores
The reflection from irregularity characterizing the cable core short circuit is
expressed in the negative polarity response and is a special case of reduced insulation
resistance. The magnitude of reflected pulse is almost equivalent to the pulse reflected