Fluke 990DSL, Руководство пользователя

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TDR Testing and Fault Location
TDR Test Operating Tips
6
6-19
3. Multiply each of the two distances by the CF to get the corrected distance
(CD) to the fault from both ends:
CD1= CF x D1 and CD2 = CF x D2
Example: Known section length L =1200 feet
TDR Measurement D1 = 400 feet
TDR Measurement D2 = 600 feet
CF = 1200 / (400 + 600) = 1.20
CD1 = 1.2 x 400 = 480 feet
CD2 = 1.2 x 600 = 720 feet
Section Length = CD1 + CD2 = 1200 feet (sanity check)
Testing for Faults Close to the CopperPro
Reflections that occur before the launch pulse has been completed (due to
faults that are very near the CopperPro connection) can be distorted or even
completely masked by the launch pulse itself. In these cases, to get a clearer
picture of the reflection, attach a
known length of jumper wire (of the same
type and gauge as in the cable, if possible) to the CopperPro test leads to
compensate for the pulse’s width. An extension of about 10 to 15 feet in length
should cover
all applications, using the CopperPro’s shortest pulse-width.