Gossen MetraWatt M281A, Operating Instructions Manual

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METRACABLE TDR PRO
Gossen Metrawatt GmbH
5 Measurements
The METRACABLE TDR PRO is connected to the voltage-free cable to be measured. It per-
forms a TDR measurement (time domain reflectometry) whose results appear at the display
as a TDR trace.
The instrument transmits an electrical pulse during measurement. Cable length can be cal-
culated based on the amount of time it takes for the pulse signal to return to the instrument
(reflection). The shape of the reflection provides information concerning:
• Any included components (e.g. a splitter)
• The wiring itself (e.g. splices, branches etc.)
• Cable faults (short-circuits, broken cable, pinching etc.)
The locations of these items are also calculated – accurate to approximately 0.3 m – based
on the time it takes for the signal to return to the instrument.
Cables with lengths of up to 14 km can be examined with the METRACABLE TDR PRO.
Proceed as follows:
1. Prepare for measurement
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12.
2. Perform the measurement.
– TDR Measurement
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13
– Measuring Coaxial Cables
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15
3. Optional: Evaluate any detected cable faults
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16.
4. Optional: Transfer your measurements to METRACABLE MANAGER PC software for
detailed viewing and evaluation

“METRACABLE MANAGER”
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18.
5.1 Preparation
1. The cable’s velocity factor (VF value) must be known in order to perform measurements.
The material-dependent velocity of propagation of the signal within the cable is taken into
consideration by means of the VF value. It must be selected individually for each respec-
tive cable so that distance can be calculated correctly.
The instrument includes a cable database which can accommodate up to 32 entries (all
of which are completed upon shipment). You can select an appropriate cable type from
the database (including velocity factor). The cable database can be maintained in
METRACABLE MANAGER software, e.g. cable types can be edited (
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18).
As an alternative, the VF value can be specified manually. You can obtain the VF value
from the cable manufacturer or determine if yourself. Set the unit of measure to half of
the velocity factor V/2 (
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
9) to this end, perform a TDR measurement on an identical
cable with a known length and manually adjust the VF value until displayed cable length
coincides with the actual length of the reference cable. This value is the VF value for all
cables of identical design.
2. The METRACABLE TDR PRO includes a number of helpful additional functions. Familiar-
ize yourself with these functions before performing measurements
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“Additional Func-
tions”
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15.
3. Read the instructions concerning pinpointing and identifying faults
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16.