Fluke 990DSL, Руководство пользователя

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990DSL
Users Guide
4-36
Each negative dip followed by a positive peak represents a single load
coil. The pair depicted in Figure 4-22 has six sets of these dip-and-peak
combinations, revealing the detected six loads. The farthest load is
represented on the extreme right side of the waveform, and will always
have a relatively smaller dip and peak.
Note
At times, small dips or peaks may be missed by the counter, yet be visually
seen in the graph. Also, the presence of an abnormally high amount of
metallic battery noise on working POTS lines may cause the counter to
register a high false number of loads, but the actual number may be
visually determined by looking at the graph.
b) Press
B
(
TDR
) to go directly to the TDR menu, which allows a more
accurate distance to the first coil to be measured.
c) Press
C
(
VF Long. Balance
) to check for possible mis-loading due to the
presence of half-loads.
d) If a “Resistive Fault” message appears, press
D
(
Shorts & Grounds
) to
measure the value of the fault.
Loop Devices Test
The Loop Devices test detects the presence of the following devices:
•
Loop treatment devices on working POTS pairs such as Loop Extenders
and Range Extenders with Gain (REGs).
•
Fault-sectionalizing devices, such as Maintenance Termination Units
(MTUs) and Network Interface Devices (NIDs).
•
Mechanical Bell Ringers (C4 and C5).
Setting Up a Loop Devices Test
The Loop Devices test has no test-specific setups.