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Maintenance
Margin Alarm Threshold
To set the Margin Alarm Threshold:
1
Select
from the System Settings Main Menu screen.
G
2
Enter the desired minimum acceptable alarm threshold from the 0 to 15 dB range. This causes a system alarm
to occur if either the margin on HDSL Loop 1 (MAL1) or Loop 2 (MAL2) drops below the selected
threshold value.
Since the margin can never drop below 0, choosing
margin alarm off.
HDSL Line Voltage Options
The HDSL Line power feed PWRF option has four settings, DISABLED, LOW, AUTO and HIGH, as described
below.
•
DISABLED disables any voltage from being applied to the HDSL cable pairs. It is useful to prevent craft
personnel from being exposed to the HDSL line voltage when they are working on the cable pairs.
•
LOW limits the HDSL simplex voltage to -140 V maximum. This is the standard voltage used in all
non-doubler applications and has no effects in these applications. It can be chosen to limit line-powered,
single-doubler circuits or locally-powered, two-doubler circuits up to 140 V, if the appropriate HiGain plugs
(EDU-409) are used along with the ELU-319 List 5E. These HiGain units are the only ones that have
sufficiently low power consumption to allow their doubler circuits to be line-powered from 140 V.
•
AUTO is the conventional mode in which the ELU automatically maintains the HDSL-like voltage at 140 V
maximum for non-doubler applications and ± 112 V for doubler applications.
•
HIGH forces the HDSL line voltage to its high ± 112 V level for applications. It is needed to allow the ELU
to power circuits that are providing power to remote Personal Communication Systems (PCS) sites.
G
F
ROUND
AULT
The ELU-319 List 5E and List 6E has a Ground Fault Detect (GFD) circuit which detects a ground or a resistive
path to ground on any wire of any loop of any span with a non-zero voltage. For low (140 V) applications, such a
circuit is active during start-up by applying the bipolar voltage to the loops. It deactivates when going to the
nominal operation mode of unipolar negative voltage (0 V and -140 V). The circuit is constantly active during
high ( ±112 V) applications.
When the circuit is active, the system is compliant with Class A2 requirements of GR-1089. When the circuit is
not active, the system is compliant with Class A3 requirements of GR-1089.
Whenever the GFD circuit detects a grounded loop, the line power is immediately removed from the spans and a
PWR FEED GND alarm is generated and displayed. The power is reapplied 30 seconds later as part of a new
start-up procedure. If the ground condition persists on the span, the power is removed when the GFD circuit
detects this condition.
The indication of the location of the ground fault can be obtained by monitoring the voltages on the spans on the
ELU side as it sequentially powers devices in subsequent spans.
28
D
ETECT
January 26, 2000
for the margin threshold turns the
0
ELU-319 List 5E and List 6E
150-319-205-05, Issue 5
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