Hdsl Line Voltage Option; Network Management; Installation - PairGain HIGAIN HLU-231 Manual
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Revision 02
6. HDSL LINE VOLTAGE OPTION
6.1
The symmetry of the HDSL line powering voltage can be set by the S2 switch, located on the printed
circuit board, as shown in Figure 5.
6.2
The factory default setting is Unipolar (-). It sets the HDSL line voltage to 0 V on loop 2 and to
either -130 V (for non-doubler applications) or -200 V (for doubler applications) on loop 1. This
setting keeps the HDSL cable pair voltage at or below ground potential, thereby avoiding corrosion
problems caused by cable voltages more positive than ground.
6.3
The bipolar selection sets the HDSL line voltage to +65 V on loop 2 and -65 V on loop 1, for non-
doubler applications. Doubler applications will have +100 V on loop 2 and -100 V on loop 1. This
setting reduces the maximum ground referenced voltage to 100 V, but applies positive voltage to the
cable pairs, which could accelerate corrosion on the cable pairs.
6.4
Setting the PWRF option to 200V forces the HDSL line voltage to the higher -200V (Unipolar) or
±100V (Bipolar) for all operating conditions.
6.5
The line voltage power supply, used for both options, is ground referenced, but also ground isolated
by 200 kohms. This ground isolation reduces problems due to induced noise currents and large surge
voltages, which are ground referenced. It also reduces ground fault currents, which improves the
product's safety. The safety issue thus depends solely on the differential voltage across loop 1 and
loop 2, and is independent of S2's setting.
7. NETWORK MANAGEMENT
7.1
The HLU-231, List 7B has a Network Management Control Bus available on pin 46. This allows the
7B to be managed by various PairGain Management System protocols through the HMU-319
common control card.
8. INSTALLATION
8.1
Upon receipt of the equipment, visually inspect it for signs of damage. If the equipment has been
damaged in transit, immediately report the extent of damage to the transportation company and to
PairGain Technologies.
8.2
The HLU-231 List 7B mounts in a 220-configuration Office Repeater Bay (ORB) shelf or equivalent
Small Cross Section Shelf (SXSS), Kentrox T-Term, Wescom 342-30 shelves, or PairGain HLS-410
(19") or HLS-419 (23"). The HLU-231 List 7B slot pin-outs are shown in Figure 4.
8.3
The ALM option must be disabled (DIS) when using the Kentrox 220 T-Term shelf. This is required
to resolve a conflict between the HLU alarm relay output and the Kentrox external equalizer output.
Both use the same pins, 20 and 21.
8.4
If the burn-in pin 23 is used in the user's shelf, R39, shown in Figure 5, must be removed to
disconnect the HLU's burn-in circuit from this backplane pin to avoid performance disruption.
HiGain Line Unit HLU-231
January 31, 1997
PairGain Engineering - Plant Series
Section 150-231-172
Page 15
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