Installation - ADC HiGain HLU-200 User Manual

150-200-114-03, Issue 03
However it does allow both down and upstream equipment to be made aware of the loss of one HDSL loop or a
loop with low margin. This is the preferred setting to be able to initiate an AIS state with just one conductor
open in either of the HDSL pairs. Short loops, below about 16 dB of loss at 196 kHz, can remain in sync with
one conductor open. Since the loop is still in sync, no LOSW condition occurs. However, the margin on a one
conductor loop drops from 5 dB to 10 dB. Thus if the Margin alarm is set 5 dB below the normal margin at
turn-up, when one conductor does open, a minor alarm occurs and causes the AIS condition. This alerts the
maintenance personnel of the problem. The 2LP choice requires both HDSL loops to be out of sync (LOSW)
before the AIS signal is transmitted. This choice preserves the integrity of the 12 surviving channels when just
one loop is lost.
The symmetry of the HDSL line powering voltage can be set by the S1 switch, located on the printed circuit
board, as shown in Figure 5.
The factory default setting is UNI (-). It sets the HDSL line voltage to 0V on loop 2 and to either
-30V (for non-doubler circuits) or -200V (for doubler circuits) on loop 1. This setting keeps the HDSL cable
pair voltages at or below ground potential, thereby avoiding corrosion problems caused by cable voltages more
positive than ground.
The bipolar selection BIP ( ± ) sets the HDSL line voltage to +65V (+100V for doubler circuits) on loop 2 and -
65V (-100V for doubler circuits) on loop 1. This setting reduces the maximum ground referenced voltage, but
applies positive voltage to loop 2, which could accelerate corrosion.
The line voltage power supply, used for both options, is ground referenced, but also ground isolated by 200k
ohms. 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 S1's
setting.
ICP
socket
Figure 5. HDSL Line Voltage Switch S1 and ICP Socket locations.

Installation

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 ADC.
The HLU-200 List 1D mounts in a Litespan-2000 channel bank. The HLU-200 List 1D slot pinouts are shown
in Figure 6.
20 November 22, 1996 HLU-200 List 1D