Appendix A - Technical Reference
150-712-200-02
20
July 26, 2000
HRE-712 List 1 and List 2
L
IGHTNING
P
ROTECTION
U
NIT
The Lightning Protection Unit (LPU), shown in Figure 8, is a printed circuit board assembly that attaches to the
card-edge connector of each slot. The LPU is used primarily for protecting the HDSL loops from lightning
activity. All HRE-712 enclosures come equipped with 12 LPUs.
Each LPU contains four gas tubes that provide surge protection to each of the slots’ four ports. The tubes have
three leads that provide protection from Tip and Ring to ground. The ground pin is connected to pin 1 of each slot.
The gas tube parameters are equivalent to a TII 47 BT. The DC breakdown ranges from 300 to 500 volts. The tube
can withstand at least 400, 10/1000, 500 amp discharges. Although the individual gas tubes are field replaceable
components, ADC recommends replacing the entire LPU when any of its protector tubes are suspected of
functioning improperly. See
“Appendix B - Specifications” on page 38
for details on replacing
an LPU.
Figure 8.
Lightning Protection Unit
Gas tube
HDSL Loop 1 Out
(Side 1 Out)
Pin 1 (ground)
Gas tube
HDSL Loop 1 In
(Side 1 In)
Gas tube
HDSL Loop 2 Out
(Side 2 In)
Gas tube
HDSL Loop 2 In
(Side 2 Out)
