150-504-100-03
Appendix A - Technical Reference
HRE-504 List 1, List 1B, and List 2
August 1, 2002
25
Lightning Protection Unit
The Lightning Protection Unit (LPU), shown in
, is a printed circuit board assembly that attaches to the
card edge connector of each slot and provides primarily lightning protection for the HDSL loops and customer T1
circuits.
All HRE-504 units come equipped with four LPUs. Each LPU contains four gas tubes that provide surge
protection to the four ports in each slot. 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. These slots are connected to the enclosure ground plane.
The gas tube parameters are equivalent to a TII 47 BT. The Vdc breakdown ranges from 300 to 500 volts. The
tube can withstand at least 400 repetitions at 10/1000 rise-time, with 500 amp discharges. Amp discharges are
quantities that occur before system degradation.
Although the individual gas tubes are field-replaceable components, replace the entire LPU when any of its
protector tubes are functioning improperly. See
“Replacement Parts” on page 37
for details on replacing an LPU.
Figure 12.
Lightning Protection Unit
Cable Stub and Pressurization
Every HRE-504 is equipped with a single-screened cable stub.
provides a complete description
of the cable stub. The stub is available as a gel- or air-filled unit. It is secured to the enclosure baseplate by a cable
strain relief adapter. The cable pair is spliced and encapsulated in the polyurethane that is poured into the enclosure
base. This provides an airtight seal at the cable entry point.
The pressurized enclosure has an air-inlet tube that accompanies the air-filled stub. The tube connects the inside
of the enclosure to the main feeder cable which enables dry air or dry nitrogen to flow from the main cable to the
cable stub through the air cutoff valve. The air cutoff valve controls the dry air or nitrogen flow through the
air-inlet tube as described in
“Air-filled Stub Unit” on page 5
The maximum pressure for an air-filled enclosure is 12 PSI.
Summary of Contents for 150-2202-01
Page 4: ...Inspecting the Shipment 150 504 100 03 iv August 1 2002 HRE 504 List 1 List 1B and List 2...
Page 8: ...List of Tables 150 504 100 03 viii Augusr 1 2002 HRE 504 List 1 List 1B and List 2...
Page 53: ...Appendix D Abbreviations 150 504 100 03 46 August 1 2002 HRE 504 List 1 List 1B and List 2...
