Appendix B - Technical Reference
150-454-111-06
26
February 25, 2000
HRE-454
Figure 12.
HRE-454 with Cover Removed
Lightning Protection Unit (LPU)
The LPU, shown in
, is a printed circuit board assembly that attaches to the card-edge
connector of each slot and provides primary lightning protection for the HDSL loops and customer T1 circuits.
All HRE-454 units come equipped with four LPUs. Each LPU contains four gas tubes which provide the surge
protection to each of the four parts. These tubes also have three leads which 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.