363-206-305
Shelf Descriptions and Configurations
Issue 3 June 2000
3-15
Lightning and Surge Secondary Protection
Assembly for T1 Extensions and HDSL
3
T1EXT/HDSL Digital lines in the outside plant environments may be exposed to
high voltages due to lightning surges and power crosses due to fallen power lines.
In order to protect a DDM-2000 shelf with T1EXT/HDSL circuit packs from such
occurrences, an external assembly that houses a secondary surge protection is
required.
The lightning and surge protection assembly, shown in Figure 3-15, is
approximately 17.5 inches wide, 3.45 inches high, and 5.65 inches deep and can
be installed in 23-inch racks. It can be equipped with one or two small backplanes.
Each backplane has seven edge connectors and can support up to seven T1
extension channels. The two backplanes together have enough capacity to
support 14 T1 extension or 6 HDSL extension channels in a FiberReach shelf (the
maximum capacity). A small circuit board with fuses, current limiting resistors, and
thermal cutoff devices for both the tip and ring conductors is installed in the edge
connector whenever the DDM-2000 FiberReach shelf is equipped with a T1EXT
circuit pack. The small circuit board provides for secondary surge and power cross
protection.
The lightning and surge protection assembly does not include any primary surge
protectors. The tip and ring conductors must have gas tubes (Lucent protector unit
4B3EW or equivalent) installed at the point of entry into a cabinet or building.
The lightning and surge protection assembly meets the requirements specified in
Section 4 of the Telcordia Technologies GR-1089-CORE, Issue 1, November 94,
as well as
UL
1459.
Figure 3-15. T1 Lightning and Surge Protection Assembly
tpa 850282/01
17.86 *
4.082
3.352
* THE 17.86" DIMENSION DOES NOT INCLUDE FRAME MOUNTING FLANGES
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