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150-454-111-06
Although the individual gas tubes are field replaceable components, ADC recommends
replacing the entire LPU when any of its protector tubes are suspect. See
on page 57
The gas tube parameters are equivalent to a TTI 47 BT. The Vdc breakdown ranges from 300 to
500 volts. The tube can withstand at least 400, 10/1000, or 500 amp discharges. (Amp discharges
are quantities of discharges that occur before system degradation.)
Cable Stub and Pressurization
Every HRE-454 is equipped with a single-screened cable stub. Refer to
description of the cable stub. The stub is available as a gel- or air-filled unit. It is secured to the enclosure plate by
a cable strain relief adapter. The cable stub is spliced out 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
HRE-454
for details on replacing an LPU.
Figure 13. Lightning Protection Unit (LPU)
"Air-filled Stub Units" on page
February 25, 2000
Table 7 on page 33
5.
Appendix B - Technical Reference
"Replacement Parts"
for a complete
27
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