Section 150-232-100
Revision 01
Page 49
C. APPLICATIONS USING HIGAIN DOUBLERS
1. GENERAL
1.01 One or two HDU-451, HDU-439, or HDU-437 Doublers may be used to extend the distance between the HLU-
232 Line Unit and the HRU-412 Remote Unit. Note that older List 1, 2, and 3 versions of the HDU-451 do not support
protection switching.
2. POWER
CONSUMPTION
2.01 The maximum current drain is the current drawn from the shelf power supply when it is at minimum voltage
(-42.5 VDC) under a worst case application. The worst case application for the HLU-232 List 1D occurs on a loop
with one HDU doubler, four 9000 ft, #26 AWG spans, and an HRU-412 that is providing 60 mA of CPE current.
Under these conditions the HLU-232 List 1D current drain from the -42.5 VDC battery is 0.80 A for the List 1 and 2,
and 0.58 A for the List 3 and 4 doublers. This CO current and other related power parameters for this doubler
application are listed in Table 14.
2.02 The maximum shelf current drain allowed is a function of the shelf -48 VDC fuse. Table 15 lists the doubler
shelf deployment guidelines, as a function of the shelf fuse, for the more popular Type 220 configuration shelves.
These guidelines limit the maximum fuse load to 85% of shelf rated capacity. Use Table 15 when selecting the
appropriate load fuses for the Building Distribution Fuse Bus (BDFB) when deploying the HiGain system equipment
in COs.
2.03 The maximum HLU-232 List 1D power dissipation is the power that is converted into heat within the unit. It
contributes to the total heat generated and is used to determine the maximum number of shelves per bay that do not
exceed the maximum power dissipation density in Watts/sq. ft.
2.04 In CO locations, the maximum power dissipation for open faced, natural convection cooled mountings is 120
Watts/sq. ft. as stated in NEBS standard TR-NWT-000063 section 4.2.3. The footprint of a 13 slot 23” SXSS shelf
is 7.024 sq. ft. Thus the maximum allowable dissipation is 840 W. This limits the number of HLU-232 List 1D units
per bay to 80 when powering the List 1 or List 2 doubler, and to 93 when powering the List 3 or List 4 doubler. Note
that this is a worst case situation since it assumes the entire CO is subjected to the maximum power density. More
favorable conditions would permit increasing the number of shelves per bay without jeopardizing the CO thermal
integrity.
2.05 The thermal loading limitations imposed when using the HLU-232 List 1D in Controlled Environment Vaults
(CEV) or other enclosures are determined by applying the HLU-232 List 1D power parameters to the manufacturer
requirements for each specific housing.
2.06 The power consumption listed in Table 14 is the total power that the HLU-232 List 1D consumes or draws from
its -48 VDC shelf power source. This parameter is needed when the HLU-232 List 1D is located remote to its
serving CO. It determines the battery capacity required to maintain an 8-hour stand-by battery reserve for
emergency situations. It thus limits the maximum number of plugs per remote enclosure. Use this data to perform
this analysis on a case by case basis.
