Section 150-388-124
Revision 01
Page 36
C. APPLICATIONS USING HIGAIN DOUBLERS
(HDU-451)
17. DOUBLER DEPLOYMENT RULES
17.01
For doubler applications, one or two doublers may
be used in the HDSL loops between the HLU-388,
List 2D and the HRU-412. When using two doublers in a
HDSL loop, the HRU-412 must be locally powered. The
HLU-388, List 2D can be used with low power HDU-451,
List 3, and List 4 doubler units and the HDU-439/437
“mini”-doublers over the entire CSA range in all 3 spans.
17.02
Use of the HLU-388, List 2D with the higher
power HDU-451, List 1 or List 2 doubler is
restricted per the following deployment rules:
1. If Span 1’s loop resistance is known, then the
maximum loop resistance of Span 2 is the smaller
of either 800 ohms or the following calculated
value:
Maximum Span 2 Loop Resistance =
[2600 - 4 (Span 1 Loop Resistance)] ohms
For example, if Span 1 Loop Resistance = 550
ohms, then Span 2 Loop Resistance must be no
more than 400 ohms. If Span 1 Loop Resistance =
400 ohms, then Span 2 Loop Resistance must be
no more than 800 ohms.
2. If Span 2’s loop resistance is known, then the
maximum loop resistance of Span 1 is calculated
as follows:
Maximum Span 1 Loop Resistance =
[650 - (Span 2 Loop Resistance/4)] ohms
For example, if Span 2 Loop Resistance = 700
ohms, then Span 1 Loop Resistance must be no
more than 475 ohms.
Note:
The Span Resistance formulas in Rules 1 and 2
above illustrate that Span 1’s resistance has four
times the effect on the total circuit’s range than
does Span 2’s resistance. In other words, if Span 1
can be reduced by 50 ohms, Span 2 can be
increased by 200 ohms. So, always minimize the
length of Span 1.
3. Only HRU-412 units with list numbers greater than
5 can be used. Thus, while Lists 1, 2, 3, 3A, 4, and
5 can not be used, Lists 6, 7, 8 and greater can.
4. The HRU-412 CPE current option must be set to 0
mA. Its 60 mA CPE current switch must be set to
0 mA, or, its card edge pins must be strapped for 0
mA in the enclosure that provides these strapping
options.
5. In two-doubler applications, the first doubler (the
one nearest the HLU) can be a List 1 or List 2.
The second doubler, however, must be a List 3
unit.
18. POWER CONSUMPTION
18.01
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-388, List 2D occurs on
a loop with one HDU-451 doubler, four 9000-foot #26
AWG spans, and an HRU-412 that is providing 60 mA of
CPE current. Under these conditions, the HLU-388, List
2D current drain from the -42.5 Vdc battery is 0.6 A. CO
current and other related power parameters for various
doubler applications are listed in Table 11.
18.02
The maximum HLU-388, List 2D 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.
18.03
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 28-slot
HLU-388 shelf is 7.024 sq. ft. Thus, the maximum
allowable dissipation is 840 W, at 9 Watts maximum per
slot. This limits the number of HLU-388, List 2D units per
bay to 94.
18.04
The thermal loading limitations imposed when
using the HLU-388, List 2D in a Controlled
Environmental Vaults (CEV) or other enclosures are
determined by applying the HLU-388, List 2D power
parameters to the manufacturer requirements for each
specific housing.
