Issue 1, Section 150-231-164
Revision 04
Page 11
B. APPLICATIONS WITHOUT USING HIGAIN
DOUBLER HDU-451
1. GENERAL
1.04
This section addresses HLU-231 List 6D
operation when used without doublers. For
applications without Doublers, the HLU-23 1List 6D is
directly connected to the HRU-412 by the two cable
pairs.
2. POWER CONSUMPTION
2.01
The three most important power demands of an
HLU-231 List 6D on the shelf power supply are
its maximum power consumption, its maximum power
dissipation and its maximum current drain. These three
parameters for the HLU-231 List 6D, on a per slot and
per shelf basis, are as follows:
Maximum Power Dissipation:
•
Per Slot = 8.0 Watts
•
Per Shelf = 104 Watts
Maximum Power Consumption:
•
Per Slot = 18 Watts
•
Per Shelf = 234 Watts
Maximum Current Drain:
•
Per Slot = 0.423 Amps
•
Per Shelf = 5.5 Amps
Note that the worst case conditions under which these
parameters were measured include a 9,000 ft., AWG 26
loop, 60 mA of Customer Premier Equipment (CPE)
current, a fully loaded 13 slot shelf, and a -42.5 V shelf
battery voltage with HLU-231, 4-character display
“OFF”.
2.02
The Maximum Power Dissipation measures the
power that is converted into heat build up within
the unit. It contributes to the total heat generated in the
space around the unit. It is used to determine the
maximum number of fully loaded shelves per bay that
does not exceed the maximum allowable power
dissipation density in Watts/sq. ft.
2.03
In Central Office locations, the maximum power
dissipation for open faced, natural convection
cooled mountings is limited to 120 Watts/sq. ft. per
Section 4.2.3 of the NEBS standard TR-NWT-000063.
The footprint of a standard 13 slot 23” HLU-231 List 6D
shelf is 7.024 sq. ft. Thus the maximum bay dissipation
is limited to 840 Watts. At 104 Watts per shelf, this
limits the number of fully loaded HLU-231 List 6D
shelves to 8 per bay. Note that this is a worst case
situation in that it assumes the entire Central Office is
subjected to the maximum power density. Conditions
other than these worst case ones would permit
increasing the number of shelves per bay without
jeopardizing the CO thermal integrity.
2.04
The thermal loading limitations imposed when
using the HLU-231 List 6D in Controlled
Environmental Vault (CEV) or other enclosures are
determined by applying the HLU-231 List 6D's power
parameters to the manufacturer's requirements for each
specific housing.
2.05
The Maximum Power Consumption is the total
power that the HLU-231 List 6D consumes or
draws from its -48 V shelf power source. This
parameter is needed when the 231 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 line units remote enclosure. Use
the above data to perform this analysis on a case by
case basis.
2.06
The Maximum Current Drain is the maximum
current drawn from the shelf power supply when
it is at its minimum voltage (-42.5 V). This determines
the shelf fusing requirements. HLU-231 List 6D shelves
are fused at 10 A. A fully loaded shelf of 13 HLU-231s
draws 5.5 A in the worst case. This is well within the 10
A fuse limit.
3. LOOPBACK OPERATION
3.01
The HiGain system has a family of loopback
options. The most important of these is the
“Smart-Jack” loopback which enables the HRU-412 to
respond to the standard (2/3 in 5) Smart-Jack in-band
loopback codes and thus emulate the functions of a
standard Network Interface Device (NID). This option
can be enabled or disabled from either the front panel
buttons or the terminal SYSTEM SETTINGS MENU.
3.02
In addition to the Smart-Jack loopback, the
HiGain system can be configured for one of five
special in-band loopback (“SPLB”) command
sequences. These are selected from the SPLB user
option shown in Table 1 and Figure 10 (non-Doubler
applications). The non-Doubler loopback locations are
shown in Figure 5.
3.03
“GNLB” is the HiGain system Generic loopback
code. The GNLB allows in-band codes to loop-
up either the HLU/NLOC (4 in 7) or HRU/NREM (3 in 7)
towards the network. In addition, it allows in-band codes
to loop-up the HLU/CREM (6 in 7) or HRU/CLOC (5 in 7)
