Section 150-232-100
Revision 01
Page 22
B. APPLICATIONS WITHOUT USING HIGAIN DOUBLERS
1. GENERAL
1.01
This section addresses HLU-232 List 1D operation when used without doublers. For applications without
Doublers, the HLU-232 List 1D is directly connected to the HRU-412 by the two HDSL cable pairs.
2. POWER
CONSUMPTION
2.01 The three most important power demands of an HLU-232 List 1D 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-232 List 1D, on a per slot and per shelf basis (assuming 12 HLU-232’s per shelf), are as follows:
Maximum Power Dissipation:
•
Per Slot = 7.0 Watts
•
Per Shelf = 84 Watts
Maximum Power Consumption:
•
Per Slot = 18 Watts
•
Per Shelf = 216 Watts
Maximum Current Drain:
•
Per Slot = 0.4 Amps
•
Per Shelf = 4.8 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 Premise Equipment (CPE) current, a fully loaded 13 slot shelf, and a -42.5 V shelf battery
voltage with HLU-232 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 (CO) 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-232 List 1D shelf is 7.024 sq. ft. Thus the maximum bay dissipation is limited to 840
Watts. At 84 Watts per shelf, this limits the number of fully loaded HLU-232 List 1D shelves to 9 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-232 List 1D in Controlled Environment Vault
(CEV) or other enclosures are determined by applying the HLU-232 List 1D'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-232 List 1D consumes or draws from its -
48 V shelf power source. This parameter is needed when the 232 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-232 List 1D shelves are fused at 10
A. A fully loaded shelf of 12 HLU-232s draws 4.8 A in the worst case. This is well within the 10 A fuse limit.
