Unit Loads - AT&T MERLIN LEGEND Communications System Release 2.0 Maintenance And Troubleshooting Manual

Introduction to System Maintenance

Unit Loads

A unit load is a measure of power (1,9 watts) used to determine the electrical
load that the following components have on each carrier's power supply:
telephones and adjuncts
Only the telephones and adjuncts that connect to the analog and
digital ports on the control unit require unit load calculation. Do not
include any equipment with its own power supply (for example, an
answering machine) in the unit load calculation.
direct-inward dial (DID) modules
Checking Unit Loads
In the event of maintenance or equipment changes, recalculate the unit loads
for each carrier resulting in a different configuration.
Use the worksheet in Appendix B.
General Rule: If you can distribute the DID modules and telephone modules
equally across the carriers, you will prevent unnecessary drain on any one
carrier.
Also, depending on the system's mode, the rules vary. The next two sections
provide the rules for calculating unit loads in various modes.
Unit Loads for the Hybrid/PBX Mode
The power supply (model 391 Al) generally supports six modules of any type
in a Hybrid/PBX system.
However, if both of the following conditions are true, the unit loads on a carrier
can exceed the 54-unit maximum:
all six carrier slots are occupied by MLX telephone or analog multiline
telephone modules
the carrier has more than 45 telephones installed (MLX-20L telephones
and/or 34-button analog multiline telephones)
1-25
Unit Loads