Unit Loads - AT&T MERLIN LEGEND Installation & Maintenance Manual

Preparation

Unit Loads

A unit load is a measure of power used to determine the
electrical load on the power supply module caused by
telephones, adjuncts, and DID modules. One unit load equals
1.9 watts.
Unit load and auxiliary power requirements for a new system are
computed automatically by the AT&T DOSS Configurator, and
any necessary auxiliary power equipment is automatically
ordered. However, in the event of maintenance or equipment
changes, you must calculate unit loads yourself to ensure proper
operation under all conditions (see Appendix D for a unit load
worksheet complete with specific unit load values).
The power supply module provides 54 unit loads to each carrier.
If the unit load requirement for a carrier exceeds 54, an auxiliary
power unit is needed to allow that carrier to support an additional
27 unit loads.
Note: Running the system with more than 54 unit loads per
carrier may not appear to do harm. However, this can cause the
system to malfunction, creating "no trouble found" situations.
An auxiliary power unit redirects the power requirements from
the last two slots on the carrier. Any station connected to the
modules in the last two slots receives power from the auxiliary
power unit instead of the power supply module.
Besides DID trunks, only telephones and adjuncts that connect
to analog and digital ports on the CU require unit load
calculations. Any equipment with its own power supply (for
example, an answering machine) does not have to be included
in the unit load calculation.
Unit Loads 2-15