Unit Loads - AT&T MERLIN LEGEND Release 3.0 Installation Manual

Unit Loads

Unit Loads
A unit load is a measure of power (1.9 watts) that you use to determine the
electrical load that the components listed below place on the control unit's
power supply.
Telephones and adjuncts
800 DID modules
Only the telephones and adjuncts that connect to the
extension jacks (ports) on the control unit require unil
calculating unit load, do not include any equipment with its own power supply.
Checking Unit Loads
In the event of maintenance or equipment changes, recalculate the unit loads
for each carrier where there is a new configuration. Use the worksheet in
Appendix B, "Unit Load Calculation Worksheet."
As a general rule, if you can distribute the 800 DID modules and telephone
modules equally across the carriers, you prevent unnecessary drain on any
one carrier. However, the rule varies depending on the system's mode. The
next two sections provide the rules for calculating unit loads in various modes.
Unit Loads for Hybrid/PBX Mode
The power supply (model 391A1) generally supports six modules of any type
in Hybrid/PBX mode, without requiring an auxiliary power unit. If the following
conditions are true, however, the unit loads on a carrier can exceed the
54-unit maximum and, therefore, require auxiliary power:
All six carrier slots are occupied by MLX telephone or analog multiline
telephone modules.
The carrier has a total of more than 45 MLX-20L telephones or
34-button analog multiline telephones installed.
2-16 Installing the Control Unit
analog and digital
load calculation, When