Specifications

Power Supply Unit Load Requirements
Unit Load Calculation Rules
Installed
Mode Modules
Calculation
Hybrid/ 6*
Not required
PBX
and
Modified
Key/
Behind
Switch
Square
4 or fewer
†
Not required
Key/
and
Behind
Switch
* The 391A1 power supply unit generally supports 6 modules of
any type in Hybrid/PBX mode. However, if all 6 carrier slots
have the following conditions, the unit load (UL) total may
exceed 54 and auxiliary power may be required.
■ Only MLX or analog multiline station modules are installed.
■ More than 45 MLX-20L or 34-button analog multiline stations
are installed.
† The 391A1 power supply unit generally supports 4 modules of
any type in Square Key mode.
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