Allied Telesis AT-SBx31CFC960 - Manual (Page 26)

Chapter 1: Overview of the Chassis and Power Supplies
26
Note
The AT-SBxPWRSYS1 DC Power Supply is not compatible with the
AT-SBxPWRSYS1 AC or AT-SBxPWRPOE1 AC Power Supply.
You should not operate the chassis with both AC and DC power
supplies. You may, however, operate the chassis for a short period
of time with AC and DC power supplies if you are converting it from
one type of power supply to another, such as from AC to DC. This
allows you to transition the chassis without having to power it off.