Xtreme Power Conversion M90S Series User & Installation Manual page 19

M90S-4S User's Manual Uninterruptible Power Supply
2.11.2 Remove the UPS module
Warning:
Before removing any power module, make sure the remaining power modules can support the critical loads.
At least one power module MUST stay in the UPS cabinet in case the UPS system is operating in Maintenance Bypass Mode. (1.)
(1.) Use a screwdriver to remove the four screws from fixing holes.
(2.) Two people pull out together and remove the UPS module from its slot.
2.11.3 Battery Module Installation/Removal
Please follow power module installation/removal steps to install and remove battery packs.
NOTE: Battery modules can be installed in any slot.
Xtreme Power Conversion Corporation Page 19