Question
How do I insert a SmartSlot device in a Smart UPS or Matrix UPS?

Answer
Warning: If SmartSlot accessories are installed into the UPS without following these instructions, a risk exists that the UPS could suffer damage.

It is very important that the Smart UPS be completely off before inserting or removing any SmartSlot card.

Please carefully follow the directions below in order to prevent undesirable behavior of or damage to the UPS:

1. Ensure all loads powered by the UPS are properly shut down and turned off.
2. Shut down the UPS via the front panel by pressing the button labeled “0”.
3. Disconnect the UPS’ input power cord from the wall receptacle.
4. Press and hold the “0” button for about 4 seconds and listen for a click from inside the unit. At this point the green sensitivity LED on the back of the unit will turn off, indicating that the unit is completely powered off. However, if the unit were previously set to low sensitivity, it is harder to notice the change in brightness.
5. Now it is safe to insert or remove the SmartSlot accessory card into/from the UPS SmartSlot.

*** For a Matrix UPS, you need to put the Matrix into bypass by the screw on the back.
Undo the screw all the way until the front display turns off. Once the display is off, the Matrix is in bypass.

From:  http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=946