In preparing for Black Friday we installed the UPS on the floor where our Operations but the final step of that would mean unplugging the switches and moving them to the PDU powered by the UPS because they don't have redundant power supplies. We do have extras from a floor that is not complete yet so we borrowed a normal one and a PoE one and went about plugging the extra in and swapping the switch to UPS power. This however lead to minor alarms on the switch about the power supply being removed.
--- JUNOS 12.3R6.6 built 2014-03-13 06:58:47 UTC 4 alarms currently active Alarm time Class Description 2014-11-27 22:39:02 UTC Minor FPC 0 PEM 1 Removed 2014-11-27 22:45:21 UTC Minor FPC 1 PEM 1 Removed 2014-11-27 22:51:55 UTC Minor FPC 2 PEM 1 Removed 2014-11-27 22:57:30 UTC Minor FPC 3 PEM 1 Removed
A minor annoyance and unfortunately Googling around for a solution did not reveal one. I can't recall what put me down this path but I happen to try
restart chassis-control gracefully. This removed the minor alarms about the power supply without any downtime so I was happy to have found this solution.