Symptom:
On a Catalyst 4500, a brief moment of packet loss may be experienced by connected PoE devices, after failing over between power supplies twice (e.g failover from PS1 to PS2, then a few mins later failover from PS2 to 1). The following logs may be printed:
 %C4K_ETHPOE-4-SUPPLYFAULT: Module 3 POE controller has been shutdown because of excessive power usage.
%C4K_ETHPOE-4-SUPPLYFAULT: Module 1 POE controller has been shutdown because of excessive power usage.

Prior to the 2nd failover that leads to the packet loss,  the inline power may not be evenly distributed across power supplies, as indicated in "show power"

<snip>

                             Output Power To Chassis            Input Power
                    =======================================  ==================
Power Measurement   System Power (12V)  Inline Power (-50V)
(in Watts)                (+/- 12W)        (+/- 50W)              (+/- 5%)
------------------  ------------------  -------------------  ------------------
PS1                        349                  695                 1290
PS2                          0                    0                    0
------------------  ------------------  -------------------  ------------------
Total                      349                  695                 1290
 
</snip>

Conditions:
This issue has been seen with a small range of PWR-C45-6000ACV power supplies. To trigger the issue, the following steps were performed:

1.Turn on both power supplies
2.Turn off power supply 1
3.Turn on power supply 1. "show power: output shows inline power is not distributed evenly across power supplies, even though both power supplies are 'good'. (there should be no impact yet)
4. Failing over from power supply 1 to power supply 2 will lead to a brief period of packet loss and the above mentioned log messages.