This error message UNBALANCED_PS indicates that there is a switch in the power stack (indicated by number in the message) with no supplies while at the same time there is a switch in the power stack with TWO supplies.
If this message only appeared once, you can safely ignore this (this can be seen while you are configuring priorities at the switches).
If it is occuring multiple times, i would like to see following outputs:
1. Show Version
2. Show stack-power
3. Show env all
Can you also have a look at the below bug:
http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCtg20513
CSCtg20513 - PLATFORM_STACKPOWER-4-UNBALANCED_PS: Switch 1's power stack has unbalanc
HTH
Regards
Inayath
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