Beeping after power irregularities?

[James H. H. Lampert]

Our AC power just blinked several times. More or less concurrently with 
that, something in our server cage (we think it's a Debian box); it 
doesn't appear to be an AS/400, any network gear, or our UPS) began 
emitting one-second beeps, approximately every two seconds (i.e., a 
one-second beep alternating with a one-second silence).

Any insights?
--
James H. H. Lampert