Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have an apc smt2200 with a network management card. It has a web server on board from which I can configure how it works. Some servers are powered by that ups and they all have PCNS software which connects to the web server on the ups. I would like to achieve the following behavior of the UPS, avoiding any special configuration on PCNS, but using only the possibilities I have on the UPS itself.

The desired behavior is:

when power fails and the UPS has a run-time of less than x minutes (Low Battery Duration parameter) it sends a low battery signal to the connected clients forcing them to shutdown (this is a default configuration on PCNS). Once the low battery signal has been sent the ups waits a Power Off Delay (specified for the outlet groups and long longer than the server shutdown estimated time) then it cuts the power to the load, no matter what happens in the meantime.
When the above procedure is completed if power returns the ups waits some time to recharge its batteries, then it reconnects the load. Servers are configured to automatically start when power return so they will return online.

I tried more times to achieve this goal but I was unsuccessfully so I'm looking for advices. The major problems I faced are:

  • when server shutdowns the load to the ups goes almost to zero so it removes the low battery condition and doesn't switch off the outlets.
  • power can return as soon as the ups has raised a low battery signal; servers will shutdown but their power will not be cycled, so they will never return online automatically.
share|improve this question

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.