Re: [foxboro] UPS backup time
- From: "Doucet, Terrence" <tdoucet@xxxxxxxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Fri, 18 May 2007 07:05:01 -0400
I agree with the concept that the UPS time is really based on holding the
control system alive until the generators kick in at the correct voltage.
Whether the kick in is automatic or manual, there will always be some zero
voltage time that you need the UPS to keep power for the computers. The most
damaging thing that UPS can prevent is the ON, OFF, ON, OFF. etc that could
happen during a utility brown out of capacitor switching times. Such voltage
losses and re-connections can kill a hard drive pretty fast.
If you have no generators, then the UPS has to hold long enough for an orderly
shutdown of the IA.
Testing of the UPS should be scheduled whenever there is a plant shutdown or
scheduled maintenance. We tested this once by pulling the main panel connection
from the Utility at a site where I was asked to help. The IA kept running OK
as the UPS worked as expected but there were a few surprises in other areas.
We scheduled the power fail days in advance and informed all departments. A
coulple minutes after we pulled the power, the IT guys came running over to say
we had killed their servers! They fouund out that their UPS was defective!
Terry
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