Narrative of the Case 2 Shutdown

Following is an analysis of t Timeline of Shutdown on Low Battery, which shows the timeline of events that occurs during a power outage when remaining battery run time reaches the UPS Low Battery Signal Time.

  1. At 0 seconds, PowerChute plus detects that the UPS runtime equals the UPS Low Battery Signal Time. PowerChute plus generates the Low Battery Condition event and begins the 30 second shutdown delay configured for that event.

  2. At 30 seconds, PowerChute plus generates the System Shutdown Starting event and begins the 60 second shutdown delay configured for that event.

  3. At 1 minute, 30 seconds, PowerChute plus does the following:

    a.
    Instructs the operating system to shut down.

    b.
    Generates the System Shutdown Complete event.

    c.
    Issues the UPS Turn Off Delay instruction from within the UNIX shutdown script. During the UPS Turn Off Delay period, the operating system completes the remaining portion of the shutdown procedure. Because the UPS Turn Off Delay is issued from within the shutdown script, a brief additional delay may occur before the UPS Turn Off Delay begins, which briefly delays the turnoff of the UPS

  4. The UPS, unless it is a Back-UPS, turns off its outlets and goes into sleep mode.

To complete all the events in the timeline in the preceding example, the UPS must run on battery power for 110 seconds (1 minute and 50 seconds) or slightly longer. Therefore, for the UPS to complete the shutdown procedure properly, the Low Battery Signal Time is set to the default (and lowest allowable) value of 2 minutes.

Low Battery Condition delay
+
System Shutdown Starting delay
+
UPS Turn Off Delay
must be less than or equal to
Run Time Bar graph time
30 seconds + 60 seconds + 20 seconds <= The total, 110 seconds (1 minute, 50 seconds), must be less than or equal to the runtime.

Timeline of Shutdown on Low Battery