Determine the adjustment intervals of the trigger point

When an AVEVA Enterprise SCADA point has a state or value change that is recognized as a trigger event, a period is entered where adjustments to the alarm limits for the Pipeline Monitor (plm) record are calculated. During this period, the plm record is in the Transient state. The adjustment period can be configured and different adjustment periods can be configured for different balance periods.

The adjustment period consists of two intervals:

The Hold interval (1)

• This is the initial interval after the trigger event. During this interval, the alarm limit adjustments are constant and at their maximum value. The time span of the Hold interval can be configured for different balance periods.

  The trigger adjustment is in the Hold interval for a balance period if:

  • The elapsed time since the trigger event is less than the configured Hold interval, or, Hold Persist is in effect which means that the system should apply an indefinite hold to the dynamic alarm adjustment.

  • A deactivation trigger event has not occurred while in the Hold interval.

    If a deactivation trigger event occurs while in Hold, the Decay interval immediately begins.

    Note: This default behavior can be changed so that the system applies a Hold interval after the deactivation trigger event. This additional hold is independent of the initial hold that gets applied after the activation trigger event.

To change the default behavior

1. Using ADE, navigate to the Application table.

2. Retrieve the row called PLMHoldAfterDeactivateTrigger. If this row does not exist, create one with the same name.

3. Check the Boolean Value checkbox (see example below).

   

4. Save your changes.

The Decay interval (2)

• This is the next interval, during which alarm limit adjustments are declining and the adjustment amount is decreased on each plm processing iteration during this interval. The time span of the Decay interval can be configured for different balance periods.

  The trigger adjustment is in the Decay interval for a balance period if:

  • The conditions for being in the Hold interval are not satisfied.

  • Elapsed time since the trigger event is less than the sum of the configured Hold interval and the configured Decay interval.