Almbracket Row Edit: Alarm Brackets tab

Enabled

Select to have the AVEVA Enterprise SCADA generate an alarm if the current value of the reference point (Current Value Source Path) rises above or falls below the Positive Deviation Limit or the Negative Deviation Limit, respectively.

When this checkbox is selected and the record is saved, the system performs an automatic rebracket to set the reference value to the current value of the reference point and adjust the bracket alarm limits to the configuration. Ensure that all fields in this tab are already saved with the desired value before setting the alarm bracket to Enabled from the Advanced Database Editor (ADE).

Current Value Source Path

Enter or select the path to the analog, rate, flowTotalConfig, or pipe_segment record whose current value becomes the reference value when bracketed. flowTotalConfig and pipe_segment records are only available when Alarm on Analog/Rate Reference Point is disabled.

The application monitors the point's current value for deviations beyond the assigned limits.

Important: Any given analog, rate, flowTotalConfig, or pipe_segment record can only be associated with one almbracket record. If you attempt to save an almbracket record configured with a reference point already associated with another almbracket record, the system generates an error message and prevents the save action.

Notes: The pipe_segment table allows you to set alarm brackets on calculated gauge (hydraulic profile) pressure values.

Due to design constraints, the Publisher - Subscriber (PubSub) does not issue messages for updates to AVEVA Pipeline Operations for Liquids tables. As a result, it may take up to five minutes for Alarm Bracketing to become aware of changes to the calculated gauge (hydraulic profile) pressure values.

If you want to change the Current Value Source Path of an existing alarm bracket, ensure that the alarm bracket is disabled before changing this value. If the bracket is configured to generate alarms on the reference point, the configured limits will be stored in the new reference point when the disabled bracket is enabled or when a rebracket operation is performed from easy eXtended Operator Station (ezXOS).

Alarm on Analog/Rate Reference Point

Select to have the AVEVA Enterprise SCADA generate an alarm against an analog or rate reference point (Current Value Source Path) instead of the almbracket record when the current value of the reference point (Current Value Source Path) rises above or falls below the Positive Deviation Limit or the Negative Deviation Limit, respectively.

Selecting Alarm on Analog/Rate Reference Point enables the Controller to access the Bracket Control dialog from an analog or a rate point's Alarm Limits dialog. When a one time or default bracket configuration is changed, or a re-bracket operation is performed, new positive and negative bracket limits are stored in the reference point. For more information, see Clamp alarm bracket limits within existing limits.

This change causes the bracket alarm state to be re-evaluated according to the new limits.

For more information, see AVEVA Enterprise SCADA RealTime Controller documentation.

Note: The Alarm on Analog/Rate Reference Point checkbox is selected by default.

Positive Deviation Limit

Enabled

Select to have the AVEVA Enterprise SCADA generate an alarm if the current value of the reference point (Current Value Source Path) rises above the Positive Deviation Limit.

Is a Percentage

Select if the value in the Value/Percentage field is a positive percentage amount of the reference value.

The reference value is the bracketed value of the reference point above and below which the current value of the reference point oscillates.

Note: A Reference Value column appears on the Alarm Bracket Summary window. For further information, refer to the "Alarm Bracketing" Controller documentation.

Value/Percentage

Enter the amount by which the current value can exceed the reference value without generating an alarm. Depending on whether or not Is a Percentage is selected, the system calculates the Positive Deviation Limit as per one of the following formulas:

• Value: Reference Value + Value/Percentage

• Percentage: (Value/Percentage x Reference Value)/ 100 + Reference Value

  Note: The Value/Percentage must be greater than, or equal to, zero.

Negative Deviation Limit

Enabled

Select to have the AVEVA Enterprise SCADA generate an alarm if the current value of the reference point (Current Value Source Path) falls below the Negative Deviation Limit.

Is a Percentage

Select if the value in the Value/Percentage field is a negative percentage amount of the reference value.

The reference value is the bracketed value of the reference point above and below which the current value of the reference point oscillates.

Value/Percentage

Enter the amount by which the current value can fall below the reference value without generating an alarm. Depending on whether or not Is a Percentage is selected, the system calculates the Negative Deviation Limit as per one of the following formulas:

• Value: Reference Value - Value/Percentage

• Percentage: Reference Value - (Value/Percentage x Reference Value)/100

  Note: The Value/Percentage must be greater than, or equal to, zero.