Alarm Limits

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The check of Alarm Limits represents the validation of correct alarm indication for defined Alarm Limits within the system.

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Introduction

Alarm Limits have to be defined in the imported Loop Check Settings. Undefined Alarm Limits are skipped.

Field Information Manager supports the Alarm Limits High-High (HH), High (H), Low (L) and Low-Low (LL). An alarm is verified by the corresponding alarm event in the System Event List which is identified by the condition name. Each of them is tested in hysteresis to ensure a correct alarm behavior, resulting in 3 test points for each alarm:
  • No Coming Alarm: Passed if no event with status indicated "New" and matching condition is raised in System Event List.
  • Coming Alarm: Passed if an event with status indication "New" and matching condition is raised in System Event List.
  • Going Alarm: Passed if an event with status indication "Inactive" and matching condition is raised in System Event List.

A failed test point indicates a mismatch of the Alarm Limit configurations in System (used for alarm event generation) and imported Loop Check Settings (used during Loop Check). 

In order to recognize a detected alarm event, the status indication, timestamp, condition and message are copied from System Event List to Loop Check Details and Reports.

For correct detection of alarm events with their timestamp, the Field Information Manager client and system connectivity node must be synchronized with regards to time.

In order to ensure a correct alarm and event sequence, existing alarms for the corresponding node are acknowledged automatically before, during and after execution of Loop Check.

Test Strategy

  • FIM forces the configured Alarm Limits in fixed hysteresis, i.e. 2% before defined Alarm Limit (No Alarm), 2% behind defined Alarm Limit (Coming Alarm) and 2% before defined Alarm Limit again (Going Alarm).
  • FIM verifies if the measured value matches the expected value (within defined tolerance).
  • FIM verifies if the alarm and event sequence is as expected for the different test points, i.e. for a coming alarm a new alarm event shall be raised in System Event List and for a going alarm, the same alarm event shall be set to inactive again.
    • An alarm event is identified by its condition name which must match in FIM Loop Check settings and in application of used system.
  • If measured value is correct and alarm event behavior is as expected, the test point is passed.
  • If one of both is not correct, the test point is failed.

Importance of Imported Loop Check Settings for defined Alarm Limits

  • Alarm Limits can only be tested if Loop Check Settings (CSV / Signal List) are imported and define values for Alarm Limits for the node.
    • Alarm Limit values are always defined in the Signal Unit (e.g. 30 degC or 70%).
  • If no values for Alarm Limits are defined, the Check of Alarm Limits is not performed for the channel.
    • Node-specific setting in Loop Check is automatically disabled and cannot be changed.
    • Undefined Alarm Limits are skipped.
  • Check of Alarm Limits can be enabled or disabled in channel-specific settings in Loop Check View or in FIM Loop Check Settings (Tools Menu > PROJECTS > LOOP CHECK SETTINGS).

System Configuration (ABB System 800xA)

  • Used library in ABB System 800xA must include Alarm Limit functionality so that the Check of Alarm Limits becomes possible.
  • Function Block or Control Module is required for configuration of Alarm Limits for a channel.
  • Alarm Limits have to be enabled and configured to appear as Alarms.
    • SignalInReal / SignalOutReal: AEConfigHH, AEConfigH, AEConfigL, AEConfigLL configured to generate alarms or events.
  • Definition of values for the Alarm Limits (HH, H, L and LL) in InteractionPar or Faceplate required.
    • InteractionPar:
      Values for Alarm Limits are defined by the fields LevelHH, LevelH, LevelL and LevelLL.
    • 800xA_AlarmLimitDefinition
    • Faceplate:
      Values for Alarm Limits are defined by the Extended Faceplate that can be accessed via Engineering Workplace > Application (e.g. Diagram) and defined Function Blocks / Control Modules (e.g. SignalInReal / SignalOutReal) > Rightclick on MainFaceplate > ExtendedFaceplate > Alarm/Event.
      • Alarm Limit values can be configured by clicking on the values.
      • Hysteresis should be set to 0.00.
      • Filter Time should be set to 0.00 s.
    • 800xA_Faceplate
  • Delay Time of each Alarm Limit should be set to 0ms not to delay alarm indications.
  • Latched status for alarm indications of some Function Blocks / Control Modules is not supported and leads to incorrect Alarm Limit results.
    • If existing in configuration of Function Block / Control Module, the parameter "Latch" has to be set to false.

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