Emerson Exchange 365

DeltaV Alarm hysteresis configuration

What is the intended use of PID1/ALM_HYS as opposed to the individual as opposed to using the specific alarm hysteresis of PID1/LO_ALM_HYS, PID1/LO_LO_HYS...?  Does one take precedence over the other?

Thanks in advance for any feedback.

• alarm hysteresis

gxmontes

• 9 Jul 2018 4:32 PM
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3 Replies

• Matt Stoner

  

  • 9 Jul 2018 5:36 PM

  The ALM_HYS is only valid when conditional alarming on the block isn't enabled. So if you are seeing the individual hysteresis parameters, you have conditional alarming enabled and should be using those parameters instead of ALM_HYS.
  
  To enable/disable the conditional alarming, right click on the block, select Assign Alarm, then there is a "Conditional alarming for all alarms" checkbox. If it is not selectable then select an enabled alarm from the alarm detection parameters list (or enable one but this will add an alarm on the module so you may have to delete the alarm manually when done) and then the "Conditional alarming for all alarms" checkbox will be available for change.

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• Andre Dicaire

  

  • 9 Jul 2018 5:49 PM

  In reply to Matt Stoner:

  It remains in the AI block for legacy reasons, for users that explicitly reference it in any control modules or displays. Prior to conditional alarming, each PID, AI, ALM blocks had one Hysteresis parameter used on all the block's alarms. When conditional Alarm was developed, dedicated Hysteresis parameters were added to allow better alarm behavior. ALM_HYS is not used by Conditional Alarms.

  Andre Dicaire

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• gxmontes

  

  • 9 Jul 2018 8:03 PM

  In reply to Matt Stoner:

  Thank You!

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