4 Replies Latest reply on Oct 5, 2018 1:56 AM by Lal_Babu_Shaik

    Rate of change analysis and event frames

    kaneb

      Good morning! I am trying to setup event frames that trigger off a rate of change versus a static value. We have high and low values that will trigger an event, but if conditions are such that a reading is high (but not necessarily high enough to trigger and event) and suddenly falls quickly but not to the level of a trigger, is there a way to capture that? If that makes any sense, I would love to hear some ideas.

      Brent

        • Re: Rate of change analysis and event frames
          Lal_Babu_Shaik

          Hi Brent

           

          Event frame start trigger can be set up to wait for predefined period using true for in the start trigger and include a condition that if process value is greater or less then trigger.

           

          Thanks

          Lal

            • Re: Rate of change analysis and event frames
              kaneb

              Thanks Lal,

               

              As an example, monitoring the electric system frequency, I have an analysis to trigger if frequency is above 60.08Hz or Below 59.92Hz. I would like an analysis that triggers if frequency deviates by .05Hz in a 20 second span, no matter what the starting value is. As I don’t have a static value to start the trigger, how would I express that? I am just learning PSE, so apologies if this is a simple matter and I am just not getting it.

               

              Thanks!

               

              Brent

                • Re: Rate of change analysis and event frames
                  TimCarmichael

                  To check deviation, you can use the Range function in an analysis; the format is Range('Attribute','start time', 'end time').

                  Now... to combine that with your existing trigger will require a little bit more work.

                  In the past, I worked with event frames that effectively had multiple start triggers and our solution was to create an analysis that looked at both start triggers and set a new trigger when either of the start triggers was true; and again, the same to end the event frame.

                  • Re: Rate of change analysis and event frames
                    Lal_Babu_Shaik

                    Hi Brent

                     

                    Start Trigger :

                     

                    (Frequency < 59.92 or Frequency >60 ) or Range(Frequency, '*-20s','*')>=0.5

                     

                    End Trigger

                    ( Frequency >=59.92 and Frequency <= 60 ) .... Please add deviation in End trigger only when required.

                     

                    Thanks,

                    Lal

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