Hi,

I am trying to do a simple Expression Analysis but it's been a long time since I haven't done so in PI AF and I'm running into a small blockage. I think the solution should be quite simple though.

I want to create a calculation for the daily production of one of our units. The calculation is basically the flow rate of the outlet multiplied by the running time of the unit.

I already have my Running Time tag for the day and my flow rate tag. The thing is that I need to take the average flow rate while the unit is running.

I did the calculation easily in Datalink by adding an expression filter in the Calculated Data for the Average flow rate but I don't know what function to use in PI AF for the Expression Analysis.

Right now in my PI Expression Analysis I'm only using TagAvg(Flowrate,'t','t-1d') but I want to filter everytime the unit is not running. Where do I add that expression filter and with what function in PI AF Expression?

Thank you,

Ben

I typically follow this KB for a filtered time-weighted average:

https://customers.osisoft.com/s/knowledgearticle?knowledgeArticleUrl=Filtered-Time-Weighted-Average

You can replace step 2 with an AF analysis that does not store history instead of a formula data reference if you desire.

Dan