Yassine Posted July 1, 2021 Share Posted July 1, 2021 Hi, I would like to calculate the MTBF (Mean Time Between Failures) of a compressor. I have the running hours signal and captured capsules for failures. I want to create a trend showing the MTBF over time (MTBF= [current running hour - running hours at the beginning of the year]/the number of failures during the running year). Q1: I used $Capsule.aggregate(count(),years(),startkey()).toStep() to display failures trend (it should be increasing over a year with the new failures) but this gives me the total over that year without showing step change against the next failure capsule. Q2: how can I implement the MTBF formula in my calculation? Thanks Link to comment Share on other sites More sharing options...
Seeq Team Patrick Posted July 1, 2021 Seeq Team Share Posted July 1, 2021 (edited) Hi Yassine - Below is one way to approach this problem: Q1: Refer to the below linked article on how to create a running count of capsules. For your use case, start by creating a Yearly Periodic Condition in your time zone of choice. Next, create a signal with a set sample rate (I picked 1 day in this case, but you can make it shorter): Then create a signal from condition to count each Maintenance Interval using the average of the signal during the maintenance capsule (which will be 1, so effectively, you're counting a single instance for each maintenance interval): Finally, create a running sum of the capsules over the yearly period w/ max interpolation of 1 year: This will result in a step signal with a continuing count of maintenance intervention capsules: Q2: To perform your yearly MTBF calculation, you can create a signal for your current running hours and start of year running hours by using the Max and Min Aggregation in Signal to condition: With those signals available, Yearly MTBF can be calculated using Formula: Edited July 1, 2021 by Patrick fixed images 1 1 Link to comment Share on other sites More sharing options...
Yassine Posted July 2, 2021 Author Share Posted July 2, 2021 Perfect.. it works.. the only thing I changed from your approach is that I used for Current_hours as the running run-hours from the compressor itself and not the created signal max_run_hours so the MTBF 1 trend looks sloped compared to the MTBF you proposed. That works pretty fine. Thanks Patrick Link to comment Share on other sites More sharing options...
Seeq Team Patrick Posted July 2, 2021 Seeq Team Share Posted July 2, 2021 Excellent tweak - that makes sense! Link to comment Share on other sites More sharing options...
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