A possible recipe for Fault Detection and Diagnosis

Think of a device that looks like a plug meter and has a screen and a built-in processor.  Lets call it FDPA for Fault Detection and Prediction in Appliances. Now you go around your house and plug in all the appliances to the FDPA- which consequently plugs into the power outlets in the house. You then tell the FDPA what appliance was plugged into (/through) it, and then operate the appliance in all the possible modes. For multi-state appliances (like a dishwasher), you run the appliance for the whole cycle.

Now what you have is a labelled database of all the signatures of all the appliances in your house. This was the training phase.

You repeat the process every so often, say- three months.- to test the “health” of your appliances; similar to a regular follow up visit to the doctor’s. The device will do a pattern matching of some sort, and if there is a distortion of some specified threshold, it will predict a malfunction, or diagnose one.

Both words – prediction and diagnosis carry tremendous research potential, I feel.

Here is a crazy idea. What if disruption of a particular circuit element, lets say a capacitor, distorts the power signature in the same way for all appliances ? That would be crazy because then, without even opening up the appliance, your FDPA could tell you where the problem lies in your appliance. All you have to do is to find some way to connect the difference in the database signature and current signature to the circuit element. On second thought, this might be too naive because sometimes failure of a circuit element would prevent current flow totally, thus eliminating all signatures. Obviously, the concept of “fault” that can be diagnosed will need to be defined clearly.

Here’s another one- what if degradation in performance follow a similar pattern ? [ I think people have done this for motor based devices by counting the number of rotations per second] I am sure signatures in this case would reveal something interesting.

One thing to study right away would be to see how different circuit elements degrade over time, and how their signature changes as this happens. Maybe this could be done for combinations of the circuit elements too. This will provide some insight into how appliance signatures can be expected to degrade.

Ok I am too sleepy right now, and I definitely need to do a lot of background reading on this. But I sense something exciting here.

8 thoughts on “A possible recipe for Fault Detection and Diagnosis

    • Great question. I was looking back at my notes from earlier meetings for the NSF project on NILM because we had two undergraduate students who had explored the literature on FDD for NILM. They reviewed a survey paper by Brambley and another guy… Suman: I’ll send you whatever files I have from that time.

      • It gets even more interesting: my e-mail record indicates that on 09/12/2011 I sent Suman the two files that I wanted to send to day again. So, Suman: check your e-mail archive from almost exactly a year ago.

        • haha. this is a sign so I would wait until 09/12 then check it.
          One thing I realized in that talk was since the HVAC systems have distributed components it facilitates the FDD process… I think a comparison of “how two systems functions physically” for an HVAC system and an appliance you are interested can sparkle some ideas in your mind.. Since Brambley and Katipamula have some pioneering work on that field…

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