[Project] Fault Detection: Power Quality

I am so thrilled Sense has added this feature!!! I have been wanting voltage graphs since day one!

Now that it is out of course I want a few tweaks!

Can you make this graph the same fidelity as the power meter graph? I want to be able to full screen it and zoom in, etc…

The first step is letting me zoom in and go back through as much history as you are willing to store.

After that, I want to be able to get alerts about power quality events and to be able to get high resolution snapshots of power quality events (beyond average data values that normally get stored). Many power quality events only last a handful of cycles and so averages may not tell the full story.

Where this should be interesting is to be able to watch online tap changers and voltage regulators operate on the utility side (and also when they do switching operations or take restoration actions after a storm).

I love it! Please make it a first class citizen feature!


I was good until Isaias hit last week(<10 drops) . I haven’t had a drop for 5 days so think it was just storm related.
There were power lines taken down across the street (actually, power lines were down on almost every street in the neighbourhood when we went for a walk after the storm hit). They still need to fix some houses down the block. We may get another spike when they are re-connected.

I would also like the ability to go back further. You can export the data until a spreadsheet, however, a graph like the power meter would be simpler.


@eric2, @jonhawkes,
Sounds like your interests in additional functionality lie in root-causing the dips/sags/swells, plus prevention if the cause is located inside your house. But if the issues are caused by utility transitions or storms, what would you hope to learn from a close zoom into the data ? And @eric2, you mention seeing events that cover a few cycles. Would it be OK seeing in the 1/2 second min resolution of the Power Meter ?

So yeah, obviously if the events are caused by a device within my house (like an AC compressor hard starting) I would like to be able to correlate that with when the AC unit fires up so I can investigate. Or if they are due to a bad joint or something in my main panel.

Most of the time however these events happen out on the power grid. I want to be able to analyze those events in order to see how severe they were and to be able to provide feedback to the power company about them if they are severe enough to warrant. This kind of data would be fantastic to help isolate issues like failing tap changers, voltage regulators, capacitors, etc…

I was frankly expecting this feature to use the same data sources and UI elements that the main usage graph uses. That way we can zoom in and look at arbitrary time periods and can watch the graph in real time during things like storm events. (incidentally, you really should build the sense to be able to operate on very low voltages so that it stays online even down to say 40 volts like what happened to a friend of mine this weekend when his phase blew but backfeed power from other customers with three phase power still was giving him minimal voltage).

As far as resolution of the data:
Power quality event reporting is actually an area I know little about, however, I do know that professional quality monitors can capture an “event” down to very detailed levels of precision (I think used to analyze what happens when protection circuitry operates to isolate a fault, etc…). I realize that storing this level of data all the time would be incredibly intensive and infeasible.

I see the use cases here as threefold:

  1. Informational / as a hobby - folks are interested in seeing what is going on but without any solid actions to come from that
  2. Information to help track down failing equipment or power quality issues within the house
  3. Information to help the power company track down issues or to hold them to task when they are not performing. Really, the ability to correlate events on a graph to specific times of day can provide clues as to what the issue is (also, I am sure this data will get used to prove that a utility caused damage to a customers equipment at some point).

I don’t need the 1/2 second resolution, just want the ability to go back more than a day.

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Tropical storm Isaias. We lost power for just over two hours on Tuesday 8/4/2020. I recall around the 10pm time frame things started flickering. The 8/5/2020 4am time frame- the ETA for the local utility to restore a large number of customers in the area was 4:00am on 8/5/2020.

Thanks for the thoughts ! I suspect that Sense will productize the Sense Labs features over time, giving them a first-class citizen UI/UX, if the interest is there vs. other features.

@eric2, @jonhawkes, @powens001, etc., if you want to have the ability to go from events to the Power Meter UI right now, for correlation, you should be able use web app’s direct URL feature to zoom in on each event. For instance, you could look closely an event at 8/9 1:59 pm using the following URL:


It would be fairly simple to set up a spreadsheet that creates these URLs based on the CSV spreadsheet that comes out of the Power Quality download, so you could peruse all of the logged dips/sags/swells en-masse. I would do it for a CSV, but I’m not seeing any current Power Quality issues. If one of you wants to PM me your CSV spreadsheet, I would do it as an example.

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I’m getting 1000s of spikes/dips per day. I wired in 4 home run circuits for all 4 window AC units in my house, and another dedicated circuit for my home office equipment, but I’m still seeing voltage spikes and dips. I have solar panels, if that makes any difference.

Interesting @dduarte527 ! Why don’t you start your own Topic under Sense Labs:


Title it “Power Quality - Thousands of Dips” or something like that. Add screenshots as noted…

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+1 for @kevin1 response here, @dduarte527.

Create a new post by navigating to Sense Labs and pressing the “New Post” button in the top right-hand corner. Just fill out the information in the template and more of the Community will be able to add their input. Reach out to me via PM if you have any issues while doing so!

I second the motion for alerting of dips/spikes - lots of feedback here, so hopefully some functions are added for that. For my part, I just noticed and am reviewing this information for my home.

That said - I expect most of mine will match up with AC Compressor start and stops. I can manually watch my voltmeter move when they do, and LED lights are impacted for me. From a feature improvement view, I think correlating large loads starting/stopping, with spikes and dips would be ideal - and something the ML/AI shoudl be able to learn.

That said - I would prefer the option to download a CSV with all of the collected volt data for a period (even if it is aggregated to say, every minute, 5 minutes, or something configurable). I downloaded the CSV of my spikes, and while it is useful, I would be more useful if i could see the measurements over time - not just during the event.


2 posts were split to a new topic: Power Quality - Frequent Dips from Utility

Just wondering…at what point do the old events past 30 days drop off? This screenshot was taken on 9/20. I’m at about 52 days for my oldest, but still tracked event.

Today sense detected a power quality issue I didn’t notice any different I was just looking around the app

Found out I had power quality issues by looking at the lab. I wasn’t aware we had a problem otherwise. We do that solar and it is split into two sets. Could that be causing any of the issues?

If your SENSE readings are correct, then you may have a loose or bad connection at the breaker panel. You will probably need an electrician to come inspect and see if all your terminations are tight.
Or maybe the SENSE monitor has a bad chip that reads your voltage on L2.

Something you might try, is to check your house external ground connection. You can read my blog below and see that I improved my power quality by cleaning the contacts and using a new grounding clamp. Turn off all your power before you attempt this. I cleaned my ground rod connection using a battery-powered drill with a wire brush attachment. This may or may not help you. Maybe other users will reply with their ideas.

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This has probably been one of the most helpful features from Sense.
We’ve lived in our home for over 5 years. We’ve noticed that large appliance turning on caused some light flickering but thought nothing of it. Over the last 6 months, we noticed that our solar panels would shut down whenever we turned on the oven and microwave at the same time, almost as if the power was temporarily shut down. The solar company could not figure it out.
Then Sense turned this feature on and reported that I was getting over 680 voltage dips. Called the power company they they detected that the ground line from the drop line was faulty. They fixed it and all the faults are gone.


2 posts were split to a new topic: Power Quality - Failing Phase


Any chance you could make the Volt dips and spikes monitoring for 240V. Yes, I know that Australia isn’t “supported”… but would be an easy tweak for us on 240V (I cant actually see my data as it’s all up I. The clouds of the graph

Would it be possible to also provide “power quality” data for the flex sensor add-ons as well?

I have an appliance (Miele TWI180) that intermittently shuts down due to detected electrical faults. After some months of back & forth Miele has replaced the DC motor for the drum however they believe that issue is with power quality of circuit (I know thanks to Sense Labs that I have no power quality issues with the mains). So recently I purchased the flex add-ons with plan to monitor just the circuit serving the dryer.