Sometimes an investigation of an emerging issue forces one to shine a new light on older analyses and offers new insights. A while back, I tried to use Sense exported hourly data from my smartplugs to see how easy or hard it was to automatically determine “On”, “Off” and “Idle” modes of the device on that smartplug by automatically analyzing the hourly usage distributions. At that point in time, I rued not having more fine-grained time-series power data to work with.
A year or two later I have a new reason to revisit that analysis, as I attempt to diagnose different modes of communications failure between Sense and smartplugs. One of the things I have discovered during diagnosis is that there are 3 different visible “states” of a smartplug that all seem to result in no exported data for the time when the smartplug is one or more of those states for the entire hour:
- An actual connectivity issue, where Sense doesn’t seem to see a pre-existing smartplug on the network. In that situation the device appears in the “off” part of the device list with an “n/a” on the control button.
- When the smartplug is turned off via the Kasa/Sense On/Off button. In that case it is in the “off” part of the device list and the control button says “off”
- When the smartplug is using a very small amount of power (less than some critical threshold) and ends up in the “off” part of the list, but still “on” per the control button.
But small fluctuations in power can take that same device into the “on” part of the device list a couple minutes later, in the “Standby” state, where there is visible energy being used.
Pushing deeper, I tried to get a better idea of the threshold between “Off” and “Standby” states for a smartplug or DCM device in Sense. The threshold between “On” and “Standby” is fairly well defined, with a user adjustable power and time threshold. For “Off” and “Standby” not so much.
After setting alerts for all the transitions (“On”, “Off”, and “Standby”) on my Washing Machine HS110 (Washer), I was able to capture a bunch of “Off” to “Standby” and “Standby” to “Off” transitions like this one.
Looking more closely in the Device Power Meter, one can see that the source of the transitions and alerts was a 1W bump.
This time around I have a way of pulling 1 second resolution data from my HS110, so I can do a detailed comparison, though I’m starting with 4 sec resolution data, so I don’t hammer my network too hard. Here’s the a view of that “bump” in the raw 4 second sampling data from the same HS110 is feeding Sense. A detailed view (17:20 = 5:20PM).
And a broader view over time. Hard to see a bump in there.
If I look back over 50k power samples, once every 4 seconds for the past 2 1/3 days, including a Washing Machine washes, I can see some interesting distributions. Looking at the whole range of measurements, it is clear that the Washer spends most of its time in “Off” or “Standby”, but the load can get as large as 1000W or so.
If I push down into the part of the data that is 1W and less, it’s pretty clear that the measurements there are bimodal, either centered around a mode at 0.60W or one at 0.74W
Looking at the distribution above 1W (in histogram below) highlights a bunch of different modes. I’m guessing that the mode on the extreme right is 11 min (165 samples) worth of spin dry cycle.