I'm not expecting this is a problem with HE... But in case it somehow is, I have a C-7 running the last release of 2.3.8, still using the custom Kasa integration.
I noticed the other day that one of my EM plugs, KP125's from memory, was making the mechanical noise as though it was switching off and then immediately on. It would do this on -> off and off-> on cycle maybe every 3-4 seconds. The dehumidifier plugged into it did not seem to lose power, but I was not taking the risk, so I unplugged the smart plug and put it aside.
When I came to look at the kasa plug yesterday, plugging it into the power it will do the switching constantly, with no gap at all.
Has anyone seen this before?
I have some spares, so am happy to let it go, but thought I would check if it can be saved first.
It would be easy to rule out a Hubitat problem by disabling the device, preventing any driver code from running, and seeing what happens. But like you, I can't imagine that is it.
More likely, you are experiencing hardware failure. This could just be due to age or bad luck; it could also have been caused by the load plugged into it (though if that's the plug, they say 15A/1800W max, which is really all you could plug into it anyway -- but they don't specify load types and I suspect motors like your dehumidifier might still be questionable). If it's still under warranty, that could be an option for further assistance.
The failure method you're noting, repeated clicking on/off, seems to be a common way smart plugs and switches fail. Just google "smart switch click of death" and you'll find similar reports. Many people here have reported this with GE smart switches, though I don't think I've seen the Kasa plug in particular mentioned (yet?).
I have a GE ZWave Switch, outdoors but covered, and one day I went outside and heard this awful screech noise. Rather high pitched too so it wasn't easy to instantly identify where it was coming from. I thought it was coming from a neighbor but soon enough I found it was that ZWave switch cycling the relay at 1500 times a second, at least. You can imagine my shock at having to replace a GE ZWave switch
I purchased five Kasa KP105 smart plugs a few years ago. 2 have since failed with exactly the failure mode you describe. One was replaced under warranty but the second was 3 days out of its 2 year warranty and TP Link refused to replace. Unfortunately you can’t get the Kasa plugs any more in Australia so they were replaced with Tapo P100 plugs.
Thankfully I have some spares I bought a while ago, but yeah, if I need anymore I believe Tapo is what we need to use now, which is ok now that they are supported by the drivers, I believe.... which was not always the case.
Kasa plugs appear to have an issue with a capacitor failure on the DC side internally resulting in this relay switching issue. Its a bad design because appliances do not react well to this sort of rapid power cycling and can easily be damaged. I am junking mine over time on critical appliances and replacing them with something better. There is a thread on the TP link forum about this and TP are being oddly silent on the matter.
Thanks for the feedback on the known problems with these Kasa/Tapo smart plugs. The forum makes interesting but scary reading. My plugs are used to feed critical smart home infrastructure and I have probably dodged a bullet with the 2 failure I have had in not killing my connected NVR or Hubitat HUB. Thinking I will now throw all 5 in the bin and replace with Meross smart plugs which seem to have a reliable reputation and I can also control them from my Home Assistant server which I use as a companion to my Hubitat HUB.
I am doing the same thing. My HASS and office servers and my pond system need a reliable supply and I have lost faith in these devices. I will keep a few for Xmas lights, they flash anyway so no harm if the device starts the erratic switching and a few for non critical stuff but otherwise the rest are going. I used to swear by TP Link, lately I am swearing at them.
