My TPLink HS110 is installed and fully functional. Thanks to all who helped!!
I downloaded the “Kasa for Mobile” app (Android) and followed the directions. TIP: It requires you to choose to set up an account, or exit. If you choose to set up an account, but scroll down to the bottom instead, there’s a link to let you continue without setting one up. It shows a nag screen of all the things you can’t do. Which of course you can do with HA anyway
After that, the setup is straightforward. It scans for and finds the device, prompts you to give it a name, and your WiFi password so it can join your local network.
Once there, the TPLink integration documentation takes over. I set up a DHCP reservation on my router so the address doesn’t change (not sure if this is required, maybe it’ll auto-detect each time.) You can get the host name, IP address and MAC address right from the app, or from your router.
The integration will detect the device, but not all the energy monitoring “stuff.” For that you need to edit configuration.yaml.
The example in the documentation is wrong! I used it and got an error validating the configuration file. The documentation indicates a period “.” in the name. This is not accepted. For example, Use “switch_my_hs110_amps” instead of “switch.my_hs110_amps”.
Once I got the YAML syntax corrected, the data started flowing. My test case is a sump pump in my cellar. I have a fieldstone foundation and we had a rainy day, so the pump ran a lot, but in short bursts. I added a history graph card to Lovelace to show the current draw, in Amps. I could also have used Watts. Basically, each spike is one time the pump came on and back off:
For the sump pump, a problem would show up as a prolonged spike. Either the motor was locked and the pump not turning, or there was so much water the pump couldn’t keep up. Presumably, I could set up a notification for that. Alternatively, if the pump never came on, that might also indicate a problem, such as a stuck float switch. This is exactly the data I was looking for!