This isn’t a question, but some observations that other North American emonPi users might find useful.
I’m a newbie emonPi user, but I have a long electrical, electronic, Linux, and software development background, going back decades. I have been looking for an energy monitoring system due to an ongoing dispute with my electrical provider, and the emonPi looked like the best fit for me. Most of the other systems I looked at wanted to upload my personal usage data to “the cloud”, with no mention of backups, who has access to it and what else it will be used for.
So I purchased a emonPi a month or so ago, with two YHDC SCT013 CT’s and a 120VAC to 9VAC adapter, and received it about 2 weeks ago. I proceeded to install it, and I discovered that the CT’s wouldn’t fit around my main feeds to my electrical panel (240V). The wires are 4/0 copper with sheathing with a diameter of 16 or 17 mm (more if the cable is curved) and the CT opening is only 13mm. Yes, I should have checked out my panel out before ordering, but I didn’t.
I knew from viewing your forum, that other CTs could be used in a situation like this. As a temporary measure, I installed one SCT013 CT on the neutral feed, which was small enough in diameter to accept it. I reasoned that since most of electrical appliances in my house ran on 120VAC, except for my water pump and clothes dryer which use 240VAC, this would show most of my usage as I explored the rest of the emonPi system.
For a week or so, everything worked as planned. I figured out how to set up feeds, use the graphs and visualizations, and explored the dashboard and apps. I figured out that my old, large deep freezer in my basement was my major electricity user, my septic pump was working hard as the snow melted here in northern Canada, and the ground became saturated with water.
I was playing around with the Apps, and it appeared that they were treating end-of-day based on UTC time, not local time, and they were always showing data a day late, so I thought I would reboot the emonPi to see if that would help the issue. After shutting the down the emonPi with the pushbutton switch, I rebooted it by removing and installing the 5VDC USB connection.
After the reboot, I discovered that the emonPi was showing positive and negative power usage, where before it was only showing positive usage. I rebooted it a number of times, with the CT disconnected, the CT connected, but not on the neutral lead, etc etc. I also noted that the vrms input display was showing a variable value, where before it always showed 110VAC. Finally tried rebooting with the 9VAC input disconnected, and now the usage was displayed as positive again.
Further research on your forums (thanks, Robert.Wall) informed me that if the AC adaptor is properly connected, the emonPi can determine the direction. So, when I was seeing positive usage from a 120 VAC circuit, the current was being drawn from one side of the 240 VAC feed, and negative was from the other side of the feed.
So I’ve learned something, and I’ve since ordered a pair of SCT023 CT’s, which appear to be the best choice, and should work on my panel, and yes, I’ve checked.
Hope somebody finds this info useful.