Yet another 3 phase question!

I have a 3 phase, 4 wire system, in Australia.
I think i have put the CTs on each phase, by connecting one to each input at the back of the mains switch.

I have solar as well, but thats not currently connected to Iotawatt (the solar is new). I seem to be getting … odd numbers on the mains, especially when im generating solar.

There is no way I am currently using that much power!

Have i got the CTs in the wrong spot ? Have i done something else wrong ? Ive tried changing the phases etc around, but nothing seems to change those numbers greatly.

I suspect that your results are the iotawatt reporting the electricity you are exporting to the grid.

The iotawatt can measure power whichever way it is flowing through the ct (that is what the little rotation symbol is to the left of some of your circuits)

At night time (no solar) you may find main c has a reading with the rotation symbol on it. As the sun comes up the reading lowers until the rotation symbol goes away and it starts rising as export commences.

If you look on the forums and in the documentation there are instructions on using the MAX or MIN function to stop the autorotate of the ct and measure flow in just one direction.

Flow to (or from) the grid = generation minus consumption

Once you put CTs on your solar things should become clearer (but you will need to use MAX and/or MIN functions.)

I’m not guaranteeing my maths/setup is correct :grin: others please chip in if you see an error

now that it its dark, main_c had a negative value, so im guessing i had it around the wrong way. Ive reversed it, and the numbers look about right.

I will keep an eye on it tomorrow – it being negative isnt the worst thing as thats going to be the power going back into the grid (i think!)

I already know ho wmuch solar im generating, solaredge pushes data to the cloud, and im pulling data out via modbus and loading it into emoncms already – maybe ill do my “smarts” on that end.

Judging by some of the power factors I see, your installation is not correct. Please see the documentation at There are many combination on CT,VT and phase thatare wrong and only one that is correct. The documentation explains how to get the mains right.

Potentially yes. I didnt actually KNOW i had 3phase until i had solar installed, so had never gone through the motions, and didnt have mains connected to iotawatt, just all the individual circuits for more specific monitoring.

You really do need to follow the steps to get the derived three-phase set up. Most of your other circuits appear to be grossly incorrect as well. Once your mains are correct, you can usually follow the wires to determine which phase each of the branch circuits are on.

The numbers seem roughly right, based on what i think i would be using.
Whats the “magic bullet” to know once i get the mains right?

Should the mains all have a PF of 1, and i just keep chaning the combination of phases until I get to that point ?

By trial and error, using highest PF wins, this seems to be the winning combination.

Ill open up the board and trace the phases to the other circuts if i can … but being a house build ~100 years ago its a bit of a nightmare!

MainC is almost certainly right, and its oriented correctly, is probably where the solar is connected.But i can’t tell much more than that. It’s extremely important that all of the CTs are oriented the same way. Checking that should be a priority.

Once you are sure the CTs are oriented the same way and the mains are correct, you can cycle loads on the branch circuits and watch which main responds, and then set the voltage reference for the branch to that of the corresponding main.

After fiddling with all the phases, im pretty sure ive got them right. Will trace wires later this afternoon. I have another 50A CT laying around somewhere that I never installed originally, but for the life of me just CANNOT find it!

I am pretty sure they are all orientated the same way, and I double checked yesterday.

Thanks for your help.