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Tuesday, November 12, 2013

Testing Wattson Transmitter to make it work for the US & Canada SplitPhase Consumer Units - Part 2

Last night, I did continue my testing to try make Wattson work for Split Phase AC installations in USA and Canada



First I started to draw and write down what I know

On the left I drew a consumer unit with 2 distinct phases lines and their set of breakers, leading to 2 different loads: Here one CT clamp / Current sensor on each line and plugged into Wattson input 1 and 2, will result in displaying the total Usage, with Wattson settings adjusted to Voltage = 120V and the latest version of Holmes, Holmes2 allow that now.

On the right is the Generation side with the Grid Tie Inverter, from Solar or Wind, feeding power into the 2 phases in 240V.
Here with one CT clamp / Current sensor we will have a reading of half the power generated only: we need to double it ...

I read earlier this week that, in order to do so, we just need to wire 2 CT clamp in series, and their voltage should add up !

Almost solved then... But how do we do this ? Well this is exactly what the Easyfit Y Cable does, and to double check that, I drew it on the lower left corner from pictures I took of it earlier and also removed the one I using on my Solar Inverter & ESS line;
I then plugged 2 CTs into it, plugged the end of the Y cable into Wattson 1 input and it displayed the Usage x 2 :-)




After that, I did plug one CT into Wattson input 1 and the 2 CTs with Y cable into Wattson Generation input, and the Net Usage displayed is of course Usage - Generation, and negative here 

So it looks like it is that simple in the end :-)

I completed my drawings and notes with that




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