it would make a lot more sense to rectify the CT and put the current sense resistor after the FWB. then feed that directly into the ADC.
use a resistor inline and a zener to clamp the voltage below 3.3 volts to keep the pic safe from 1000 amp line transients blowing it up.
you will have to make sure that the 1.4 volts in addition to the voltage dropped across the current sense resistor does not saturate the CT.
I am not sure what you mean by FWB.
I guess you mean to rectify the CT current rather than the CT voltage.
That was what crossed to my mind. Apparently, CT (a current source) should happily flow undistorted current through the Diode-Resister-Diode configuration. So, apparantly, I should have got a perfectly Full-wave rectified waveform across the resister.
But unfortunately, when I tested in hardware, It was nowhere near. I am puzzled.
View attachment 64944
When there is no rectification, I get a nice smooth, nearly sinusoidal voltage across the Resiter
View attachment 64945
I used 1n4007s, do you think it was the problem?
In your last paragraph, I am not sure how you can estimated if the CT will saturate by adding up voltages. The nameplate says it can provide 10VA, so I guess, V*I shouldn't cross 10.
In the above graph, this limit wasn't crossed.
Please mind that all these waves are when the primary current was sinusoidal. Not for the DC-offset and discontinuous current I am currently facing.
When I had to sense such currents, the CT didn't work.
I got something like this.
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