@AMS it isn't a cheap design (those isolation ICs are like £10 each) but it's still a lot cheaper than buying a commercial one with half as many features.
@gsuberland My thought was resistive voltage and nice closed loop LEMs (or fluxgate LEMs if I find some cheap) for current.
@AMS yeah that's another way to go with it
thing is, I'm gonna be measuring voltage on each line anyway since I want to be able to see if breakers do anything wonky, for example, so since I already have to have some sort of isolated voltage measurement I might as well do the current measurement while I'm at it
@vxo @AMS they end up being a bit more expensive in total, last I checked. with something like AMC3330 + AMC3302 it's about £10 per voltage + current channel (assuming I use the MCU's ADC to measure the amplified output, and I don't need any more opamps for biasing and such), whereas with the ADuM3473 option I can use commodity ADCs and get three voltage + current channels for about £22.
Edited 14d ago
@gsuberland @vxo Yeah, they're like $4 in ones I guess (I'm used to the 100k+/yr pricing at work). 8mm isolated though and nice >80dB noise floor which makes things nice and easy from an isolation standpoint. Being cheap means I'd probably go non-isolated neutral-referenced power and voltag and isolate the current sense. Wifi makes for cheap and cheerful isolation to get the data out.