Reading current with YDHC SCT013 split core transformer and RPi or Arduino

Question

I've got a few split core current probes YDHC SCT013 that I used to use with an Open Energy Monitor module that has failed some time ago.

Now I'm looking at building a replacement power monitor myself but am unsure how to interface this power clamp? Should I just connect it to a burden resistor and measure the voltage over it with Arduino's ADC? What value should the burden resistor be though?

Also the output will be 50Hz AC - how do I measure that in some sensible way? Sampling fast enough? Or rectify it and smooth it with a big enough capacitor?

At the moment I'm not really looking at an exact Amps metering, let alone calculating RMS or true watts. I'd be more than happy to get some relative readings based on the load connected.

Any pointers how to do that?

EDIT: I have found a discussion and calculation of the burden resistors here. However still looking at solving the AC problem. Any ideas?

Answer 1

Sampling 50Hz AC and averaging using math is definitely possible, an RPi or Arduino will sample at 100Hz, no problem (and much higher). You could also rectify and smooth in the analogue domain. In that case you will still have some ripple, and will need to do some averaging also. But because you already rectified, you only need to do a running average, rather than an RMS calculation. If this is a one-off project, I'd personally try both (make a board with the analogue circuit, but be able to bypass it) and see which I liked more. It may be that eventually there isn't much in it.