current monitoring - without OpenEnergyMonitor

Other Hardware General Electronics
1

Hello,
I'm following the circuit suggest for current monitoring from Open Energy. The circuit basically turns the the current transformer into a voltage output going into an Arduino analog pin.

http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface

Their diagram shows a sinusoidal voltage output from the circuit. Is that true? What's a good way of using the Arduino to measure the current...ummm...current. Do I need to say measure the analog voltage every half second and do an average to determine the current?

The examples on Open Energy use the OpenEnergy library. I just want to get a number out to use for my own wireless transmitter.

Thanks for any advice.

2

The waveform will be roughly sinusoidal if your mains supply is half-decent!

You have to measure rapidly across the whole waveform and do RMS averaging
to get true current readings, but you can cheat and just record peak values.

Remember to record the midpoint reading as your baseline before calculating -
you can calibrate this by averaging a whole number of cycles at full sample rate.