The ACS712 measures current in two directions.  It means that if we sample fast enough and long enough, we sure to find the peak in one direction and the peak in another direction as the ACS712 have 5 μs output rise time in response to step input current. We are measuring AC current of 50Hz i.e. 20mSec per cycle and we get around 4000 Samples in one cycle.

With both peaks known, it is a matter of knowing the shape of the waveform to calculate the current.   In the case of line or mains power, we know that waveform to be a SINE wave.   Knowing that allows us to apply a basic electronic formula to yield a decent result.

RMS Current =  root(2) * Peek Current Continue reading AC Current Measurement using ACS712 →