Currently, I am using the ACS712 current sensor module for measuring the peak current then computing RMS Current and thus the Apparent Power (Vrms × Irms = Apparent Power).
Currently, I am not using any method for measuring the Vrms, I am measuring Vrms directly using the Digital Multimeter and putting it in the calculation.
Now, the factor missing is the Power Factor for the calculation of True Power (Vrms × Irms × Power Factor = True Power) which is producing an error of about 20%.
I am facing problem in the measuring the Power factor of the appliance using ESP Microcontroller.
Following is the circuit diagram I am implementing, Please have a look at it and let me know if I am making any mistake which is also responsible for the error.
Best Answer
Trying to measure the power factor seems easy but in reality it's a tortuous path and I'll cut to the chase - don't bother because you'll be dissapointed. The only way you can reliably measure power factor is calculate apparent power, calculate real power and take the ratio.
For relatively pure sine waves you could use zero crossing detectors and calculate phase angle and take the cosine but this is not practical in a real-world situation. Harmonic distortion of the current waveform is such that there is no reliable method. Consider the current taken by a household appliance that uses a bridge rectifier and smoothing capacitor: -
As you can see the current is not sinusoidal but pulsing in nature and trying to establish phase angles from the above is a waste of time.
My answer here goes into greater detail about why zero-crossing is so problematic.
Ditto this answer.
To measure true power you mutiply the voltage waveform and the current waveform and take the average: -