I’m sending the Vout of an ACS712 20A to an ADC pin on Arduino Uno. According to it’s datasheet, the Output sensitivity is 66mV/A. So what I do is multiply by 5/1024, then -2.5V and then divide by 66mV/A or 0.066V/A
When it’s a resistive load, I get the same Amp value as my Tester does, but when it’s an inductive load, I don’t get a quality measure. I mean, with an AC motor, my tester prints 0.3A and my ACS712 ‘‘senses’’ 1.2A. What could it be? Do I have to make a special filter? I think what my ACS712 senses is some harmonics produced by the motor’s inductive load.
I can think of three possible issues (or a combination thereof):
- Electrical noise on the ADC input line. Check with an oscilloscope.
- The sensor senses peak rather than RMS.
- You’re not actually supplying only 0.3A.