Hello guys! I'm using two analog inputs voltage & current with serial communication from arduino to labview. I use ACS712 for the current sensor. The readings I get are ranging from -6 to +5 from the AC signal after the calculations. If I take the RMS, I will get around 3.9 - 4.0. I use 230AC supply with load 229ohms so I should get around 1.004? The value I get should be near to 1 but I'm getting 3.9 RMS? I've double checked the hardware(connection) and software(calculations) and I don't think there is anything wrong? What should I do? This value I'm getting is totally far from 1A that I should be getting! I'm taking the reading from Analog input 0 to divide 1023 then * 5000. Then I minus the 2500 offset and divide 185. Here is my code: const int analogIn0 = A0;const int analogIn1 = A1;int mVperAmp = 185; // use 100 for 20A Module and 66 for 30A Moduleint RawCurrentValue= 0;int RawVoltageValue= 0;int ACSoffset = 2500; int Denominator = 0;float AcVoltage = 0;float Voltage0 = 0;float Voltage1 = 0;float Amps = 0;void setup(){ Serial.begin(9600);}void loop(){ RawCurrentValue = analogRead(analogIn0); RawVoltageValue = analogRead(analogIn1); Denominator = 10000/130000; Voltage0 = (RawCurrentValue / 1023.0) * 5000; Voltage1 = (RawVoltageValue / 1023.0) * 5000; AcVoltage = (Voltage1 / Denominator ) ; Amps = ((Voltage0 - ACSoffset) / mVperAmp); Serial.print(Amps);Serial.print(", ");Serial.println(AcVoltage);} Really appreciate if you guys can help!

LabVIEW

Wrong AC Current reading?

Author

It's alright I think, if I just divide by 4, I still can get the correct reading regardless if I change the load.. So I guess probably there is a part of calculation or reading with mistake. Anyway, thanks for your help!

Message 11 of 12

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I hope you are not using the results of your measurement for anything which is critical to safety, or which will be published or used as part of a thesis.

Multiplying by an arbitrary "fudge" factor without any more justification than "it gives the answer I want" is not acceptable behavior for most purposes.

You really should find out what is going on.

Lynn