ACS712 Current Sensor Not Working

Other Hardware Sensors
1

Hello everyone, I have ACS712 Current Sensor I am trying to measure current of 220V AC. But it keeps giving the same value even though on load. I have both tried with multimeter and ardunio.

What am I doing wrong?

Edit: According to 'jremington''s answer, its because its a sine wave and multimeter will show average which is zero. I want to update my question;

How can i measure 220V AC with ACS712 +-5A and Arduino? Is it possible?

2

How much current is flowing though it?
If no current is flowing the output will be halt of the power supply, normally if you power it with 5V with no current flowing the Vout will be 2.5V.
If you see the datasheet there is a graphic(Output Voltage versus Sensed Current) there that shows you that.
It's located at page 8.
http://www.google.pt/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CDsQFjAE&url=http%3A%2F%2Fwww.allegromicro.com%2F~%2Fmedia%2FFiles%2FDatasheets%2FACS712-Datasheet.ashx&ei=AqKFU9m2IeWg0QWl6YC4Bg&usg=AFQjCNEsuWeWEOng-Vn4AXDUAjxAgXNkjg&bvm=bv.67720277,d.ZGU&cad=rja

3

I tried to connect my LCD monitor which says 1.1A 220V AC on it. Nothing changes. Is it because of AC?

4

The current sensor senses the instantaneous current, which is a sine wave. A multimeter will show the average, which is zero current (or sensor output equal to half the sensor power supply voltage).

5

Post your code

6

Here is my method to measure current;

void getSensorValues(){
  unsigned long currentAcc = 0;
  unsigned int count = 0;
  unsigned long prevMicros = micros() - sampleInterval ;
  while (count < numSamples)
  {
    if (micros() - prevMicros >= sampleInterval)
    {
      int adc_raw = analogRead(0) - adc_zero;
      currentAcc += (unsigned long)(adc_raw * adc_raw);
      ++count;
      prevMicros += sampleInterval;
    }
  }
  
    float rms = sqrt((float)currentAcc/(float)numSamples) * (75.7576 / 1024.0);
    mySerial.println(rms);
}
7

jremington:
The current sensor senses the instantaneous current, which is a sine wave. A multimeter will show the average, which is zero current (or sensor output equal to half the sensor power supply voltage).

I'm not good at this stuff but I've read that before. Is it possible to use ACS712 with Arduino to measure 220V AC?

8

Here is my method to measure current;

Post ALL the code. The snippet that you posted is not enough to show some of the possible problems.

9

You seem to have an undeclared variable sampleInterval.

AC current will be surging backwards and forwards in the wire, changing direction at a very frequent rate, depending on which half of Japan you live in.

To determine the effective value of the current, you have to measure it many times.

10

Yes these ACS sensors are find for AC, but you need to perform analogReads frequently
to see the changing values of current.

Which sensor are you using, that one comes in 5A, 20A and 30A versions I believe.

First test it with a DC current in either direction (easy to see with just a multimeter),
that will prove its working fine. For high current DC try a car indicator bulb powered
by a car battery or car battery charger (unless you have a bench power supply handy!)