Reading AC Current through 5A Monophase AC Transformer

Other Hardware Sensors
1

Hello,
I have this item and I cant figure how to read correct current values.
I also search for examples but none from them works.

Does anybody know how to figure it (have code) or had similar problem?

Thanks!

2

Seems to be a sensor with only a digital output. With a pot to set the threshold.
Used e.g. for motor overload protection, or to see if a load is still working.
Not suitable to measure current.
Leo..

3

That appears to be a standard current transformer with an op amp precision rectifier/amplifier, producing a DC voltage output proportional to the AC current through the sense coil opening.

The product page does not provide any useful details about how to use it, so why did you buy it?

However, it should not be difficult to figure out how it works. I would run a single wire, carrying various known AC currents, through the sense coil. Apply 5V between Vcc and GND, and measure the DC output voltage with your multimeter.

Adjust the trimpot on the sensor to see what effect that has on the output voltage.

For more info on AC current measurements with Arduino, see this tutorial.

4

And let us know what you find - it may be useful to others.

5

Wow guys, you are awesome. Thanks for fast reply and for being helpful.

I ordered because on item page is written:
"The module can measure less than 5A AC current, the corresponding analog output can be adjusted"
So this can measure through analog pin or? I'm confused?!?

Also, I just measure DC out and found strange thing again. It drops from 200mV to 15mV and goes up again. When lamp is turned off, multimeter shows around 15mV?!? (Nonsense numbers). As I order few pcs, i tested with arduino second one and it shows same so, if i measure with multimeter , perhaps numbers will stay same...

6

Test it with various AC currents, some higher than 5 Amps (e.g. use a 1 kW room heater for a load), and let us know what you find.

7

Hallucin:
When lamp is turned off, multimeter shows around 15mV?!? (Nonsense numbers).

That's just the lowest output the OpAmp can give. Don't expect a high end rail to rail OpAmp. Just make sure the current you measure gives an output of say 300 mV - 4.7V and you'll be in the linear region.

Sensors are never at their best when measure <5% of their range. A simple lamp, drawing 5-10W or so, draws some 30-100 mA depending on your AC voltage (110-240V depending on your locality). That's 1-2% of the range of that sensor. If you want to measure that kind of currents you're better off with a sensor that has a 0-500 mA range or even less.

8

Hi again.
I tried almost all and get some almost accurate readings with Emon Library

Here is simple code:

#include "EmonLib.h"
// Include Emon Library
EnergyMonitor emon1;


void setup()

{
Serial.begin(9600);
 emon1.current(0, 145);             // Current: input pin, calibration.
}

void loop()
{
  
  double  Irms1 = emon1.calcIrms(150);  // Calculate Irms only 
  Serial.println(Irms1);             // Irms
  delay(100);
}

But even then, I doesnt like how it works (to get fully accurate readings, value of calculations "150" should be at least 1000+ and if there are like 10 analog emon readings, it lags too much), so I ordered ACS712 5A module.

Also, I found few videos on youtube that works and read values like a charm, even with small load as simple lamp.

What do you think about ACS712?

9

What happens when you adjust the trimpot on the module?