[AVR] current sensing through acs712-30a

[amanpreetk]

I am using an acs712-30a hall effect sensor module for measuring ac current interfaced to adc of atmega16.
I have taken load as a 15 watt bulb and my supply is 230v AC. Now, the problem I'm facing is that, I am not getting the proper value of curent. What all formulaes shall I use to get the required value of current?

 

[KlausST]

Hi,

this is basic stuff:

P = U x I (because you have a resistive load)==> I = P / U

The rest is yours.

Klaus

 

[paulfjujo]

hello

Your ACS712-30A has a to large range for measuring 15/230=> 0.06Amps efficace !
don't forget that te output of ACS712 is also a AC signal !

 

[amanpreetk]

hello

Your ACS712-30A has a to large range for measuring 15/230=> 0.06Amps efficace !
don't forget that te output of ACS712 is also a AC signal !

Thanks for your help.
So can you suggest me a circuit so that I can interface my hall sensor with atmega16 to measure the above mentioned ac current?

 

[D.A.(Tony)Stewart]

I am using an acs712-30a hall effect sensor module for measuring ac current interfaced to adc of atmega16.
I have taken load as a 15 watt bulb and my supply is 230v AC. Now, the problem I'm facing is that, I am not getting the proper value of curent. What all formulaes shall I use to get the required value of current?

Keep in mind tungsten bulb resistance changes 10:1 as temperature rises to max and ACS gain is user choice such as x20A gives 100mV/A with 0A at Vcc/2. Gain also affects resolution S/N ratio.

 

[paulfjujo]

Is your maximum load, this 15W buble lamp ?

I agrere with extra current for the bulb at start of ignition ,
but 0,06x10=> 0,6 A maxi during a few second then 0,06 Amp only

model ACS712-5B has a range of +-5 Amps and deliver 185mV/amps
with an offset of VCC/2 as SunnyZSkyguy said in previous post.


you also need to rectify the signal to get a DC signal for an ADC input .
see Typical Application of Allegro datasheet ..

or sample the signal at ~ 10Khz to get Peak to peak values..
185*0.06*3=>about 35mV peak to peak AC signal
but Poor resolution for an ADC 10bits !

an maybe you can use an AOP LM321 amplifier to have
enough resolution for a so low value of Amps.
see Application 3 of datasheet