Hi ,

m Designing energy meter using ade7880

I am using 252:1 external CT with max. input of 63A. Output current for 63A input is 250ma.

Using following formula for Burden resistor in evaluation i am calculating the values according to my CT.

R1=R2=1/2*(0.5/root2)*(n/Ifs)

I am taking following values to be put into the formula:

n=252

Ifs(rms)=63A/root2=44.55A

I am getting the result of burden resistor as 1 ohms.

Please confirm the above solution and correct me if am wrong.

Thanks

With Regards

anur

Hi anur

The calculation seems to be correct as long as you are aware that you are fixing the setup in such a way that your maximum input current will exactly equal to the analog full scale of the IC. Though, it is fine and safe to do so, if you feel the need to provide a little headroom for the possibility of current exceeding the maximum value that you have stated or any other sudden transients, you may do so by reducing the value of your burden resistors suitably.

Regards

hmani