Question asked by vindhyachal.takniki@gmail.com on Nov 30, 2016
Latest reply on Dec 13, 2016 by vindhyachal.takniki@gmail.com

I have to measure voltage, current & active power.

1. Calculations of voltage I have done are, as per page 27 of datasheet 05.V is 1,561,400 in decimal. So I read the VRMS(0x17) & use below formula for get voltage value. Divider is 1M:1K
V = (0.5 / 1561400.0) * Vrms * 1001.0
Is this formula correct?

I have done that there were some shift in values. But after two point calibration now values i read are ok.

2. Similarly for current, page 26 gives, 0.5V is 1,868,467. I am reading IRMS(0x16), burden is 10ohm & CT is 1800:1.
I = (0.5 / 1868467.0) * Irms / 10.0 * 1800.0;
Is this formula correct?

Even after calibration, I am getting some wrong values in it. I am checking hardware if it has some issues. But right now I dont know yet.

3. In the library link above, ADE7753.h, CLKIN is defined 4Mhz at line 186. But I use 3.579545 MHz crsytal as mentioned in datsheet. So should I change this value here only? Or anything else to be changed also? OR I should also chnage crystal to 4Mhz in my board. But datasheet has 3.579545 MHz

4. I need to measure 1Watt to 6KW in the system. So at 220V(suppose), equivalent current for 1W is 0.00455A & for 6Kw it is 27.27A. I keep 30A to add safety limit
Can I measure such low current with IC while I use CT=1800:1 & burden 20ohm.