Hello

I’m working on a board based on ADE7880 that should measure voltage, currents and energy in a mono / three phase system and expose all the measure values in a web page..

For the moment I’m performing all my test using only one phase at time ( because I don’t have any three phase source available in my office ).I’m

working with:

voltage = 230Vac 50Hz

load resistive that drains about 1.8Kw

TA with 50/5 amps ratio

Rshunt = 0.25 ohm

Everything seems working well with voltages and currents. If I multiply xVRMS register for a value that depends on my input stage ( 1M/1K) I get exactly

the rms value of voltage applied. If I multiply the XIRMS registers for a value that depends on TA ratio and Shunt resistor, I get exactly the rms values

of the current.

The same for the Power: By applying the equation n 21 ( pag 44 datasheet) to the XWATT registers, I get the correct value for the active power .

**But I can’t measure energy.**

By reading the “billable registers” XWATTHR I was expecting to read an increasing value, but I read only a value that move up and down, around a

certain value.

If I switch off the load, this value is a short number ( < 30 ). If I switch on the load, this value is something much bigger (20000.- 30000 or more)

but it increases and decreases time by time around this value. In one word, I don't see any "accumulation".

Also I’m not able to get any pulse out from CF1 output… I don’t know if these two fact are related…

I made several attemps with different values for the registers WTHR , ACCMODE , CF1DEN but with no results…

Can you give me some suggestions?

Thankyou in advance

Roberto

Hi r.simoncelli@antgroup.it

The line cycle accumulation procedure seems to be fine. But I have another question. What is the value set to in ZXSEL bits of the LCYCMODE register? This selects the phase voltage whose zero crossings are considered for line cycle measurements. That might need to be adjusted to point to just one phase voltage, and make sure that the particular phase voltage is more than 10% FS in amplitude level. You must get an LENERGY interrupt after 5 secs based on your LINECYC register setting ( for 50 Hz input). If not check to see if there is a SAG detection in that corresponding phase or a ZX missing interrupt.

Regarding your other question about negative PF and powers, can you provide a set of example data that you have collected which show erroneous results. State your input conditions as well. That might help me to understand where the error occurs.

Regards

hmani