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ADE7880 - Energy measurement

Question asked by r.simoncelli@antgroup.it on Sep 9, 2013
Latest reply on May 8, 2014 by hmani

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

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