AnsweredAssumed Answered

ADE7868 linearity issues on current channels

Question asked by sedgewicks on Jan 29, 2016
Latest reply on Feb 8, 2016 by hmani

Hello,

while testing ADE7868 on a custom board we are experiencing linearity issues on the current channels.

 

We have 2500:1 CTs connected to the current channels, these are the values obtained for various points of operation (ADE uncalibrated).

 

P.1 I=0.28A

I1 3632 I2 3738 I3 3475 V1 3014804 V2 3011450 V3 3014501

I1r 0.007709251 I2r 0.007490637 I3r 0.008057554

 

P.2 I=1.62A

I1 19807 I2 19786 I3 19506 V1 3002985 V2 2999628 V3 3002679

I1r 0.008178927 I2r 0.008187607 I3r 0.008305137

 

P.3 I=2.91A

I1 35405 I2 35204 I3 35195 V1 3014990 V2 3011596 V3 3014684

I1r 0.008219178 I2r 0.008266106 I3r 0.00826822

 

P.4 I=3.34A

I1 40660 I2 40387 I3 40288 V1 3011103 V2 3007706 V3 3010741

I1r 0.008214461 I2r 0.008269988 I3r 0.00829031

 

I1=AIRMS I2=BIRMS I3=CIRMS

I1x=Amps/LSB ratio

 

As you can see, the response is not linear, and phase current 3 behaves strangely.

 

We already verified the CTs and their are linear, the behaviour is the same even swapping CTs.

Attenuation networks and burdens are the same on all the 3 lines.

 

What can we do?

Thank you.

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