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About connecting Neutral wire to AGND

Question asked by markushug on Mar 24, 2017

Hi all,

 

I have a question about the supply and sensing circuit situation of the AFE.

We use ADE7854A, supplied by a hot buck converter circuit directly from line.

The Neutral wire (N) is directly connected with AGND from the AFE.

The voltage dividers for measuring the voltages are connected between Lx and AGND, with a filter cap between VxP Pin and AGND. The VN Pin is connected to AGND by a filter too.

The current paths (secondary side of CTs) are also filtered with respect to AGND.

So far it matches with the Eval board and reference designs.

 

But now we have to do some changes at the buck converter because of EMI problems.

And now my question: If an inductor is inserted between Neutral wire and AGND (so AGND is not directly connected to N any more), do I have to expect any impacts on metering accuracy? Or will everything keep fine as it is?

 

Thanks for answers

Markus

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