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ADE7912: circuit configuration

Question asked by apenasa on Dec 10, 2013
Latest reply on Dec 20, 2013 by apenasa

Good morning everybody.

I'm developing a system to monitoring the energy consumptions for industrial applications.  The system is based on a direct measure using shunt and voltage divider, so was chosen an ADE7912 to convert the current and voltage signals into digital form.

The main characteristics of the meter are:

  • Nominal current 48A
  • Range from 1.5A to 100A
  • Bandwidth 2.5KHz
  • Suhnt resistance value 300 uOhm

 

How you can see into the attached configuration, there are two anti-aliasing filters (LPF) in front of the differential current channel. I need to increase their cut-off frequency from  4.8KHz to 48KHz to avoid phase changes in the frequency range from 400Hz to 5KHz. For this purpose i changed the R15 and R16 with a 3.3KOhm resistance, and the C12 and C15 with a 1nF. I have some question about this operation:

  1. Is the attenuation of 20dB at 500KHz (half of sampling frequency) sufficient to avoid aliasing?
  2. Is it also necessary to change R14, R13, R12 and C11, C9, C10 with the same values of R15 and C12?

 

And finally, it is possible to remove the protection diodes in front of the channels of the current and voltage, and replace them with three varistors connected between the phases A, B, C and neutral?

 

Best Regards,

AP

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