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ADE7753 Current Measurement Question

Question asked by pico20191 on Apr 15, 2013
Latest reply on Apr 19, 2013 by hmani

Hi

I have an ADE7753 circuit design that I would like to adapt to sum voltages on 2 phase legs and sum the currents of those phases sensed by 2 different Current Transformers. 

For this, I reference the V2N and V2P to the different phase legs (120V each), and get the expected 208V read by the 7753.  I then hook 2 current transformers, each serving one phase leg, in series and connect the resulting P and N to V1P and V1N, but I do not read the expected current.  If I just connect 1 of the CT’s to the ADE (either one), the circuit works and I read the expected current.  Each CT has its own burden resistor network.

In text, the circuit looks like :

ADE V1N -> CT_B minus -> (CT B) -> CT_B plus -> CT_A minus -> (CT A) -> CT A plus -> ADE V1P

Each CT pin is connected to analog GND via a 4.99 ohm burden resistor.

 

Am I wrong in expecting this to work?  I realize that the implementation is a little strange, but we would like this same basic design to function in 2 different modes.

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