Is there an example of how to connect the ADE7933 with current transformers?
Hi Fausto Bartra,
The ADE7933 is an isolated ADC most typically meant for use with a shunt current sensor. If you are using a current transformer then isolation is already present in the transformer.
Could you tell me more about the application? Maybe there is a more appropriate metering IC to choose from with use with CT's. Do you need to use CT's over shunts? Is this a 3-phase application?
The maximum input level on the current channel is +/-31.25mV Peak, therefore a small burden would have to be chosen to not over range this input.
thanks for your reply
Because of the application we must use a CT
It is only a standard life-neutral and ground configuration (110V - 220V)
Adding a shunt current sensor will be more expensive and complicated
It will require some mechanical changes which are ussually very expensive
We already have a current trasnformer version with several customers
I can scale the CT output to match the ADE7933 input
I understand the redundancy of the isolation of both devices but it is simpler to use a current transformer
This device together with the ADE7978 will simplify our firmware implementation.
any notes on current transformer or any other device that you could suggest will be appreciated
I understand better now, I can also suggest the ADE7923, this is a non-isolated version of the ADE7933 with the same footprint and slightly different package (without increased creepage).
As for connecting the CT, it is very similar to using a shunt with the addition of a burden resistor. The input still should look like the diagram in the data sheet, with the 1kOhm and 33nF anti-aliasing filter.
Then a burden resistor value needs to be chosen based on the maximum current expected, the turns ratio of the CT and the full scale inputs to the current channel.
Once this burden value is found, I would recommend a center-tapped burden like the diagram above.