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# [ADE9000] How to calculate physical(real) value with xRMS value?

Hi, I'm the user of ADE9000 evaluation board.

I'm stuck how to get real physical value with xRMS value.

For your information, I connected 2 line- live and neutral line to VAP and VAN respectively to test single phase output, 220V. And I also connected IAP and IAN to each line of CT sensor(1000:1) respectively.

A hole of CT sensor is linked to the neutral line of 220V.

And I got the RMS value at the RMS window of ADE90xx evaluation software.

Here's the value.

- AIRMS : 224,817 decimal (PGA_IA : x1 / ADC_REDIRET_IA : 7 / AIGAIN : 0 / AIRMSOS : 0)

- AVRMS : 33,908,007 decimal (PGA_VA : x1 / ADC_RED_VA : 7 / AVGAIN : 0 / AVRMSOS : 0)

- Full-scale ADE code of xRMS : 52,702,092

I think it's right way to calculate with CONVERSION CONSTATNS but i don't know how to calculate IFSP and VFSP.

Referring to the SYSTEM PARAMETERS, the IFSP value needs burden resistor value, voltage divide resistor value, V nominal, I nominal, CT ratio etc. However I have no idea how to calculate with is value especially current transfer function and voltage transfer function(Vrms/Arms).

- V nominal = 220Vrms

- I nominal = 0.27Arms

- Frequency = 60 Hz

- CT ratio = 1000:1

- Burden resistor = 10Ω * 2 (20Ω)

- Voltage Divider = ?? (I didn't customize ADE9000 eval board, so the R7A, R8A, R9A value would be 330kΩ, but it dropped 220kΩ when I connect VAP and VAN pin to live and neutral line. It's so weird. Did i connect wrong?)

Please let me know how to solve this problem.

Parents
• Hi gary,

As you mentioned,I totally understand whole steps the theoretical value, 16,399,519.

But what happens with my Measured Codes, 33,908,007? It's almost 2 times more! I think it's not a predictable value if considering calibration things.

As you said, you can totally guarantee the value of resistor calculation, R11A/(R7A+R8A+R9A+R11A), right?

I still don't understand why the R10A is not included when calculating the voltage divider.

Moreover I don't get it when is the VAN port used if all the single phase and 3 phase should connected to VAP and NEUTRAL point.

And also, if your saying is right, your company should modify the information of AN-639 APPLICATION NOTE, page 13.

regards,

ghsung

AN-639applicationnote.pdf
• Hi gary,

As you mentioned,I totally understand whole steps the theoretical value, 16,399,519.

But what happens with my Measured Codes, 33,908,007? It's almost 2 times more! I think it's not a predictable value if considering calibration things.

As you said, you can totally guarantee the value of resistor calculation, R11A/(R7A+R8A+R9A+R11A), right?

I still don't understand why the R10A is not included when calculating the voltage divider.

Moreover I don't get it when is the VAN port used if all the single phase and 3 phase should connected to VAP and NEUTRAL point.

And also, if your saying is right, your company should modify the information of AN-639 APPLICATION NOTE, page 13.

regards,

ghsung

AN-639applicationnote.pdf
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