# ADE7758 - Calibration for Rogowski Coil

Question asked by Faustin on Apr 8, 2015
Latest reply on Apr 11, 2015 by hmani

Hi everyone,

In order to calibrate my ADE7758 for using Rogowski Coil, I designed a test card to simulate the signal provides by the Rogowski Coil (so I am trying to calibrate the ADE for using Rogowski Coil but without Rogowski Coil)

The ADE7758 is integrated on a wattmeter and it is currently working for Current Transformers instead of Rogowski Coils.

If I am right, the Rogowski Coils induce these properties :

- The output voltage corresponds to the derivate of image of the current you want to calculate

- A shift phase of +90°

- A gain of +20dB/decade

So to simulate those properties I set a derivator between my current generator and my current inputs to derivate my signal (see the attachement)

Moreover the derivator is doing the shift phase of 90° right ? Cause if I derivate the input signal which is a sinus, I get cosinus ?

About the values, I randomly choose to simulate a calculation of a 2000A conductor. The datasheet of the Rogowski Coil I will use says 109,2mV/1000A so for 2000A the output voltage should be about 220mV

I set my resistor at 1kOhm, so my current input should be : i = v / r = 0,220 / 1000 = 0,22mA

And then I want a gain of +20dB which corresponds to 20log(10), so I want RCw = 10 : C = 10 / (r * 2 * pi * f) = 10 / (1000 * 2 * pi * 50) = 33µF

So this is the way I see things but I am not sure about it, I hope this is clear, if anyone can confirm that it is good, or otherwise tell me that it is not, I am here to discuss..

Regards,

Faustin.