Dear Kai & Other Forum Members,

At last I have had success with using rogowski coils for precisely measuring currents of the order of upto 50,000 Amperes. I wanted to post this post into old thread but sad Its closed now.

If you guys remember first I was trying to use digital approach for integration but latter I realised that the spike produced by rogowski coil when thrystor turns on is not trivial to digitally integrate since it has a very narrow width of approx 100us and is has got huge magnitude. Should it have been a non thryristor say Contactor switching the digital integration with 188 samples per cycle it would have worked fine due to absence of this spike.

At last I made my mind to use an analog integrator approach I used the circuit given by KAI here... http://www.8052.com/forum/read.phtml?id=76137

Since I wanted to do it quickly and I dont have good analog skills I used only the integrator section of the above circuit and the amplifier op-amp part totally skipped. The component values I used are...
C3=100nF
R5=4M
R4=4.7k
The rogowski signal directly connected to R4.

It worked fine and is giving repeatable correct values. I also tested this integrator for drift by keeping the ciruit on for approx 3 hours but no significant drift seen at all.

I know the integrator that I have made with three passive components and an Opamp TL082 isn't really very good but a crude effort that worked. It will be a great help if analog masters on the forum please let me know what would be the best way to do this integrator task.

Thanks & Regards,
Prahlad Purohit