Rogowski coils are " pretty easy to make" The trick is no the detection of signal (there is lots), the problem is non-linearity, and that is what you pay lots of money for. There is nothing to say it needs to be really toroidal, merely topographically toroidal, providing that that the flux generated by the conductor links the coil.

We made one by strapping two backwrapped coils to either side of our solid copper busbar. But we were measuring 2000 amps.

If you are dealing with low currents, say less than 100 A I'd look at hall effect sensors or the neat, ready made HEME sensors.

Are your waveforms sinusoidal ? What frequency are they ? An op-amp integrator will work fine, subject to the usual checks.


Steve