50/60Hz Leakage and Bearing Currents

Rogowski coils can be used to measure relatively small currents at 50/60Hz and as well as higher harmonics from a few 100mA to several 10A’s. 

For example, in very large machine shaft diameters (up to 3m in some cases), Rogowski coils can be used to measure leakage currents that result from non-symmetrical magnetic fields in the motor (or generator) due to rotor asymmetry, or arising from capacitive coupling from the VSD or even electrostatic events close to the motor such as lightning or discharge from local coupled machines.