Rogowski Coil with Ferromagnetic Core for Precise Monitoring of Low-frequency Currents

Abstract

Sensitivity of precise Rogowski coils can be increased by using low-permeability magnetic core instead of air core. This allows to increase the resolution for small current values. We have studied an impact of cores with µr = 14 and 26 on linearity, frequency dependence, crosstalk from external currents and sensitivity to misplacement of the measured current. Both 3D FEM simulations and measurement were used. While we found negligible effect on crosstalk and resistance to misplacement and also on frequency characteristics, the linearity was significantly degraded. However, the linearity error in case of µr = 14, 80 mm diameter Rogowski coil with 1000 A range is still below 0.2 %, which is sufficient for energy meters.