Analysis of Influencing Factors on Current Measurement Accuracy of PCB Rogowski Coil

The key to the intelligent development of low-voltage plastic shell circuit breakers is to achieve real-time and accurate detection of the internal current. PCB Rogowski coil has the characteristics of high measurement accuracy, wide measurement frequency band, small size, and low cost. Moreover, PCB Rogowski coil does not directly contact with the measured primary current in the process of current detection, which is a very safe method. However, the internal space of low-voltage plastic shell circuit breaker is compact and complex. PCB Rogowki coil placed in the circuit breaker inevitably is interfered by various factors and it is difficult to achieve the theoretical high precision. This article makes use of mathematical analysis to identify the main factors that affect the performance of PCB Rogowski coils, including the influence of temperature on the skeleton, the eccentricity accuracy of the measured primary current, and the crosstalk accuracy of adjacent phase currents. Measures are proposed to reduce or even eliminate these effects. Through the analysis of these main factors, a three-phase uniform and densely winding PCB Rogowski coil with equal area return turns is proposed in this article. Finally, the experiment verifies that the eccentricity error does not exceed 0.2% and the crosstalk error does not exceed 0.3%. The PCB Rogowksi coil proposed in this article has a good linearity and has a current measurement accuracy of 0.5%.