Individual or Group Error Compensation: An Experimental Demonstration on the Frequency Response of Rogowski Coils

Instrument transformers (ITs) play a crucial role as interface elements in power systems, enabling the acquisition of electrical quantities necessary for assessing system health. Consequently, they have been a focal point in research, with numerous studies aiming to enhance their performance in field applications. One critical issue affecting the accuracy of ITs is the differentiation between type and routine tests, which underscores the need for individual or group error compensation. This study investigates the limitations of group error compensation techniques for ITs, providing experimental evidence to demonstrate their potential drawbacks. Specifically, low-power current transformers, such as Rogowski coils, were evaluated to examine variability among individual devices. The study tested three series of six devices from three manufacturers under varying temperature conditions. The findings reveal significant variability among the tested devices, indicating that group error compensation often degrades the accuracy of ITs. These results highlight the importance of considering individual error characteristics to ensure optimal performance in practical applications.