Estimation Method of the Errors Limits of Electromagnetic Current Transformers

Abstract

A method for estimating the limits of errors of electromagnetic current transformers is proposed. In contrast to the standard technique, the proposed method considers not only the basic factors, but also additional ones, that affect the results of measurements. The additional influencing factors are the residual magnetization of the core and the nonsinusoidality of the current under measurement. The method was developed and explored based on a known nonlinear mathematical model of the current transformer. By the example of the standard TOL-10 current transformer, it is shown how the limits of errors of the current transformers can be determined for the operating conditions. Based on the estimation of the error limits, an accuracy class can be accurately attributed to the newly manufactured transformers and the conformity of the limits of errors of the current transformers in service to their class of accuracy can be verified. The method also allows increasing the reliability and accuracy of the measured results and the efficiency of the current transformers without making any design alterations.