Iterative calculation of electromagnetic processes in the current transformer by the approximated magnetization curve

The article gives a general analysis of the most common international practice models of electromagnetic processes disadvantages in current transformers. On the basis of these results, the authors have proposed more simpler and practical mathematical models and algorithms. These models make it possible to consider the residual magnetic induction in the current transformer, to determine all the necessary characteristics of relay protection current transformer for use in engineering. Also these models require minimal computational cost. Numerical methods for differentiation and integration laid the foundation to Models proposed by the author. Capabilities and effectiveness of the proposed models are shown by the example of the current transformer type TFNK - 330.