Evaluating Core Loss Effects in Toroidal Current Transformers:A Simulation-Based Comparative Study

This study investigates the impact of core losses on the performance and design optimization of toroidal current transformers (TCTs) by comparing iron loss and ideal lossless models in both time and frequency domains. A toroidal current transformer with a 600 A/5 A current ratio and a 120-turn secondary winding of 1.2 mm diameter wire was analysed using COMSOL Multiphysics. A 2D finite element model was developed, integrating Magnetic Fields (mf) and Electrical Circuit (cir) physics interfaces to simulate the electromagnetic behaviour of the transformer. Two models were evaluated: one incorporating magnetic core losses and another assuming a lossless core. Comparative simulations were performed to quantify the influence of core losses on magnetic flux distribution, power dissipation, and coil impedance. The results highlight significant performance deviations in the presence of core losses, particularly under high-frequency operating conditions. This study provides a structured methodology for evaluating TCT performance using Multiphysics Simulation, enabling realistic analysis of energy losses and efficiency. The findings offer valuable insights for optimizing core material selection, transformer geometry, and winding design to enhance accuracy and operational reliability in power distribution and measurement systems. © 2025 IEEE.