An overview of technical challenges in the design of current transformers

This paper presents approximate equations that may be used to obtain the lower cutoff frequency f_L and higher cutoff frequency f_H and thereby the bandwidth of a current transformer. The equations are validated by a PSpice simulation. The Bode plots for both low-frequency range and high-frequency range for a selected design are presented. Also an overview of the various problems that should be considered while designing a current transformer is given, including leakage inductance, stray capacitance, ringing, parasitic resonance, saturation, and mechanical clamping