Susceptibility of Current Transformer Measurements Due to Pulsed Currents

The use of more energy efficient solutions and products contribute to the increased use of non-linear equipment, for example in households. Inherent to the switching nature of such equipment, the currents show a pulsed behavior with high peak values and fast rising slopes. Consequently, this increases the conducted emission and many electromagnetic interference problems have been reported. When analysing such problems the accurate reconstruction of a current waveform is of importance. For this, suitable current sensing elements are needed, of which the current transformer is a widely used sensing principle. However, this paper presents the susceptibility of current transformers when measuring pulsed currents that are represented by square-wave signals. As a consequence the measured current does not represent the actual current accurately.