Standard DC Discharge Test Method for the Inductors Characterization: Stray Factors, Uncertainty and Repeatability

This paper deals with the practical application of the so called DC discharge test method described in the international standard EN 60076-6 for the measurement of the magnetic characteristic of inductors, namely the plot of the linked magnetic flux vs the inductor current. The standard procedure above is applied here to a benchmark inductor with laminated FeSi core and suitable air gaps made for the harmonic current mitigation, using different periods of the transient discharge. The aim of this work is to underline some unexpected phenomena during the test, due to stray factors, that can affect the uncertainty and repeatability of the test. Moreover, the paper indicates, according to the analysis done, how to mitigate these effects. The practical feasibility and the advantages of the proposed modification are shown using the benchmark inductor.