A new method of determining the mean curve of lightning impulses according to IEC 60060-1

In this contribution a new method for the determination of mean curves of lightning impulses is presented. The method is in accordance with the actual standard IEC 60060-1 and based on mathematical curve fitting using the least mean square (LMS) error as quality criterion and the Gauss-Newton or the Levenberg-Marquardt algorithms in order to solve the nonlinear equations. The presented procedure reproduces measured lightning impulses in a more suitable way than conventional functions and is therefore able to determine mean curves of standard lightning impulses as well as of lightning impulses superimposed by oscillations or overshoots. A comparison of results obtained with the described method and other curve fittings by using the IEC-TDG and measured data produced by a special generating circuit shows that the new method is more favourable.