Determining the test voltage factor function for the evaluation of lightning impulses with oscillations and/or an overshoot

In order to remove the present IEC 60060-1 and IEEE Standard 4 ambiguities in the evaluation of the test voltage when oscillations and/or an overshoot appear superimposed in a lightning impulse, at the end of the 1990s, a European Project within the Standard, Measurement and Testing (SMT) program was developed by KEMA (Netherlands), Schering Institute (Germany), LCOE (Spain), and NGC (United Kingdom) in coordination with the CIGRE Working Group 33.03. The conclusion of this European Project is a new evaluation method called test voltage function K(f) derived on the breakdown behavior of different dielectric media, that removes the standard ambiguity to determine the test voltage of an impulse with oscillations and/or an overshoot. This paper presents the experimental results of the project and deals in depth with the definition of K(f).