Analysis of Full and Chopped Lightning Impulse Voltages from Transformer Tests Using the New K-factor Approach

The analysis of the lightning impulses is made graphical according to IEC 60060-1: 1989. A new algorithm has been proposed to analyse the parameters, front time, time to half, peak value, of full and chopped lightning impulses. The algorithm provides a procedure for obtaining the parameters of the impulse voltages from waveforms with varying degrees of distortions in the front part of the impulse. Oscillations or overshoot in the peak region of the impulse are such distortions. The new algorithm was tested in different laboratories with different program languages and the results were compared to the IEC 60060-1: 1989 evaluation. Investigations with the new k-factor approach are already made with 52 TDG test data but the scientific view of real test data is missing. Therefore, full and chopped lightning impulses of transformer tests from manufacturers were investigated with the global and the residual filtering methods and were compared to the IEC 60060-1: 1989 evaluation.