Proposal of Precise Approximation Formulae for Time Parameters of the Generalised Switching Impulse Voltage

This paper proposes approximation formulae which provide precise values of Tp (time to peak) and T2 (time to half-value) of switching impulse voltage waveform from the definitions T1 (front time) and T2 used for the test voltage curve of the standard lightning impulse voltage. The time to peak of switching impulse voltage waveform now has to be calculated using approximation formula provided iEC 60060-1:2010. The formula was derived from standard switching impulse waveform (250/2500 impulse) and has 2% error but yields more than 20% error for the non-standard switching impulse voltage whose time to peak value can reach 20 ?s. Using the proposed formulae, both Tp and T2 errors are evaluated within 0.01% error.