High Precision Determination Methods of Time to Peak of Switching Impulse Voltage

In IEC publication 60060-1, “high-voltage test techniques”, the time to peak Tp of the switching impulse voltage is defined as “the time interval between the actual origin and the instant when the voltage has reached its peak value”. In this case, it is very difficult to determine precisely the time to peak due to the flatness of the switching impulse around the peak. The situation becomes even more so when digitally recorded switching impulse data include noise around the peak. Therefore, IEC 61083-2, “Digital recorders for measurements in high voltage impulse tests” introduced, as an appendix, an approximation formula which determines the value of Tp from the interval time between the instants when the switching impulse reaches 30% and 90% of the peak value in its front. Authors checked the formula and propose more precise approximation formula and a graphical method. The details of the newly proposed methods are discussed in this paper.