Evaluation of Impulse Parameters for
Standard Lightning Impulses
The
raw data are available in the respective measuring channel and subject to store
in the database or in an ASCII-file for later availability.
2. Smoothed Raw Data
The
raw data are smoothed by 200MS/s with a smoothing interval of 20 samples and
temporary stored in the virtual evaluating channel.
3. Zero Line
is
calculated as the mean value of 50 samples before the virtual origin T0.
4. Peak Value
The
peak value is calculated as the highest sample of the smoothed raw data.
5. Time instant T30
is
calculated by linear interpolation as the 30% value of the peak value from the
smoothed raw data.
6. Time instant T90
is
calculated by linear interpolation as the 90% value of the peak value from the
smoothed raw data.
7. Virtual Origin T0
is
calculated with T0 = T30 - (T90 - T30)/2.
8. Front Time T1
is
calculated with T1 = (T90 - T30)/0.6.
9. Time-to-chopping Tc
1. Tc
is pre-determined as the first value smaller than the peak value for front
chopped impulses or as the first value smaller than the voltage at chopping for
impulses chopped in the tail.
2. Tc is
calculated as the cross section of the peak value respectively of the voltage
at chopping instant for impulses chopped at the tail with a straight line
determined by the 90% value and the 50% value of the breakdown lapse.
10. Time to half
value T50
T50
is calculated as the 50% value of the peak value by linear interpolation of the
raw data smoothed with a smoothing interval of 10 samples.