Abstract
This paper clarifies a source for estimate error of an input voltage waveform of a capacitive voltage divider, when a frequency transform method is applied. From experimental and numerical analyses, an offset voltage of a digital waveform recorder causes significant error to an estimated voltage waveform. Because the offset voltage acts as DC. error, the effect of the offset is quite significant for an input wave which has more DC. component such as a switching surge waveform compared with a lightning surge.
An offset voltage correction method is proposed in this paper. This method is also applicable to the surge waveform is superposed upon a steady state sinusoidal voltage. Estimated inputs corrected by the proposed method show a good agreement with input voltage wave forms.
The input voltage-waveform estimation-method with the offset correction has quite high generality, and is applicable not only to lightning but also to switching surges.
