Map SPD clamping voltages on to spectral clusters generated by Wavelet transformation

This study employed wavelet transformation to disclose the spectrograms of IEC standard impulses and real transient voltages generated by the cloud to ground discharges. The spectral details of each impulse were subdivided into different spectral clusters and the outcome was mapped into respective voltage levels and time to develop correlations. Eventually different protection voltage levels of commercially available surge protection devices (SPDs) and the voltage levels of different spectral clusters were compared to determine whether harmful energy infringements could be possible when the spectral clusters are wrapped by SPDs. This study revealed that all IEC impulses have identical spectral clusters whereas real transient voltages demonstrated that they are inherited with much random spectral distributions. Thus, planning for foolproof through benchmarking real transient impulses against IEC impulses would not produce guaranteed outcomes. Hence, a poor selection of clamping voltages may create a permanent window to infringing a small quantum of harmful energy on a constant basis into sensitive systems to trigger silent killing of basic functional units.