How physical attributes of transient voltages limit the efficiency of SPD array

This study was conducted to understand what inherent limitations are associated with SPD arrays in confronting with real transient over voltages. To devise the study 403 transient voltages were selected with different physical attributes covering a range of peak-to-peak voltages, starting from 175 V up to 2861 V. The sample comprises 218 cloud-to-clouds and 185 clouds to ground generated transient voltages with mean and median values of 676.80 V and 551.00 V respectively. Impulses were segregated into three subclasses based on their physical attributes and assessed the tendency to drift through the protection array once they placed at the +90, zero and -90 phaser angles. The study revealed that 100% of positive impulses in the sample could drift through the selected array once pitched at any phaser angle on 230 V, 50 Hz utility signal. It was observed that out of the negative pulses, 90.35% at +90, 74.39 % at zero and 42.21% at -90 phaser angles, could freely move through the array. In addition to that, almost 100% of the positive portions of bipolar impulses too can reach the sensitive systems through the protection array irrespective of the pitching phaser angle.