Looking at Safety Criteria for Transients

We take it for granted that when an earth fault occurs on the power system that the hazards created will be assessed against a set of criteria in some appropriate or required manner. What is usually not appreciated, particularly by our oblivious public, is that there is no such assessment of hazards generated by other sources or with alternative characteristics. There is no safety criteria for lightning, static discharges or other transients sources causing hazards within the power system or to the built environment to which it connects.

Shorter events, less than a few cycles of the power system, are more complex than their longer counterparts. The transient nature of the power system itself becomes a consideration, which is treated by some some standards. But then as the durations become even shorter the nature of the hazard should no longer be even considered to be sinusoidal, and the frequency of the excitation increases. How it increases and how the response on the human body changes has not been explored.

For these reasons most of the published safety criteria only consider fault durations down to a tenth of a second and not much further. This paper is an attempt to open the conversation in this space with the goal of one day defining safety criteria for transients and lightning related events. It may be all we do is look at events down to a fraction of a cycle, but it is a beginning!

Safety Criteria
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