Currents, Charges and Fields — Lesson 2

This lesson covers the properties of lightning and its influence on protection systems. It delves into the characteristics of lightning such as currents, charges, and electromagnetic fields that affect earth-bound systems. The lesson also explains the process of a lightning flash, including the leader phase, return stroke, and continuing current phase. It further discusses the effects of lightning on structures and the importance of return strokes and continuing currents in lightning protection. The lesson concludes with a discussion on step and touch potential due to lightning and the need for designing protection systems to mitigate these risks.

Video Highlights

00:13 - Vertical electric field waveshape
08:25 - Lightning flash current from triggered lightning
18:02 - Lightning return stroke current and parameters
23:00 - Electric field parameters from cloud to ground lightning
29:43 - Induced voltages from lightning
33:22 - Exploding wires due to impulse lightning type currents
38:26 - Potential rise in buried earthing grid
41:48 - Lightning current on cable shields

Key Takeaways

- Lightning has two main properties that affect earth-bound systems: currents and charges from a lightning flash, and the electromagnetic fields it produces.
- The process of a lightning flash involves a leader phase, return stroke, and continuing current phase.
- The return strokes and continuing currents are the most important aspects of lightning protection.
- Lightning can cause significant damage to structures, including heating effects, potential rise of grounding, and exploding wires.
- Step and touch potential due to lightning can be harmful to humans, hence the need for designing protection systems to mitigate these risks.