Sliding discharges in lightning protection, a ZANDZ project webinar, Professor E.M. Bazelyan
Sliding Discharges in Lightning Protection, a ZANDZ project webinar by Professor E.M. Bazelyan. Watch other webinars on lightning protection and grounding: https://bitly.su/quGYLaya
Webinar Contents:
05:32 Dangers of Sliding Discharge
08:01 Do regulatory documents not address the dangers of sliding discharges?
08:46 Experiment at a Research Institute
10:55 Soil Breakdowns According to Regulatory Documents
12:25 Actual Soil Breakdown Experimental Parameters
14:16 Formation Mechanism
15:12 Specific Resistivity of Soil and Black Steel
16:20 Ionization in Soil
17:44 Streamers Are Not Required to Form a Spark Channel in Soil
21:25 Computer Calculation Methodology
23:35 Validation of the Calculation Model
25:34 Numerical Simulation of Spark Channel Growth Dynamics
26:45 Effect of Lightning Current Amplitude
28:45 Reducing Ground Resistance to Lightning Current Amplitude
32:11 Negative Channel Phenomenon
32:58 Latest Experimental Research
35:52 Measurement Results
36:48 Lightning Current Fragmentation
38:02 Reducing Ground Resistance
39:24 Channel Interception by a Grounding Bus
41:47 Forced orientation of the sliding channel
43:52 Mobile generators
46:40 Rope lightning rod system
49:35 Requirements for the protective circuit around the object
50:35 Combining the lightning rod grounding conductor with the complex grounding conductor of the object
52:40 Isolation of lightning protection
55:06 Spark discharge trajectory
56:20 Free-standing lightning rod
59:35 Statistics of sliding discharges
1:02:00 Size of the building spot and area for the installation of rope lightning rods
1:03:26 Lightning rod and grounding circuit
1:05:43 What determines the number of descents
1:06:34 Lightning protection at Baikonur
1:10:15 How to calculate the distance of the circuit placement from the protected object
1:11:05 Lightning protection of a building with metal Elements
1:12:50 Clarification on Baikonur Protection
1:15:09 Is it sufficient to ground the conductor loop at a single point?
Webinar program: the nature of the phenomenon, the danger posed, a perspective from regulatory documents, practical countermeasures, and issues that remain to be resolved.
It has been known since almost the beginning of the last century that, upon reaching a lightning rod or some other ground-based structure, lightning can continue to develop by forming a spark channel along the ground surface. Such sliding discharges can travel tens of meters, leaving characteristic marks on the ground surface, similar to furrows in a field. Thus, lightning current can penetrate the protected area not from above, but from below, bypassing installed lightning rods.
Until a few years ago, it was believed that extended sliding channels were typical only of high-resistivity soils, where their length could be on the order of hundreds of meters. Recently, Russian specialists developed a mobile pulse current source with record-breaking parameters, capable of simulating lightning currents with amplitudes up to 100 kA. Tests using it have demonstrated the ability to generate sliding spark discharges tens of meters long in highly conductive soils, such as black soil or moist clay. These can pose a very serious hazard to underground control and automation cable circuits and can ignite leaking liquid hydrocarbon fuels or heavy gas mixtures, thereby causing fires.
Unfortunately, Russian regulatory documents RD 34.21.122-87 and SO-153-34.21.122-2003 do not mention sliding discharges or methods for mitigating their effects. For this reason, the planned webinar will focus on calculation methods for estimating the maximum length of spark channels, methods for reducing it, and means of preventing their penetration into protected areas. Watch other webinars on lightning protection and grounding: https://bitly.su/quGYLaya