# 4. CALCULATING THE PROTECTION RELIABILITY OF THE GRID

From a series of articles The Truth About the Lightning Protection Grid.

From the electrophysical standpoint, the grid is a multi-wire system, for which calculations may be performed, e.g. using the probabilistic technique that was developed almost 50 years ago by the Krzhizhanovsky ENIN and that is still in use in Russia. Using the technique, all protection zones were generated for the Lightning Protection Instruction SO-153-34.21.122-2003. The software is publicly available on the website.

Thus, the calculation can reproduce the efficiency of the grid operation in its normal conditions. It is assumed that, when it is located at the height of 30 m above the ground level, it protects people and equipment at the top floor of the building having a dielectric roof. For a building 48 x 24 m, the grid 12 x 12 m is used in the calculation software with three wires, 48 m each, and 5 perpendicular wires, 24 m each. For the 6 x 6 m grid over the same building, 14 wires should be added in the software. The variable parameter in the calculation is the elevation of the grid over the protected building elements.

Fig. 2.

Сетка 12 х 12 м - Grid 12 x 12 m
Сетка 6 х 6 м - Grid 6 x 6 m
Вероятность прорыва - Breakthrough probability
Здание 48 х 24 м - Building 48 x 24 m
Превышение сетки, м - Grid height, m

Fig. 3.

Сетка 12 х 12 м - Grid 12 x 12 m
Замкнутый трос 48 х 24 м - Closed wire 48 x 24 m
Вероятность прорыва - Breakthrough probability
Здание 48 х 24 м - Building 48 x 24 m
Превышение сетки, м - Grid height, m

E. M. Bazelyan,Э. М. Базелян, Dr. Sc. (Eng.), Professor
Krzhizhanovsky Energy Institute, Moscow

Read further 5. The Reason For a "Strange" Grid Operation.

Related Articles: