Furse Earthing & lightning protection

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Vydal: ABB s.r.o.

Strana 114 z 132

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Type arrangement This arrangement essentially fully connected ring earth electrode that sited around the periphery the structure and contact with the surrounding soil for minimum 80% its total length (i. The choice of material for the earth electrode and its connections vital importance. The agreement of the operating authority owner the relevant systems should obtained prior to any bonding taking place.e. Foundation earth electrodes This essentially type earthing arrangement. This will minimize any chance partial lightning current being introduced internally the structure. 20% its overall length may be housed say the basement the structure and not direct contact with the earth). the electrical insulation) between the external LPS and the structural metal parts essentially required. Three basic earth electrode arrangements are used: • Type arrangement • Type arrangement • Foundation earth electrodes Type arrangement This consists horizontal vertical earth electrodes, connected each down conductor fixed the outside the structure. So, the lightning discharge strikes the lightning conductor, cannot ‘bridge the gap’ and flash over the adjacent metalwork. 114 FURSE® EARTHING LIGHTNING PROTECTION QUALIT SOLUTIONS FOR SAFEGUARDING PEOPLE, STRUCTURES AND SERVICES .— Technical reference IEC/BS 62305-3 Physical damage to structures life hazard Earth termination system The earth termination system vital for the dispersion lightning current safely and effectively into the ground. any additional lengths electrodes are required they need meet the same criteria those for type arrangement.e. This can achieved placing lightning conductors sufficiently far away from any conductive parts that have routes leading into the structure. A good earth connection should possess the following characteristics: • Low electrical resistance between the electrode and the earth. The standard recommends single integrated earth termination system for structure, combining lightning protection, power and telecommunication systems. Separation (isolation) distance the external LPS A separation distance (i. will be buried soil for many years has be totally dependable The standard advocates low earthing resistance requirement and points out that the earthing system should have overall resistance to earth path Ohms less. The lower the earth electrode resistance the more likely the lightning current will choose flow down that path preference to any other, allowing the current conducted safely and dissipated the earth • Good corrosion resistance. It comprises conductors that are installed in the concrete foundation the structure. Foundation earth electrodes can used augment the steel reinforcing foundation mesh