Application of IEC 62305 to a large power and desalination plant-lightning protection system

Abstract

Lightning is a natural phenomena, in which when strikes any grounded objects/structural buildings causes heavy loss including loss of human life, damage to structures, buildings, fire explosion, etc. The heavy discharge of electric charge from clouds can be safely diverted to earth by providing properly designed lightning protection system. In this paper Electro-Mechanical concept has been applied to protect the power plant buildings. The three methods such as protective angle, mesh and rolling sphere method are advised in IEC 62305. The power and desalination plant has been protected by using rolling sphere method with class I protection which is the highest level of protection available. The power plant comprises metal insulated panel roof buildings, concrete roof buildings and 65m high carbon steel stack. By applying rolling sphere method a sphere of radius 20m is virtually rolled over the buildings/structures wherever the sphere touches the building, an external/natural air termination is provided. Thus the sphere touches only the air-termination and ground. As the power plant have much electrical installation such as air-handling units, Ventilating fans at roof level separate 3m high steel structure supports for mounting the 2m high air-termination rod is used. Natural/External down conductors are provided to connect the air termination system to the low resistance earth termination system, wherever the metal roof is available with sufficient thickness they are used as natural air-termination system. The bracket component was designed to hold the above items with minimize deflection of the structure by using Finite element Analysis (FEA) techniques. With the aid of Simulation software stress and deflection were identified for the designed component. As a result, necessary changes have been opted in the structural design as to minimise the deflection level and improve the stiffness of the structure. The power plant is protected against the Lightning strikes using rolling sphere method.