Current distribution and electric field inside a gasometer due to direct lightning

Gasometers are used in Austria to store a big quantity of explosive gas and represent exposed objects due to lightning of their height of several 10 meters. A floating disk on the top of the gas inside the tank divides the gasometer volume into two chambers, one at the bottom filled with gas and one above the disk with seldom explosive gas mixture (gas and air). According to the lightning protection standard EN 62305 on structures are taller than 60 m a lightning stroke to the side of the structures may occur, especially to corners and edges of the surface. Due to the average lighting flash density in Austria it is important to ensure the protection against direct strokes and to ensure no uncontrolled discharge inside the gasometer tank. To evaluate the effect of lightning inside the gasometer shell, a numerical simulation model was performed to investigate the current distribution and electric field strength inside the gasometer. With the distribution of the electric field strength, the voltage potential in several points and furthermore the voltage difference could be calculated.