EXPERIMENTAL EVALUATION OF LIGHTNING PROTECTION ZONE THROUGH IMPULSE VOLTAGE TESTS ON A SCALED DOWN SHIP MODEL

Summary

Lightning protection of ships is not thoroughly addressed by the relevant international regulations although ships are potentially vulnerable to lightning strikes with a high risk of damage to electronic equipment, navigation and communication systems. For this purpose various models for the estimation of the protection zone of a lightning rod are experimentally evaluated through measurements on a scaled down metal ship model. At first the breakdown probability distributions of 50cm, 75cm and 100cm rod-plane gaps for both impulse polarities were determined using the “multiple level” method according to IEC. At the next stage the ship model was inserted in the rod-plane gap and “multiple-distance tests” were performed analogous to the “multiple level tests” in order to obtain interception probability distributions for the highest superstructure of the model. The experimental values of the interception radius and the striking distance, both referring to a 50% interception probability, are then compared to the theoretical values calculated with the Rolling Sphere Model, an Elliptical Model, a Statistical Model based on lightning interception probability and its updated version which takes proximity effects into consideration. The rolling sphere model produces results on the safe side only for negative polarity strikes, while the performance of the Elliptical Model is more accurate for both polarities in the calculation of the striking distance. Both Statistical Models yield in most cases the most satisfactory results. Proximity effects and lightning interception probability are highlighted as additional factors that influence the efficient placing of the air terminals of a ship.

Additional informations

Authors

Prosr Pavel, Bastos Marcelo , Wenger Philipp, Pihera Josef