Blixtströmsfördelning på kommunikationsmaster - mätningar och beräkningar på en skalmodell

This report presents the results of a study concerning comparisons and evaluation of different simulation models for lightning current distribution on communication towers. This work is in line with the Swedish Defence Material Administration´s (FMV) ambitions to define relevant protection levels for electronic equipment connected to cables in communication towers. In order to specify protection requirements for electronic systems, the expected level of signal disturbance due to a lightning strike must be determined. It is desirable that the level of disturbance can be determined by use of simple simulation tools since full scale testing is complicated, time consuming and expensive. This report shows how different lightning current simulation models can be applied on a relative complex structure. At a first stage, the simulation models have been verified by comparisons with measurement on a scaled communication tower mounted on a metallic groundplane. Hence, realistic ground effects are not included in this study. The model scale is 1:100. The parameters that have been studied are the peak current amplitude and the rise time of the current pulses that occur at different positions on the tower configuration. The results show that the moment method and the Transmission Line model (TL-model) correspond well with measurements. The TL-model calculates the coupling to an internal wire inside the tower better than the moment method. Resonances are more accurately calculated using the moment method since radiation is not included in the TL-model. Another conclusion from the results is that it is important to model the lightning channel correctly.