Current Impulses in the Lightning Protection System of a Test House in Poland

The full scale test house was equipped with the lightning protection system and connected to the 15 kV/400 V transformer station. The simulated stroke current was injected into the installation with a current surge generator. Distribution of current in the lightning protection system and connected power supply installation is presented. Measurements were done for several configurations of the LPS, and for current amplitudes ranging from 1 to 10 kA. The results indicated variation with both the amplitude and the shape of the waveforms. The resistance was measured for several groundings individually and for entire grounding system with respect to the surge generator location. Measured waveforms showed frequency-dependent behavior of the circuit. Therefore, in order to improve current simulation accuracy the grounding system impedance should be considered rather than pure resistance. The vertical ground rods of the test house have capacitive impedances, while the long underground cable connected to the grounding system of the transformer has inductive impedance.