A technique for the evaluation of lightning-induced voltages in complex low-voltage power-installation networks

In order to gain knowledge of the effects of lightning-electromagnetic fiel d pulses (LEMP)in low-voltage power installations (LVPIs), the transient re sponse of two electrical networks was measured when they were exposed to li ghtning electromagnetic fields in the summer of 1998. Both networks were is olated from the energy supply. One network was a simple circuit installed i n a room of a single storey wooden residential house and the other consiste d of the house's whole electrical wiring circuit. The main goal of this pap er is to develop a practical method with which to estimate the transient re sponse of LVPIs to LEMP. The method uses the information contained in a sma ll portion of the time domain waveform of the electric field, which can be approximated as a unit step function and the corresponding induced voltage, which, in turn can be approximated as the unit step response. It is shown how this unit step response can be used in determining the induced overvolt age in the network due to any complex electric-field waveform. Advantages, limitations and considerations associated with the application of this meth od are also discussed.