Induced voltages in a low-voltage power installation network due to lightning electromagnetic fields: An experimental study

This paper presents the experimental results on the induced common-mode (CM ) voltages in a residential low-voltage power installation (LVPI) network e xposed to electromagnetic fields from lightning, The objective of this inve stigation was to find out the severity of induced voltages in a low voltage network due to direct coupling of the lightning electromagnetic fields wit h the network in the absence of transient overvoltages coming through the d istribution lines. Therefore, during the experiment the LVPI network was di sconnected from the distribution network to exclude conducted transients in the measured signals entering through the mains. The induced CM voltages i n a power outlet of the network were measured simultaneously with the verti cal component of the electric field near the installation. The sequence of induced voltage events during the complete duration of one negative cloud t o-ground (CG) flash, one positive CG flash, and one cloud hash (CC), though t to be typical, is presented simultaneously with the electric held, It is shown that in addition to the return strokes in ground flashes, other disch arge events taking place in the cloud; notably, the bipolar pulse trains as sociated with the initiation of both CG lightning and cloud lightning, are also important in determining the transient environment of electronic devic es connected to a LVPI network. Flashes at a distance of about 25 km produc ed many induced-voltage pulses as large as 100 V, six such pulses in a time period of 0.4 ms in a negative CG flash, and 11 such pulses in a time peri od of 3 ms in a CC that immediately followed the ground flash.