![]() The earth’s potential around the point of impact rises dangerously. In the latter two cases, the hazardous currents and voltages are transmitted by the power supply network.Ī lightning stroke can fall near a building (see Fig. It is the electromagnetic radiation of the lightning current that produces a high current and an overvoltage on the electric power supply network. A lightning stroke can fall near an electric power line (see Fig. J5 c).The overcurrent and overvoltage can spread several kilometers from the point of impact. A lightning stroke can fall on an overhead electric power line supplying a building (see Fig.by indirect impact of the lightning strike on the building:.by the direct impact of the lightning strike on the building (see Fig.Lightning strikes can affect the electrical (and/or electronic) systems of a building in two ways: Lightning is a high-frequency electrical phenomenon that causes overvoltages on all conductive items, especially on electrical cabling and equipment. Moreover, the cost of operating losses may be far higher than the value of the equipment destroyed. faults generated in the running of programmable logic controller programs and control systems.disturbances caused to computers and telecommunication networks.But it is very hard to assess the consequences of: The cost of repairing the damage caused by lightning is very high. Lightning damages electrical and electronic systems in particular: transformers, electricity meters and electrical appliances on both residential and industrial premises. The energy conveyed by the lightning stroke is therefore very high.įig. J3 – Examples of lightning discharge values given by the IEC 62305-1 standard (2010 – Table A.3) As can be seen, 50% of lightning strokes have a current exceeding 35 kA and 5% a current exceeding 100 kA. The table in Figure J3 shows some lightning strike values with their related probability. Lightning flashes hit the ground at an average of 30 to 100 strokes per second, i.e. These storms are accompanied by lightning strokes which represent a serious hazard for persons and equipment. of short duration (from a microsecond to a millisecond)īetween 20 storms are constantly undergoing formation throughout the world.of high frequency (approximately 1 megahertz).of several thousand amperes (and several thousand volts).Lightning strokes in a few figures: Lightning flashes produce an extremely large quantity of pulsed electrical energy (see Figure J4) Overvoltage characteristics of atmospheric origin Overvoltages caused by electrostatic discharge: very short overvoltages (a few nanoseconds) of very high frequency caused by the discharge of accumulated electric charges (for example, a person walking on a carpet with insulating soles is electrically charged with a voltage of several kilovolts).Power-frequency overvoltages: overvoltages of the same frequency as the network (50, 60, or 400 Hz) caused by a permanent change of state in the network (following a fault: insulation fault, breakdown of the neutral conductor, etc.).J1) caused by a change in the steady-state in an electrical network (during operation of switchgear). ![]() Switching surges: high-frequency overvoltages or burst disturbance (see Fig.Four types of overvoltage can disturb electrical installations and loads: ![]()
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