Indirect lightning induced surge Due to the opening and closing action of nearby electrical equipment, overvoltage transient surge may occur on AC power line. Lightning strikes nearby can also produce transient surges on AC power lines, especially in outdoor environments. At the moment of a lightning strike, the level of electrostatic discharge from the cloud to the ground usually reaches millions of volts. Lightning strikes occurring several miles away can induce induced voltages of up to several thousand volts on current carrying copper wires, such as underground cables for street lamps. These indirect shocks are characterized by specific waveforms that usually contain a large amount of energy in excess of 1000a2s.About 70% of lightning strikes occur on land in the tropics, where most thunderstorms occur. African countries have experienced the worst and longest lightning strike in history. The most frequent lightning strike is located near kifka, a small village in the eastern mountainous area of the Democratic Republic of Congo, at an altitude of about 975 meters. On average, there are 158 lightning strikes per square kilometer per year in the region. A large area around the site has also been severely affected, as lightning induced surge impacts increase the risk of damage to outdoor LED lighting. According to NASA's research on lightning frequency around the world, there are similar lightning frequencies in central and South America, Africa, South Asia and Southeast Asia. Therefore, in the United States, we suggest that the equivalent Surge immunity should be between 5ka and 10kA. For other regions with less lightning frequency, such as Europe, East Asia and Australia, low surge immunity from 3KA to 5ka can be considered. A kind stormy weather, this type of indirect lightning energy will have adverse effects on outdoor LED lighting devices. Luminaires are vulnerable to damage in both differential mode and common mode conditions Differential mode: high voltage / current transients between the phase and neutral terminals or between the phase and phase line terminals of the luminaire may damage the components in the power supply unit or LED module board. Common mode: high voltage / current transients between the phase and ground or between the zero and ground wires of the luminaire may penetrate the safety insulation in the power supply unit or LED module board, including the LED radiator insulation.
