Different kinds of surges and their damage
Surges exist in nature and in our daily lives. The typical duration and magnitude of surge voltages vary from source to source. Below we have categorized the sources of surges.
Different kinds of surges
Lightning strikes: Thunderstorms or minefields often occur. Street lights are installed in relatively open places, so they are easy to be directly hit by lightning, which requires high character; among all surges, it is the most potentially harmful. The transient overvoltages they cause can extend over great distances and are often associated with high-amplitude inrush currents. Even the indirect effects of lightning strikes can cause surge voltages of thousands of volts and surge currents of tens of thousands of amps. Although short in duration – hundreds of microseconds to milliseconds – such events can cause equipment failure or even damage installed equipment (including burning, etc).
Surge caused by equipment switching: These exist in the electrical grid and affect the light fixtures through the power line. For example, the daily switch of lamps, or the start and stop of large equipment, often have surges in the circuit. These switching operations can cause induced surge voltages to be generated and propagated across the supply lines. In the event of large switching currents or short circuits, very high currents can flow within milliseconds, and these short-term current changes can cause transient overvoltages.
Induced surges: There are times when a thundercloud approaches but does not directly hit a building, and electrical sparks are generated from metal equipment inside the building. People call this phenomenon of not directly hitting, but only sensing the energy of the lightning strike as induced surge. Induced surge is also called lightning induction or induced overvoltage. According to the principle of generation, it is divided into electrostatic induced surge and electromagnetic induced surge. Electrostatic induced surge is mainly because when the electrocumulus cloud is close to the ground, the charge on the cloud layer and the ground object is different, resulting in electrostatic voltage (induced voltage), which in turn causes the discharge to cause harm to the power supply system. Electromagnetic induced surge, this is because when the lightning discharges, the huge impact lightning current generates a rapidly changing strong magnetic field in the surrounding space, and the strong magnetic field generates an induced current, which affects the equipment, outdoor luminaires(such as sports light and street light) and power supply system.