Led Lighting Spd Design Installation Guide Page 3 LED Lighting SPD Design & Installation Guide

2015 Littelfuse LED Lighting SPD Module Design and Installation Guide www.littelfuse.com LED Lighting Surge Protection Modules Design and Installation Guide Introduction LED lighting is increasingly replacing legacy light sources (mercury vapor, metal halide and sodium vapor) in outdoor applications as a result of technological revolutions in LED efficiency (higher lumens per watt), secondary optics (better lenses/reflectors), and greater thermal dissipation. However, the initial cost of installing outdoor LED lighting can be substantial; this cost is justified and payback is established based on the lower wattage demand, lower maintenance cost, and longer lifetime it offers. In order to protect outdoor LED lighting from failing within an investment payback period of about five years, the lighting must offer high durability and reliability. Transient surge events in AC power lines, which can damage lighting fixtures, represent a significant threat to outdoor LED lighting installations. Indirect Lightning-Induced Surge When nearby electrical equipment is switched on or off, over-voltage transient surges can occur in AC power lines. Nearby lightning strikes can also generate transient surges in AC power lines ( Figure 1 ), especially in outdoor environments. Figure 1. Transient over-voltage on an AC power line resulting from an indirect lightning strike. Lightning strikes are electrostatic discharges, which usually travel from cloud to cloud or cloud to the ground, with magnitudes of millions of volts ( Figure 2 ). Indirect lightning strikes, even those that occur several miles away, can induce magnetic fields that generate surges of thousands of volts through current-carrying copper wires, such as the overhead and underground cables that power streetlights. These indirect strikes, which produce levels of energy with magnitudes greater than 1000A 2 s, can be characterized with specific waveforms. F Fi igu Introduction and Indirect Lightning-Induced Surge 3

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