If you have thought about switching to LED lighting, you probably already know there are good reasons that applications for this technology continue to grow. LED purchase prices have come down as demand has increased and manufacturing has become more economical; LEDs use less electricity to provide more light, reducing operating costs; they last longer than traditional lighting, which reduces maintenance requirements; and they offer great flexibility because they can be made to be addressable and to offer multicolored output.
As LED lighting becomes more popular in upgrade and retrofit applications, it has become more important than ever for electrical contractors and lighting system designers to understand how LED technology differs from traditional lighting. Having appropriate protection in place to handle common power quality issues, such as overvoltages, is important when making the switch to LEDs to avoid unexpected difficulties. Especially in the case of retrofits and upgrades, added protection might be in order.
The reason is simple: although LED luminaires generally are more physically rugged than many of their more traditional counterparts, they are more sensitive in an electrical sense. LED luminaires include an internal or external driver that is essentially a piece of sensitive electronic equipment. That driver processes the electricity provided to the LEDs. Like any other semiconductor-based technology, LED luminaires can be damaged over time – or ruined instantly – by voltage variations, especially surges and spikes.
The source of the problem
The most severe power surges come from lightning strikes, either directly or indirectly, and this has become more of a concern as more LED luminaires are installed in outdoor lighting systems.
Direct strikes are best avoided through other means. But surge protection devices should be installed to curb the effects of indirect lightning strikes, which include conducted power surges, a rise in earth potential, and radiation. For outdoor LED lighting installations in particular, surge protection devices are a must. Without it, equipment life is likely to be severely shortened.
Of course, potentially harmful overvoltages also can be caused by other sources. Switching surges are common on electrical networks as opening of protection devices or opening and closing of control devices rapidly modify the network structure. Temporary overvoltages can be generated by neutral breaking on three-phase systems, which is most harmful for low voltage consumers whose equipment is set to operate on single-phase voltage but suddenly finds itself at nearly phase-to-phase voltage. Devices specifically designed to meet that challenge are available. For example, we offer a threshold tripping device that permits progressively higher voltages for progressively shorter durations before it trips.
We suggest using a combination of surge arresters and temporary overvoltage protection from the range of devices available to protect both the power circuit and the information or control circuit. Some devices are adapted for installation in a main low voltage board or in luminaire enclosures. Schneider Electric’s modular products are configured to be mounted on a symmetrical rail.
To fully protect the investment in your LED lighting systems, be sure your installation includes complete protection with zero-crossing contactors (see our previous post “How to solve the mysterious LED electrical network problem”), surge protection devices, and voltage threshold tripping devices.
For more information on designing protection into your LED lighting, download our “Application guide for LED public lighting” guide.