SURGE – How you should properly protect your LED lighting.
SURGE – how you should properly protect your LED lighting (and is this the Elephant in the room….)?
Most of us in the LED industry would admit (whether we would like to or not), that there are some drawbacks to LED lighting. A LED fixture is an electronic device, and as such, it is more susceptible to electrical surge damage than its fluorescent, high-pressure sodium, or metal-halide forefathers.
But what is surge, where does it come from, and what should we do to protect our LED lighting? There are hundreds of articles, advertisements and white papers on the web discussing surge (one of the more informative ones can be found here), but here is my attempt at a quick summary:
- Surge is NOT just a lightning strike issue. Although these ‘destructive’ surge events are well understood (and you will certainly know when you’ve been hit with one of these!), it is often the ‘dissipative’ events originating from inside the building that cause long-term damage to systems and electronics. These high-energy transients arise when disconnecting large inductive loads or switching banks of capacitors in an industrial environment. Studies have shown that exterior sources only account for 20% of all electrical surges, whereas the remaining 80% can be accounted for by culprits within the facility! On a lesser scale, electrostatic discharges (ESD) can also affect electronic components, such as the LEDs themselves, but this is typically only relevant in the LED assembly process.
- Surge protection should be done in layers or zones. Therefore, your ‘beefier’ surge protection (Type I) should protect against the destructive transients on the incoming utility line, the next layer (Type II) should be installed inside the building, typically in distribution and sub-distribution panels, or machine control cabinets. These SPDs protect against the insidious dissipative surges commonly found in an industrial environment. Lastly, your finer (Type III) protection is generally installed in front of the LED fixture itself. Is Type III a financially viable solution? Well, that would depend, I believe, on the cost of the LED fixture itself. Ask yourself – is it cheaper to replace the SPD, or the complete LED fixture?
- SPDs are sacrificial devices and will ultimately fail after experiencing multiple surge events. They can be installed in series in the circuit (i.e. if the SPD fails then the LED fixture no longer receives any power), or in parallel. If installed in parallel, then it is important that some sort of indicator (visual, audio, or electronic) is included otherwise you will never know it’s failed, and your LED fixtures will begin to be adversely affected.
- EN 61547 (part of the compulsory CE certification) requires LED fixtures to pass a certain surge ‘robustness’. However, this level of resistance is quite often insufficient to protect the LED fixtures from most Type I and many Type II events. Additional surge protection is strongly advised, and quite often required to satisfy the manufacturer warranties.
As an additional note on the side – manufacturers may often state a level of in-built surge protection to ‘up-sell’ their products. Quite often this is just the surge protection within the driver, and they are never sufficient to handle all levels of destructive and dissipative surges. Also, if these drivers are built into the product then it’s not very practical to exchange drivers in the case of surge damage. Here at Verde LED, our recommendation is to always have additional surge protection on-site, and if necessary, external to the product (interestingly, if you read the fine-print in some of the driver datasheets, they themselves are stating additional surge protection is required for their warranties…).
In summary, if you are an end-user, then it’s relatively cheap to install surge protection and protect yourself from any replacement/repair costs, as well as the unplanned system downtime. But it must be done correctly – the surge protection required for LED lighting is different to that of legacy lighting. Consult with experts in the field if you are at all uncertain of your requirements – companies such Phoenix Contact are well-versed in the different options available.
Dr.Matthew Branch – Engineering Team Leader – VERDE LED