All LEDs are not the same, and smart energy managers do a lot of due diligence to make sure that they buy and install those that won’t prematurely fail – or even create dangerous situations.
Rizwan Ahmad, the Vice President of Engineering and Technology for Dialight, believes that the entire LED – what is made of, the way in which those elements are put together and how it is tested and certified – all are keys. Energy Manager Today spoke with Ahmad about the steps involved in making sure that LEDs live up to expectations.
It is vital to look at the overall device design strategy. The bottom line is clear: Something built by the same team working on the same project – be it a recipe, a car or an LED – is more likely to perform better than something that is fabricated in a piecemeal fashion.
This isn’t because outside contributors don’t care. It’s that the intricacies enabling elements to work together are better handled if they are designed as a package from the start. “Having an integrated design, he said, “means that there is chemistry between different components from the same team, the same company or people who work together on a daily or hourly basis to ensure each component behaves in a way which results in overall reliability.”
The main elements to consider are the LED, the power supply and the casing. Vendors should be able to prove that each component meets specifications and that they work together as designed before being put in the box for shipping. “They should go through a final screening process that is designed so any issue during manufacture comes out before the box is shipped to the customer,” Ahmad said. “That is the definition of a fully integrated platform.”
Organizations buying upgrading their lighting must make sure that the LEDs are high quality. The reports that attest to this are LM-80 and TM-21. Companies must insist on seeing these. They are even more vital in cases in which the vendor supplying the luminaire is using an LED made by a third party.
Lights fail when they overheat. Thus, they are designed to reduce power if they approach their thermal limits. Dialight, in a white paper on LED luminaire reliability, said that some manufacturers place the point at which power is reduced – the roll off point – too close to the highest temperature at which the luminaire can operate. This can lead to premature failures and, in some cases, dangerous overheating.
Another important issue that should be tracked by those charged with buying LEDs should check for is whether or not accelerated lifecycle testing has been done. One of the attractions of LEDs is that they have a long lifespan. That must be proven, however.
Ahmad suggests that it is prudent to ask vendors about is whether accelerated life testing (ALT) and high accelerated stress screen (HASS) testing has been done. The two are different, but center around the same idea: It is possible to bombard the product with the challenges it is liable to find once it is in the field. Indeed, it is possible to push it much further than it is likely to be pushed once it is sold.
ALT, Dialight says, occurs during the design phase of the components. The company shopping for LEDs must demand the ALT results – even if the testing was done by an OEM and not the vendor itself. HASS goes beyond the typical four- to six- hour burn-in period some vendors rely upon, the company said in the white paper.
The bottom line is that organizations should not take vendors at their word: There are plenty of questions to ask and documentation to look at that will indicate whether or not the promised guarantee is likely to be fulfilled. “If [a vendor says] I am giving you a light that will last ten years, they are really saying that they’ve done their homework,” Ahmad said. It ultimately is up to the organization buying the lights to make sure that they are telling the truth.