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140 TECHNOLOGY / LEDS


Tim Whitaker provides an update on the work of the Zhaga Consortium, including its newly expanded library of LED light-engine Books.


BY THE BOOK


Zhaga, the international consortium that is developing specifications to enable the interchangeability of LED light sources, is working to expand its portfolio of specifi- cations, while also finalising and publishing the existing ones. The Zhaga specifications, known as Books, define the interfaces between LED light engines and LED luminaires. Currently there are seven such specifications, namely Books 2 to 8, while Book 1 contains common information and definitions. Now, driven by input from member companies, Zhaga has started work on Books 9 and 10, and several other proposals are also being considered. While each Book starts life inside Zhaga, the long-term goal is to publish them all for use by the entire lighting industry. Books 1, 2 and 3 have already been published, joined recently by Books 7 and 8, and the full specifications can be downloaded from the Zhaga website. The other Books are currently under revision, and the newest versions are likely to be made public in the next few months. The final stage in a Book’s lifecycle is, where possible, to transfer the specifica- tion to a standards-developing organisation (SDO) such as the IEC. Discussions are un- derway between Zhaga and IEC to turn Book 3 into a fully-fledged international standard. The other Books are expected to follow in due course.


Certification and the Zhaga logo The Zhaga testing and certification proce- dures are now in place for all the approved Books (this does not apply to Book 1). Members can use approved test labs to test a product against a specific Zhaga Book. The next step is certification, after which the product is allowed to display the Zhaga logo. The Zhaga logo conveys the concept of interchangeability. It has no intended mean- ing for quality, reliability, safety, energy efficiency, lifetime, colour stability or other parameters that are not directly related to interfaces and interchangeability. However, Zhaga supports standards for safety, quality, and efficiency that are set by governments


and other industry bodies. For example, Books 2 and 8 now reference the SSL 7A standard for LED dimming that was devel- oped by NEMA. To date, there are 130 products listed in the Certified Products database on the Zhaga website. Over the next few months, Zhaga is launching a rebate programme for its members to boost the number of certified products. The consortium will provide rebates to offset the testing cost for up to three products per company.


What is interchangeability? The concept of interchangeability is central to Zhaga’s activities. Although interchange- ability is often confused with replaceability, the two terms have different meanings. Some LED modules and light engines can be replaced after the luminaire is installed, either by qualified personnel or by the end user, for example in designs where the light engine or module fits into a socket. Howev- er, there are many LED luminaires designs and many types of LED module for which replacement is not an option. Likewise there are many LED lighting applications where replacement is neither necessary nor appropriate. However, at the luminaire manufacturing stage, interchangeability can be relevant in all cases. Zhaga defines two LED light engines as being interchangeable when one can be used instead of the other with- out changing the design of the luminaire. Adherence to Zhaga interface specifications avoids arbitrary variations in different fea- tures. For example, Zhaga may define the position of screw holes that enable mechan- ical fixation of a module, or the size and position of the light-emitting surface. As a consequence, compatible modules can be used interchangeably without changing the luminaire’s physical dimensions, or without altering the heat sink or reflector. At the manufacturing stage, an LED lu- minaire maker that has designed a Zha- ga-based fixture can choose between a range of suppliers that offer compatible Zhaga-based components. This can reduce the supply-chain risk of relying on a single


The Zhaga logo is intended to indicate interchangeability and is not a comment on quality, reliability, safety, energy efficiency, lifetime or colour stability.


Philips’ 2000lm Fortimo LED Line, an example of an LED source covered by Book 7.


Book 8 addresses round light engines and holders.


Osram’s PrevaLED Compact high-luminance LED light engine is covered by Book 4.


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