Question 1

What are the notable differences between LM84 and IEC 62717 / IEC 62722-2-1 in terms of the comprehensiveness of their test methods?

Accepted Answer

LM84 merely provides a procedure for testing the photometric performance of LED products, with a relatively limited scope of testing. The corresponding reports contain only information relating to color coordinates, but lack relevant test items such as color rendering index (CRI), CCT and color tolerance, and are therefore unable to comprehensively assess the color performance of luminaires; IEC 62717 and IEC 62722-2-1 incorporate a variety of test schemes, covering a more comprehensive range of parameters. Taking IEC 62722 as an example, in addition to providing CRI (What's CRI?), CCT and chromaticity coordinates (MacAdam ellipse), it also includes tests for other optical performance aspects, such as luminous intensity distribution, accelerated operational life testing and Ts.

Question 2

How does the IEC system utilize LM80 data to simplify LED lifetime testing? What are the specific prerequisites for its use?

Accepted Answer

It is common practice in the industry to estimate the lifetime of light sources by combining LM80 data from LED modules with in-situ temperature measurements of the luminaire; two sets of IEC standards explicitly support the reuse of LM80 reports to reduce the testing workload. The testing methodology of IEC 62717 (About IEC 62717, IEC 62722 and ENEC+) is similar to that of LM80 and recognizes that existing LM80 data satisfies the requirements for lumen maintenance testing; IEC 62722-2-1 stipulates that, provided the LED module possesses a test report compliant with IEC 62717, the luminaire requires only a short period of supplementary testing to verify its lifetime. The mandatory prerequisite for this tiered testing approach is that the luminaire’s actual operating current and temperature conditions are no less favorable than those of the LM80 test conditions; if these conditions are met, the need for lengthy ageing tests on the complete luminaire can be eliminated, resulting in significant savings in terms of samples, energy consumption and time.

Question 3

What are the negative implications of LM84 not permitting the reuse of LM80 data?

Accepted Answer

ANSI IES LM84 does not permit the use of LM80 test results from upstream LED modules, and mandates that new, long-term lumen maintenance tests be conducted on the complete luminaire. Repeated, prolonged ageing tests increase testing costs for companies—including those for equipment, samples and labor—and also prolong product development and time-to-market, adversely affecting both luminaire manufacturers and end-users. Although LM80 is an IES standard introduced in the United States, it has now become a de facto global standard for LED packaging manufacturers. The vast majority of light sources are shipped with accompanying LM80 lumen depreciation data, ensuring strong data interoperability; this is the core reason why the IEC system is willing to be compatible with and reuse this set of test data to predict LED lifetime.

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LED Street Light

High Mast Light

Led Flood Light

Solar Flood Light

LED High Bay Light

LED Tunnel Light

LED Garden Light

Led Bollard Light

Solar Street Light

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Lighting Accessories

Smart Systems

Simulation Design

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