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Testing of LED products.The North American LM-79 and LM-80 standards have been around for some time and are useful in characterising the performance of LED products. The LM-80 test is a life & temperature limit test for LED modules and is typically performed by the manufacturer. When you design your luminaire with the module you perform an LM-79 test to determine the photometric and colorimetric performance and an ISTM test (In situ temperature measurement test) to determine whether the module is operating within spec and to estimate the life of the LED module when operated in the luminaire.
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Photometry:Information we provide to you takes many forms. Traditional communication of results is in the form of printed or secured PDF test reports. We will supply NATA or NVLAP endorsed reports (varies by laboratory) for those laboratory activities that are covered by our accreditations. Regardless of whether the measurements are covered by our accreditation or not you can rest assured we will perform the test to the same exacting standards. Please refer to our laboratory quality document for further information.
For applicable test types (refer to the table below) we will provide photometric data files. We can generate photometric data in many formats recognized internationally and by all lighting design software:
All of our printed test reports can be supplied in an industry standard electronic format. You gain the ease of use of electronic reports, in distribution, publishing and archiving while retaining the security of unambiguous traceability. For more information about our electronic publishing services please contact us. Photometric data is the raw currency of lighting design. We can put your photometric data to work. With many decades of experience in lighting design and the application of lighting in architecture our designers can create pleasing designs whatever your requirements. |
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LM-79 Testing:LM-79 is an approved method by the Illuminating Engineering Society of North America (IESNA),for taking electrical and photometric measurements of SSL products. It covers total flux (light output), electrical power, efficacy, chromaticity, and intensity distribution. The five required metrics on the LED Lighting Facts label come from LM-79 test results. Testing can only be completed by an EPA-Recognized Laboratory.
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ISTM Testing (In-Situ):The ISTM test measures the operating temperature and drive current of the LEDs inside the luminaire as would be encountered when the luminaire is normally used ("In-Situ"). The LM80 report specifies the location of the Temperature Measurement Point (TMP), the same point is measured duing the ISTM test. The Standard prescribing the luminaire conditions during the ISTM test is UL1598 in the USA and AS 60598.1 in Australia. The TMP temperature and drive current must be below that in the LM80 report for the LM80 results to be applicable to the luminaire.
LM-80 Reports and Driver Spec sheets are needed to complete this test and determine Tc locations. |
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LM-80 & TM21 Calculations:The North American IES standard LM80 prescribes a test method whereby a batch of LEDs are mounted onto a carrier and are tested at a specific drive current and ambient temperature. At intervals during this test the luminous flux, CCT and other metrics are measured. Three ambient temperatures are used in the test: 55°C, 85°C and a temperature chosen by the LED manufacturer. The samples are operated at these temperatures and at a specific drive current for a period of 1000hrs, then the LEDs are removed from the oven, allowed to cool to 25°C ambient and their light output characteristics are measured as per the LED manufacture's specified method; typically by energising the LED for a short interval between 10 and 20 ms. The LEDs are then placed back in the oven and the process repeated for a minimum of 6000hrs (approximately nine months).
Once the LM80 test has concluded, the measurements are used to determine a depreciation curve for the luminous flux at each temperature. The data is extrapolated using the method described in the North American Technical Memorandum TM21 to determine the "Lumen Maintenance Life Projection (Lp)". The end point of the extrapolation is typically 70% of the initial light output. There is a spreadsheet calculator available at the www.energystar.gov website to perform the calculations. |