What’s the reasons for LED power deviation?

LED power deviation is a big problem for the enterprise development. Recently, various media frequently reported that the national and local quality inspection departments randomly checked the quality of LED light sources and LED lamps.In the unqualified test project, the actual tested LED power of the luminaire does not match the declared power of the product. The high-quality "quality door" incident seriously damaged the company's own image and the brand image of China's LED industry on the international stage. The situation is alarming.

As early as 2010, China has issued the National Standard GB/T24908-2010 "Performance Requirements for Self-ballasted LED Lamps for General Lighting", which states that "the actual LED power consumption and rating of the lamp when it is operated at rated voltage and rated frequency" The difference in LED power should not exceed 15% or 0.5W". The International Electric Technical Commission also requires in paragraph 7 of IEC62722-1 that "the deviation between the nominal and actual values of LED power should not exceed 10%".

The author believes that the reasons for the product with LED power deviation are as follows:

Firstly, due to cost pressures, the production process cut corners and reduced the necessary product testing process. The unqualified products were not removed from the factory and shoddy to the market.

Secondly, the LED lamp bead heat dissipation design margin is insufficient, the assembly process, the deviation of the incoming material causes the lamp bead to overheat, and the forward voltage drop (Vf) drops out of control, causing the actual LED power of the lamp to deviate from the lower limit.

Thirdly, the thermal power supply of the selected driving power supply is poor, and the output current temperature drifts greatly, which directly causes LED power to deviate in a wide range.

Finally, in order to reduce the cost of LED lamp bead purchase, the lamp purchase did not select the LED Vf distribution BIN according to the design requirements, resulting in the actual power consumption of the LED deviating from the design center value.