LEDs are currently the most efficient source of light - they are characterized by low energy consumption, high durability and no susceptibility to voltage spikes. However, in a natural way, their intensity decreases under the influence of use. The lifetime of the LEDs is determined using the LxBy parameters, which estimate how long the luminaires will expire and how large the margin of error is inherent in their operation. How should these parameters be interpreted then?
The "aging" period measurement system for LEDs was created on the initiative of IES (Lighting Technology Association) in 2011. It contains methods of collecting parameters of their operation along with working conditions, the number of samples and measurement methods , as well as compilation of auxiliary data with formulas, analysis of statistics and the method of counting itself. This in-depth study led to the development of LxBy parameters to characterize the lifetime of LED technology. The norms of this lifetime are defined in the European standard PN EN 62717: 2017.
The L parameter specifies the minimum value of the luminous flux that will be maintained for a specific time of use . The L80B10 example tells us that after the indicated time the LED will be 80% of its initial brightness. This lamp should be replaced when the luminous flux has dropped to this value.
The B value is unchangeable, it means the possibility of a parametric error, i.e. failure to meet the specified luminous intensity value after a given time . At L80B10, 10% of the LEDs will be less than 80% of their original brightness. The B coefficient can reach even 50%, it gives a longer lifetime to the LEDs, but at the same time increases the allowable degradation of their brightness.
When writing 50,000h L80B10, for 50,000 hours the luminous flux from 90% of the LEDs will not fall below 80% of the declared initial value.