What affects the lifetime of LED-luminaires?
The expected life depends on a number of factors, including:
- Choice of LED (brand and type).
- How hard the selected LED is driven (how much current it is driven with).
- Luminaire design (in view of the LED or LED module's temperature).
- Choice of ballast (driver).
- The use of the luminaire.
- Other materials used in the design.
- The environment in which the product is installed.
Life time LED-modules
LED-modules themselves are shown as L70, L80 or L90. The L value describes the percentage of the initial luminous flux being produced within an estimated timeframe. This value is then combined with a B or C value.
The B value describes accuracy or variation of the estimation shown in the L value. The B value for most products is B50, which means that the declared luminous flux can be regarded as a mean value. The B value does not include any total failures of modules.
Example: L80B50 70,000 h means that after 70.000 hours the luminous flux will correspond to 80 % of the luminous flux the product produced when new.
The C value stands for “catastrophic failures” or complete failures, i.e. no light is emitted from the module. The value is specified in combination with a percentage. Failure of an individual LED on a module with many LEDs is not shown in the C value but is instead included in the B value. The C value can, for example, be C10 or lower. C10 means that at the specified time 10 % of the modules will not produce any light. The C value is for standard modules that are not commonly used indoors (~1 %) and it is often possible to disregard the value. The C value will therefore not be reported as standard for indoor products.
Life time drivers
The life time of a ballast is not affected by its design, component electronic parts or the temperature of these. Drivers are given a reference point called tc. The temperature of this metering point must never exceed what is stated by the manufacturer. The life time of a ballast is often stated as for example 50.000 hours /10 %. This means that if the temperature of the tc point is maintained at a certain specified level, a maximum of 10 % of the driver will fail within the specified time.