Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 4 replies
  • Subscribers 32 subscribers
  • Views 458 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Relationship between Lumen Degradation and Ambient Temperature of LED Luminaires.

Accel
Hello Everyone,


I would like to ask how would someone calculate the lumen degradation of a certain LED Luminaire in varying ambient temperatures.

For example, this luminaire from TRILUX -------->https://www.trilux.com/products/en/7650B-LED4000-840-ET-05/

It has a mean rated service life L85 (50 deg C) = 50 000 hrs

How would I calculate in order to get the L value at e.g. t = 25 deg C?

TRILUX has their own Lifetime Calculator and it gave an L value of 94.

How did they arrive with that value? Does it have a formula or only a rule of thumb?


Thanks,
Parents
  • 0

    gkenyon:

    It is likely to be based on standard statistical calculations for MTTF, modified by an acceleration factor Af using the Arhenius Equation:

    08c1e2736e0a24085d4ce234cd0004bf-huge-capture7.jpg


    I've not plugged numbers in to check, mind ... you'd need to know, or search up, the activation energy of the type of LED junction you were considering to do this. Basically, this is the forward voltage drop of an individual LED at the point the LED turns on.




    Hello,


    Sorry for the late reply because I live in a different timezone.


    I have tried re-arranging the equation and ended up isolating the ratio of Ea/h since it is a constant value. I have checked the equation and it was from IES TM-21-11 which is used in estimating degradation lifetime of lumen output for LED sources. It looks like I need to enquire to the manufacturers for the specific data in order to proceed.


    Thanks,

Reply
  • 0

    gkenyon:

    It is likely to be based on standard statistical calculations for MTTF, modified by an acceleration factor Af using the Arhenius Equation:

    08c1e2736e0a24085d4ce234cd0004bf-huge-capture7.jpg


    I've not plugged numbers in to check, mind ... you'd need to know, or search up, the activation energy of the type of LED junction you were considering to do this. Basically, this is the forward voltage drop of an individual LED at the point the LED turns on.




    Hello,


    Sorry for the late reply because I live in a different timezone.


    I have tried re-arranging the equation and ended up isolating the ratio of Ea/h since it is a constant value. I have checked the equation and it was from IES TM-21-11 which is used in estimating degradation lifetime of lumen output for LED sources. It looks like I need to enquire to the manufacturers for the specific data in order to proceed.


    Thanks,

Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines