Lightech power supplies - life time considerations
At Lightech we are well aware that luminaire manufacturers, want to provide a high quality, long life product. This is all the more important as the industry moves to high brightness LED lighting, where a key value proposition sold to the end customer is that the fixture will work maintenance-free - without the need to "change a light bulb" - for many years. Many of Lightech's customers offer multi-year warranties for their fixtures, especially LED fixtures.
Although nothing lasts forever, Lightech typically invests more than other power supply vendors to ensure high quality long-life components and to test, improve and retest the thermal design of Lightech products in order to minimize the wear and tear of components and maximize product lifetime. Particular attention is paid to electrolytic capacitors which are often the weakest link in the lifetime chain.
Some in the industry use approximate models and "rules of thumb" to estimate a product's lifetime, such as "accelerated lifetime testing". Unfortunately these models are inaccurate. Therefore Lightech's long product warranties are based on uncompromising testing of the working temperature, at maximum ambient temperature, of each individual critical component in every one of our products. On our five year warranty products, Lightech aims to ensure that every one of the high quality components we use is rated for a lifetime of at least 50,000 hours, even when the product is running in maximum allowed ambient temperature.
Of course, 50,000 hours is more than five years, it equals 5.7 years. In practice most products do not work 24 hours a day and do not always work at maximum allowed ambient temperature. Add to that the extra margin of error which Lightech builds in and you will understand why we believe that the vast majority of the millions of Lightech products installed around the world are working well after ten years and more.
For more information on Lightech's approach to product lifetime see also
Derating (higher Ta, lower power)
Customers sometimes wish to exceed the maximum permitted Ta (ambient temperature) in case they are drawing less than the maximum power from a Lightech power supply. Whenever drawing less than maximum power, Ta may indeed be exceeded, provided that Tc (the maximum allowed case temperature) is never exceeded - as measured at the point marked Tc on the label.
When designing your fixture please test to ensure the Tc is never exceeded - this should be tested with several units, over several days, in the maximum likely room temperature, and in the most insulated likely installation scenario.
Exceeding Tc
Based on industry models, exceeding Tc is likely to affect lifetime as follows:
- Exceeding maximum Tc by 10°C (18°F) may halve the lifetime to 25,000 hours (for 5 year warranty products)
- Exceeding maximum Tc by 20°C (36°F) may reduce the lifetime to one quarter, or 12,500 hours.
- Still higher temperatures are highly unpredictable.
Important notes:
This is a general model and actual lifetime may vary considerably
- Exceeding the temperature may invalidate safety certifications such as UL and ENEC.
- Exceeding the temperature may trigger the on/off thermal protection at some predefined point
- Therefore exceeding Tc will invalidate your warranty and is not sanctioned by Lightech - customer discretion is advised.
Lowering Tc
Based on industry models, running the product with Tc consistently below the recommended maximum is likely to increase lifetime as follows:
- If Tc is always 10°C (18°F) or more below the maximum, expected lifetime may be doubled to 100,000 hours
- If Tc is always 20°C (36°F) or more below the maximum, expected lifetime may be quadrupled to 200,000 hours
- Extra benefit for even lower temperatures is not predictable.
Important notes:
- This is a general model and actual lifetime may vary considerably
- Since Lightech is unable to validate running temperatures, or to provide certainty about their effect, the Lightech warranty is not extended beyond the stated number of years even if products are running at lower temperatures, or not running continuously.
