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FAQ about LED

LEDs, or light-emitting diodes, are semiconductor light sources that emit light when current flows through them. LEDs have many advantages over traditional light sources – this includes longer lifetimes, better durability, lower power consumption, faster switching, and their compact size. In this section, you will find answers to some of the most frequently asked questions about LEDs and the technology behind them.

Subject Explanation

What are typical LED luminaire lifetimes?

For all luminaires, we list:

  • The median useful life according to the IEC 62717 standard – as LxB50 at an ambient temperature (Ta) of 25°C. The “x” value may vary from 70 to 90 depending on the product, and the corresponding lifetime goes up to 100,000 hours.
  • The lamp lumen maintenance factor (LLMF) after 50,000 h, B50, Ta 25°C. This is a factor from 0 to 1.0.

For industrial luminaires, we also list:

  • The median useful life according to the IEC 62717 standard – as LxB50 at the maximum Ta. The “x” value may vary from 70 to 90 depending on the product, and the corresponding lifetime goes up to 100,000 hours.

A selection of our luminaires may yield L70 50,000 hours at 55°C. Read more about LED lumen degradation in the LED section on our website.

LED driver/converter  lifetimes

LED driver lifetimes in Glamox luminaires are at least 50,000 hours at the maximum rated Ta. As a minimum, the Ta is 25°C. Normally, a failure rate of maximum 10% applies. Special drivers have a lifetime of up to 100,000 hours at the listed maximum temperature.

LED lifetime documentation

LED module and driver lifetimes are documented by measuring the components’ Tc point temperature (the Tc point is a specific point on the component) and comparing it to the component’s maximum rated temperature. Temperature measurements are performed at Glamox’ laboratories and carried out at an ambient temperature of 25°C. Heat measurement reports and lifetime calculations are available on demand.

What is the Ta for Glamox fixtures?     

Glamox luminaires are tested and approved for an ambient temperature (Ta) of 25°C, unless otherwise noted. A selection of our luminaires are approved for a Ta of 55°C.

What if one diode in the LED module stops working?

The standard safety design for most Glamox LED modules ensures that any single LED failure in the LED modules containing more than one LED will result in a short circuit rather than an open circuit. The short circuit will secure that the current is flowing through the defective LED and that the other LEDs will continue to work.

What is the lumen output of the LED luminaire? 

Glamox provides the actual lumen output or “lumen out” of all our LED luminaires in the datasheet and on our web site. We advise our customers to carefully note the difference between the light output of the LED module itself and that of the complete luminaire.

What is the variation in luminous flux across modules/fixtures (within the same LED generation)?

The variance in lumen output on Glamox luminaires is +/- 10%. This means that the luminous flux from a luminaire is stable, but may vary across many luminaires.

What is the colour temperature?

The colour temperature of Glamox luminaires are listed in the datasheet and on the website.

What is the colour tolerance?

The colour tolerance of Glamox luminaires are expressed by a number of MacAdam steps. The more steps, the higher the tolerance. An explanation can be found in the LED section of our website. Most of our luminaires have an initial tolerance of 3 MacAdam steps. This equals +/- 100 K at 3000 degrees Kelvin, but this Kelvin tolerance increases with higher colour temperature. Other tolerances up to 5 MacAdam steps may occur and are properly marked in the product documentation.

What is the colour stability over the luminaire’s lifetime?     

A small shift in colour over time may be experienced because of changes inside the LEDs themselves. This shift is not visible in most cases, but may sometimes lead to a higher MacAdam tolerance, e.g. from 3 to 4 steps.

What is the Ra

The colour rendering index (CRI, or Ra) of most Glamox luminaires is 80. For certain products, the Ra may have other values, and they are always properly marked.

Does the Ra change over the luminaire’s lifetime?        

The Ra for Glamox luminaires is normally listed as a minimum value, which means that the Ra value will never drop below the stated Ra over the lifetime of the luminaire.

What is the chemical compatibility (corrosion resistance) of the LED module?     

Certain types of LED packages are susceptible to degradation caused by chemical substances such as fluoride, sulphur oxide and others. In case of the presence of such chemicals, special care needs to be taken when selecting LED types. Please consult our customer service for more information relevant to your project.

What is the technology used for dimming? 

There are basically two ways to dim LEDs. One is through linear current reduction, where the output current magnitude, and hence the light level, is reduced (also called amplitude regulation). The other is PWM (Pulse Width Modulation), where the output current is reduced by chopping the output current. Dimming by amplitude regulation or a mix of amplitude and PWM are preferred by the major LED driver manufacturers. If PWM dimming is used, Glamox and Luxo luminaires have a PWM output frequency of minimum 400 Hz, to avoid flickering.

Is light-technical data available?

Yes, via our web site.

Is there any documentation regarding photobiological hazards (e.g. eye damage)?

Yes, all Glamox LED fixtures comply with the EN 62471 standard – Photobiological safety of lamps and lamp systems. The ENEC and CE marks on our products confirm this compliance.

Are LED modules replaceable?   

Yes, by qualified personnel only. LED module replacement is only recommended for positive cost-benefit analyses, since there may be other issues with different light output values and possible driver incompatibility with the new module. A selection of our luminaires has completely integrated LED modules.

If the module is replaceable, is it future-proof, i.e. forward compatible?

Yes. Zhaga-approved modules have a layout and mounting method that allow them to be replaced with similar modules in the future. Most Glamox downlights and linear luminaires have Zhaga-compliant modules. Modular luminaires will follow.


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