5 years ago

leD StrIPe - Frizen AS

leD StrIPe - Frizen AS

SPeCIal FeatUreS oF

SPeCIal FeatUreS oF leDS 90 CRI 70 LEDs have experienced a rapid development in the last ten years, and are now a viable alternative to traditional lamps. Fluorescent lamps have been developed over a period of around 100 years. The properties of fluorescent lamps are well-known. The intention of the following section is to show the similarities and – more importantly – the differences between the two lamp types. 60°C AMBIENT TEMPERATURE 25°C 100% LUMIOUS FLUX 90% 5600K COLOUR TEMPERATURE 3000K 10 NORKA LED Product Range 2012_2

SIMIlarItIeS aND DIFFereNCeS betweeN leDS aND FlUoreSCeNt laMPS SIMIlarItIeS Influence of colour temperature on the luminous flux: — As with fluorescent lamps, the light efficiency and luminous flux are increased at higher colour temperatures. Colour rendering index (CRI) and luminous flux: — The light efficiency of fluorescent lamps is reduced at an increased colour rendering index with the same electrical power – this also applies to LEDs. DIFFereNCeS Temperature dependency of the luminous flux: Fluorescent lamps show a reduction in luminous flux when the temperature is reduced. Therefore, special luminaire versions are available which intentionally generate a build-up of heat inside the luminaire. This means that optimal operating temperatures can be achieved, even at low ambient temperatures. The LED shows exactly the opposite behaviour. The luminous flux on the LED is reduced at high ambient temperatures and – also of importance – the service life is reduced. NORKA luminaires are designed so that a service life of at least 50,000 operating hours can be reached Luminous flux, depending on ambient temperature °C +60 90% t a Colour temperature 5600k/5400k 4000k 3300k/3000k CrI +50 93% +40 96% +30 99% +25 100% +20 101% +10 103% 0 106% -10 109% -20 112% -28 114% -30 115% > 70 95% > 80 (providing they are operated in the permissible ambient temperature range). If the temperature is significantly below this temperature range, then the service life increases accordingly. PraCtICal aPPlICatIoNS The following diagram for white LEDs gives an overview of the effects of the different influencing factors. The luminous flux in the product tables is always that specified by the manufacturer. These are based on a junction temperature of 25 °C, which is never reached in actual operation. These are then classified as “cold” lumens. NORKA measures all luminous fluxes on the LEDs at a 25 °C ambient temperature on the test bench. These luminous flux values are comparable with those given for fluorescent lamps. These values are then classified as “warm” lumens. They reflect the actual luminous flux values reached in the luminaire. The LED has better or worse cooling depending on the thermal management of the luminaire, which also has an effect on the light output ratio. In the following diagram, the “warm” luminous flux is set at 100%. As a rule of thumb, the “cold” lumen value specified by the manufacturer is 25 % above the measured luminous flux. This means that 125 % can be set at 25 °C. In the diagram, the luminous flux for other ambient temperatures and colour 85% > 80 temperatures is specified based on the “warm” luminous flux at 5400/5600 K. Higher colour rendering indexes can be reached at lower colour temperatures. Special versions with a CRI value above 90 and colour temperature of approx. 3000 K are available on request for luminaires with LED arrays – however, the luminous flux is then around 20 % lower than at 5600 K. eXaMPle oF a roUgH eStIMate: A LED array is used in 5600 K with 4800 lm luminous flux according to the manufacturer’s specifications. The luminous flux is queried at -10 °C and a CRI value above 80 is required. The light output ratio is 90%: Luminous flux: (4800 lm/1.25) x 1.09 x 0.95 x 0.90 = 3579 lm > Adhere to the permissible ambient temperatures specified in the table for each luminaire used 11

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