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Rated input power, P [W – watt]

The rated input power shows the amount of energy consumed by a luminaire, including its power supply. It is expressed in watts.

Rated luminous flux, Φ [lm – lumen]

It corresponds to the light emitted by the luminaire which is expressed in lumen (unit of light output).

LED luminaire efficacy, ηv [lm/W – lumens per watt]

The measured initial luminous flux divided by the measured initial input power of the same individual LED luminaire. It is expressed in lumens per watt.

Luminous intensity distribution

The spatial distribution of the luminous flux graphically depicted in a luminous intensity distribution curve, which is usually expressed in a polar coordinate diagram representing the light intensity as a function of angle about a light source. It is expressed in cd = lm × sr-1.

Rated Color Rendering Index, CRI

The color rendering of a LED luminaire giving white light is the effect on the color appearance of objects by conscious or subconscious comparison with their color appearance under a reference illuminant.

Correlated Color Temperature, CCT [K - kelvin]

The color temperature of a LED module giving white light is determined by comparing the light emitted by the LED luminaire with light of an ideal black-body radiator at the given temperature. It is expressed in Kelvin.

Rated life [h – hour]

of the LED luminaire and the associated rated lumen maintenance (Lx). The length of time during which a population of LED luminaires provides more than the claimed percentage (x) of the initial luminous flux always published in combination with the failure fraction. It is expressed in hours.

Failure fraction, By/Fy

Gradual Failure Fraction, By

Corresponding to the rated life of the LED luminaire. The failure fraction for By expresses only the gradual light output degradation as a percentage y of a number of LED luminaires of the same type that at their rated life designates the percentage (fraction) of failures. Abrupt light output degradation is excluded.

Example.

L80F10 50 000 h means that after 50 000 hours 90 % of the luminaires have at least 80 % of the initial luminous flux remaining. This applies the whole luminaire including the driver.

Combined Failure Fraction, Fy

Corresponding to the rated life of the LED luminaire. The percentage (y) of a number of LED luminaires of the same type at their rated life designates the percentage (fraction) of failures. This failure fraction expresses the combined effect of all components of a luminaire including mechanical, as far as the light output is concerned. The effect of the LED could either be less light than claimed or no light at all.

Example.

L70B50 100 000 h means that after 100 000 hours 50 % of the luminaires have at least 70 % of the initial luminous flux remaining. This applies the light source of the luminaire excluding the driver.