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LLE smd LED 3000K 120cm single, no luminaire

Posted by Marcel van der Steen in Led lights, Light measurements Add comments

presents a measurement set of one 1200 mm smd-LED tube without luminaire. In this article the measurement data can be found as well as in Eulumdat format.
See this overview for a comparison with other light bulbs.

Summary measurement data

parameter meas. result remark
Color temperature 3430 K Between neutral to warm white
Luminous intensity Iv 324 Cd
Beam angle 122 deg A wide beam, which is to be expected from an FL-tube.
Power P 24.1 W
Power Factor 0.87 For every 1 kWh net power consumed, there has been 0.56 kVAhr for reactive power.
Luminous flux 1045 lm
Luminous efficacy 43 lm/W
CRI_Ra 66 Color Rendering Index.
Coordinates chromaticity diagram x=0.4250 and y=0.4306
Fitting FL-tube
L x W x H external dimensions 1200 x 26 x 26 mm External dimensions of the tube in a simple luminaire that only holds the tube (no cover, no reflector).
L x W dimensions luminous area 1260 x 21 mm Dimensions of the luminous area (used in Eulumdat file). This is the area of the led strips in the tube.
General remarks The ambient temperature during the whole set of measurements was 20.0-20.5 deg C.

Warm up effect: the consumed power increases about 10 % which is a small effect.

Voltage dependency: consumed power and illuminance are dependent from the light bulb voltage. It is a linear dependence.

For the eulumdat file follow this link.

The light tube

The led tube uses smd LEDs. At the back side of the tube the ribs of the aluminum heatsink are visible. This tube is robust and heavy.

At the top the front view, then side view and at bottom the back view.

Eulumdat lichtdiagram

With this article an eulumdat file is added. This is a file that a.o. indicates the radiation pattern around the light bulb. There are more parameters in the file, and these all can be read with help of the free open source program  Qlumedit.

An interesting graph is the light diagram, indicating the intensity in the C0-C180 and the  C90-C270 plane.

The light diagram giving the radiation pattern in the C0-C180 and C90-C270 planes.
The C0-C180 plane is perpendicular to the length axis of the tube. It indicates the luminous intensity sideways of the tube. The tube itself has a plastic transparent cover with ribs in it, explaining the somewhat dented curvature of the radiation pattern in this plane.

The C90-C270 plane indicates the radiation pattern in the plane in the same direction as the tube’s length.

Illuminance at 1 m distance, aka Iv

Herewith the plot of the averaged luminous intensity Iv as a function of the inclination angle with the light bulb.

The radiation pattern of the light bulb.

This radiation pattern shows a wide beam.

These averaged values are used (later) to compute the lumen output.


The intensity measurements (of each turn angle) as function of inclination angle.

This plot shows per inclination angle the intensity measurement results for each turn angle at that inclination angle.

When using the average values per inclination angle, the beam angle can be computed, being 122 degrees. However, this value is dependent from the plane observed.

Luminous flux

With the averaged illuminance data at 1 m distance, taken from the graph showing the averaged radiation pattern,it is possible to compute the luminous flux.

The result of this computation for this lamp is a luminous flux of 1045 lm.

Luminous efficacy

The luminous flux being 1045 lm, and the power of the lightbulb being 24.1 W, yields a luminous efficacy of 43 lm/W.

A power factor of 0.87 means that for every 1 kWh net power consumed, a reactive component of 0.56 kVAr was needed.

Light bulb voltage 230 V
Light bulb current 120 mA
Power P 24.1 W
Apparent power S 27.6 VA
Power factor 0.87

Color temperature and Spectral power distribution

The spectral power distribution of this light bulb.

The measured color temperature is about 3450K, and the light is between neutral and warm white.

Chromaticity diagram

The chromaticity space and the position of the lamp’s color coordinates in it.

The light coming from this lamp is distant from the Planckian Locus (the black path in the graph).

Its coordinates are x=0.4250 and y=0.4306.

Color Rendering Index (CRI) or also Ra

Herewith the image showing the CRI as well as how well different colors are represented (rendered). The higher the number, the better the resemblance with the color when a black body radiator would have been used (the sun, or an incandescent lamp).

Each color has an index Rx, and the first 8 indexes (R1 .. R8) are averaged to compute the Ra which is equivalent to the CRI.

CRI of the light of this lightbulb.

The value of 66 is lower than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.013 which is higher than 0.0054, which means that the calculated CRI result is not meaningful. This is because the chromaticity value of this lamp is too far away from the Planckian Locus.

Voltage dependency

The dependency of a number of lamp parameters on the lamp voltage is determined. For this, the lamp voltage has been varied and its effect on the following lamp parameters measured: illuminance E_v [lx], color temperature CT or correlated color temperature CCT [K], the lamppower P [W] and the luminous efficacy [lm/W].

Lamp voltage dependencies of certain light bulb parameters, where the value at 230 V is taken as 100 %.

The power consumed and the illuminance measurements depend on the light bulb voltage applied. This dependence is linear.

To check whether this dependency can lead to visible changes in illuminance for possible grid voltage changes, it is noted what variations occur when the lamp voltage varies around 230 V + and – 5 V. Then the illuminance varies between + and – 10 % and will not be visible or noticeable.

Warm up effects

After switch on of a cold lamp, the effect of heating up of the lamp is measured on illuminance E_v [lx], color temperature CT or correlated color temperature CCT [K], the lamppower P [W] and the luminous efficacy [lm/W].


Opwarmen van de lamp en het effect op lampparameters; 100 % niveau aan het begin en aan het eind gelegd

No noticeable effects seen. The power consumption increases about 10 % during the warm up period that takes 40minutes. This effect is small and hence there is no meaningful warm up period.

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