Renewable Energy

NoName 12V Halogen lamp 20 W via halogene transformer

Posted by Marcel van der Steen in Light measurements Add comments

Herewith the results of a NoName 12 V 20 W halogen lamp that has been connected via a transformer to the 230 V AC grid. This results in a voltage of 10.1 V on the pins of the lamp. The lamp emits a warm white light.

This article shows the measurement results. Many parameters are also found in the Eulumdat file.

See this overview for a comparison with other light bulbs.

Summary measurement data

parameter meas. result remark
Color temperature 2659 K warm white
Luminous intensity Iv 292.8 Cd Measured straight underneath the lamp.
Illuminance modulation index 10 % Measured with a light sensor looking at the lamp (angle not defined). Is a measure for the amount of flickering.
Beam angle 29 deg 29 deg is the beam angle for all C-planes since the lamp is symmetrical along its 1st axis.
Power P 14.9 W Follow the link for more information on electrical properties.
Power Factor 0.88 An electrical load with this power factor means that for every 1 kWh net energy consumed, there has been 0.53 kVAhr for reactive energy.
THD 45 % Total Harmonic Distortion.
Luminous flux 112 lm This luminous flux results with 10.1 V AC on the pins.
Luminous efficacy 7 lm/W This is including the consumption of the transformer.
EU-label classification E The energy class, from A (more efficient) to G (least efficient).
CRI_Ra 97 Color Rendering Index.
Coordinates chromaticity diagram x=0.4689 en y=0.4207
Fitting GU5.3/MR16 This lamp has been connected via a transformer to the 230 V AC voltage.
PAR-value 3.9 uMol/s/m2 The number of photons seen by an average plant when it is lit by the light of this light bulb. Value valid at 1 m distance from light bulb.
PAR-photon efficacy 0.1 uMol/s/We The total emitted number of photons by this light, divided by its consumption in W. It indicates a kind of efficacy in generating photons.
S/P ratio 1.3 This factor indicates the amount of times more efficient the light of this light bulb is perceived under scotopic circumstances (low environmental light level).
D x H external dimensions 50 mm x 38 mm External dimensions of the lamp.
D luminous area 42 mm Dimensions of the luminous area (used in Eulumdat file). The light comes from the reflector from the front.
General remarks The ambient temperature during the whole set of illuminance measurements was 24.1 – 24.5 deg C.

The temperature of the housing gets maximally about 85 degrees hotter than ambient temperature.

Warm up effect: during the warm up time the illuminance increases about 10 % and the consumed power decreases about 3 %.

Voltage dependency: There is a constant dependency of the illuminance when the power voltage varies between 200 – 250 V AC.
There is a constant dependency of the consumed power when the power voltage varies between 200 – 250 V AC.

At the end of the article an additional photo of the transformer and some photos of the lamp.

Eulumdat file olino_eulumdat Right click on icon and save the file.

Overview table

The overview table is explained on the OliNo website.

Please note that this overview table makes use of calculations, use this data with care as explained on the OliNo site. E (lux) values are not accurate, when within 5 x 42 mm (maximal luminous size, eventually diagonally measured)= 210 mm. Within this distance from the lamp, the measured lux values will be less than the computed values in this overview as the measurements are then within the near field of the lamp.

EU Energy label classification

With the measurement results of the luminous flux and the consumed power the classification on energy efficacy of this lamp is calculated. This information is requested in the EU for certain household lamps, see also the OliNo site that explains for which lamps it is requested, how the label looks like and what information it needs to contain.

Herewith the labels for this lamp in color and black and white.

EU energy label of this lamp

Label in black and white.

The lamp’s performance in the lumen-Watt field, with the energy efficacy fields indicated.

Eulumdat light diagram

This light diagram below comes from the program Qlumedit, that extracts these diagrams from an Eulumdat file. This light diagram is explained on the OliNo site.

The light diagram giving the radiation pattern.

The light diagram indicates the beam in the C0-C180 plane and in the plane perpendicular to that, the C90-C270 plane. These beams are equal as the lamp has symmetry over its first axis (the vertical axis).

Illuminance Ev at 1 m distance, or luminous intensity 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 is the average of the light output of the light diagram given earlier. Also, in this graph the luminous intensity is given in Cd.

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

Intensity data of every measured turn angle at each inclination angle.

This plot shows per inclination angle the intensity measurement results for each turn angle at that inclination angle. There normally are differences in illuminance values for different turn angles. However for further calculations the averaged values will be used.

When using the average values per inclination angle, the beam angle can be computed, being 29 deg for the C0-C180 plane and 29 deg for the C90-C270 plane.

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 light spot is a luminous flux of 112 lm.

Luminous efficacy

The luminous flux being 112 lm, and the consumed power of the lamp being 14.9 Watt, results in a luminous efficacy of 7 lm/Watt.

Electrical properties

The power factor is 0.88. An electrical load with this power factor means that for every 1 kWh net energy consumed, there has been 0.53 kVAhr for reactive energy.

Lamp voltage 230.0 V
Lamp current 0.073 A
Power P 14.9 W
Apparent power S 16.9 VA
Power factor 0.88

Of this lamp the voltage across and the resulting current through it are measured and graphed. See the UI acquisition on the OliNo site how this is obtained.

Voltage across and current through the lightbulb

This current waveform has been checked on requirements posed by the norm IEC 61000-3-2:2006 (including up to A2:2009). See also the IEC 61000-3-2:2006 explanation on the OliNo website.

Harmonics in the current waveform and checked against IEC61000-3-2:2006 and A2:2009

When the consumed power is <= 25 W there are no limits for the harmonics.

The Total Harmonic Distortion of the current is computed and its value is 45 %.

Temperature measurements lamp

The lamp gets very hot.

status lamp > 2 hours on
ambient temperature 22.5 deg C
reflected background temperature 22.5 deg C
camera Flir T335
emissivity 0.95
measurement distance 0.4 m
IFOVgeometric 0.136 mm per 0.1 m distance
NETD (thermal sensitivity) 50 mK

Color temperature and Spectral power distribution

The spectral power distribution of this light bulb, energies on y-axis valid at 1 m distance.

The measured color temperature is 2659 K which is warm white.

This color temperature is measured straight underneath the light bulb. Below a graph showing the color temperature for different inclination angles.

Color temperature as a function of inclination angle.

The color temperature is given for inclination angles up to 60 deg. Beyond that value the illuminance is so low (< 5 lux) that it has not been used for color determination of the light.

For the C0-C180 plane: the beam angle of 29 deg is equivalent to 14.6 deg inclination angle,which is the area where most of the light falls within. The maximum variation of color temperature in this inclination area is about 1 %.

For the C90-C270 plane: the beam angle of 29 deg is equivalent to 14.6 deg inclination angle,which is the area where most of the light falls within. The maximum variation of color temperature in this inclination area is about 1 %.

PAR value and PAR spectrum

To make a statement how well the light of this light bulb is for growing plants, the PAR-area needs to be determined. See the explanation about PAR on the OliNo website how this all is determined and the explanation of the graph.

The photon spectrum, then the sensitivity curve and as result the final PAR spectrum of the light of this light bulb

parameter value unit
PAR-number 3.9 uMol/s/m^2
PAR-photon current 1.5 uMol/s
PAR-photon efficacy 0.1 uMol/s/W

The PAR efficiency is 66 % (valid for the PAR wave length range of 400 – 700 nm). This is the maximum percentage of the total of photons in the light that is effectively used by the average plant (since the plant might not take 100 % of the photons at the frequency where its relative sensitivity is 100 %).

S/P ratio

The S/P ratio and measurement is explained on the OliNo website. Here the results are given.

The power spectrum, sensitivity curves and resulting scotopic and photopic spectra (spectra energy content defined at 1 m distance).

The S/P ratio of the light coming from this lamp is 1.3.

More info on S/P ratio can be found on the OliNo website.

Chromaticity diagram

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

The point of the light in this diagram is inside the area indicated with class B. This area indicates an area for signal lamps, see also the article on signal lamps and color areas on the OliNo website.

The color coordinates are x=0.4689 and y=0.4207.

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). Practical information and also some critics about the CRI can be found on the OliNo website.

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.

This value of 97 indicates how well the light of this lamp can render well a set of reference colors, this in comparison with the light of a reference source (for color temperatures < 5000K a black radiator is used as reference and for color temperatures > 5000K the sun or the light outside during the day).

The value of 97 is much bigger than the value of 80 that is considered as a minimum for working areas in general.

Note: the chromaticity difference is 0.0030 and indicates the distance to the Planckian Locus. There is no norm yet that states what the max deviation from white light is allowed to be. A reference with signal lights as a reference is given in the chromaticity diagram.

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 light bulb parameters measured: illuminance E_v [lx], the lamppower P [W] and the luminous efficacy [lm/W] (this latter is estimated here by dividing the found E_v value by P).

Lamp voltage dependencies of certain light bulb parameters

There is a constant dependency of the illuminance when the power voltage varies between 200 – 250 V AC.
There is a constant dependency of the consumed power when the power voltage varies between 200 – 250 V AC.

When the voltage varies abruptly with + or – 5 V AC then this results in a variation of the illuminance of maximally 9.6 %. This difference in illuminance is possibly visible (when it occurs abruptly).

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], the lamppower P [W] and the luminous efficacy [lm/W].

Effect of warming up on different light bulb parameters. In the first graph the 100 % level is put at begin, and in the last graph the 100 % level is put at the end.

The warmup time is about 20 minutes during which the illuminance increases with 10 % and the consumed power decreases with 3 %.

Measure of flickering

An analysis is done on the measure of flickering of the light output by this light bulb. See the article on flickering on OliNo site for more information.

The measure of fast illuminance variation of the light of the light bulb

parameter value unit
Flicker frequency 99.8 Hz
Illuminance modulation index 10 %

The illuminance modulation index is computed as: (max_Ev – min_Ev) / (max_Ev + min_Ev).



The used 12 V halogen transformer.

This transformer gave 10.1 V AC on the pins of the connectd 12 V 20 W lamp.

It is possible that other transformers when used will give different voltage values, which will result in different luminous flux (see voltage dependency graph). The more volt the more luminous flux but on the other hand also the higher the temperature of the lamp and the shorter its life.

Close view of the filament.

Side view of the lamp.

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