presents a led spot light with GU5.3 fitting. This light bulb is dimmable and emits a warm white light. The ledlamp is tested on 12 V AC (together with a transformer, to be able to test dimmability) abd directly on 12 V DC.

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	2772 K	Warm white
Luminous intensity Iv	552 Cd	Measured straight underneath the lamp
Beam angle	31 deg	Valid for all C-angles as there is symmetry along the 1st axis.
Power P	4.3 W	When the lamp is measured on 12 V DC, the consumption is 4.3 W. When measured on 12 V AC then a transformer is used and the total consumption is then 5.2 W. The transformer is used to be able to test on dimmability.
Power Factor	0.39	For every 1 kWh net power consumed, there has been 2.4 kVAhr for reactive power. The setup with transformer is reported here.
Luminous flux	206 Lm	This value when tested on 12 V DC only. When the 12 V transformer is used and the lamp on 12 V AC, then 202 lm is measured.
Luminous efficacy	48 Lm/W	This value is valid without transformer so the lamp directly on 12 V DC. With transformer on 12 V AC the efficacy is 38 lm/W.
CRI_Ra	83	Color Rendering Index.
Coordinates chromaticity diagram	x=0.4534 and y=0.4077
Fitting	GU5.3/MR16
PAR-value	5.5 μMol/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	0.4 μMol/s/We	The toal 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	1.2	This factor indicates the amount of times more efficient the light of this light bulb is perceived under scotopic circumstances (ow environmental light level).
D x H external dimensions	50 x 43 mm	External dimensions of the lamp (D = diameter).
D luminous area	40 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the surface of the glass on the front.
General remarks		The ambient temperature during the whole set of measurements was 22.5-24.5 deg C. The maximum temperature of the light bulb gets about 37 degrees hotter than ambient. The lamp’s base gets 34 deg C warmer. Warm up effect: during the warm up time there is no significant change in illuminance nor power. Voltage dependency: the power consumption and illuminance do vary when the voltage is varied from 200 – 250 V for the setup where the transformer is used. This article contains the test results of dimming the lamp at the end, which works well with the by the supplier delivered dimmer.
Measurement report (PDF)	tbc
Eulumdat file		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 40 mm = 200 mm. Within this distance from the lamp, the measured lux values willl be less than the computed values in this overview as the measurements are then within the near field of the lamp.

Note also that this data is baed on the measurement with the transformer inclusive,. So the lamp on 12 V AC.

Eulumdat light diagram

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

The light diagram giving the radiation pattern.

It indicates the luminous intensity around the light bulb. The directions C90-C270 and C0-C180 give the same result as there is a symmetry along the 1st 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 31º.

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 202 Lm (AC) or 206 lm (DC).

Luminous efficacy

The luminous flux being 202 Lm, and the power of the light bulb and transformer being 5.2 W, yields a luminous efficacy of 38 Lm/W.

On DC directly the efficacy is 48Lm/W.

Electrical properties

A power factor of 0.40 means that for every 1 kWh net power consumed, a reactive component of 2.4 kVAr was needed (only with the transformer included).

Lamp voltage	230 VAC
Lamp current	58 mA
Power P	5.2 W
Apparent power S	13.5 VA
Power factor	0.40

Of this light bulb the voltage across ad the resulting current through it are measured and graphed. See the OliNo site how this is obtained.

Voltage across and current through the lightbulb

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

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

There are no limits for the harmonics for led lighting equipment <= 25 W.

The Total Harmonic Distortion of the current is computed as 86 %.

Temperature measurements lamp

Temperature image (overview) of the light bulb

Tape is put on the light bulb to get an approximately known emissivity.

status lamp	> 2 hours on
ambient temperature	24 deg C
reflected background temperature	24 deg C
camera	Fluke Ti25
emissivity	0.95(1)
measurement distance	0.20 m
IFOVgeometric	0.5 mm
NETD (thermal sensitivity)	100 mK

⁽¹⁾ The emissivity of the masking tape is used which is about 0.95. The masking tape is so thin that it quickly takes the same temperature as the light bulb’s heat sink.

The tube on its hotttest place is on the heat sink blades, at a temperature of approximately 61 degrees.

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 about 2775 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 measurement of CCT is measured for inclination angles up to 55º since then the illuminance value was decreased to very low values (< 5 lux).

The beam angle is maximally 31, meaning a 15.5º inclination angle. In this area the majority of the light is present. The variation in correlated color temperature in this area is < 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 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	5.5	μMol/s/m²
PAR-photon current	2.0	μMol/s
PAR-photon efficacy	0.4	μMol/s/W

The PAR efficiency is 65 % (valid for the PAR wave length range of 400 – 700 nm). So maximally 65 % of the total of photons in the light 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 is 1.2.

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 light coming from this lamp is on top of the Planckian Locus (the black path in the graph).

Its coordinates are x=0.4534 and y=0.4077. There is no norm yet that states what the max deviation from white light is allowed to be.

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.

The value of 83 is higher than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.0005 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.

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], the (Correlated) Color Temperature [K] 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 illuminance and consumed power do not vary significantly when the voltage is varied.

When the voltage at 230 V varies with + and – 5 V, then the illuminance varies < 4 %, so when abrupt voltage changes occur this effect is not visible in the illuminance output.

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].

Effect of warming up on different light bulb parameters. At top the 100 % level is put at begin, and at bottom at the end.

The warm up time is not meaningful, as there is little variation in parameters.

Dim function

The lamp has been measured on its ability to be dimmed. See the following graph that gives the result of the dimming function. The general interpretation of the parameters and the graph and the way the dimming function is tested is explained on the OliNo website.

The dim-test is done with the by LedItLight delivered dimmer.

The lamp is well dimmable with this dimmer. It is a dimmer that works with low power loads. It is put in series with the lamp. The maximum illuminance level (or minimum light level) can be set with help of a knob at the back of the dimmer. By turning CW or CCW the maximum or minimum illuminance level is set.

This dimmer is used at 8 different positions, from 100 % (no dimming, position 4) to 12.5 % (minimal dimming position 1). The effect of dimming on some lamp parameters is measured and determined.

Lamp parameter values dependent on the dim position

Mechanical range for dimming: from 35 – 90 %, this is a wide range.

Illuminance/Intensity value range: from 4 – 100 %, a wide range.

Consumed power decreases about as fast as the illuminance value decreases.

The color temperature stays constant.

The powerfactor at no dimming is 0.44 which is bit lower than without dimmer. When dimming is increased the power factor stays at this value.

Used transformer