Bailey – LED filament ST64 E27 240V 2W CL
Posted by Marcel van der Steen in Light measurements Add commentsBailey presents an LED filament lamp. The measurements from OliNo show that the lamp emits a warm white light with a color temperature of 2678 K. The lamp consumes 2.2 W and has a luminous flux of 240 lm. This results in an efficacy of 107 lm/W. The lamps energy category label is A++.
This article shows the measurement results.
See this overview for a comparison with other light bulbs.
Summary measurement data
parameter  meas. result  remark 

Color temperature  2678 K  warm white 
Luminous intensity I_{v}  4.7 Cd  Measured straight underneath the lamp. 
Illuminance modulation index  97 %  Measured with a light sensor looking at the lamp (angle not defined). Is a measure for the amount of flickering. 
Beam angle  325 deg  325 deg is the beam angle for all Cplanes since the lamp is symmetrical along its 1st axis. 
Power P  2.2 W  The net power consumed. 
Power Factor  0.46  An electrical load with this power factor means that for every 1 kWh net energy consumed, there has been 1.91 kVAhr for reactive energy. 
THD  59 %  Total Harmonic Distortion. 
Max inrush current  0.449 A  This current has been found at a voltage start angle of 80 degrees. 
Luminous flux  240 lm  Measured with photogoniometer, calculation done as described in LM7908. 
Luminous efficacy  107 lm/W  
EU2013label classification  A++  The energy class, from A++ (more efficient) to E (least efficient). This label is an update of the previous version, and compulsory from Sept 2013. 
CRI_Ra  80  Color Rendering Index. 
Qa_CQS  82.7  QCS (v9.0.3) is an improved indicator (over CRI) of how well colors are rendered. 
Qg_CQS  0.91  Gamut Area Ratio. 
Coordinates chromaticity diagram  x=0.4171 en y=0.4651  
Fitting  E27  This lamp is connected directly to the grid voltage. 
PARvalue  0.0 uMol/s/m^{2}  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. 
PARphoton efficacy  0.9 uMol/s/W_{e}  The total emitted number of photons by this light, divided by its consumption in W. It indicates a kind of efficacy in generating photons. 
Photon current  3.3 uMol/s  The total number of photons in the light of this lamp. 
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 (low environmental light level). 
D x H external dimensions  63 mm x 142 mm  External dimensions of the lamp. 
L x W x H luminous area  2 mm x 10 mm x 30 mm  Dimensions of the luminous area (used in Eulumdat file). It is the surface of the sum of all LED wires. 
General remarks  The ambient temperature during the whole set of illuminance measurements was 24.6 – 25.6 deg C.
The temperature of the lamp gets maximally about 9.5 degrees hotter than ambient temperature. Warm up effect: During the warmup time the illuminance varies during 8 minutes and decreases with 9 %. Voltage dependency: There is a constant dependency of the illuminance when the power voltage varies between 200 – 250 V AC. At the end of the article an additional photo. 

Effvariation  2 %  This is the variation in efficacy (calculated as indication by simply dividing the illuminance by the power) during the warming up. A very high negative value indicates a significant decrease for instance due to heating up of the lamp (decrease of lifetime). 
Dimmable  no  Info from manufacturer. 
Biologic effect factor 
0.282  According to prenorm DIN V 5031100:200906. 
Blue Light Hazard risk group  0  0=exempt, 1=low, 2 = moderate, 3=high risk. 
form factor  bulb  
EAN code  8714681353851  
Brand  Bailey  
Overview table
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 32 mm (maximal luminous size, eventually diagonally measured)= 160 mm. Within this distance from the lamp (data given in red), 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 2013 Energy label classification
Since Sept 2013 these labels will be needed.
Important for the energy classification are the corrected rated power and the useful luminous flux.
The measured rated power is 2.2 W and might need to be corrected. The correction is dependent from the lamp type and whether or not the lamp control gear is included or not. The choice for this lamp is the following classification: Lamps with own control gear (external or internal). As a result the corrected rated power becomes: 2.2 W.
The luminous flux measured is 240 lm. The classification of this lamp needed to determine the useful flux is: Nondirectional lamps. Then the useful flux becomes 240 lm. Now a reference power can be calculated.
The energy efficiency coefficient is P_corr / P_ref = 0.09.
EU energy label for this lamp
Zip file with 6 EU energy labels of this lamp
The lamp’s performance in the lumenWatt 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.
The light diagram giving the radiation pattern.
The light diagram indicates the beam in the C0C180 plane and in the plane perpendicular to that, the C90C270 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 325 deg for the C0C180 plane and 325 deg for the C90C270 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 240 lm.
Luminous efficacy
The luminous flux being 240 lm, and the consumed power of the lamp being 2.2 Watt, results in a luminous efficacy of 107 lm/Watt.
Electrical properties
The power factor is 0.46. An electrical load with this power factor means that for every 1 kWh net energy consumed, there has been 1.91 kVAhr for reactive energy.
Lamp voltage  230.19 V 
Lamp current  0.021 A 
Power P  2.2 W 
Apparent power S  4.8 VA 
Power factor  0.46 
Of this lamp the voltage across and the resulting current through it are measured and graphed.
Voltage across and current through the lightbulb
This current waveform has been checked on requirements posed by the norm IEC 6100032:2006 (including up to A2:2009).
Harmonics in the current waveform and checked against IEC6100032:2006 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 59 %.
Inrush current
The inrush current has been measured for different voltage start angles; from 0 – 170 degrees with a 10 degrees step. The current and voltage values have been acquires at a sample speed of 39.9 kS/s. Then this data has been fed into a second order 2kHz low pass Butterworth filter. This removes the current spikes that do not represent relevant values.
The lamp was two minutes off before every inrush current measurement was made.
Test voltage  230.0 V  
Frequency of the voltage  50.0 Hz  
Maximum inrush current  0.449 A  This current has been found at a voltage start angle of 80 degrees. 
Pulse width of max inrush current  3.3E4 s  This is the time that the pulse is higher than 10 % of the max inrush current. 
Minimal inrush current  0.059 A  This current has been found at a voltage start angle of 0 degrees. 
I^2 x t after 10 ms at 0 deg voltage start angle  4.000E6 A  This is the I^2 t value when a zero crossing detector is used to start the voltage from 0 degrees. 
Inrush current found at worstcase voltage start angle
First cycle of the maximum inrush current
The energy I^{2}t during the first 10 ms of the first current cycle
Temperature measurements lamp
Temperature image(s).
status lamp  > 2 hours on 
ambient temperature  25.2 deg C 
reflected background temperature  25.2 deg C 
camera  Flir T335 
emissivity  0.95 
measurement distance  0.5 m 
IFOV_{geometric}  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 yaxis valid at 1 m distance.
The measured color temperature is 2678 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 90 deg. Beyond that angle has not been measured.
For the C0C180 plane: the beam angle of 325 deg is equivalent to 162.5 deg inclination angle,which is the area where most of the light falls within. The maximum variation of color temperature in the first 90 degrees of this inclination area is about 12 %.
For the C90C270 plane: the beam angle of 325 deg is equivalent to 162.5 deg inclination angle,which is the area where most of the light falls within. The maximum variation of color temperature in the first 90 degrees of this inclination area is about 5 %.
PAR value and PAR spectrum
To make a statement how well the light of this light bulb is for growing plants, the PARarea needs to be determined.
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  0.0  uMol/s/m^2 
PAR photon current  2.0  uMol/s 
PAR photon efficacy  0.9  uMol/s/W 
The PAR efficiency is 63 % (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 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 1.2.
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.
The color coordinates are x=0.4171 and y=0.4651.
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.
This value of 80 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 80 is equal to the value of 80 that is considered as a minimum for working areas in general.
Note: the chromaticity difference is 0.0019 and indicates the distance to the Planckian Locus. There is a value mentioned of max 5.4E3 in section 5.3 of CIE 13.31995 however not further explanation of it.
An other reference with signal lights as a reference is given in the chromaticity diagram.
Color Quality Scale
QCS (v9.0.3) is an improved indicator (over CRI) of how well colors are rendered.
CQSvalues of the light of this light bulb.
CQSvalues for the light of this light bulb compared with those of a reference source with the same color temperature.
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 1.2 %. This difference in illuminance is not 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.
During the warmup time the illuminance varies during 8 minutes and decreases with 9 %.
During the warmup time the power varies during 20 minutes and decreases with 7 %.
The variation in efficacy (calculated as indication by simplydividing the illuminance by the power) during the warming up is 2 %. A very high negative value indicates a significant decrease for instance due to heating up of the lamp (decrease of lifetime).
Measure of flickering
An analysis is done on the measure of flickering of the light output by this light bulb.
The measure of fast illuminance variation of the light of the light bulb
parameter  value  unit 

Flicker frequency  100.0  Hz 
Illuminance modulation index  97  % 
Flicker index  0.735  [] 
The illuminance modulation index is computed as: (max_Ev – min_Ev) / (max_Ev + min_Ev).
Biologic effect
The biologic effect shows the level of impact the light of this lamp can have on the daynight rhythm of human beings (as well as the suppression of melatonin production).
The important parameters (according to prenorm DIN V 5031100:200906):
biologic effect factor  0.282 
k_{biol trans} (25 years)  1.000 
k_{biol trans} (50 years)  0.779 
k_{biol trans} (75 years)  0.533 
k_{pupil}(25 years)  1.000 
k_{pupil}(50 years)  0.740 
k_{pupil}(75 years)  0.519 
Blue Light Hazard
The amount of blue light and the harm it can cause on the retina has been determined. Herewith the results.
The level of blue light of this lamp related to the exposure limit and the different classification areas.
L_lum0 [mm]  10  Dimension of brightest part of lamp in C0C180 direction. 
L_lum90 [mm]  2  Dimension of brightest part of lamp in C90C270 direction. 
SSD_500lx [mm]  96  Calculated distance where Ev = 500 lux. This computation is valid when it is in the far field of the lamp. Note: if this value 200 mm then the distance of 200 mm is taken as proposed in the norm IEC 62471:2006. 
Start of far field [mm]  51  Minimum distance at which the lamp can be seen as apoint source. In this area the Ev is linearly dependent from (1/distance)^{2}. 
300350 nm values stuffed with 0s  yes  In the event OliNo has measured with a SpB1211 spectrometer without UV option then the irradiance data of 300349 nm is missing. For lamps where there is already no energy content near 350 nm, the values 300349 can also be set at zero then. 
alpha_{C0C180} [rad]  0.050  (Apparent) source angle in C0C180 direction. 
alpha_{C90C270} [rad]  0.010  (Apparent) source angle in C90C270 direction. 
alpha_{AVG} [rad]  0.030  Average (apparent) source angle. If average >= 0.011 rad then the exposure limit is computed with radiance Lb. Otherwise with irradiance Eb. 
Exposure value [W/m^2/sr]  3.40E+1  Blue Light Hazard value for this lamp, measured straight underneath the lamp. Computation is referenced to Lb. 
Blue Light Hazard risk group  0  0=exempt, 1=low, 2 = moderate, 3=high risk. 
Extra
Additional photos.
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