See this overview for a comparison with other light bulbs.

Summary measurement data

parameter	meas. result	remark
Color temperature	3109 K	Warm white
Luminous intensity Iv	36 Cd
Beam angle	248 deg
Power P	11.1 W
Power Factor	0.58	For every 1 kWh net power consumed, there has been 1.4 kVAhr for reactive power.
Luminous flux	331 Lm
Luminous efficacy	30 Lm/W	This is the luminaire efficacy (including reflection, absorption, power supply, temperature losses).
CRI_Ra	71	Color Rendering Index.
Coordinates chromaticity diagram	x=0.4338 and y=0.4113
Fitting	E27
PAR-value	0.3 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. Valid for roughly the region within the beam angle.
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	100 x 178 mm	External dimensions of the light bulb.
D x H luminous area	100 x 78 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the size of the glass of this light bulb.
General remarks		The ambient temperature during the whole set of measurements was 24.5 deg C. Warm up effect: during the warm up time the illuminance and the consumed power decrease with 24 % and 12 % respectively. Voltage dependency: the power consumption nor light output depend on the voltage applied.
Measurement report (PDF)	tbc
Eulumdat file		Right click on icon and save the file.

Eulumdat light diagram

An interesting graph is the light diagram, indicating the intensity in the C0-C180 and the C90-C270 plane. This light diagram below comes from the program Qlumedit, that extracts these diagrams from an Eulumdat file.

The light diagram giving the radiation pattern.

It indicates the luminous intensity around the light bulb. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane since there is symmetry over the z-axis (height of the light bulb).

The unit is Cd/1000Lm, meaning the intensity in Cd assuming there would be 1000 Lumen in the measured light bulb. This enables comparing different types of light bulbs.

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 248 degrees.

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 331 Lm.

Luminous efficacy

The luminous flux being 331 Lm, and the power of the light bulb being 11.1 W, yields a luminous efficacy of 30 Lm/W.

A power factor of 0.58 means that for every 1 kWh net power consumed, a reactive component of 1.4 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it are measured and graphed.

Voltage across and current through the lightbulb

The current is out of phase with the voltage, and it shows peaks as well.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

The peaks in the current result in a lot of higher harmonics.

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 3100 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.

Measured is in the angles 15 and 195 degrees, and the measurement of CCT has been stopped when less than 5 lux (low illumination value) were measured or when the inclination angle was 90 degrees. With this light bulb the measurements were stopped at 90 degrees inclination angle.

In this area of inclination angles the correlated color temperature does not vary more than 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. PAR stands for Photosynthetic Active Radiation which is that radiation that participates actively to photosynthesis and is expressed in μMol/s/m².

Photosynthesis is the essence for growth and flowering of plants, where the blue part of the light spectrum is responsible for growth and the red part is responsible for flowering and budding (for gemmation). For photosynthesis it is more important to count the number of photons rather than the power in the light.

The power spectrum (power per wave length) of the light of the light bulb is converted into the number of photons (number of photons per wave length) and then these number of photons is weighted against the relative sensitivity of an average plant (which varies in value dependent on the wave length). The relative sensitivity curve in DIN-norm 5031-10:2000 is used for this. The next image shows the result.

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

The black curve gives the power spectrum of the light of this light bulb, in number of photons per wave length.

In red the relative sensitivity curve of an average plant (according to DIN norm 5031-10:2000).

Multiplying these two results in a curve showing the number of photos per wave length of the light of this light bulb, the PAR spectrum.

Summing all the photons, gives a PAR number that for this light results in 0.3 μMol/s/m². This value is valid at 1 m distance from the light bulb and for the area within the beam angle.

Dividing the PAR number by the total number of photons of the light of this light bulb gives a sort of PAR efficiency, which is 63 % (valid for the PAR wave length range of 400 - 700 nm). So maximally 63 % 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 %).

Note: when mentioning this percentage of efficiency, it is important to verify if all wavelengths are present in a sufficient manner. Not that only blue light is available, when the plant is going to be used for flowering where specifically red light is needed.

S/P ratio

The human eye uses rods and cones. The rods work at scotopic light levels (twilight, night) and the rods at high(er) light levels (daytime, but also close to twilight). Each type of receptor has its own sensitivity for light. The rods are 2.7 times more sensitive than cones, and most for light at a blueish-greenish color whereas compared to the cones’ sensitivity for green light (555 nm).
The S/P ratio gives the maximum difference in sensitivity of the rods at their most sensitive wavelength compared to the cones at their’s. The more blueish (cold white) the light, the more the S/P ratio can be.

The light of this light bulb has a certain spectrum leading to an S/P ratio of 1.2. The light of this lightbulb at scotopic light levels is perceived this factor higher than it would be a photopic light levels.

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

There’s a little bit of blue with respect to green/yellow (see the blue line), resulting in an S/P ratio which is low being 1.2.

More info on the background of the S/P ratio  will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.4338 and y=0.4113.

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 71 is lower than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.0033 indicates the distance to the Planckian Locus. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 %.

Variation of parameters is small and insignificant when the voltage varies between 200-250 V.

When the voltage at 250 V varies with + and - 5 V, then the illuminance varies within 0.1 %, 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.

During a warm up time of about 25 minutes, the illumination drops with 24 % and the consumed power with 12 %.

See this overview for a comparison with other light bulbs.

Summary measurement data

parameter	meas. result	remark
Color temperature	6399 K	Cold white
Luminous intensity Iv	59 Cd
Beam angle	244 deg
Power P	10.4 W
Power Factor	0.60	For every 1 kWh net power consumed, there has been 1.3 kVAhr for reactive power.
Luminous flux	517 Lm
Luminous efficacy	50 Lm/W	This is the luminaire efficacy (including reflection, absorption, power supply, temperature losses).
CRI_Ra	78	Color Rendering Index.
Coordinates chromaticity diagram	x=0.3151 and y=0.3244
Fitting	E27
PAR-value	0.5 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. Valid for roughly the region within the beam angle.
S/P ratio	2.1	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	100 x 178 mm	External dimensions of the light bulb.
D x H luminous area	100 x 78 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the size of the glass of this light bulb.
General remarks		The ambient temperature during the whole set of measurements was 23-23.5 deg C. Warm up effect: during the warm up time the illuminance and the consumed power decrease with 18 % and 10 % respectively. Voltage dependency: the power consumption nor light output depend on the voltage applied.
Measurement report (PDF)	tbc
Eulumdat file		Right click on icon and save the file.

Eulumdat light diagram

An interesting graph is the light diagram, indicating the intensity in the C0-C180 and the C90-C270 plane. This light diagram below comes from the program Qlumedit, that extracts these diagrams from an Eulumdat file.

The light diagram giving the radiation pattern.

It indicates the luminous intensity around the light bulb. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane since there is symmetry over the z-axis (height of the light bulb).

The unit is Cd/1000Lm, meaning the intensity in Cd assuming there would be 1000 Lumen in the measured light bulb. This enables comparing different types of light bulbs.

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 244 degrees.

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 517 Lm.

Luminous efficacy

The luminous flux being 517 Lm, and the power of the light bulb being 10.4 W, yields a luminous efficacy of 50 Lm/W.

A power factor of 0.60 means that for every 1 kWh net power consumed, a reactive component of 1.3 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it are measured and graphed.

Voltage across and current through the lightbulb

The current is out of phase with the voltage, and it shows peaks as well.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

The peaks in the current result in a lot of higher harmonics.

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 6400 K which is cold 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.

Measured is in the angles 15 and 195 degrees, and the measurement of CCT has been stopped when less than 5 lux (low illumination value) were measured or when the inclination angle was 90 degrees. With this light bulb the measurements were stopped at 90 degrees inclination angle.

In this area of inclination angles the correlated color temperature does not vary more than 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. PAR stands for Photosynthetic Active Radiation which is that radiation that participates actively to photosynthesis and is expressed in μMol/s/m².

Photosynthesis is the essence for growth and flowering of plants, where the blue part of the light spectrum is responsible for growth and the red part is responsible for flowering and budding (for gemmation). For photosynthesis it is more important to count the number of photons rather than the power in the light.

The power spectrum (power per wave length) of the light of the light bulb is converted into the number of photons (number of photons per wave length) and then these number of photons is weighted against the relative sensitivity of an average plant (which varies in value dependent on the wave length). The relative sensitivity curve in DIN-norm 5031-10:2000 is used for this. The next image shows the result.

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

The black curve gives the power spectrum of the light of this light bulb, in number of photons per wave length.

In red the relative sensitivity curve of an average plant (according to DIN norm 5031-10:2000).

Multiplying these two results in a curve showing the number of photos per wave length of the light of this light bulb, the PAR spectrum.

Summing all the photons, gives a PAR number that for this light results in 0.5 μMol/s/m². This value is valid at 1 m distance from the light bulb and for the area within the beam angle.

Dividing the PAR number by the total number of photons of the light of this light bulb gives a sort of PAR efficiency, which is 66 % (valid for the PAR wave length range of 400 - 700 nm). So maximally 66 % 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 %).

Note: when mentioning this percentage of efficiency, it is important to verify if all wavelengths are present in a sufficient manner. Not that only blue light is available, when the plant is going to be used for flowering where specifically red light is needed.

S/P ratio

The human eye uses rods and cones. The rods work at scotopic light levels (twilight, night) and the rods at high(er) light levels (daytime, but also close to twilight). Each type of receptor has its own sensitivity for light. The rods are 2.7 times more sensitive than cones, and most for light at a blueish-greenish color whereas compared to the cones’ sensitivity for green light (555 nm).
The S/P ratio gives the maximum difference in sensitivity of the rods at their most sensitive wavelength compared to the cones at their’s. The more blueish (cold white) the light, the more the S/P ratio can be.

The light of this light bulb has a certain spectrum leading to an S/P ratio of 2.1. The light of this lightbulb at scotopic light levels is perceived this factor higher than it would be a photopic light levels.

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

There’s a lot of blue with respect to green/yellow (see the blue line), resulting in an S/P ratio which is high being 2.1.

More info on the background of the S/P ratio  will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.3151 and y=0.3244.

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 78 is a little lower than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.0036 indicates the distance to the Planckian Locus. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 %.

Variation of parameters is small and insignificant when the voltage varies between 200-250 V.

When the voltage at 250 V varies with + and - 5 V, then the illuminance varies within 0.1 %, 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.

During a warm up time of about 30 minutes, the illumination drops with 18 % and the consumed power with 10 %.

See this overview for a comparison with other light bulbs.

Summary measurement data

parameter	meas. result	remark
Color temperature	3379 K	Cold side of warm white
Luminous intensity Iv	16 Cd
Beam angle	283 deg
Power P	7.2 W
Power Factor	0.58	For every 1 kWh net power consumed, there has been 1.4 kVAhr for reactive power.
Luminous flux	160 Lm
Luminous efficacy	22 Lm/W	This is the luminaire efficacy (including reflection, absorption, power supply, temperature losses).
CRI_Ra	75	Color Rendering Index.
Coordinates chromaticity diagram	x=0.4111 and y=0.3931
Fitting	E27
PAR-value	0.1 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. Valid for roughly the region within the beam angle.
S/P ratio	1.4	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	80 x 152 mm	External dimensions of the light bulb.
D x H luminous area	80 x 68 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the size of the glass of this light bulb.
General remarks		The ambient temperature during the whole set of measurements was 24.5-26 deg C. The case temperature was maximally 27 deg C higher than ambient. Warm up effect: during the warm up time the illuminance and the consumed power decrease with 45 % and 25 % respectively. Voltage dependency: the power consumption nor light output depend on the voltage applied.
Measurement report (PDF)	tbc
Eulumdat file		Right click on icon and save the file.

Eulumdat light diagram

An interesting graph is the light diagram, indicating the intensity in the C0-C180 and the C90-C270 plane. This light diagram below comes from the program Qlumedit, that extracts these diagrams from an Eulumdat file.

The light diagram giving the radiation pattern.

It indicates the luminous intensity around the light bulb. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane since there is symmetry over the z-axis (height of the light bulb).

The unit is Cd/1000Lm, meaning the intensity in Cd assuming there would be 1000 Lumen in the measured light bulb. This enables comparing different types of light bulbs.

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 283 degrees.

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 160 Lm.

Luminous efficacy

The luminous flux being 160 Lm, and the power of the light bulb being 7.2 W, yields a luminous efficacy of 22 Lm/W.

A power factor of 0.58 means that for every 1 kWh net power consumed, a reactive component of 1.4 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it are measured and graphed.

Voltage across and current through the lightbulb

The current is out of phase with the voltage, and it shows peaks as well.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

The peaks in the current result in a lot of higher harmonics.

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 3375 K which is on the cold side of 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.

Measured is in the angles 15 and 195 degrees, and the measurement of CCT has been stopped when less than 5 lux (low illumination value) were measured or when the inclination angle was 90 degrees. With this light bulb the measurements were stopped at 90 degrees inclination angle.

In this area of inclination angles the correlated color temperature does not vary more than 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. PAR stands for Photosynthetic Active Radiation which is that radiation that participates actively to photosynthesis and is expressed in μMol/s/m².

Photosynthesis is the essence for growth and flowering of plants, where the blue part of the light spectrum is responsible for growth and the red part is responsible for flowering and budding (for gemmation). For photosynthesis it is more important to count the number of photons rather than the power in the light.

The power spectrum (power per wave length) of the light of the light bulb is converted into the number of photons (number of photons per wave length) and then these number of photons is weighted against the relative sensitivity of an average plant (which varies in value dependent on the wave length). The relative sensitivity curve in DIN-norm 5031-10:2000 is used for this. The next image shows the result.

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

The black curve gives the power spectrum of the light of this light bulb, in number of photons per wave length.

In red the relative sensitivity curve of an average plant (according to DIN norm 5031-10:2000).

Multiplying these two results in a curve showing the number of photos per wave length of the light of this light bulb, the PAR spectrum.

Summing all the photons, gives a PAR number that for this light results in 0.1 μMol/s/m². This value is valid at 1 m distance from the light bulb and for the area within the beam angle.

Dividing the PAR number by the total number of photons of the light of this light bulb gives a sort of PAR efficiency, which is 64 % (valid for the PAR wave length range of 400 - 700 nm). So maximally 64 % 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 %).

Note: when mentioning this percentage of efficiency, it is important to verify if all wavelengths are present in a sufficient manner. Not that only blue light is available, when the plant is going to be used for flowering where specifically red light is needed.

S/P ratio

The human eye uses rods and cones. The rods work at scotopic light levels (twilight, night) and the rods at high(er) light levels (daytime, but also close to twilight). Each type of receptor has its own sensitivity for light. The rods are 2.7 times more sensitive than cones, and most for light at a blueish-greenish color whereas compared to the cones’ sensitivity for green light (555 nm).
The S/P ratio gives the maximum difference in sensitivity of the rods at their most sensitive wavelength compared to the cones at their’s. The more blueish (cold white) the light, the more the S/P ratio can be.

The light of this light bulb has a certain spectrum leading to an S/P ratio of 1.4. The light of this lightbulb at scotopic light levels is perceived this factor higher than it would be a photopic light levels.

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

There’s a little blue with respect to green/yellow (see the blue line), resulting in an S/P ratio which is low being 1.4.

More info on the background of the S/P ratio  will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.4111 and y=0.3931.

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 75 is lower 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. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 %.

Variation of parameters is small and insignificant when the voltage varies between 200-250 V.

When the voltage at 250 V varies with + and - 5 V, then the illuminance varies within 0.1 %, 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.

During a warm up time of about 20 minutes, the illumination drops with 45 % and the consumed power with 25 %. The rate of decrease for the illuminance is very fast, so the perception of the loss will be less than45 %, nevertheless there is a big decrease in illuminance level with respect to the very first time switch on.

See this overview for a comparison with other light bulbs.

Summary measurement data

parameter	meas. result	remark
Color temperature	6804 K	Cold white
Luminous intensity Iv	33 Cd
Beam angle	294 deg
Power P	7.1 W
Power Factor	0.57	For every 1 kWh net power consumed, there has been 1.4 kVAhr for reactive power.
Luminous flux	348 Lm
Luminous efficacy	49 Lm/W	This is the luminaire efficacy (including reflection, absorption, power supply, temperature losses).
CRI_Ra	78	Color Rendering Index.
Coordinates chromaticity diagram	x=0.3089 and y=0.3204
Fitting	E27
PAR-value	0.3 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. Valid for roughly the region within the beam angle.
S/P ratio	2.2	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	80 x 152 mm	External dimensions of the light bulb.
D x H luminous area	80 x 68 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the size of the glass of this light bulb.
General remarks		The ambient temperature during the whole set of measurements was 24.5-25.5 deg C. The case temperature was maximally 30 deg C higher than ambient. Warm up effect: during the warm up time the illuminance and the consumed power decrease with 30 % and 22 % respectively. Voltage dependency: the power consumption nor light output depend on the voltage applied.
Measurement report (PDF)	tbc
Eulumdat file		Right click on icon and save the file.

Eulumdat light diagram

An interesting graph is the light diagram, indicating the intensity in the C0-C180 and the C90-C270 plane. This light diagram below comes from the program Qlumedit, that extracts these diagrams from an Eulumdat file.

The light diagram giving the radiation pattern.

It indicates the luminous intensity around the light bulb. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane since there is symmetry over the z-axis (height of the light bulb).

The unit is Cd/1000Lm, meaning the intensity in Cd assuming there would be 1000 Lumen in the measured light bulb. This enables comparing different types of light bulbs.

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 294 degrees.

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 348 Lm.

Luminous efficacy

The luminous flux being 348 Lm, and the power of the light bulb being 7.1 W, yields a luminous efficacy of 49 Lm/W.

A power factor of 0.57 means that for every 1 kWh net power consumed, a reactive component of 1.4 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it are measured and graphed.

Voltage across and current through the lightbulb

The current is out of phase with the voltage, and it shows peaks as well.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

The peaks in the current result in a lot of higher harmonics.

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 6800 K which is cold 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.

Measured is in the angles 15 and 195 degrees, and the measurement of CCT has been stopped when less than 5 lux (low illumination value) were measured or when the inclination angle was 90 degrees. With this light bulb the measurements were stopped at 90 degrees inclination angle.

In this area of inclination angles the correlated color temperature does not vary more than 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. PAR stands for Photosynthetic Active Radiation which is that radiation that participates actively to photosynthesis and is expressed in μMol/s/m².

Photosynthesis is the essence for growth and flowering of plants, where the blue part of the light spectrum is responsible for growth and the red part is responsible for flowering and budding (for gemmation). For photosynthesis it is more important to count the number of photons rather than the power in the light.

The power spectrum (power per wave length) of the light of the light bulb is converted into the number of photons (number of photons per wave length) and then these number of photons is weighted against the relative sensitivity of an average plant (which varies in value dependent on the wave length). The relative sensitivity curve in DIN-norm 5031-10:2000 is used for this. The next image shows the result.

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

The black curve gives the power spectrum of the light of this light bulb, in number of photons per wave length.

In red the relative sensitivity curve of an average plant (according to DIN norm 5031-10:2000).

Multiplying these two results in a curve showing the number of photos per wave length of the light of this light bulb, the PAR spectrum.

Summing all the photons, gives a PAR number that for this light results in 0.3 μMol/s/m². This value is valid at 1 m distance from the light bulb and for the area within the beam angle.

Dividing the PAR number by the total number of photons of the light of this light bulb gives a sort of PAR efficiency, which is 66 % (valid for the PAR wave length range of 400 - 700 nm). So maximally 66 % 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 %).

Note: when mentioning this percentage of efficiency, it is important to verify if all wavelengths are present in a sufficient manner. Not that only blue light is available, when the plant is going to be used for flowering where specifically red light is needed.

S/P ratio

The human eye uses rods and cones. The rods work at scotopic light levels (twilight, night) and the rods at high(er) light levels (daytime, but also close to twilight). Each type of receptor has its own sensitivity for light. The rods are 2.7 times more sensitive than cones, and most for light at a blueish-greenish color whereas compared to the cones’ sensitivity for green light (555 nm).
The S/P ratio gives the maximum difference in sensitivity of the rods at their most sensitive wavelength compared to the cones at their’s. The more blueish (cold white) the light, the more the S/P ratio can be.

The light of this light bulb has a certain spectrum leading to an S/P ratio of 2.2. The light of this lightbulb at scotopic light levels is perceived this factor higher than it would be a photopic light levels.

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

There’s a lot of blue with respect to green/yellow (see the blue line), resulting in an S/P ratio which is high being 2.2.

More info on the background of the S/P ratio  will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.3087 and y=0.3204.

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 78 is a little lower than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.0023 indicates the distance to the Planckian Locus. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 %.

Variation of parameters is small and insignificant when the voltage varies between 200-250 V.

When the voltage at 250 V varies with + and - 5 V, then the illuminance varies within 0.1 %, 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.

During a warm up time of about 25 minutes, the illumination drops with 30 % and the consumed power with 22 %.

See this overview for a comparison with other light bulbs.

Summary measurement data

parameter	meas. result	remark
Color temperature	3144 K	Warm white
Luminous intensity Iv	8.6 Cd
Beam angle	290 deg
Power P	3.6 W
Power Factor	0.49	For every 1 kWh net power consumed, there has been 1.8 kVAhr for reactive power.
Luminous flux	88 Lm
Luminous efficacy	24 Lm/W	This is the luminaire efficacy (including reflection, absorption, power supply, temperature losses).
CRI_Ra	70	Color Rendering Index.
Coordinates chromaticity diagram	x=0.4319 and y=0.4116
Fitting	E27
PAR-value	0.1 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. Valid for roughly the region within the beam angle.
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	60 x 111 mm	External dimensions of the light bulb.
D x H luminous area	60 x 52 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the size of the glass of this light bulb.
General remarks		The ambient temperature during the whole set of measurements was 25-25 deg C. The case temperature was maximally 33 deg C higher than ambient. Warm up effect: during the warm up time the illuminance and the consumed power decrease with 25 % and 20 % respectively. Voltage dependency: the power consumption nor light output depend on the voltage applied.
Measurement report (PDF)	tbc
Eulumdat file		Right click on icon and save the file.

Eulumdat light diagram

An interesting graph is the light diagram, indicating the intensity in the C0-C180 and the C90-C270 plane. This light diagram below comes from the program Qlumedit, that extracts these diagrams from an Eulumdat file.

The light diagram giving the radiation pattern.

It indicates the luminous intensity around the light bulb. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane since there is symmetry over the z-axis (height of the light bulb).

The unit is Cd/1000Lm, meaning the intensity in Cd assuming there would be 1000 Lumen in the measured light bulb. This enables comparing different types of light bulbs.

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 290 degrees.

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 88 Lm.

Luminous efficacy

The luminous flux being 88 Lm, and the power of the light bulb being 3.6 W, yields a luminous efficacy of 24 Lm/W.

A power factor of 0.49 means that for every 1 kWh net power consumed, a reactive component of 1.8 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it are measured and graphed.

Voltage across and current through the lightbulb

The current is out of phase with the voltage, and it shows peaks as well.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

The peaks in the current result in a lot of higher harmonics.

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 3150 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.

Measured is in the angles 15 and 195 degrees, and the measurement of CCT has been stopped when less than 5 lux (low illumination value) were measured or when the inclination angle was 90 degrees. With this light bulb the measurements were stopped at 90 degrees inclination angle.

In this area of inclination angles the correlated color temperature does not vary more than 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. PAR stands for Photosynthetic Active Radiation which is that radiation that participates actively to photosynthesis and is expressed in μMol/s/m².

Photosynthesis is the essence for growth and flowering of plants, where the blue part of the light spectrum is responsible for growth and the red part is responsible for flowering and budding (for gemmation). For photosynthesis it is more important to count the number of photons rather than the power in the light.

The power spectrum (power per wave length) of the light of the light bulb is converted into the number of photons (number of photons per wave length) and then these number of photons is weighted against the relative sensitivity of an average plant (which varies in value dependent on the wave length). The relative sensitivity curve in DIN-norm 5031-10:2000 is used for this. The next image shows the result.

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

The black curve gives the power spectrum of the light of this light bulb, in number of photons per wave length.

In red the relative sensitivity curve of an average plant (according to DIN norm 5031-10:2000).

Multiplying these two results in a curve showing the number of photos per wave length of the light of this light bulb, the PAR spectrum.

Summing all the photons, gives a PAR number that for this light results in 0.1 μMol/s/m². This value is valid at 1 m distance from the light bulb and for the area within the beam angle.

Dividing the PAR number by the total number of photons of the light of this light bulb gives a sort of PAR efficiency, which is 63 % (valid for the PAR wave length range of 400 - 700 nm). So maximally 63 % 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 %).

Note: when mentioning this percentage of efficiency, it is important to verify if all wavelengths are present in a sufficient manner. Not that only blue light is available, when the plant is going to be used for flowering where specifically red light is needed.

S/P ratio

The human eye uses rods and cones. The rods work at scotopic light levels (twilight, night) and the rods at high(er) light levels (daytime, but also close to twilight). Each type of receptor has its own sensitivity for light. The rods are 2.7 times more sensitive than cones, and most for light at a blueish-greenish color whereas compared to the cones’ sensitivity for green light (555 nm).
The S/P ratio gives the maximum difference in sensitivity of the rods at their most sensitive wavelength compared to the cones at their’s. The more blueish (cold white) the light, the more the S/P ratio can be.

The light of this light bulb has a certain spectrum leading to an S/P ratio of 1.2. The light of this lightbulb at scotopic light levels is perceived this factor higher than it would be a photopic light levels.

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

There’s little blue with respect to green/yellow (see the blue line), resulting in an S/P ratio which is low being 1.2.

More info on the background of the S/P ratio  will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.4319 and y=0.4116.

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 70 is lower than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.0037 indicates the distance to the Planckian Locus. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 %.

Variation of parameters is small and insignificant when the voltage varies between 200-250 V.

When the voltage at 250 V varies with + and - 5 V, then the illuminance varies within 0.1 %, 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.

During a warm up time of about 30 minutes, the illumination drops with 25 % and the consumed power with 20 %.

See this overview for a comparison with other light bulbs.

Summary measurement data

parameter	meas. result	remark
Color temperature	6504 K	Cold white
Luminous intensity Iv	14 Cd
Beam angle	298 deg
Power P	3.4 W
Power Factor	0.47	For every 1 kWh net power consumed, there has been 1.9 kVAhr for reactive power.
Luminous flux	145 Lm
Luminous efficacy	43 Lm/W	This is the luminaire efficacy (including reflection, absorption, power supply, temperature losses).
CRI_Ra	78	Color Rendering Index.
Coordinates chromaticity diagram	x=0.3133 and y=0.3236
Fitting	E27
PAR-value	0.1 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. Valid for roughly the region within the beam angle.
S/P ratio	2.1	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	60 x 111 mm	External dimensions of the light bulb.
D x H luminous area	60 x 52 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the size of the glass of this light bulb.
General remarks		The ambient temperature during the whole set of measurements was 24.5-25 deg C. The case temperature was maximally 28 deg C higher than ambient. Warm up effect: during the warm up time the illuminance and the consumed power decrease with 17 % and 14 % respectively. Voltage dependency: the power consumption nor light output depend on the voltage applied.
Measurement report (PDF)	tbc
Eulumdat file		Right click on icon and save the file.

Eulumdat light diagram

An interesting graph is the light diagram, indicating the intensity in the C0-C180 and the C90-C270 plane. This light diagram below comes from the program Qlumedit, that extracts these diagrams from an Eulumdat file.

The light diagram giving the radiation pattern.

It indicates the luminous intensity around the light bulb. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane since there is symmetry over the z-axis (height of the light bulb).

The unit is Cd/1000Lm, meaning the intensity in Cd assuming there would be 1000 Lumen in the measured light bulb. This enables comparing different types of light bulbs.

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 298 degrees.

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 145 Lm.

Luminous efficacy

The luminous flux being 145 Lm, and the power of the light bulb being 3.4 W, yields a luminous efficacy of 43 Lm/W.

A power factor of 0.47 means that for every 1 kWh net power consumed, a reactive component of 1.9 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it are measured and graphed.

Voltage across and current through the lightbulb

The current is out of phase with the voltage, and it shows peaks as well.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

The peaks in the current result in a lot of higher harmonics.

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 6500 K which is cold 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.

Measured is in the angles 15 and 195 degrees, and the measurement of CCT has been stopped when less than 5 lux (low illumination value) were measured or when the inclination angle was 90 degrees. With this light bulb the measurements were stopped at 90 degrees inclination angle.

In this area of inclination angles the correlated color temperature does not vary more than 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. PAR stands for Photosynthetic Active Radiation which is that radiation that participates actively to photosynthesis and is expressed in μMol/s/m².

Photosynthesis is the essence for growth and flowering of plants, where the blue part of the light spectrum is responsible for growth and the red part is responsible for flowering and budding (for gemmation). For photosynthesis it is more important to count the number of photons rather than the power in the light.

The power spectrum (power per wave length) of the light of the light bulb is converted into the number of photons (number of photons per wave length) and then these number of photons is weighted against the relative sensitivity of an average plant (which varies in value dependent on the wave length). The relative sensitivity curve in DIN-norm 5031-10:2000 is used for this. The next image shows the result.

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

The black curve gives the power spectrum of the light of this light bulb, in number of photons per wave length.

In red the relative sensitivity curve of an average plant (according to DIN norm 5031-10:2000).

Multiplying these two results in a curve showing the number of photos per wave length of the light of this light bulb, the PAR spectrum.

Summing all the photons, gives a PAR number that for this light results in 0.1 μMol/s/m². This value is valid at 1 m distance from the light bulb and for the area within the beam angle.

Dividing the PAR number by the total number of photons of the light of this light bulb gives a sort of PAR efficiency, which is 66 % (valid for the PAR wave length range of 400 - 700 nm). So maximally 66 % 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 %).

Note: when mentioning this percentage of efficiency, it is important to verify if all wavelengths are present in a sufficient manner. Not that only blue light is available, when the plant is going to be used for flowering where specifically red light is needed.

S/P ratio

The human eye uses rods and cones. The rods work at scotopic light levels (twilight, night) and the rods at high(er) light levels (daytime, but also close to twilight). Each type of receptor has its own sensitivity for light. The rods are 2.7 times more sensitive than cones, and most for light at a blueish-greenish color whereas compared to the cones’ sensitivity for green light (555 nm).
The S/P ratio gives the maximum difference in sensitivity of the rods at their most sensitive wavelength compared to the cones at their’s. The more blueish (cold white) the light, the more the S/P ratio can be.

The light of this light bulb has a certain spectrum leading to an S/P ratio of 2.1. The light of this lightbulb at scotopic light levels is perceived this factor higher than it would be a photopic light levels.

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

There’s a lot of blue with respect to green/yellow (see the blue line), resulting in an S/P ratio which is high being 2.1.

More info on the background of the S/P ratio  will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.3133 and y=0.3236.

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 78 is a little lower than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.003 indicates the distance to the Planckian Locus. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 %.

Variation of parameters is small and insignificant when the voltage varies between 200-250 V.

When the voltage at 250 V varies with + and - 5 V, then the illuminance varies within 0.1 %, 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.

During a warm up time of about 25 minutes, the illumination drops with 17 % and the consumed power with 14 %.

REVA

REVA is the brand of the Reva Electric Car Company, a Bangalore-based company formed as a joint venture between Maini Group of India and AEV LLC of California and backed by US investors Global Environment Fund and Draper Fisher Jurvetson. Today, REVA is selling, or being test marketed, in 24 countries worldwide and has the largest deployed fleet of electric cars on the market with over 3,000 EVs on the road and more than 70 million kilometres of user experience. REVA’s business model includes: electric vehicle design, development and manufacture, electric vehicle technology licensing and electric vehicle manufacturing franchising. REVA develops all key technologies including energy management, fast-charge and telematics systems in-house. European distribution is in the following countries: Norway, UK, Spain, France, Germany, Austria, Belgium, Ireland, Hungary, Portugal, Cyprus and Greece with other distributors being appointed over the next few months.The company is building a new ultra low carbon vehicle assembly plant in Bangalore, with a capacity of 30,000 units per annum, to accommodate increased production and is planning to introduce even more measures to ensue that it has the cleanest and greenest production.

REVA NXR

The REVA NXR has keyless entry and operation, dual charge ports, intelligent digital display and a range of telematics. These include SMS alerts and commands such as distance-to-empty and time-to-full charge, remote cabin heat/cool, a monthly eco-drive check by email, service and insurance alerts, remote diagnostics and healing and REVive remote emergency charge. REVive is exclusive to REVA and acts like an invisible reserve fuel tank and addresses ‘range anxiety’. If a customer runs out of charge, they can telephone or SMS REVA’s customer support centre. The advanced telematics feature will assess the car’s batteries remotely and activate a reserve amount of energy while protecting the battery life. Within minutes, a few extra kilometres of range are made available via the telematics and the driver can continue home or to a place where the NXR can be charged.

Prices of the NXR will vary across Europe depending on taxes and subsidies. Customers will be offered the option of purchasing the car and batteries separately, or at an all-inclusive price. If bought separately, the benefit will be a lower purchase price, with the batteries paid for on a monthly basis – just like petrol - as part of a monthly mobility fee, which could also include electricity, telematics and other services. Average prices in Europe, excluding batteries, will be around 14,995 euros for the lithium-ion NXR Intercity version. The REVA NXR City, with lead acid batteries that has an 80 km (50 mile) range and a speed of 80 kph (50 mph) is also available from 9,995 euros and a small monthly mobility fee.

Chetan Maini, deputy chairman and chief technology officer of REVA said today; “The NXR is a stylish city car packed full of user-friendly technology. You can order one from today and production will start early next year, so you can be one of the first to own the latest generation of electric cars.”

Reva NXR driving in front

Specifications REVA NXR Li-Ion

REVA NXG

Styled by Dilip Chhabria, the REVA NXG is a M1 category, two-door, two-seater car with a targa top. The REVA NXG has a range of 200km (125 miles) per charge and a top speed of 130 kph (80 miles per hour). It features the same telematics as the REVA NXR, including REVive and, using the fast charge, it has an effective range of 400 kms (250 miles) a day. This showcar, the REVA NXG, is REVA’s 2011 model and its first showing is at the Frankfurt Motor Show (IAA). Pricing in Europe excluding batteries is from 23,000 euros plus a monthly mobility fee.

Specifications REVA NXG

Dust-to-dirt

‘Dust-to-dirt’ is a term used for the complete lifecycle of a car from the carbon emissions generated in the parts manufacture, assembly, operation and disposal / recycling of a REVA electric car. This is a commitment and the beginning of the process that will take time to determine, starting with the assembly and operation and then extending down the supply chain to tier 1 suppliers and up to second life / end of life. REVA is committed to mitigating climate change with the creation of ultra low carbon cars – it has only ever made EVs. Every REVA NXR and REVA NXG will be Born Green, meaning they will have one of the lowest dust-to-dirt carbon footprints of any car in mass production. The REVA NXR has been designed to use approximately 80% fewer parts than a conventional or hybrid car and will be assembled in REVA’s new ultra low-carbon assembly plant in Bangalore powered by solar energy and using natural light and ventilation and rainwater harvesting. Preparations have begun to create a ‘second life’ for the lithium batteries to optimise energy efficiency and reduce the cost to consumers via the creation of guaranteed residual values. From 2010 REVA will publish the carbon emissions for the assembly and lifetime operation of both these new cars and by this environmental disclosure, customers can make an informed buying decision.

Range anxiety

Range anxiety is the fear that one day you’re going to find yourself somewhere that is too far from your home (so you can’t just go back and plug in), yet far from known charging stations, or if you are close, you just don’t have the time in your schedule to stop for a long time to allow the battery to recharge. REVive addresses ‘range anxiety’. The amount of reserve energy in a battery depends on several parameters including the temperature, usage (that day and historically) and the age of the batteries. The REVA support centre assesses information from the car via telematics (information and communication technology) to calculate the amount of reserve energy available for that particular car. Then, within a few minutes the digital display will indicate ‘Revive’ and the ‘distance to empty’ gauge will display the additional amount of range available and the driver can continue their journey.

Reva NXG driving in front

Videos

REVA NXR electric car - first test drive

A Glance at Reva New models NXR & NXG

World Launch of REVA NXR

World Launch of Reva NXG

REVA Revive: Remote Emergency charge

Related information

REVA Electric Car

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	2758 K	warm white
Luminous intensity Iv	624 Cd	Measured straight underneath the lamp
Beam angle	28 deg
Power P	3.8 W
Power Factor	0.65	For every 1 kWh net power consumed, there has been 1.2 kVAhr for reactive power.
Luminous flux	195 Lm
Luminous efficacy	52 Lm/W
CRI_Ra	81	Color Rendering Index.
Coordinates chromaticity diagram	x=0.4541 and y=0.4074
Fitting	GU5.3/MR16
PAR-value	6.1 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.
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 L external dimensions	50 x 43 mm	External dimensions of the lamp. Excluding the pins.
D luminous area	33 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the surface of the frosted plate at the front.
General remarks		The ambient temperature during the whole set of measurements was 22-22.5 ºC. Warm up effect: during the warm up time the illuminance and consumed power decrease with 6 % and 2 % respectively. Voltage dependency: the power consumption and illuminance hardly depend on the lamp voltage, except when it drops below 11 V AC.
Measurement report (PDF)
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.

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. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane as it has a symmetry around its height 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 28 degrees.

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 195 Lm.

Luminous efficacy

The luminous flux being 195 Lm, and the power of the light bulb being 3.8 W, yields a luminous efficacy of 52 Lm/W.

A power factor of 0.65 means that for every 1 kWh net power consumed, a reactive component of 1.2 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it+its constant current driver power supply are measured and graphed. See the OliNo site how this is obtained.

Voltage across and current through the lightbulb

The current does look not like a sine, it has peaks that will result in higher harmonics. Also the phase is not the same as the voltage (as the peaks do not coincide with the summits of the voltage). Result is a low power factor of less than 0.7.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

A lot of higher harmonics, as there are very steep edges in the current shape.

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 2750 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 Correlated Color Temperature has been stopped when the inclination angle was 72.5 as the illuminance value was decreased to very low values there (< 5 lux).

The beam angle is 28º, meaning an inclination angle of max 14º. Almost all light falls within this angle. The variation of the color temperature within this angle 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 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

The PAR number for this light results in 6.1 μMol/s/m². This value is valid at 1 m distance from the light bulb and valid roughly inside its beam angle.

The PAR efficiency is 64 % (valid for the PAR wave length range of 400 - 725 nm). So maximally 64 % 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 will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.4541 and y=0.4074.

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 81 is higher than 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.0007 indicates the distance to the Planckian Locus. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 12 V is taken as 100 %.

The consumed power and the illuminance vary only when the volatge drops below 11 V.

When the voltage at 12 V varies with + and - 0.25 V (equivalent to + and - 5 V at 230 V grid voltage), then the illuminance varies within 1 %, 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 about 25 minutes. During that time the illuminance decreases with 7 % and the consumed power with 2 %.

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	2878 K	warm white
Luminous intensity Iv	432 Cd	Measured straight underneath the lamp
Beam angle	30 deg
Power P	5.7 W
Power Factor	0.93	For every 1 kWh net power consumed, there has been 0.4 kVAhr for reactive power.
Luminous flux	147 Lm
Luminous efficacy	26 Lm/W
CRI_Ra	82	Color Rendering Index.
Coordinates chromaticity diagram	x=0.4466 and y=0.4084
Fitting	GU10
PAR-value	4.2 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.
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 L external dimensions	50 x 48 mm	External dimensions of the lamp. Excluding the pins.
D luminous area	35 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the surface of the frosted plate at the front.
General remarks		The ambient temperature during the whole set of measurements was 22.5 ºC. The max temp on the lamp was 32 ºC higher (so 55 ºC). Warm up effect: during the warm up time the consumed power increases with 20 %. Voltage dependency: the power consumption and illuminance depend linearly on the voltage when it is varied from 200 - 250 V. This article contains the test results of dimming the lamp at the end, which failed.
Measurement report (PDF)
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.

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. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane as it has a symmetry around its height 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 30 degrees.

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 147 Lm.

Luminous efficacy

The luminous flux being 147 Lm, and the power of the light bulb being 5.7 W, yields a luminous efficacy of 26 Lm/W.

A power factor of 0.93 means that for every 1 kWh net power consumed, a reactive component of 0.4 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it+its constant current driver power supply are measured and graphed. See the OliNo site how this is obtained.

Voltage across and current through the lightbulb

The current does look like a sine but is not perfect, and its steep edges will result in some harmonics. It is in phase with the voltage. The power factor ends on a nice result, being > 0.9.

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

A few higher harmonics, as there are steep edges in the current shape.

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 2875 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 Correlated Color Temperature has been stopped when the inclination angle was 80 as the illuminance value was decreased to very low values there (< 5 lux).

The beam angle is 30º, meaning an inclination angle of max 15º. Almost all light falls within this angle. The variation of the color temperature within this angle is about 2 %.

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

The PAR number for this light results in 4.2 μMol/s/m². This value is valid at 1 m distance from the light bulb and valid roughly inside its beam angle.

The PAR efficiency is 64 % (valid for the PAR wave length range of 400 - 725 nm). So maximally 64 % 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 will come in a separate article.

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=0.4466 and y=0.4084.

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 82 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. Its value is lower than 0.0054, which means that the calculated CRI result is meaningful.

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 consumed power varies and the illuminance vary linearly when the voltage is varied.

When the voltage at 230 V varies with + and - 5 V, then the illuminance varies within 5 %, so when abrupt voltage changes occur this effect is most likely 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 about 15 minutes. During that time the illuminance increases with 4 % and the consumed power with 20 %.

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.

Dim result on the lamp parameters (0% is maximally dimming)

The lamp is not well dim-able; there is no nice continuous decrease of illuminance when dimming is increased.

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	7603 K	Cold white
Luminous intensity Iv	647 Cd	Measured straight underneath the lamp
Beam angle	121 deg	118º for the C0-C180 plane (length direction of tube), and 121º for C90-C270 plane (perpendicular). These values are virtually the same.
Power P	25.8 W
Power Factor	0.99	For every 1 kWh net power consumed, there has been 0.1 kVAhr for reactive power.
Luminous flux	2009 Lm
Luminous efficacy	78 Lm/W
CRI_Ra	80	Color Rendering Index.
Coordinates chromaticity diagram	x=0.3011 and y=0.3018
Fitting	FL-tube	It is connected directly to the grid.
PAR-value	6.4 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.
S/P ratio	2.2	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 L external dimensions	30 x 1197 mm	External dimensions of the lamp. Excluding the pins.
L x W luminous area	1150 x 17 mm	Dimensions of the luminous area (used in Eulumdat file). This is equal to the surface on which the leds are mounted.
General remarks		The ambient temperature during the whole set of measurements was 23-25 deg C. The tube ends are measured on surface temperature (37º C en 52º C where the power supply houses). Warm up effect: during the warm up time the illuminance and the consumed power decrease with 11 % and 12 % respectively. Voltage dependency: the power consumption and illuminance depend linearly on the voltage when it is varied from 200 - 250 V. This article contains the test results of dimming the tube at the end.
Measurement report (PDF)
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.

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. This light bulb has the same light diagram for the C0-C180 as for the C90-C270 plane.

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 118-121 degrees.

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 2009 Lm.

Luminous efficacy

The luminous flux being 2009 Lm, and the power of the light bulb being 25.8 W, yields a luminous efficacy of 78 Lm/W.

A power factor of 0.99 means that for every 1 kWh net power consumed, a reactive component of 0.1 kVAr was needed.

Of this light bulb the voltage across ad the resulting current through it+its constant current driver power supply are measured and graphed. See the OliNo site how this is obtained.

Voltage across and current through the lightbulb

The current does look like a nice sine and it has the same phase as the voltage, hence the power factor is about 1, perfect!

Also the power spectrum of the current is determined.

Current power spectrum in % of the first harmonic (50 Hz).

No relevant higher harmonics.

Temperature measurements lamp

Temperature image of cold side of the tube, after warming up

⁽¹⁾ The emissivity has been set such that the measuremed temperatures were corresponding as much as possible to those measured directly with a contact measurement probe. The contact measurement probe measured 3 degrees lower, but had a lowering effect when it touched the surface for measurement. As a compromise the reported temperature here is the average temperaure of both these calibrated temperature sensors was taken.

On the other side of the tube it gets hotter, as the power supply is housed in there.

Temperature of the heat sink

This side gets above 52º C.

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 7600 K which is cold 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 has been stopped when the inclination angle was 75 as the illuminance value was decreased to very low values there (< 5 lux).

The beam angle is 121º, meaning an inclination angle of max 60.5º. Almost all light falls within this angle. The variation of the color temperature within this angle is about 14 %.

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

The PAR number for this light results in 6.4 μMol/s/m². This value is valid at 1 m distance from the light bulb and valid roughly inside its beam angle.

The PAR efficiency is 67 % (valid for the PAR wave length range of 400 - 725 nm). So maximally 67 % 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 2.2.

More info will come in a separate article.

Chromaticity diagram

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

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

Its coordinates are x=0.3011 and y=0.3018.

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 80 is equal to 80 which is considered a minimum value for indoor usage.

Note: the chromaticity difference is 0.0082 indicates the distance to the Planckian Locus. Its value is higher than 0.0054, which means that the calculated CRI result is not meaningful.

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 consumed power varies and the illuminance vary linearly when the voltage is varied.

When the voltage at 230 V varies with + and - 5 V, then the illuminance varies within 3 %, 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 about 35 minutes. During that time the illuminance decreases with 11 % and the consumed power with 12 %.

Dim function

The tube has its own dim function, which is operated as follows (explanation Lioris):

Step 1. Switch on the Tubo. It will switch into it’s previous choosen setting (memory).
Step 2. Within 10 seconds switch the Tubo off and on again.
Step 3. The dimming program will start.
3 blinks to indicate program mode
Within 6 seconds the Tubo will go to 100% light output and will blink 2 times
User has 4 seconds to select 100% or can select within the previous 6 seconds.
Within 6 seconds the Tubo will go to 75% light output and will blink 2 times
User has 4 seconds to select 75% or can select within the previous 6 seconds.
Within 6 seconds the Tubo will go to 50% light output and will blink 2 times
User has 4 seconds to select 50% or can select within the previous 6 seconds.
Within 6 seconds the Tubo will go to 25% light output and will blink 2 time
User has 4 seconds to select 25% or can select within the previous 6 seconds.
Tubo switches to 100% instantly
Step 4. If within step 3, the tube is switched off: then that dim setting will be selected when it is switched on again.

This is easy to dim, and this way all tubes connected to the same on/off switch can be dimmed to the same position.

The following graph gives the result of the dimming function. The general interpretation of the parameters and the graph is explained on the OliNo website.

Dim result on the lamp parameters

The tube is well dim-able. The illuminance decreases linearly with the dim-preset values being 100 %, 75 %, 50 % and 25 %.

The consumed power decreases at even a little higher speed, resulting in an even better efficacy.

The color temperature decreases a bit when dimming is done.