Photometric Testing: Lamp – LED – Luminaire Testing
What is Relative Photometry?
What is relative photometry?
Total Lumen output of a bare lamp is measured in relative photometry for more clarity; the total luminous flux of the lamp is measured separately without the Fixture. In IES LM-80- 08, IES LM 82-12, the relative photometry is used. The purpose is to find light output, Efficacy, color over temperature for light engines.
Relative photometry can measures:
- Total luminous flux of the bare lamp
- Luminous intensity distribution
- Scale the luminous intensity values by the ratio of the measured lamp lumens to the rated lamp lumens.
Some important features regarding relative photometry:
- Relative photometry is performed for luminaries with conventional sources.
- Luminaries test is referenced to the luminous Flux measured for bare lamp.
- The result produced is in the units of candela per rated lumens( cd/rated lm)
- It can also measure the efficiency of luminary.
- Normalize ballast factor, Lamp age.
- Specific lamp performance doesn’t matter
Relative photometry is not used in SSL with integrated lamps due to many reasons:
- The LED‘s are difficult to remove from the Luminaries.
- A large number of LED devices will not work properly without heat sinks provided with luminaries.
- The thermal environment that the LED devices undergo within the luminary is often radically different from the thermal environment it will practice in its “bare lamp” configuration.
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What are LM 79 Test Outcomes?
What are LM 79 Test Outcomes?
LM-79 is approved test method for electrical and photometric measurements of Solid State Lighting Products. It describes the procedure in measuring total luminous flux, electrical power, luminous intensity distribution, chromaticity under standard conditions. It covers LED based SSL products with control electronics and heat sink incorporated with AC or DC power supply. This does not include LED chips, LED package or LED module but luminaries (fixtures incorporating light source) as well as integrated LED lamps.
The equipment used in LM-79 is integrated sphere and goniophotometer.
Integrating Sphere Goniophotometer
The test report shall list all significant data for each SSL product tested together with performance data. The outcomes of the LM-79 test are:
- Correction factor applied ( e.g. spectral mismatch, self absorption , intensity distribution etc.)
- Measured total luminous flux( lumen(lm)), input voltage(v), current(a), power(w), Luminous intensity distribution(cd), efficacy(lm/w)
- Color quantities( chromaticity coordinates, CCT, CRI )
- Spectral power distribution
- Bandwidth of spectoradiometer, if spectral distribution and/or color quantities are reported.
- Statement of uncertainties (if required)
- Deviation from standard operating procedures, if any.
Here is the link of a test report issued by our prestigious company. LM 79 Test Outcomes
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What is LM 79 Test methodology?
What is LM 79 Test methodology?
LM 79 is an approved method that describes the procedure to be followed and precautions to be observed in performing reproducible measurements of total Luminous flux, electrical power, luminous intensity distribution, chromaticity of Solid-State lighting products for illumination purposes under standard conditions.
LM 79 covers- LED based SSL products with control electronics and heat sinks. Luminaries (fixtures incorporating light source) as well integrated LED lamps.
LM 79 doesn’t cover– fixtures without a light source, SSL products that require external operating.
LM 79
Test method for total luminous flux Measurements:
The total luminous flux of SSL product shall be measured with an Integrating Sphere or Goniophotometer. The method may be chosen depending upon what other measurements quantities (color, intensity distribution) need to be measured., the size of SSL products, and other requirements.
The integrating sphere is suited for total luminous flux and color measurements of integrated LED lamps and relative small size LED luminaries. Advantage of using integrating sphere is that it does not requires the “ Dark Room”., and also it is less time consuming.
The Goniophotometer provides measurements of Luminous Intensity Distribution as well as total luminous flux. It can take measurements of larger size luminaries as well as small size luminaries. It has to be installed in Dark Room. Measurements in goniophotometer are time consuming.
| Integrating Sphere | Goniophotometer | |
| Conditions | No Dark room | Dark Room |
| Size of SSL | Small Size luminaries | Large size as well as small size Luminaries |
| Measurements | Total Luminous Flux | Light Intensity Distribution , Total Luminous Flux |
| Duration of Test | Fast Measurements | Time consuming as compared to Sphere photometer. |
If you’re Buyers Demanding for Luminaries Testing– Contact Now!
Wish this blog post will be help. If you have any other questions, please feel free to contact us. ITCIndia team looking forward work with you and get better together!
Mr. Puneet Sharma | Call: 08196980555 | E-mail: [email protected]
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Photometric Testing Experts
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If you are looking for Photometric Testing Laboratory for LED Lighting In your Area, ITCIndia Electrical Safety testing Laboratory Approved from NABL. ITC India one of the best Photometric Testing Laboratory in India, Mumbai, Chennai, Ahmedabad, New Delhi, Pune, Kolkata, Bangalore, Hyderabad, Surat, Visakhapatnam.
ITCIndia “Institute of Testing and Certification India Pvt. Ltd” are a leading testing lab having a NABL accreditation under ELECTRICAL, ELECTRONICS and PHOTOMETRY testing with certificate no. T-3509, T-3570 and T-1811. ITCIndia Lab is following the procedure as required by International Standard IEC 17025 and is already certified for ISO/IEC 17025.
As the development of LED technology continues to grow and diversify, the need for consistent and standardized testing procedures for LED has become more prevalent than ever. ITCIndia is NABL Accredited laboratory for Photometric Testing for LED Lighting, LM 79 Testing.
Institute of Testing and Certification India Pvt. Ltd has made strides to stay current with the new testing standard LM-79 set forth by the IESNA (Illuminating Engineering Society of North America). In addition, “ITCIndia” testing is now a priority when testing our LED light systems for more reliable results.
ITCIndia Lab has made strides to stay current with the new testing standard LM-79 set forth by the IEC/EN 60598. In addition, ITC INDIA testing is now a priority when testing our LED light systems for more reliable results. Fixtures tested by LM-79 standards will now feature a Lighting Facts label provided through the program created by the IEC/EN.
LM-79 Electrical and Photometric Measurements of Solid-State Lighting Products
Approved method describing procedures and precautions in performing reproducible measurements of LEDs:
- Total luminous flux
- Electrical powers
- Luminous Intensity distribution
- Efficacy (lm/watt)
- Chromaticity
How To do Photometric Testing?
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Absolute Photometry Basis
- LM-79 requires complete luminaire testing
- Traditionally, photometric evaluation of lighting products is based on separate tests for lamps and luminaires
- For SSL products, LED lamps typically cannot be separated from their luminaire because of heat effects
Relative vs. Absolute Photometry
Relative testing – Lamps of interest and luminaire are measured separately. Then the actual light distribution and intensity of the complete luminaire of interest is derived by normalization of the test data
Absolute testing – The actual light distribution and intensity of the luminaire of interest is measured directly from the complete luminaire.
