EMRP-ENG05: Metrology for Solid State Lighting

• Research unit: METAS
• Project number: F-5213.30001

Key words (English)

Metrology, solid state lighting, energy consumption, power measurement, power quality

Short description (English)

SSL (Solid State Lighting) is evaluated as the most efficient lighting technology; it is predicted to be typically twice as energy efficient as fluorescent lamps and ten times more efficient than incandescent lamps, although current products are still in their early stages. As the world electricity consumption for lighting is one fifth of the global grand total, considerable reduction of energy consumption is obtained when replacing conventional lighting products by SSL technology. However, both professional users and consumers have so far been reluctant to embrace solid-state lighting, often due to unjustifiable or simply false claims about SSL product performance, partially relating to poor metrology.

The supporting metrological framework for successful wide-spread implementation of SSL technology in the EU is still lacking. This project is a JRP (Joint Research Project) within the EMRP (European Metrology Research Program) framework. A complete description of the project can be found at http://www.euramet.org/index.php?id=a169jrps. It is the aim of the project to provide traceable photometric, electrical test methods and guidelines that take into account the peculiarities of SSL that are often underestimated by manufacturers and users of this technology.

This project is part of the European Metrology Research Programme (EMRP, http://www.euramet.org/index.php?id=emrp); it is partly funded by the European Union on the basis of Decision No 912/2009/EC.

Project aims (English)

METAS participates in the following parts of the project:

Traceable measurement of electrical power: The electronic (and optical) signature of commercial SSL has, in contrast to incandescent or compact fluorescence lamps, a complex repetitive non-sinusoidal shape. Highly distorted current drawn by the luminaries lead to power flow at frequencies other than 50 or 60 Hz. In addition higher harmonics up to 100 kHz are also introduced when dimmable SSL luminaries are based on pulse width modulation. At present, high-current power measurements can be made traceable only up to a few kHz, which is not sufficient to meet present state-of-the-art in SSL. The following will be realized:

• A measurement capability and traceability whose uncertainty for electrical power measurement for SSL products is smaller than 0.1%.
• A set of guidelines for traceable electrical power measurements of SSL including minimum requirements for the measurement set-up.

Electrical properties of SSL sources. Energy saving claims are based on measured electrical power consumed by SSL products. Especially for dimmable SSL products, the electronic signature contains higher harmonics that, if the power meter is not properly calibrated, will introduce measurement errors. Furthermore large scale implementation of SSL devices, especially with pulse width modulation (PWM), can deteriorate the power quality of the grid, which urgently needs to be addressed.

In this task the measurement facilities developed in the first part of the project will be used to perform an extensive study on the best measurement capability in electrical power and power factor determination of SSL products for various applications.

Abstract (English)

The motivation for this project was a need for a measurement system for the electrical power and power factor in SSL devices as well as measurement procedures for traceable measurements. This lead to the development of a test set capable of generating arbitrary voltage waveforms as well as a sampling acquisition system for the voltage and current of the SSL being characterised. The system bandwidth was set to 150 kHz to ensure the capture of high frequency harmonics or interharmonics. An intercomparison among three laboratories took place with a set of fifteen lamps (three identical sets of five lamps).
The measurements revealed many unknown facts about electrical measurements with SSL. Namely, the measure of the power factor strongly depends on the bandwidth of the current measurement. Secondly, the power consumed by SSL devices is very dependent on the reactive impedance of the voltage source. And thirdly, the presence of harmonics in the voltage source can also greatly impact the consumed power. The presence of harmonics in the voltage source leads to harmonic power flow that can increase or decrease the total power. Some SSL behave as constant power sink (constant power irreverently of the spectrum), while other exhibit a power consumption that depends on the phase of the harmonics.

Transfer and application (English)

The results and experience gained throughout this project is used at METAS for routine and special measurements of SSL devices. In general, the dissemination of adequate metrology for the unambiguous and reliable characterization of solid state lighting products, developed during the project, supports the large scale implementation and application of energy saving SSL devices.

Publications / Results (English)

The Influence of Source Impedance in Electrical Characterization of Solid State Lighting Sources, Proceedings of 2012 Conference on Precision Electromagnetic Measurements, 1-6, July, 2012 ISBN: 978-1-4673-0441-2, D. Zhao and G. Rietveld

D. Zhao (VSL), J-P. Braun, F. Overney (METAS), T. Lippert, A, Christensen (Trescal), Comparison Report on Measurement of Electrical Quantities of Selected SSL Lamps; Project document

Further publications in preparation.