Street Lighting with LED Light Sources Application Note Abstract The following application note provides an insight into street lighting with LED light sources. Some possible lighting designs with the Golden DRAGON OVAL and an OSRAM OSTAR-Lighting with Fraen reflector for a flexible design solution are presented.
Review of street lighting standards Each country has its own set of requirements for street lighting applications. In addition, the requirements are divided into different categories as well, requiring a considerable amount of investigation before beginning the design of a street lighting fixture. In the following, summaries and examples of the standards in the various countries are presented. European (German) standard DIN EN 13201 – Road lighting, consists of four separate sections as follows: DIN 13201-1 Road lighting – selection of lighting classes (only applicable for Germany), DIN EN 13201-2 Road lighting – performance requirements, DIN EN 13201-3 Road lighting – calculation of performance, and DIN EN 13201-4 Road lighting – methods of measuring lighting performance. In the above standards, the requirements define specific values with respect to luminance, illuminance, uniformity and further requirements in categories including measurement and calculation methods as well as the appearance of the lighting installations. General specifications for applications which conform to the standards are listed in the following table. January, 2014
Table 1: Example of German standard In terms of disability glare, its restriction is specified by a calculated value of Threshold Increment (TI) for ME class, but, in case that the TI value cannot be calculated especially for CE class, it is restricted by installed luminous intensity classes (G classes) in cd/klm at certain angles from downward vertical line. And, for S class, discomfort glare is restricted by glare index classes (D classes) in cd/m, which is a combination of maximum luminous intensity at an angle of 85° from downward vertical line and apparent area of luminous part.
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The European standard does not specify the values for road width, pole height, or pole to pole distance.
Intersections (only illuminance) Road surface classifications for pavement Four classes (from mostly diffuse to mostly specular) Requirements Illuminance (e.g. 3-15 lx) Luminance (e.g. 0.3-1.2 cd/m2) Uniformity of the above Veiling luminance ratio Glare The glare level is not provided by the standard, and it is described as just information Road width, pole heights, pole to pole distance
Chinese standard 中华人民共和国行业标准 城市道路照明设计 标准 Road criteria Urban road Expressway Arterial road 30/50 lx Secondary trunk road 20/30 lx Branch road 15/20 lx Residential road Conventional road lighting Lamp height 2 lx at the pavement (recommendation for residential streets in Japan so that it is possible to recognize person’s action from a distance of 4 m.) > 10 lx at the roadway (technically equivalent to the requirement described in JIS for a roadway with a concrete surface) The following conditions were used for the calculation:
Figure 11: Example of a street light with metal housing and integrated cooling fins (source: Softray)
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Pavement width: 4 m Roadway width: 8 m Pavement light height: 4.5 m Roadway light height: 10 m Pavement light pitch (pole): 20 m Roadway light pitch (pole): 25 m Arrangement of pavement lighting pole: single-sided
Arrangement of roadway lighting pole: alternate, double-sided Light source example for pavement lighting fixture: Golden DRAGON with OVAL lens (LW W5JM, 60 lm), 15 pieces per fixture;
Figure 14(a): Illuminance at pavement (by Golden DRAGON with OVAL lens)
Light source example for pavement lighting fixture (another case): Golden DRAGON Plus (LUW W5AM, 121 lm), 15 pieces per a fixture; Light source example lighting fixture:
for
Figure 14(b): Illuminance at pavement (by Golden DRAGON Plus)
roadway
OSRAM OSTAR-Lighting (LE UW E3B, 865 lm) with reflector (Fraen FRC M1), 10 pieces per fixture; The overall radiation pattern of the combination of the OSRAM OSTAR-Lighting product and the reflector is shown in Figure 13. 1.2 1
intensity
0.8 0.6
Figure 15: Illuminance at roadway (by OSRAM OSTAR-Lighting) As shown by the above results, it was found that with feasible product specifications, it is possible to design a street lighting fixture using LED light sources which meets the criteria of more than 2 lx at the pavement and more than 10 lx at the roadway. A rendering of the simulation result is shown in Figure 16.
0.4 0.2 0 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 angle (deg)
Figure 13: Radiation pattern of the OSRAM OSTAR-Lighting with a reflector (Fraen FRC M1) The calculated illuminance at the pavement and roadway are illustrated in the contour graphs in Figures 14 and 15. Figure 16: Simulation result
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Summary In the above simulation, efficiencies (percentage of luminaire luminous flux arriving on the street) are: pavement (LW W5JM) 33.8% pavement (LUW W5AM) 18.2% roadway (LE UW E3B with reflector Fraen FRC M1) 32.4%
LEDs have many advantages in comparison to current light sources - high-pressure sodium, metal halide, high-pressure mercury, low-pressure sodium, and compact fluorescent lamps. An LED is especially environmentally friendly, due to its high efficiency, long lifetime and low maintenance requirements. When designing a street lighting fixture, the minimum requirements must be met in each lighting category for the specific country. In addition, other factors must be taken into consideration such as glare or appearance. LEDs also offer several advantages in these areas, compared to conventional light sources, since the light output can be directed and controlled. With the use of DIALux, it was demonstrated that it is possible to design a street lighting fixture using OSRAM Opto Semiconductors LED products - the Golden DRAGON with OVAL lens, the Golden DRAGON Plus and the OSRAM OSTAR-Lighting which can provides more than 2 lx at the pavement and more than 10 lx at the roadway.
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Appendix
Don't forget: LED Light for you is your place to be whenever you are looking for information or worldwide partners for your LED Lighting project.
www.ledlightforyou.com Authors: Masaki Ono, Yoshiharu Chikazawa
ABOUT OSRAM OPTO SEMICONDUCTORS OSRAM, Munich, Germany is one of the two leading light manufacturers in the world. Its subsidiary, OSRAM Opto Semiconductors GmbH in Regensburg (Germany), offers its customers solutions based on semiconductor technology for lighting, sensor and visualization applications. Osram Opto Semiconductors has production sites in Regensburg (Germany), Penang (Malaysia) and Wuxi (China). Its headquarters for North America is in Sunnyvale (USA), and for Asia in Hong Kong. Osram Opto Semiconductors also has sales offices throughout the world. For more information go to www.osram-os.com.
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