Ma gorzata GÓRCZEWSKA, Sandra MROCZKOWSKA
Politechnika Pozna ska, Instytut Elektrotechniki i Elektroniki Przemys owej, Zak ad Techniki wietlnej i Elektrotermii
Valuation of road lighting parameters for luminaires with LED
Streszczenie. Ocena wp ywu wiat a bia ego na warunki widzenia w o wietleniu zewn trznym jest od wielu lat przedmiotem bada . Strumie
wietlny lamp jest wyznaczany dla widzenia fotopowego, natomiast w wielu przypadkach poziom adaptacji wzroku odpowiada warunkom widzenia
mezopowego. Dla takich warunków stosowanie lamp LED mo e by uzasadnione z powodu korzystniejszego rozk adu widmowego promieniowania.
W artykule przedstawiono porównanie parametrów o wietlenia drogowego z lampami sodowymi i przyk adow opraw z diodami LED.
(Ocena parametrów o wietlenia drogowego dla opraw LED)
Abstract. Valuation of influence of white light in outdoor lighting has been tested for years. Usually luminous flux is determined for photopic vision,
but in many cases for road lighting the level of adaptation for human eyes corresponds to mesopic vision. For such conditions using LEDs could be
more useful from the point of spectral distribution of light. In the paper the results of comparation parameters of outdoor lighting will be presented for
chosen LEDs.
S owa kluczowe: o wietlenie drogowe, ród a wiat a, widzenie mezopowe, diody LED.
Keywords: road lighting, lamps, mesopic vision, LED
Introduction
In the outdoor lighting, there are mostly applied the low-
pressure and high-pressure sodium discharge lamps, metal
halide lamps and mercury discharge lamps.
The most frequently used light sources in the road and
public places lighting installations are the high-pressure
sodium discharge lamps. Their shear in the total number of
the applied light sources results presently 70% - 75%. The
shear of the commonly used until now mercury discharge
lamps results approximately 25%. These lamps are
presently applied in the lighting installations of the parks,
local roads, estate roads, etc.
The main obstacle in the replacement of the mercury
discharge lamps with another lamp type is the shortage of
the substitutional product which respects the specific
Fig.1. LED luminaire
requirements concerning the energy saving and durability
as well as the light quality, i.e. the light colour and light
rendering [1].
The sodium discharge lamps are characterised by their
high durability and luminous efficacy, however the colour
features of their light do not correspond to the lighting
needs, for example on the green and housing area.
The metal halide lamps, considering their quality of the
light, more and more often replace the sodium discharge
lamps. They are characterised by a lower durability and
lower luminous efficacy. They are also more sensitive to the
supply voltage variations. For that reason LEDs, more and
more often used in the road and park luminaires , seam to
be the solution that includes all required features of the
lamps applied in the outdoor lighting. These features
include: high durability, light colour and high luminous
efficacy.
Fig.2. Light spot of LED luminaire
Parameters of luminaires with LEDs
Presently, the manufactured LEDs and luminaires optics
The intense works on improvement of the LEDs
with their application are characterised by better and better
production technology lead to a visible improvement of the
usable parameters. The luminous flux distribution of the
light quality and increase of their luminous efficacy.
road lighting luminaires is normally formed by the individual
In the luminaire presented on the drawing 1, there have
reflecting elements and lenses  single ones or a set of
been applied the Cree LEDs having the power of 1W and
them in a form of a plate, positioned on the LED panel [2].
colour temperature of 6500K. The luminous efficacy of
The distributions of the luminous flux are precisely
LEDs without power supply system and lenses, measured
adopted to the oblong shape of the illuminated surfaces. On
in the laboratory conditions, results 78 lm/W. The luminous
the drawing 1, there has been presented the luminaire with
efficacy of LEDs with lenses themselves results 68 lm/W.
LEDs and the view of the light spot obtained with use of the
The complete luminaire has got the luminous efficacy
lenses system, shown on the drawing 2.
resulting approximately 56 lm/W. These parameters are
lower than for the sodium discharge lamps and luminaires
but the obtained light colour quality is significantly higher.
Colour rendering index Ra = 67.
PRZEGL D ELEKTROTECHNICZNY (Electrical Review), ISSN 0033-2097, R. 86 NR 10/2010 197
The luminous efficacy of the luminaires with LEDs is Exemplary values S/P:
presently lower than of the luminaires with the sodium High pressure sodium lamp SON  T Plus 70W  0,66
discharge lamps. However, in case of LEDs the final LED luminaire - 2,1
illumination effect depends non only on the lighting For a given spectral distribution of the lamp described
equipment energetic efficiency but also on a better with use of the S/P parameter and for a given adaptation
adaptation of the light characteristics to the sight adaptation luminance determined for the photopic vision, the  effective
in the mesopic vision conditions. The visual sensation luminance values are read from the table.
depends on the spectral luminous efficacy that changes From the table 1 results that the visible differences in
with the sight accommodation level variations [3]. the luminance reception, depending on the spectral
The lighting levels applied in the outdoor illumination are distribution of the lamp radiation, arise for the luminance
contained within the range where the lamps luminous flux lower than 0,6 cd/m2 that is for the illumination levels of the
calculated for the photopic vision not always corresponds roads and streets having the lower communication
with the real visual perception. importance.
Calculations
For comparison of the sodium discharge lamps and
lamps with LEDs application effects, there have been made
measurements and calculations for an exemplary typical
street and for various illumination requirements, including
variable conditions for the sight adaptation.
The following data have been considered for calculation:
Width of the roadway  7 m, height of the luminaires  8 m,
surface R3, luminaire location  over the edge of the road.
Luminaires:
SGS 103/70W SON-T Plus 70W
LLp-S60 LED 60W
There have been measured the distribution of the
luminous flux of the LED luminaire LLp-S60 and the data
have been introduced to the Relux Professional 2007
Fig.3. Photopic, scotopic and one mesopic luminous efficiency
programme.
functions [4 ]
The results of calculation have been compiled in the Table
For the luminance level of 3 cd/m2 the spectral 2.
Table 2. Energy consumption of lighting system with use of the
sensitivity of the eye corresponds to the photopic vision.
luminaires for the sodium lamps and LEDs for the various street
The scotopic, rods vision corresponds to the adaptation
lighting levels, including changes of the eye adaptation
luminance level of 0,001 cd/m2 that does not occur on the
illuminated roads. For the intermittent luminance, the eye
Photopic luminance level cd/m2
Luminaires
sensitivity changes and corresponds to the mesopic vision.
1,0 0,5 0,3
In practice, it can be assumed that for the roads and streets
SGS 70W
100% 103% 112%
having the high illuminating requirements the adaptation
SON-T 70W
level corresponds to the photopic vision. For the low levels Ref = 100%
The luminaire SGS 103 with the sodium discharge lamps
of the luminance the sight adaptation corresponds to the
having the luminous flux determined for the photopic vision
mesopic vision.
LLp-S60
114% 107% 94%
For the low levels of the illumination, the maximum of
LED 60W
the eye spectral sensitivity shifts towards shorter waves.
The eye responds stronger to the radiation within the short-
The calculation results indicate the sense of purpose the
wave part of the spectrum and it is exactly the feature of the
application of the luminaires with LEDs and in particular in
radiation spectrum of typical LEDs. The radiation spectrum
the lighting of streets and places having the low lighting
of the sodium discharge lamps does not have this feature.
requirements.
For the residential streets, there are applied the lighting
For the mesopic vision the eye spectrum sensitivity has
requirements basing on the illuminance level criterion while
been described by the curve positioned between the curves
the luminance level is determinant for the adaptation
for the photopic and scotopic vision  see drawing 3. In the
conditions. The recalculation of the parameters basing on
subject literature [5] there has been described the simplified
the illuminance into the luminance parameters requires to
method of determining the  effective luminance that
be acquainted with the street surface reflection
corresponds to the present sight adaptation level. There is
characteristics for typical observation conditions.
used the S/P parameter  i.e. the ratio of the lamp luminous
For valuation of the visual conditions variations on the
fluxes recalculated for the eye adapted to the darkness (S)
local road  Fig.4, with the surface made of concrete
and to the brightness (P).
blocks  Fig.5, there have been performed measurements
Table 1. Values of unified luminance for different base light levels
of the luminance and illuminance.
and S/P ratios [5]
The luminance measurements have been performed for
Base photopic luminance level cd/m2
S/P the observation distance of 20  30 m. For this observation
0,1 0,2 0,3 0,4 0,5 0,6
(measurements) distance the measurements results gives
0,25 0,0355 0,1009 0,2012 0,3250 0,4604 0,60
average luminance coefficient q:
0,65 0,0747 0,1649 0,2659 0,3739 0,4862 0,60
1,05 0,1040 0,2054 0,3055 0,4047 0,5033 0,60
L/E = q = 0,06
1,55 0,1330 0,2422 0,3402 0,4315 0,5182 0,60
The obtained measurements results have been utilised
2,05 0,1568 0,2705 0,3661 0,4512 0,5291 0,60
in calculations of the lighting parameters of the streets
2,55 0,1770 0,2933 0,3865 0,4664 0,5375 0,60
having the low lighting requirements (S - class). For the
198 PRZEGL D ELEKTROTECHNICZNY (Electrical Review), ISSN 0033-2097, R. 86 NR 10/2010
street shown on fig.4 and for various illumination The obtained results indicate the significant
requirements, there have been made calculations including improvement of visual conditions on the local roads,
variable conditions for the sight adaptation. illuminated with use of the lamps with LEDs in comparison
The calculation results have been shown in the table 3. with the sodium discharge lamps.
Conclusions
Basing on the shown calculation results there can be
expected that in a short time the luminaires with LEDs shall
find a broad application range in the outdoor lighting. It is a
foregone effect resulting from the expected high luminous
efficacy, advantageous radiation spectral distribution and
significantly higher durability when comparing with the other
lamps as well as practical independence of the operation
parameters of the energy supply conditions.
It is necessary to elaborate simple methods basing on
the equivalent levels of the luminance and illuminance
determination that shall allow in designing practice to
include variations within the eye spectral sensitivity.
There are also necessary the experimental research
works concerning the visual conditions and operation
features of the lighting systems with use of LEDs.
Fig.4. Residential road
REFERENCES
[1] P. Baranowski A. Sta czyk  Concavity and convexity of
illumination Przegl d Elektrotechniczny nr 8/2008
[2] Górczewska M. Zastosowanie diod LED w o wietleniu
zewn trznym. Przegl d Elektrotechniczny, 11/2009, s.229-232.
[3] Sagawa K. Vision of the elderly and visual impared - for
accessible design In light and lighting, CIE Proceedings, Pekin
(2007), D1 62-65
[4] Roadway Lighting. Lighting Research Center. Strona:
http://www.lrc.rpi.edu/programs. 22.02.2010
[5] Outdoor Lighting. January 2009. Lighting Research Center:
http://www.lrc.rpi.edu/programs. 14.01.2010
Authors: dr in . Ma gorzata Górczewska, Politechnika Pozna ska,
Instytut Elektrotechniki i elektroniki Przemys owej, ul. Piotrowo 3a,
60-965 Pozna , E-mail: [e-mail];
Fig.5.Typical concrete blocks
mgr in . Sandra Mroczkowska, Politechnika Pozna ska, Instytut
Table 3. Values of unified luminance for different S-classes lighting
Elektrotechniki i elektroniki Przemys owej, ul. Piotrowo 3a, 60-965
levels, for sodium and LED lamps
Pozna , E-mail: [e-mail]
Lighting levels
S
Luminance level cd/m2
Illumi
nation
photopic unified
L=0,06 SON LED
E [lx]
E S/P = 0,66 S/P = 2,1
15 0,9 0,9 100% 0,9 100%
S1
10 0,6 0,6 100% 0,6 100%
S2
7,5 0,45 0,43 96% 0,49 109%
S3
5 0,3 0,27 90% 0,37 123%
S4
3 0,18 0,15 83% 0,25 139%
S5
2 0,12 0,09 75% 0,18 150%
S6
PRZEGL D ELEKTROTECHNICZNY (Electrical Review), ISSN 0033-2097, R. 86 NR 10/2010 199