Transcript Slide 1

LED ROADWAY LIGHTING
Presented by DaTran Lighting
AGENDA
• Of the numerous illumination platforms currently available,
only Solid State Lighting offers our nation the potential to
save energy and enhance the quality of our environment.
AGENDA
Introduction and Highlights
- Solid State Lighting standards
- Luminaire efficiency
- Photopic / Scotopic considerations
- Thermal Management
- Lightning protection
- LED roadway and post lighting examples
Solid state lighting standards
• All lighting products used in the United States are subject to
the standards governing safety and performance. Solid-state
lighting (SSL) is an emerging technology that is difficult to
qualify under the existing standards covering HID roadway
lighting. As a result, new standards and testing methods have
been developed for solid state luminaires.
• LM-79*, “IESNA Approved Method for the Electrical and
Photometric Measurements of Solid-State Lighting Products,
specifies procedures for measuring total luminous flux,
electrical power, luminous efficacy, and chromaticity of solid
state lighting.
• LM-80*, “IESNA Approved Method for Measuring Lumen
Depreciation of LED Light Sources, specifies procedures for
determining lumen depreciation of LEDs and LED modules
(but not luminaires) related to effective useful life of the
product.
Luminaire efficiency
The inherent directionality of LED emitters make them an ideal
choice for roadway lighting. All conventional roadway HID fixtures
have a low CRI (color rendering index) and require the use of
reflectors / refractors which can be up to 40% inefficient. This
inefficiency substantially reduces a HID lamp’s actual lumen and
foot candle output when measured on the ground.
LED’s, on the other hand, have a high CRI and emit light only in
one direction without the need of a reflector. This allows for
unprecedented control of the light patterns on the ground and the
near total elimination of wasted light. It demands, however, that
lighting designers are cognitive of these features up-front and not
rely on the 360° nature of conventional bulb technology. Slides #69 demonstrate these concepts.
Luminaire efficiency
Luminaire efficiency
TYPICAL 150 WATT HIGH PRESSURE SODIUM STREET LIGHT
MEASUREMENT OF LUMENS REACHING THE GROUND
• TOTAL LUMEN OUTPUT OF HPS LAMP
22000lm
100%
• DOWNWARD STREET SIDE
• DOWNWARD HOUSE SIDE
• DOWNWARD TOTAL LUMENS
6656lm
6057lm
12712lm
30.3%
27.5%
57.8%
• REFLECTOR INEFFICIENCY
-9278lm
42.2%
Luminaire efficiency
Luminaire efficiency
Luminaire efficiency
• The efficiency of LED luminaires is based on its calculated
efficacy. Actual measured efficacy can be difficult to calculate as
LED and power supply performance vary greatly and can offset
the efficacy value.
• All LED products should be evaluated with photometric and IES
files to verify the true performance of the LED luminaire.
Photopic / Scotopic
considerations in lighting
• Low light/Starlight - Scotopic vision (rods)
• Interior lighting
- Photopic vision (cones)
• Outdoor lighting - Mesopic vision (rods and cones)
Visible light measurement is based on a photopic standard
developed by the CIE. Photopic measurement is the human
retinal response to visible light. Lumens, foot-candles, lux,
etc., are all photopic measurements.
Lower the photopic light level and retinal sensitivity begins
to shift into a very low light energy region, defined as human
scotopic response and is only active in very low starlight
conditions.
The area between photopic and scotopic is known as
mesopic, which all outdoor lighting falls under.
Thermal Management
• Thermal management and an awareness of the operating
environment are critical when considering an LED luminaire
for general illumination.
• Successful LED luminaires will employ adequate heat sinks
and an Advanced Processor based Thermal Management
System that prevents the LED’s from overheating.
• Maintaining the LED junction temperature as low as possible
and within the manufacturer’s specification is necessary in
order to maximize the performance and longevity of post and
street light luminaires. The following slide provides an
example of an efficient thermal design by the Niland Fixture
Company.
Thermal Management
Lightning protection
Electronic power supplies and LED luminaires are sensitive to power surges and
impulse lightning events.
Without sufficient protection, these events will destroy an LED luminaire.
Electronic power supplies and LED luminaires need to be rated for 15kV + and pico
second response time in order to prevent damage.
Additionally, all power supplies should contain components rated for 100,000 hour +
lifespan. No short life components such as electrolytic capacitors should be used in
the design as these will fail in less than 2000 hrs of use.
Lightning damage to
unprotected power supply
Lightning protection circuit
HID vs LED
LED street light fixtures
LED street light fixtures
LED post light fixtures
LED post light fixtures
LED high bay fixtures
Questions and comments
Thank -You For Your Time Today