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Design Considerations - Federal Aviation Administration

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LEDs - Past, Present and Future
FAA Eastern Region Airports Conference
Thursday, 3 March 2011
Presented by Pete Butler, P.E.
1
Agenda
• Definition of LED
• Characteristics of LED Fixtures
• Evolution of LEDs in Airfield Lighting Systems
• Recent Developments
• Future Implementation
• Design Considerations
• Roundtable Discussion
2
Definition of LED
• Light Emitting Diode
• Semiconductor light source
• Within device, electrons
jump a gap to recombine with
electron holes
• During jump, energy is released in form of photons
• Result - phenomenon called electroluminescence
• Color of LED determined by energy gap of
semiconductor
3
Characteristics of LEDs
Positive Characteristics
• Lower energy consumption
• Longer lifetime
• Improved robustness
• Smaller size
• Faster switching
• Greater durability
• Higher reliability
++
4
Characteristics of LEDs
Negative Characteristics
• More expensive
• Require more precise current
• Sensitive to high temperatures
– Light output decreases
– Light spectrum in negatively impacted
– Heat sinks / beveled or ridged exterior
(-)
(-)
5
Evolution of LEDs in Airfield Lighting Systems
• Implemented in clusters to create a
light source
• LED-lamped taxiway elevated
edge lights emerged in early 2000s
• Original fixtures resembled
lighthouses with lamp / LED
cluster at base of fixture
• Inherent maintenance issues
• Water infiltration
6
Evolution of LEDs in Airfield Lighting Systems
• LED technology improved, airport
interest increased - additional
manufacturers developed edge lights
• Mid 2000s, at least three vendors of
edge lights
• Fixtures better resemble typical
edge lights
7
Evolution of LEDs in Airfield Lighting Systems
• Fixtures installed in existing 5kV airfield
lighting environment
• LEDs are DC-based devices that operate in
milliamp range
• As LED technology improved, experts
discussed alternate power sources
• Test beds reviewed
alternate power
sources
8
Evolution of LEDs in Airfield Lighting Systems
Prescott Municipal Airport Testing
• Modified LED edge lights, incandescent
edge lights, and LED guard lights
• Modified edge lights – 2.8A max
• 0.28/0.84/2.8A circuit vs. 4.8/5.5/6.6A
circuit (traditional)
• Testing proved successful, system still
operating after five years with no fixture
failures
9
Evolution of LEDs in Airfield Lighting Systems
Hartsfield-Jackson Atlanta International
Airport Test Bed (2006 – present)
• Modification to Standards / airport funded
• Re-used existing series circuit infrastructure
• DC-based system with LED taxiway
centerline and edge lights (600V DC)
• Small, rack-mounted power
supply
• Fixtures directly connected to
circuit
10
Evolution of LEDs in Airfield Lighting Systems
• LED Equipment has evolved significantly
• Lighting equipment available
– Obstruction Lights
– Elevated and in-pavement taxiway
edge lights
– Taxiway centerline lights
– Elevated and in-pavement guard lights
– Medium-intensity runway edge lights
11
Evolution of LEDs in Airfield Lighting Systems
• Other equipment available
– Signage
– Wind Cones
– REILS
• LED-supporting equipment
available
– Smaller constant current regulators
– Isolation transformers
– Sign Retrofit Kits
12
Recent Developments
Orlando International Airport Test Bed (2010
to present)
– DC-powered circuits, pulse width
modulated
– Two interleaved circuits
– LED Taxiway Centerline Lights
– No isolation transformers
– Rack-mounted power supply
13
Recent Developments
False River Airport Test Bed (2010 to present)
– Funded by State of Louisiana
– DC power supply fed by batteries
connected to solar panels
– Two interleaved circuits
– LED Taxiway Edge Lights
– Rack-mounted power supply
14
Recent Developments
• Runway centerline and touchdown zone
lights certified over last year
• Moratorium on acquisition and
installation
• Pilots – fixtures too bright at lower steps
• FAA tested circuits and verified operation
• Result - LED fixtures brighter at lower
steps than incandescent fixtures
• Light curves differ between fixture types
15
Recent Developments
• Incandescent fixture output is linear, LED output is
non-linear
• Engineering Brief 67C recently issued,
moratorium lifted
• Light Dimming Curve modified for white
LED lights only
16
Recent Developments
• Airport / manufacturer focus on runway
edge lights
– Will impact majority of airports
– Main restriction is intensity of white LEDs
– High-intensity elevated edge lights
anticipated in 2011
– FAA requirement for in-pavement
light to match elevated fixtures
will hinder production
17
Future Implementation
• System Approach needed
– Embrace LED properties and maximize
efficiency
– Cease adapting to existing environment /
infrastructure
• Two approaches evolving
– Lower current system (possible
maximum current of 2.8A)
– DC-based system with pulse
width modulation
18
Design Considerations
• Consider LEDs for lights, signs, wind cones, etc.
– Maximize energy savings
• Interspersing of LED and incandescent fixtures - not
acceptable
• Segmenting of circuiting / operations
• Separate circuits for incandescent and
LED fixtures
• Match isolation transformer
sizes to maximize efficiency
19
Design Considerations
• Analyze impact of circuit load on circuits, vault,
airport
• Perform Benefit Cost Analysis (BCA)
–
–
–
–
Higher material cost
Longer lamp life
Lower energy consumption
Higher replacement cost
$$$
• Training/expertise of maintenance staff
20
Design Considerations
• Arctic Kit or no Arctic Kit
– Apprehension to use LED lights, because fixture won’t
melt snow
– Snow melting is inherent property of incandescent
fixture
– Arctic kit negates lower energy consumption
– Selection impacts circuit load, regulator size
– Snowplowing impacts
21
Design Considerations
• Test Beds – w/ and w/o Arctic Kit
– Multiple sites in Midwest
• Taxiway Edge Lights
• Guidance Signs
– Current Testing at JFK
• Taxiway Centerline Lights
• Multiple vendors
22
Roundtable Discussion
• Denise De Natale - Director of Sales, Multi Electric
Manufacturing Inc.
• Galen Dixon - Regional Sales Manager, ADB Airfield
Solutions
• Tony Mancini - Director of Marketing, Cooper
Crouse-Hinds
23
Roundtable Discussion
• Topics of Discussion
– Feedback / Lessons Learned on existing LED
installations
– Interpretation / Impacts of recently issued Engineering
Brief 67C
– Recent developments with LEDs / emerging
equipment
24
THANK YOU
25
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