SCHRÉDER - LUX LIVE 2016
HIGH TEMPERATURE LUMINAIRES
TREVOR LEIGHTON – REGIONAL TECHNICAL OFFICER IMEA
GCC: BEST PLACE FOR LED?
• -20°C
• 1 year warranty?
• L20 B90?
CRITICAL LED ISSUES IN GCC?
High Temperature Ta = 35-50°C
Light output
Lifetime
TRANSPORT LIGHTING IN EUROPE
NO LIGHT (!)
TRANSPORT LIGHTING IN GCC
HUGE ROADS
PUSHING THE CURRENT TECHNOLOGY TO THE EDGE
2 lanes, then 4 lanes
4 lanes, then 6…
14m pole height, then 20m
2cd/m2…
HOW CAN WE MANAGE THIS?
1500 mA + (!)
CHIP TECHNOLOGY – POWER DENSITY
1 mm2
350-500mA
2 mm2
350-700mA
4 mm2
700-1400mA
HOW DOES A CLIENT KNOW WHAT A “GOOD” FITTING FOR GCC IS?
QUALIFY YOUR REQUIREMENTS FIRST
CRI (colour rendering index) shall be >80?
Industry standard = >65
QUALIFY REQUIREMENTS
3 Steps Macadam's Ellipse?
Industry standard = 5
QUALIFY REQUIREMENTS
M class selection?
SZR = 6 – 2.5 = M3 = 1 cd/m2
BOQ?
• Wattage - 1,000 pcs x 200W LED?
• Lumen Package – 1,000 pcs x 14 klm?
• Design validation!
WHICH TEMPERATURE?
• 25? 35? 50? 55?
• Ta / Tq / Tj / Ts
• Highest daytime temperature?
• Average nighttime temperature?
EFFECT OF TEMPERATURE ON LED LUMINAIRES
The 3 types of temperature:
• Thermal Safety
• Ambient temperature factor
• Lifetime lumen losses
THERMAL SAFETY
Can the luminaire operate safely at 50°C or 55°C?
1. Driver – Tc / thermal cutout / ramp down
2. LED – Chip life 100,000 hours -> 99,950 hours?
3. Lens – Soften or melt = no photometry!
Thermal test report to include critical areas!
IEC 60598 / 62722 / UL 1598 / LM-84 flawed
SILICON LENSES?
Higher tolerance to heat = higher drive current
THERMAL SAFETY
Must make assumptionsabout 50°C Ta operation!
• Centre of luminaire
• Centre of PCBs
• Driver Tc
• Thermal camera?
• Take manufacturers advice
AMBIENT TEMPERATURE FACTOR
Luminaire
Ambient
Temperature
Factor LM-82
• LED Module, NOT luminaire
• Photometric test• Initial temperature x°C• Increase initial by 25°C• Increase by an additional amount
LM-82(Module NOT luminaire)
Ts – Solder point
Initial temp 25°C
Initial + 25°C (50°C)
One other temp:
(Schréder) 85°C
LM-82
ADQCC / Trustmark
DMA Spec
LUMEN DEPRECIATION OVER TIME AT TEMPERATURE (LLD)
50°C or 55°C Ambient for 50,000 hours? (Ta)
35°C = Realistic conditions for GCC (Tq)
1. Thermal Test – we need to know the Ts (solder point)
2. LM-80 – Data from Manufacturer (α & β)
3. TM-21 – Formula to calculate Lxx @ t
THERMAL TEST
1. Hottest Ts (solder point) @ 25°C Ta
2. Add difference for Tq (e.g. 35°C = + 10°C)
3. Go to LM-80 to find Alpha and Beta
LM-80
Take most appropriate α & β(E.G. DMA Spec.)
(3rd Party?!)
TM-21
LLD = β e^ (-αt)
t = 50,000 hours (DMA)
LLD = β e^ (-αt)Driving current
mASolder point
Temp. α α β Time hrs. (-αt) e^(-αt) LLD(%)
35055 7.52606 0.0000001 7.526E-07 0.979558 50000 -0.0376303 0.963068922 94.34%
85 7.52606 0.0000001 7.526E-07 0.979558 50000 -0.0376303 0.963068922 94.34%
500
55 7.52606 0.0000001 7.526E-07 0.979558 50000 -0.0376303 0.963068922 94.34%
85 7.52606 0.0000001 7.526E-07 0.979558 50000 -0.0376303 0.963068922 94.34%
105 7.52606 0.0000001 7.526E-07 0.979558 50000 -0.0376303 0.963068922 94.34%
700
55 1.07498 0.000001 1.075E-06 0.971213 50000 -0.053749 0.947669942 92.04%
85 1.07498 0.000001 1.075E-06 0.971213 50000 -0.053749 0.947669942 92.04%
105 1.07498 0.000001 1.075E-06 0.971213 50000 -0.053749 0.947669942 92.04%
100085 1.66797 0.000001 1.668E-06 0.978485 50000 -0.0833985 0.91998446 90.02%
105 3.9224 0.000001 3.922E-06 0.990859 50000 -0.19612 0.821913599 81.44%
(3rd Party test TM-21 certificate)
CRITICAL POINTS
• Thermal safety at daytime / max operating temperature
• Ensure LATF is not significant (LM-82 as a check)
• Make sure LLD is proven and applied to MF
MF = LLD x LDD
MF is not 0.7 for every case!
STANDARDS FOR LIFETIME
Component
LM-84 TM-26 / TM-28System
LM-80 TM-21
LM-84-14
Approved method for measuring lumen and colour maintenance for LED• Lamps
• Light Engines
• Luminaires
Main points of document
• Testing according to LM-79
• Rack for continuous burning, “interval testing”
• L50 and L70 mentioned – Not for Roadway luminaires
• Thermal Camera to detect hottest parts of PCB
• LM-80 is 6-10K hrs, LM-84 6K hrs = 2 years behind?
• No LED driver Tc mentioned
• Not realistic operating conditions – No glass? No lenses?
• Not practical nor sytemise-able for LED luminaire manufacturers !
THERMAL CAMERA - LM-84-14
STILL NOT PUBLISHED
TM-26
• LM-80 + TM-21 make no assumptions about catastrophic failure probability
• LM-80 uses very small sample size (e.g. 20-25 pieces)
• Driver to be considered
• Early / Spontaneous / Wear-out
• Projection model to assess confidence levels
TM-28-14
• Two methods: “Direct” and “Combined”
• 6,000 hours benchmark
• LM-79 periodically
• Sample set:
Direct = 3 luminaires
Combined = 5 luminaires
• 5 luminaires can extrapolate 1.5 x testing time (e.g. 6,000 x 1.5 = 9,000 hours)
• 50,000 hours? 6 x testing time maximum
• 15 luminaires tested for 8,333 hours!
• Third party? 30-40K USD minimum
• Product life cycle?
Not useful for high performance roadway luminaires!
KEY TAKEAWAYS
• Emphasis on System, not Components Luminaire Lumens per Circuit Watt at Temp and Time
Acurately delivered lumens per AED…
• LM-79 is good for 25 Deg C
• LM-82 is “reasonable” for increased temp
• Thermal testing needs to be logical and maybe regional
• MF needs to be adapted for LED and region
• Initial lumens into design is EVERYTHING
• LM-84/TM-28 for retrofit LED lamps only