Introducing UL Subject 8750: Outline of Investigation for LEDs used Lighting Products August 25, 2009 Prepared by: Rahul Mehta
Topics for Discussion • An Introduction to LED • Overview of Outline of Investigation
What Are LED’s? • LED is an acronym for Light Emitting Diode • Instead of a filament type use semiconductor diode which emits narrow spectrum light. • Depending on the composition & condition of the semiconductor material used (silicon, germanium), they come in either Infrared for sensing heat, Visible for every day use, or Near-Ultraviolet for spotting stains at a crime-scene. • An LED consists of a chip of semiconducting material that has been “doped” with impurities in order to create a P-N junction. • A P-N junction is basically a junction between an anode and cathode. • Current flows easily from P-side to N-side, but never in reverse order. • The wavelength and the color of the LED depends on the band-gap energy of the materials forming the P-N junction.
Where do we see LED’s? Everywhere!!
Current uses of LED’s • Status indicators on all sorts of equipment: your cell phone, computer, monitor, stereo • Traffic lights • Architectural lighting • Exit signs • Motorcycle and bicycle lights • Railroads crossing signals • Flashlights • Emergency Vehicle lighting • Message displays at airports, railways, bus stations, trams, trolleys, and ferries • Military and Tactical missions utilize red and/or yellow lights to retain night vision. • Movement Sensors • LCD backlight in televisions • Christmas Lights
Incandescent Positives Cheap to manufacture & buy Easier to come by Generally stronger light output Better for seeing through Fog and Smoke Negatives VERY breakable Horrible patterns in light Hot burning Heavy on battery consumption Short lifespan Yellowish color filters out anything with yellow in it, IE: White looks yellow, yellow doesn’t show, red looks brown, green looks black. LED Positives Virtually indestructible 100,000 hour lifespan Low energy consumption Symmetrical beam with little-to-no artifacts Cheap to manufacture Available in a multitude of colors without requiring a filter. Pure white light means no color will be filtered out. Low functioning temperature Negatives Less potential output (for now) Slightly more expensive to purchase LED’s Vs. Incandescent’s
Potential Benefits of LED • Potential to be highly energy efficient • Potential to be cost effective • Potential for very long life • Impact and vibration resistant • Small size enables new fixture and system designs • Directional beam puts light where needed
Potential uses in the future • LED’s are already being used in tail-lights for cars, and some companies like Lexus are experimenting with LED headlights • Home lighting: Imagine a “light-bulb” with 100,000 constant hours of use. In other words: 100,000 hours/24 hours a day = 4,166 days 4,166 days/365 days a year = 11.4 years. • Not only will the light bulb last for 11.4 years, but it will also require much less current than a traditional light-bulb. If one LED-light bulb requires half the energy of one Incandescent light-bulb, we may not have to suffer through rolling blackouts ever again! • LED’s are already getting brighter. Here is an example of one of the most recent LED’s to hit the market titled the “Luxeon Rebel”. It is both twice as bright, and uses half the current of it’s predecessor of only 2 years. • Technology will eventually dictate that LED’s are the light source of the future.
Impact of LED’s on the world of Business • With the horizons of LED technology broadening, many light manufacturer’s are putting their top scientists to work: Maglite, for instance, always made Incandescent lights, but have recently begun creating drop-in LED modules for their incandescent torches. • If one car company comes out with LED headlights that manage to function at a higher efficiency and also increase output, it is inevitable that all other car companies will follow. Nobody likes a burnt out headlight! • Energy is an expensive commodity! The more money we can save on energy, the more money we can spend on more important business aspects. One office building that solely uses LED bulbs could save thousands a year in Energy use alone.
What is an Outline of Investigation? • Outline Of Investigation: A published document that contains requirements that are used to certify a product when a published Standard is not available. • This is a collection of the requirements utilized by ETL to certify LED lighting products to date. • It serves as a guide for the investigation of LED components for use in Lighting applications. • It will become the base document for a formal Standard to be developed by a Standards Panel.
Why an Outline Investigation is needed? • Not all Lighting Standards adequately address LED light sources • Significant advances in LED light source technology bring about specific challenges • Customers benefit from consistent LED requirements across regions and product types • Facilitates component sourcing and interchangeability
Applications for LED’s • Architectural Lighting • Seasonal Lighting • Sign Components • Emergency Lighting • Task Lighting • Night Lights • Hand Lamps • Solar Landscape • General Illumination • Flood Lights • Stage and Studio Lighting
Main Definitions • LED PACKAGE: An assembly of one or more LED die that contains wire bond connections, possibly with an optical element and thermal, mechanical, and electrical interfaces. The device does not include a POWER SOURCE and is not connected directly to the branch circuit. • LED ARRAY: An assembly of LED packages on a printed circuit board, possibly with optical elements and additional thermal, mechanical, and electrical interfaces. The device does not contain a POWER SOURCE and is not connected directly to the branch circuit. • LED MODULE: A component part of an LED light source that includes one or more LED’s that are connected to the load side of LED power source or LED driver. Electrical, electronic, optical, and mechanical components may also be part of an LED module. The LED module does not contain a power source. • LED CONTROL MODULE: electronic circuitry interposed between the POWER SOURCE and an LED ARRAY to limit voltage and current, dim, switch or otherwise control the electrical energy to the LED ARRAY
Power Supply Requirements Power Source • Power supplies evaluated to: • UL1310 < Class 2 power limited • UL1012 > Class 2 • UL60950 SELV, ELV, LPS • Transformer • UL1585 < Class 2 power limited • UL1411 Either • UL506 or UL1561 >Class 2
Construction Requirements Mechanical (UL1310 &1598) • Enclosures & barriers • Conductor protection • Strain Relief Electrical (UL 879, 879A, 935 & 1310) • Accessibility • Input / Output Connections & Terminals • Internal wiring • Insulating materials & PWB’s • Spacings • Protective Devices
Required Testing Performance Tests • Input Test • Normal Temperature Test • Dielectric Voltage Withstand Abnormal Tests (UL 1310) • 50 w power measurements • Unreliable component faults
LED Outline of Investigation Markings • Power source • Per the Standard evaluated to • LED & Control Modules • Manufacturer • Model No. • Input V, I or W • Date of Mfr.