LEDLightingSave Energy Save Your money Harendra Vishwakarma
LED – LIGHT EMITTING DIODELED, a semiconductor diode which when operated in forward biased (switched on),electrons are able to recombine with holes within the device, releasing energy in the formof photons. This effect is called electroluminescence.The wavelength of the light emitted, and therefore its color, depends on the band gapenergy (Eg) of the materials forming the p-n junction. Light “The radiant energy that is capable of excite human retina and creating visual sensation.” Light by definition connotes Electromagnetic radiation that has a emission in visible part of spectrum (wavelength in the range of 380 nm to about 780 nm) Visible Light 380 nm – 780 nm
Structure of LED LED Manufacturing StagesThe Wafer – The Substrate on which chip P-Nis grown. junction Electrical ContactsThe Die – P-N junction between p-typedoped semiconductor and n-type dopedsemiconductor.The Package – Enclosed structure of diein the epoxy or plastic case withappropriate phosphor for colour andlenses for view angle determination.
Selection of LEDs Binning: Variation of color in LED Batch Color Temperature: A measurement of the color of light radiated by a black body while it is being heated. This measurement is expressed terms of absolute scale, or degrees Kelvin. Lower Kelvin temperatures such as 2400K are red; higher temperatures as 9300K are blue. Neutral temperature is white, at 6504K. Forward Voltage Colour Color Rendering Index : To help indicate how colors will appear under different light sources, Lumen Output Lumen output is in mcd for smaller packages and lumen for power LEDs. Trade-off Summary Color Temperature* Efficacy CRI* Efficacy Heat Efficiency / Output Heat Life / Durability
Availability of various shade of colours 3000 K 3500 K 6500 KAppearance of similar product in different CCT Light
Reliability Greater Design Flexibility Long Life over 11 yrs (12 hrs a day Various Colors availableoperation) Instant On Lower Life Cycle Cost (Less wattagesgives more lumen & Longer life) Dimming, & Intelligent control. Less Maintenance Cost No IR and UV. Shock & Vibration Proof Wide range of CCT and CRIEfficient Technology Environmental friendly High efficiency No Mercury Due to directional source. (Minimal Less waste creation due to longbackward losses) life. Due to High Lm/W of LED.(Gradually increasing with technology) Less carbon emission. Low Voltage
Comparison Between Various Light sourcesPower Consumption for White Light Source Incandescent Fluorescent MH LED Visible Light 7.5 % 21 % 27 % 15-25 % Infrared 73.3 % 37 % 17 % ~0% Ultraviolet 0% 0% 19 % 0% Total Radiant Energy 80.8 % 58 % 63 % 15-25 %Heat (Conduction + Convection) 19.2 % 42 % 41 % 75-85 % Total 100 % 100 % 100 % 100 %
Comparison of Life of Various Light sources Light Source Typical Typical Rated Lumen System Life Depreciation @ Efficacy (Hrs) Rated Life (lm/W) Incandescent 10-18 750- 2000 10-15 % Halogen 15-20 3,000-4,000 30% Incandescent CFL 35-60 8,000-10,000 30%Linear Fluorescent 50-100 20,000 – 30,000 5- 10 % (T5, T8) Metal Halide 50-90 7,500 – 20,000 20%White LED 5000K 60-100 50,000-100,000 30 %Warm White LED 45-80 50,000-100,000 30% 3300K
LED Lamp & Luminaires A luminaire is a lighting fixture complete with the light source or lamp, the reflectorfor directing the light, an aperture (with or without a lens), the outer shell or housing forlamp alignment and protection, an electrical ballast and/or power supply (if required), andconnection to a power source, and usually a light socket to hold the lamp and allow for itsreplacement Simple Model of LED luminaire More Accurate model of LED luminaire
IlluminanceIESNA Definition: the areal density of the luminous flux incident at a point on asurface.Illuminance is calculated as the number of lumens (lm) per unit area.Two common units used to measure illuminance are: footcandles (fc) = lm/ft2 lux (lx) = lm/m2 Luminance IESNA Definition: the quotient of the luminous flux at an element of the surface surrounding the point, and propagated in directions defined by an elementary cone containing the given direction, by the product of the solid angle of the cone and the area of the orthogonal projection of the element of the surface on a plane perpendicular to the given direction. Luminance is the photometric quantity most closely associated with ones perception of brightness. It usually refers to the amount of light that reaches the eye of the observer measured in units of luminous intensity (candelas) per unit area (m2). IESNA – ILLUMINATION ENGINEERING SOCIETY OF NORTH AMERICA
MacAdam ellipses and SDCMDimension of a MacAdam ellipse is given by the so called Standard Deviationof Color Matching (SDCM), SDCM characterises the quality of colordifferences 1 SDCM 2-3 SDCM 4 SDCM No Color difference Hardly any color visible difference possible Color Difference VisibleSpectral Power Distribution IESNA Definition: A pictorial representation of the radiant power emitted by a light source at each wavelength or band of wavelengths in the visible region of the electromagnetic spectrum (360 to 770 nanometers).
• Optical instruments: – Integrating Sphere – Lumen measurement of luminaire, Chromaticity, Color Rendering Index, Dominant Wavelength, FWHM, – Lux meter – illuminance (Lux value , Ft-Cd) measurement at specific distance. – Luminance Meter –Luminance measurements at surface (Cd/ m2) – Spectroradiometer – Exact Color and spectrum (W/ m2 –sr-nm) – Goniophotometer/ Goniospectrometer - Generating IES files for luminaire, polar curves,
• Thermal Measurements: – Thermocouples, (Contact mode method) – Temperature profile of LED module and Luminaire with respect to room temperature, Thermocouple needs to be <+/-1.1C or +/- 0.4% accuracy for Case Temperature during test – Infra-red pyrometers, (Non-contact mode method)– Junction temperature measurement, heat sink temperature. – Digital Temperature Meter - Temperature profile of LED Luminaire
List of testing standard. ANSI/NEMA Standards to SSL products -•C78.377-2008 - Specifications for the Chromaticity of Solid State LightingProducts•NEMA SSL-1 † Power Supply - Will specify operational characteristics andelectrical safety of SSL power supplies and drivers.•C82.77-2002 - Harmonic Emission Limits – Related Power QualityRequirements for LightingIESNA Documents –•TM-16-05 - IESNA Technical Memorandum on Light Emitting Diode (LED)Sources and Systems.•RP-16-05 - Addendum a Nomenclature and Definitions for IlluminatingEngineering.•LM-79-08 - IESNA Approved Method for the Electrical and PhotometricMeasurements of Solid-State Lighting Products,•LM-80-08 - IESNA Approved Method for Measuring Lumen Maintenance of LEDLight Sources.•TM-21† - Lumen Depreciation Lifetime Estimation Method for LED Light.•LM-80. LM-XX† Method for the Measurements of High-Power LEDs