Electrical Power Utilization LEDs Guide Dr S S

Electrical Power Utilization ‐ LEDs Guide: Dr. S. S. Bhatt Pranav Deshpande Dhiraj Deshmukh Vamsi Sriram Ashlesha Dupare Preethi Eashwar BT 14 EE 021 to BT 14 EE 025

Topics What are LEDs? Working Principle of LEDs Applications Advantages and disadvantages LEDs vs. Conventional Lighting Sources Government Schemes on LEDs Domestic Lighting Street Lighting LED Lens and Beam Angle LED Drivers LED Downlights Comparison Of Various LED Brands

What Is An LED? LED ‐ Light Emitting Diode LED is a two lead semi conductor light source which emits monochromatic light when operated in forward bias. The LED is actually a PN Junction diode. Available in many colours as well as infra‐red radiation. The wavelength of the light emitted depends upon the material used.

What is an LED?

Working Principle The P‐N junction emits light when electrical energy is applied to it. This phenomenon is called electroluminescence, defined as the emission of light from a semi‐conductor under the influence of an electric field. The charge carriers recombine in a forward‐biased P‐N junction as the electrons cross from the N‐region and recombine with the holes existing in the P‐region. Some energy must be dissipated here. It is released in the form of photons.

Working Principle In Gallium arsenide phosphide (Ga. As. P) and Gallium phosphide (Ga. P) semiconductors, the electrons dissipate energy by emitting photons. The LED should always be operated in forward bias. If operated in reverse bias, the LED may get damaged. Longer lead ‐ Anode Shorter lead ‐ Cathode

Working Principle

HISTORY OF LED For over 30 years, LEDs have been used in various areas of application, whether for industrial systems, car lights or advertising. In the course of recent years, the white LEDs' luminous efficacy has increased to a startling 130 lumens per watt and more. A short glance back over the history of the LED: 1907 - The Englishman Henry Joseph Round discovers that inorganic materials can light up when an electric current is applied. In the same year, he publishes his discovery in the journal "Electrical World". 1921 - The Russian physicist Oleg Lossew again observes the "Round effect" of light emission. In the succeeding years, from 1927 to 1942, he examined and described this phenomenon in greater detail.

1935 - The French physicist Georges Destriau discovers light emission in zinc sulfide. Today Georges Destriau is credited as the inventor of electroluminescence. 1951 - The development of a transistor marks a scientific step forward in semiconductor physics. It is now possible to explain light emission. 1962 - The first red luminescence diode (type Ga. As), developed by American Nick Holonyak, enters the market. This first LED in the visible wavelength area marks the birth of the industrially‐produced LED. 1993 - Japanese Shuji Nakamura develops the first brilliant blue LED and a very efficient LED in the green spectrum range (In. Ga diode). Some time later he also designs a white LED. . 1995 - The first LED with white light from luminescence conversion is presented and is launched on the market two years later. 2006 - The first light‐emitting diodes with 100 lumens per watt are produced. This efficiency can be outmatched only by gas discharge lamps. 2010 - LEDs of a certain color with a gigantic luminous efficacy of 250 lumens per watt are already being developed under laboratory conditions. Today, further development towards OLED is seen as the technology of the future.

Efficiency and operational parameters Color Wavelength range(nm) Typical Efficacy (Lumen/watt) Typical efficiency coefficient 620 < λ < 645 Red-orange 610 < λ < 620 72 98 0. 39 0. 29 520 < λ < 550 490 < λ < 520 460 < λ < 490 93 75 37 0. 15 0. 26 0. 35 Green Cyan Blue

Applications Of LED Mobile phone technologies Signs and Hoardings Automative Application Signal application Illumination Indicators Sensors

Applications in Mobile Technologies Flash feature the in camera of mobile phones. Generally white LEDs are used for mobile phones. Used in LCD(liquid crystal display): LCD is a display technology for televisions and tablets and mobile phones as well. Nowadays LED screens are available as well.

Signs and Hoardings: Full Color Video Screen. Traffic Lights : For stop , look and go actions. Automative Applications: Interior Lighting ‐ Instrument Panels & Switches. Exterior Lighting ‐ CHMSL, Rear Stop/Turn/Tail Truck/Bus Lighting ‐ Retrofits, New Turn/Tail/Marker Lights

Sensors Daylight sensor Bar Code Readers Line follower sensors Optical Switches

ADVANTAGES OF LED Efficiency: LEDs emit more lumens per watt than incandescent light bulbs. The efficiency of LED lighting fixtures is not affected by shape and size, unlike fluorescent light bulbs or tubes. Color: LEDs can emit light of an intended color without using any color filters as traditional lighting methods need. This is more efficient and can lower initial costs. Size: LEDs can be very small (smaller than 2 mm) and are easily attached to printed circuit boards. Warm Up time: LEDs light up very quickly. A typical red indicator LED will achieve full brightness in under a microsecond. LEDs used in communications devices can have even faster response times.

Cycling: LEDs are ideal for uses subject to frequent on‐off cycling, unlike incandescent and fluorescent lamps that fail faster when cycled often, or high‐intensity discharge lamps (HID lamps) that require a long time before restarting. Dimming: LEDs can very easily be dimmed either by pulse‐width modulation or lowering the forward current. This pulse‐width modulation is why LED lights, particularly headlights on cars, when viewed on camera or by some people, appear to be flashing or flickering. This is a type of stroboscopic effect. Cool light: In contrast to most light sources, LEDs radiate very little heat in the form of IR that can cause damage to sensitive objects or fabrics. Wasted energy is dispersed as heat through the base of the LED. Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt failure of incandescent bulbs. Lifetime Shock resistance Focus

DISADVANTAGES High initial price Temperature dependence: LED performance largely depends on the ambient temperature of the operating environment or "thermal management" properties. Toshiba has produced LEDs with an operating temperature range of ‐ 40 to 100°C, which suits the LEDs for both indoor and outdoor use in applications such as lamps, ceiling lighting, street lights, and floodlights. Voltage sensitivity: LEDs must be supplied with a voltage above their threshold voltage and a current below their rating. Current and lifetime change greatly with a small change in applied voltage. They thus require a current‐regulated supply (usually just a series resistor for indicator LEDs). Blue hazard: There is a concern that blue LEDs and cool‐white LEDs are now capable of exceeding safe limits of the so‐called blue‐light hazard as defined in eye safety specifications. Blue Pollution

LED Tubelight vs. Fluorescent Tubelight T‐ 8 LED Tubelight Costs Rs. 1600‐ 2000 Payback 3‐ 4 years Life 10‐ 15 years T‐ 5 Fluorescent Tubelight Rs. 500 6 months to 3‐ 4 years 1 year Regular Fluorescent T‐ 8 Tubelight Rs. 100 3‐ 4 years Efficiency About 110‐ 120 lumens per watt 110 lumens per watt 60‐ 80 lumens per watt (lower for one with electromagnetic ballast)

LEDs vs. conventional lighting technologies Light Output Light Emitting Diodes (LEDs) Incandescent Light Bulbs Compact Fluorescents (CFLs) Lumens Watts 450 4 -5 40 9 -13 800 6 -8 60 13 -15 1, 100 9 -13 75 18 -25 1, 600 16 -20 100 23 -30 2, 600 25 -28 150 30 -55

LEDs vs. conventional lighting technologies Environmental Impact Contains TOXIC Mercury Ro. HS Compliant Light Emitting Diodes (LEDs) Incandescent Compact Fluorescents Light Bulbs (CFLs) No Yes ‐ Mercury is very toxic to the health and the environment Yes No ‐ contains 1 mg‐ 5 mg of Mercury and is a major risk to the environment 204 kg/year 2041 kg/year 477 kg/year No Carbon Dioxide Emissions (30 bulbs per year) Lower energy consumption decreases: CO 2 emissions, sulfur oxide, and high‐level nuclear waste.

LEDs vs. conventional lighting technologies Energy Efficiency & Energy Costs Light Emitting Diodes (LEDs) Incandescent Light Bulbs Compact Fluorescents (CFLs) Life Span (average) 50, 000 hours 1, 200 hours 8, 000 hours 6 - 8 watts 60 watts 13 -15 watts 329 KWh/yr 3285 KWh/yr 767 KWh/yr Watts of electricity used (equivalent to 60 watt bulb). LEDs use less power (watts) per unit of light generated (lumens). LEDs help reduce greenhouse gas emissions from power plants and lower electric bills Kilo-watts of Electricity used (30 Incandescent Bulbs per year equivalent)

Government Schemes A National programme for LED‐based Home and Street Lighting has been launched by the government of India ‐ Domestic Efficient Lighting Programme (DELP). Under the scheme, LED bulbs are sold at heavily subsidized rates. The main aim is to save electricity by replacing lighting sources incandescent bulbs. As of 19 th March 2016, a total of 8 crore LED Bulbs have been distributed under the scheme. This led to a savings of 28. 58 GWh of energy per day.

Domestic and Commercial Lighting Omnidirectional LED Bulbs – These use a diffusing lens to scatter light in all directions. Dimmable LED Bulbs LED Tubelights – Intended as a replacement for conventional tubelights. Some have a power consumption of 8 Watt or 16 Watt unlike conventional tubelights. Flood Lights

LED STREET LAMPS An LED street light (also referred to as LED road lighting) is an integrated light‐emitting diode (LED) light fixture that is used for street lighting. The current trend is to use high power 1 watt LEDs Heat sinks are used. They facilitate the flow of hot air away from the LEDs. The lifespan of an LED street light is determined by its light output compared to its original design specification. Once its brightness decreases by 30 percent, an LED street light is considered to be at the end of its life.

Advantages of LED street lights: Low energy consumption Long and predictable lifetime: The projected lifetime of LED street lights is usually 10 to 15 years. LEDs themselves do not generally fail or "burn out" in a way comparable to other technologies, lifetimes are typically set by a decrease in luminous output of 30%. But the functional lifetime of an LED typically projected to last about 50, 000 hrs. More accurate color rendering: The color rendering index(CRI)is the ability of a light source to correctly reproduce the colors of the objects in comparison to an ideal light source. Improved color rendering makes it easier for drivers to recognize potential road hazards. Quick turn on and off: LEDs once switched on come on with full brightness instantly. No problem with immediate restart: Unlike mercury vapor, metal halide and sodium vapor lamps (commonly used in street lighting), LEDs do not have a problem restarting immediately. Higher light output even at low temperatures.

Disadvantages of LED street lights: There is a main risk from glare. A luminance level higher than 10, 000 cd/m 2 causes visual discomfort. LEDs have concentrated point sources which cause luminance of 1000 times greater than comfort visual level. The initial cost of LED street lighting is high. The material used in LEDs are often made on sapphire or other expensive substrates. LED street lights make light pollution , they emit more blue and green light(which is sensitive for human eyes) It also increases impacts on bird migration and animal behaviour!

Beam Angle Refers to the angle between the two planes of light where the intensity is at least 50% of the maximum intensity at center beam. The average beam angle on most par lights is 25 degree, which works well for most purposes. Example – Consider a 40° light bulb. At 20° on either side of that central point the light intensity is ½ the intensity right under the bulb(20° + 20° = 40°). Also, the lamp with greater beam angle looks dimmer. 25° & 40° lamps both have the same light output, but the 40° covers much more space and, therefore, looks a little dim.

LED Lens The beam angle is determined by the type of lens used in the LED fixture. The smaller lens on the right is typical in RGB fixtures (one color lamp under each lens) and this sample is a 25 degree lens. Beam angles ranging from 10 degree (narrow) to 60 degree (wide) are common.

LED Lens The lens on the right is a larger lens This type is common on Quad‐LED fixtures in which all 4 LED color lamps are located under each lens, hence the reason for the larger size. Larger lenses have wider beam angles of 25 ‐ 60 degrees. Notice the textured surface, the purpose of this is to produce better color mixing. However, the textured surface will reduce beam intensity by a small percentage.

Different Types Of Beam Spread In LED Lens 25° Beam spread

Different Types Of Beam Spread In LED Lens 45° Beam spread

LIGHT SPREAD OF DIFFERENT LED BEAM ANGLES FOR VARIOUS CEILING HEIGHTS

NAMES OF LED BULB BEAM ANGLES

LED Drivers An LED driver is an electrical device which regulates the power to an LED or a string of LEDs. It provides a constant quantity of power to the LED as its electrical properties change with temperature. The power level of the LED is maintained constant by the LED driver as the electrical properties change throughout the temperature increases and decreases seen by the LED or LEDs. Without the proper driver, the LED may become too hot and unstable, therefore causing poor performance or failure.

LED DRIVER CIRCUIT

Applications Of LED Drivers Industrial / outdoor lighting Commercial lighting Residential lighting Cell phone camera flash Automotive interior or tail lights Garden lighting Portable flashlight / torch Signage Elevator lighting LCD backlighting

LED DOWN LIGHT LED down lights are advanced low energy luminaires that outperform halogen and CFL. Energy efficient and providing substantial energy savings. These units are extremely small in size so they can be discreetly hidden within the decor.

Advantages Of LED Downlight 1. LED down light bulbs can last up to 50, 000 hours, which is 10 times longer than your average halogen or CFL down light. 2. Another benefit you get from LED down lights is that they are safe and do not produce a lot of heat, which means they can even be installed near flammable. 3. Although they cost more, their energy savings of up to 90 percent mean that they will easily pay for themselves within 1 or 2 years after installation, depending on usage.

1. 2. 3. 4. 5. 6. PHILIPS HAVELLS OSRAM EVEREADY WIPRO OREVA 7. 8. 9. 10. BAJAJ SYSKA SURYA NTL LEMNIS

Top Branded LED bulb comparison:

NOW QUESTION IS WHICH BRAND IS THE BEST ? Technical parameters to consider while buying a high quality light are Lumens output (Lumens/watt), Power Factor, CRI (Color rendering index) and LED life in hours. Parameter Average Good Best Lumens/watt 75 90 100 Power factor 0. 7 0. 8 0. 9 CRI 60 70 80 Led life in hrs 15000 20000 25000

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