UNIT-2 ILLUMINATION

UNIT-2 ILLUMINATION. Dr. S. RAMESH KUMAR Associate Professor, EEE Government College of Engineering Srirangam Trichy, Tamilnadu.

[Audio] We will explore the basics of illumination engineering and its various applications, beginning with a definition of terms used in the field and exploring the different types of light sources as well as how to design illumination systems best. Both indoor and outdoor lighting schemes will be discussed, such as flood lighting and street lighting, as well as energy efficient lamps and LED technology. Let's get started!.

[Audio] Light is a vital element in our lives, from how cultures plan and organize their day-to-day activities according to the sun's availability to the way we make use of artificial lighting to make the day seem longer. Nowadays, with lighting systems, a variety of physical principles can be taken advantage of to give us the light we need. In this section, we will look into the basics of light sources and learn how to use them in the most effective manner..

[Audio] Light is a fundamental part of our lives, from helping us with tasks to creating the atmosphere in a room. We will look at illumination - the amount of light reaching a surface. Illumination is indicated by 'E' and is measured in lumens per square meter. It is calculated by the amount of lumens in a certain area, for example, 500 lumens on a 10m2 surface would result in an illumination of 50 lumens per square meter. The formula for this is F/A, which can be used to work out illumination of any surface..

[Audio] Luminous flux and luminous intensity are key concepts to understanding the output and efficiency of any light source. Luminous flux is the total quantity of light energy emitted per second from a luminescent body and is measured in lumens, while luminous intensity is the luminous flux emitted by the source per unit solid angle and is measured in candela or lumens/steradian. This is found by dividing the luminous flux by the solid angle of ω steradian in any particular direction - I =F/ ω lumens/steradian or candela (cd)..

[Audio] Luminous flux, measured in lumens, is the total amount of visible light emitted from a source in all directions. Lumens measure the amount of light falling on a surface from a source at a given distance. Candlepower, on the other hand, is a measure of how much light is radiating from a source in a given direction. It is expressed as the number of lumens given out by the source in a unit solid angle in a given direction. When multiplied by the solid angle of the source, it gives the total lumens given off by the source. Lumens and candlepower are thus essential in understanding illumination..

[Audio] Lux or meter-candle is the unit of illumination used to measure the luminous flux falling on a surface per square meter. It is based on the light emitted from a source of candle-power, one meter away, in all directions that are perpendicular to the rays. A candle is the unit of luminous intensity, which is based on the luminous intensity per centimeter squared of a black body radiator at a temperature of solidification of platinum. Mean Horizontal Candle Power is an average of the candle powers in all directions in the horizontal plane that is containing the source of light..

[Audio] I will discuss the eighth slide of the presentation titled "Unit-2 Illumination". It gives us an overview of several key aspects of light sources. We will start with Mean Spherical Candle Power (M S C P), which is the mean of the candle powers in all directions and in all planes from the source of light. Mean Hemi-Spherical Candle Power (M H S C P) is the mean of candle powers in all directions above or below the horizontal plane passing through the source of light. Reduction Factor is the ratio of the M S C P to the M H C P Lamp Efficiency is the ratio of the luminous flux to the power input, expressed in lumens per watt. Lastly, Specific Consumption is the ratio of the power input to the average candle power, expressed in watt per candela..

[Audio] Brightness is the luminous intensity of a light source or reflecting surface, measured as the candela per square meter (nit). Glare is an extreme brightness which can be considered too strong to be comfortable, wherein the light causes annoyance, discomfort, or interferes with vision. To ensure comfort and visibility, it is important to keep artificial lighting at an appropriate level in order to avoid glare..

[Audio] In this slide, two terms related to illumination are discussed: Utilization factor and Maintenance factor. Utilization factor is the ratio of the total lumens that reach the working plane to the total lumens emitted by the lamp. Maintenance factor is the ratio of illumination under normal working conditions to the illumination when the fixtures are perfectly clean. It is important to understand these factors as they measure the effectiveness of lighting, and help identify areas for improvement..

[Audio] When dealing with multiple sources of light, there is a certain amount of light that can be wasted due to overlapping edges. To account for this, the theoretical number of lumens required should be multiplied by 1.2 for rectangular areas and 1.5 for irregular areas. An additional factor to consider is the absorption of light in certain places. In foundries, for instance, the ratio of lumens available after absorption to the total lumens emitted by the source of light can be as low as 0.5, a ratio referred to as the Absorption Factor..

[Audio] Light is a key factor in illumination. The Beam Factor shows the ratio of lumens in a projector beam with regards to the lamp's output. The Reflection Factor reveals how much light is bounced off of a surface. Additionally, the Plane Angle measures the radian angle between two intersecting lines in a plane. All these components are integral in understanding illumination science..

[Audio] Light is a powerful force that lets us observe our environment. To unwrap its secrets, we have to delve into the solid angle. This angle is denoted by 'ω' and measured in steradian. It can be calculated with 'ω = A/r2', in which 'A' is the area and 'r' is the radius. Solid angles are particularly useful in calculating the surface area of a sphere, which is '4πr2/r2 = 4πsteradian'. This allows us to understand the complicated interplay between light and space in our surroundings..

[Audio] Illumination is an important concept in the field of lighting. Two of the main laws in this field are the Inverse Square Law and Lambert's Cosine Law. The Inverse Square Law states that illumination on any given surface is inversely proportionate to the square of the distance between the surface and the light source. Lambert's Cosine Law states that illumination on any given surface is directly proportionate to the cosine of the angle between the line of flux and the normal at any given point. This can be represented mathematically using the equation E = I cos ? / r2. Both of these Laws of Illumination serve as the basis for further exploration of this field, and I will be discussing them today in more detail..

[Audio] For centuries, light has been a powerful tool to humanity, enabling us to progress our world in so many ways. Natural sources of light such as the sun and stars have been around for billions of years, while artificial sources such as lamps, torches and bulbs have been with us for more recent times. All these light sources have allowed us to undertake activities in all corners of the world and to see in the dark..

[Audio] Illumination is the process of providing light, and there are three main types of light sources. Incandescent sources emit light as a result of being heated, like candles and incandescent lamps. Luminescent sources create light as a result of accelerating charges in a luminescent material, which is seen in fluorescent tubes, CFLs, and electric bulbs. Finally, gas discharge sources create light by passing electricity across a certain gas at very low pressure, visible in neon lamps and sodium lamps..

[Audio] An arc lamp consists of a glass envelope, anode and cathode end caps, as well as a cathode. When electric current is supplied, an arc is generated in the space between the two electrodes, producing light. This type of lamp is commonly used in many light fixtures and applications..

[Audio] Incandescent lamps are the most commonly used source of light, operating on the principle of incandescence, where the filament is heated by the flow of electricity, resulting in light emission. They are available in a range of sizes, voltages and wattages from 1.5V to 300V, and are relatively inexpensive, providing good task lighting with an expected life expectancy of around 800 hours. The structure of an incandescent lamp is composed of a filament and a bulb, as indicated by its symbol..

[Audio] A light bulb is a perfect example of how technology can make our lives easier. It is comprised of several parts that work together to produce light. Inside the bulb, two contact wires are connected to a tungsten filament which is enclosed by a glass bulb that is filled with an inert gas. Together with a glass mount and insulation, these components enable electricity to flow through and create light. Being familiar with the way a light bulb works assists us in gaining knowledge of how electricity is utilized to illuminate the world..

[Audio] The glass bulb of an incandescent lamp is filled with inert gas like argon or nitrogen to reduce the evaporation rate of the filament, thus increasing the bulb's life. The filament is made of tungsten metal, which can withstand a very high temperature. The bulb also has two contact wires at the base, providing electrical connections to the filament..

[Audio] Slide taking a look at supporting elements that make a light bulb work focuses on support wires - small connecting threads that help keep the filament in place, and a glass mount that runs through the bulb to keep electrical contacts from leaking air or gas. Most lamps screw into a socket, and the base is protected with plaster of Paris, porcelain, aluminum, or glass insulation. All these intricate components come together to make a light bulb function correctly and give us the light we need..

[Audio] In this slide, we will explore the working of an incandescent lamp. An incandescent lamp works on the principle of incandescence, where heat is used to generate light. The current is supplied to a thin metal filament, usually composed of tungsten, which is then heated until it glows, emitting light. The filament can reach very high temperatures, up to 4,500 degrees Fahrenheit, and is contained within a glass enclosure to prevent it from overheating and oxidizing quickly due to oxygen in the air. This type of lamp is efficient and suitable for a variety of applications..

[Audio] Despite the modern world, incandescent lighting remains relevant. Gas-filled lamps are one example, utilizing a filament in an inert gas to contain evaporation of the filament, allowing it to last longer. This type of lighting provides a cost- and energy-efficient solution..

[Audio] Halogen lamps are the latest incandescent lamps that offer powerful lighting, of up to 5 kW, in a more efficient and compact size. The addition of a small amount of halogen vapor returns evaporated tungsten to the filament, which leads to improved life, color rendition and smaller dimensions. Halogen lamps are well-suited for outdoor applications such as gardens, car parks, building perimeters, playing fields, fountains and airport runways, as well as indoors in places like factories, public halls, sports venues, TV studios and photo films..

[Audio] Incandescent lamps are highly valuable in modern life. They supply a warm and luminous light which can be easily adjusted and they switch on immediately. They are also reasonably priced, making them an affordable option for most. Moreover, they provide an extra source of heat during winter. All of these benefits make the incandescent lamp an integral part of every home..

[Audio] An incandescent lamp is of limited use as it has a comparatively short lifespan, emits a warm light, and is relatively inefficient in terms of lumens per watt. Consequently, these lights are rarely chosen for large areas and require some care when handling. Nevertheless, its popularity persists in a variety of applications, such as for table lamps, desk lamps, hallway lighting, accent lighting, chandeliers, and closets..

[Audio] Sodium Vapor Lamps are electric discharge lights that produce a thick blue or yellow light, depending on the gas used. These lights are highly efficient and capable of producing high intensity light, making them an ideal choice for areas that need to be illuminated over large distances. Developed in the 1930s by Philips of Holland, Sodium Vapor Lamps have since become a preferred option for outdoor lighting. They are very energy efficient and durable, making them one of the most reliable lighting sources available. If you are looking for a reliable and effective lighting solution for outdoor areas, consider a Sodium Vapor Lamp..

[Audio] Sodium vapour lamp is a preferred choice for industrial and street lighting because of its high power and efficiency. It works by vaporizing sodium metal combined with other gases and materials to modify the colour of light it produces. Market offers two types of Sodium vapour lamps - low-pressure sodium vapor lamp (LPS) and high-pressure sodium vapor lamp (HPS). In comparison to other lighting options, sodium vapour lamps offer businesses an effective cost solution with optimal illumination..

[Audio] For this particular slide, an effective voiceover might sound something like this: "This lighting system consists of two electrodes, E1 and E2, placed inside of a G1 glass tube that is filled with a combination of sodium and a small amount of argon or neon gases. This G1 glass tube is then encased in a G2 evacuated exterior tube..

[Audio] Sodium vapor lamp is an essential part of today's lighting systems due to its ability to maintain precise temperatures, ensuring optimum efficiency and working conditions. A choke and a small step-down transformer work together to regulate the discharge and voltage supply, while the capacitor helps to heat the cathode electrode, enhancing arc performance. As a result, the sodium vapor lamp provides a dependable and effective lighting solution..

[Audio] When a sodium vapour lamp is connected to the power supply, heat is generated from the discharge of neon gas, which then vaporizes the sodium, creating red-orange light. After fifteen minutes this light turns to a bright yellow hue. However, due to the low power factor of this circuit, a capacitor is included to improve the rectification process in order to achieve the best results from the sodium vapour lamp..

[Audio] Sodium vapor lamps boast a number of benefits, from their high efficiency and long lifespan to their ease of disposal, low operating temperature, and energy efficiency. Furthermore, the cool light and minimal heat they generate make them a great choice for foggy and rainy situations. Plus, they come in a range of grades, providing warm color temperatures that make them ideal for an array of applications..

[Audio] Sodium Vapour lamps can provide great lighting solutions, but they come with disadvantages as well. These lamps require ballasts and controlling elements to regulate glare, and are not suitable for areas with colour identification needs. The sodium content can also make them dangerous, as they can ignite when exposed to air. Furthermore, they require an extra transformer and have low power factors. Inside, the yellow colour may not be suitable and long tubes are often needed to get an adequate light output. Lastly, they need to warm up for 5 to 10 minutes before reaching full brightness..

[Audio] Sodium Vapor lamps have multiple applications, ranging from airports and goods yards, to advertisement purposes. The most common ratings for these lamps exceed 250 watts. They are also used in industrial settings, and for outdoor area lighting from roadways to parking lots. Sodium vapor lamps are a great choice as they provide a practical and reliable solution for illuminating many areas..

[Audio] Mercury vapor lamps are a revolutionary form of illumination, capable of providing brighter and longer-lasting light with greater efficiency. Consisting of vaporized mercury used to generate an electric arc for light, the lamp ionizes the mercury before generating light, giving it a positive or negative electric charge. This cold-resistant, high-intensity discharge lamp produces bright white light with a long rated life of 24000 hours. It can often be seen illuminating streets, providing reliable and energy-efficient lighting..

[Audio] Lamps, designed for both indoor and outdoor lighting, are a popular source of illumination. Generally, they consist of a metal or ceramic base that secures a lightbulb, lamp shade, reflector, and other components. A switch also may be present to turn the lamp on or off. To understand how the components of a lamp work together to generate light, let's take a closer look at each of the pieces..

[Audio] The design of a lamp comprises an inner tube made of hard glass containing mercury vapor and a percentage of argon gas, as well as an outer glass cover to shield it from temperature and light fluctuations. It has two main electrodes made of tungsten, as well as an auxiliary or starting electrode placed near one of the main elements. This design guarantees the lamp's efficient and reliable operation..

[Audio] When the circuit is complete, the supply voltage is applied between the main and auxiliary electrodes, causing the argon gas between the electrodes to become ionized and a glow appears. The current then flows through the starting resistor in series with the auxiliary electrode, building up the pressure due to heating of mercury. As the gaseous medium between the main electrodes is ionized, the current can be regulated by the choke in the main circuit. To further improve the power factor of the circuit, which would otherwise be very low, a capacitor is added to the lamp circuit..

[Audio] Mercury vapor lamps are a popular choice for many applications as they produce a clear white light with high intensity and are energy efficient and available in a wide range of shapes, sizes, and ratings. They have a long lifespan of 24000 hours, though they need 5 to 8 minutes to warm up before reaching their full brightness and are sensitive to voltage fluctuations. Additionally, they have poor lumen maintenance and cooling time of 5 to 7 minutes..

[Audio] Mercury vapor lamps are a reliable and energy-efficient light source offering a range of applications. Their affordability and minimal need for maintenance make them the ideal choice for both households and industrial areas, as well as security settings. Providing bright, uniform lighting, they are suitable for garages, storerooms, street lighting and stairwells, making any area safer and more efficient..

[Audio] Fluorescent lamps provide a unique and efficient way to light up our lives. Operating on the principle of fluorescence, these lamps generate visible light from an electric current and mercury vapor. Contained within the tube is a special phosphor coating which produces the glowing effect that is associated with fluorescent lighting. This technology has become increasingly popular due to its amazing efficiency, and its ability to offer a bright and consistent light..

[Audio] I will be discussing fluorescent lamp starters and their importance in regulating and sustaining the electricity flow in electrical circuits. The ballast found in starters can supply enough voltage to start the lamps, which is key in ensuring that the current supplied does not surpass the light's specified limit. This is necessary to keep lamps at optimum performance level for an extended period..

[Audio] The starter switch is filled with argon gas, which ionizes, creating a glowing effect that heats up the bimetallic strip. This bending of the bimetallic strip then short circuits the starter terminals, completing the circuit and allowing current to flow effectively when the circuit is energized..

[Audio] The process of illumination is made possible by the flow of electrons through a filament. The filament is coated with oxides of barium and strontium and when the starter switch is triggered, a high voltage surge is induced in the choke, resulting in a momentary high potential difference between the filaments that ionizes the surrounding components such as mercury and argon. This exciting of the mercury vapor in the tube produces ultraviolet rays, which fall on a phosphor coating and result in visible light being emitted. Through this process, the light that we use is made possible..

[Audio] Fluorescent lamps have been around for some time, and they have some great uses. When it comes to efficiency, they can't be beat. They have a long life span, cost less to run, and they don't put out a lot of heat. On the down side, fluorescent lamps can suffer from stroboscopic effect, and the choke used in them can cause some kind of magnetic hum that may cause disturbance. Additionally, if you need low wattage, you may need a large number of fittings. But all in all, fluorescent lamps can still be a great choice for a variety of lighting needs..

[Audio] Fluorescent lamps are a great choice for a variety of applications. With their ability to offer light output in large areas, they are an ideal choice for industrial lighting. Additionally, they provide efficient and uniform light levels for offices, making them perfect for the workplace. In residential applications, fluorescent lamps provide effective lighting for kitchens, valences, and fascia, and can even be used for classroom and retail lighting. If you're looking for a reliable and effective lighting solution, fluorescent lamps are certainly something to consider..

[Audio] Fluorescent lamps are a popular choice of lighting due to their ability to produce visible light through a low-pressure mercury vapor gas discharge via fluorescence. An electric current excites the mercury vapor to create ultraviolet rays that are then converted to light when they hit a phosphor coating on the inside of the lamp. In addition, fluorescent lamps are known to produce the stroboscopic effect, a phenomenon of making running or moving objects seem stationary or running slower than their actual speed, which is caused by periodic fluctuations in the light output of the lamp triggered by cyclic variations of the AC supply current..

[Audio] As you can see in this slide, a fluorescent lamp operating on 50 Hz AC supply has a flicker rate of 100 times per second due to the double frequency of the supply. While this is typically not noticed by the human eye, it can create an illusion when light falls on a moving object; the object may appear to run slower or in reverse, or may seem stationary. This phenomenon is known as the stroboscopic effect, and is more pronounced at lower frequencies..

[Audio] The stroboscopic effect is a phenomenon that can cause hazardous accidents in industrial settings. To lessen the likelihood of such occurrences, fluorescent lamps are generally not used in industry. To minimize the stroboscopic effect, three lamps can be employed on separate phases of a three-phase supply. By doing this, the zero crossings of the two lamps will not be the same, decreasing the risk of accidents..

[Audio] Lighting is a key element in design, able to help create the perfect atmosphere for a given space. Various types of lighting schemes can be applied, such as direct lighting, semi-direct lighting, indirect lighting, semi-indirect lighting, and general lighting, depending on the requirements and how light needs to reach the surfaces to make them visible. It is important that lighting is carefully considered and applied to show the design at its best..