TYPES OF LAMPS

Types of Lamps

Light sources• Incandescent lamp• Discharge lamp– Florescent lamp– Sodium lamp– High pressure mercury vapour lamp

INCANDESCENT LAMP• HOT WIRE – FILAMENT

SEALED IN A GLASS JAR (BULB)

• ELECTRIC CURRENT PASS THROUGH THE WIRE HEATS IT TO INCADESCENCE, AND THE WIRE EMITS LIGHT. USE STANDARD VOLTAGE CIRCUIT.

Incandescent lamp An , incandescent lamp or incandescent light globe is

an electric light which produces light with a filament wire heated to a high temperature by an electric current passing through it, until it glows (see Incandescence). The hot filament is protected from oxidation with a glass or quartz bulb that is filled with inert gas or evacuated. In a halogen lamp, filament evaporation is prevented by a chemical process that redeposit metal vapour onto the filament, extending its life. The light bulb is supplied with electrical current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections .

• Inside gas is argon with nitrogen.

• At the center of the lamp is a tungsten filament.

• Electricity heats this filament up to about 2,500 degrees Celsius.

• Light output is 15 lumens/watt• Operating life 1000 hour• Efficency increased by using– Coiled filament– Coiled coil filament

Parts

1. GLASS BULB2. VACUUM OR GAS

FILLED3. WIRE/FILAMENT 4. 5. LEAD-IN WIRES6. SUPPORT WIRES7. NECK8. 11. ELECTRIC FUSE9. BASE

Pros and Cons ADVANTAGES:

1. LESS EXPENSIVE2. EASIER TO DIM WITH

RHEOSTATS3. WARMER COLOR THAN

FLUORESCENT AND THUNGSTEN-HALOGEN LAMPS

4. LIGHT OUTPUT IS RELATIVELY HIGH

5. CAN BE DIMMED

DISADVANTAGES:

1. ENERGY INEFFICIENT

2. SHORT LAMP LIFE TIME

3. WARM SOURCE

Discharge lamps• Light is produced by

passage of an electric current through a vapor or gas, rather than through a tungsten wire as in incandescent lamp.

FLUORESCENT LAMP

FLUORESCENT LAMP• Inside bulb is coated with florescent powder• Oxide coated tungsten filament is used as

electrodes• Light output is 70 lumen/watt• Average life is 7500 hours

A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent lamp; some types fit into light fixtures formerly used for incandescent lamps. The lamps use a tube which is curved or folded to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp.

Compared to general-service incandescent lamps giving the same amount of visible light, CFLs use one-fifth to one-third the electric power, and last eight to fifteen times longer. A CFL has a higher purchase price than an incandescent lamp, but can save over five times its purchase price in electricity costs over the lamp's lifetime

• ADVANTAGES:

•Heat is relatively low•Energy efficient•Range from low grade to high grade•Long lamp life•Usually Cool source

• DISADVANTAGE:

•Color temperature•Require ballast: preheat, instant-start, rapid-start•Requires controlling elements for glare control

Sodium Lamp• gas-discharge lamp that uses sodium in an

excited state to produce light• Efficency is 75 lumens/watt• Average life 60000 hours

• A sodium-vapour lamp is a gas-discharge lamp that uses sodium in an excited state to produce light. There are two varieties of such lamps: low pressure and high pressure. Low-pressure sodium lamps are the most efficient electrical light sources, but their yellow light restricts applications to outdoor lighting such as street lamps. High-pressure sodium lamps have a broader spectrum of light than the low pressure, but still poorer colour rendering than other types of lamps. Low pressure sodium lamps only give monochromatic yellow light and so inhibit colour vision at night.

A neon lamp (also neon glow lamp) is a miniature gas discharge lamp that typically contains neon gas at a low pressure in a glass capsule. Only a thin region adjacent to the electrodes glows in these lamps, which distinguishes them from the much longer and brighter neon tubes used for signage. The term "neon lamp" is generally extended to lamps with similar design that operate with different gases. Neon glow lamps were very common in the displays of electronic instruments through the 1970s; the basic design of neon lamps is now incorporated in contemporary plasma displays. Neon was discovered in 1898 by William Ramsay and Morris W. Travers. The characteristic, brilliant red colour that is emitted by gaseous neon when excited electrically was noted immediately; Travers later wrote, "the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget."Neon's scarcity precluded its prompt application for electrical lighting along the lines of Moore tubes, which used electric discharges in nitrogen. Moore tubes were commercialized by their inventor, Daniel McFarlane Moore, in the early 1900s. After 1902, Georges Claude's company, Air Liquid, was producing industrial quantities of neon as a by product of his air liquefaction business, and in December.

Neon lamp

Mercury lampsA mercury vapour lamp is a gas discharge lamp that

uses an electric arc through vaporized mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger borosilicate glass bulb. The outer bulb may be clear or coated with a phosphor; in either case, the outer bulb provides thermal insulation, protection from the ultraviolet radiation the light produces, and a convenient mounting for the fused quartz arc tube.

Led lamp• An LED lamp is a light-emitting diode (LED)

product that is assembled into a lamp (or light bulb) for use in lighting fixtures. LED lamps have a lifespan and electrical efficiency that is several times better than incandescent lamps, and significantly better than most fluorescent lamps, with some chips able to emit more than 100 lumens per watt.

• Like incandescent lamps and unlike most fluorescent lamps (e.g. tubes and CFL), LED lights come to full brightness without need for a warm-up time; the life of fluorescent lighting is also reduced by frequent switching on and off. Initial cost of LED is usually higher.

Halogen Lamp• A halogen lamp, also known as a tungsten halogen, quartz-

halogen or quartz iodine lamp, is an incandescent lamp that has a small amount of a halogen such as iodine or bromine added. The combination of the halogen gas and the tungsten filament produces a halogen cycle chemical reaction which redeposit evaporated tungsten back onto the filament, increasing its life and maintaining the clarity of the envelope. Because of this, a halogen lamp can be operated at a higher temperature than a standard gas-filled lamp of similar power and operating life, producing light of a higher luminous efficacy and colour temperature .

Cont..

• Discharge will not start at low voltage

• Leak transformer produce starting voltage of about 400V

• First neon gas will discharge after sodium vaporises and discharge continues

• Pf is too low(0.3) to correct capacitor is used

High pressure mercury vapour lamp

• Inner gas used is Argon and mercury

• Efficiency 40 lumen/watt• Inner tube have two main

electrodes and an auxiliary electrode

Artificial Light Sources• Incandescent Lamps• Fluorescent Lamps• High – Intensity Discharge Lamps• Mercury Lamps• Metal Halide Lamps• High Pressure Sodium Lamps• Low Pressure Sodium Lamps• Electrodeless Lamps• Compact arc xenon &Mercury Lamps• Electroluminescent Lamps• Light Emitting Diodes (LED)• Carbon arc Lamps• Gaslights

Lamp efficiency & efficacy• Efficacy for a light source is how well it turns

input power into the desired output, which is lumens

• Efficiency is the actual percentage of power in which comes out as photons.

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