1. Illumination (Lighting)

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Outline
 Introduction
 Important Terms
 Lighting Schemes
 Design Of Indoor Lighting Schemes
 Types Of Lamps
 Halogen Lamps
 Discharge Lamps
 Fluorescent Tubes/Lamps
 Industrial Lighting
 Street Lighting

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Introduction
 In absence of natural lights artificial light
required
 Artificial light is clean,comfortable,reduce
accidents
 When it falls on any surface, it is illuminated.

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Important Terminology
 Light:-
 Electromegnatic energy
 Radiated from a hot body
 Luminous Flux:-
 The total quantity of light energy emitted per
second
 Measured in lumens

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Conti…
 Luminous Intensity:-
 Intensity of emission of luminous flux in specific
direction.
 Unit=Candela
 Illumination:-
 Lights falls on any surface, the phenomenon is
called Illumination.
 Measured in Lumens/m2

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Lighting Schemes
 Direct Lighting:-
 About 80% to 90% of the total light flux is made
to fall directly upon the working plane with the
help of suitable reflectors.
 Causes hard shadows and glare.
 Used for general outdoor lighting.

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Conti…
 Semi-Direct Lighting
 60%-90% of the total light flux
is made to fall directly
downwards with the help of
semi-direct reflectors.
 Remaining light is used for
illuminate ceilings and walls.
 Causes soothing brightness.

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Conti…
 Semi-Indirect Lighting:-
 60%-90% of the total light flux is thrown upwards
to the ceiling for diffused reflection by using
inverted reflectors.
 The remaining light reaches the work plane
directly except for some absorption by the
reflectors.
 Causes soft shadows and glare free lighting
scheme.
 Used for indoor light decorations.

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Conti…
 Indirect Lighting
 More than 90% of the total light flux is thrown
upwards to the ceiling for diffused reflection by
bowl reflectors.
 Causes soft, glare-free, diffused illumination.
 Used in cinemas, hotels, theatres, etc.

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Conti…
 General Lighting
 Causes diffused and glare-less lighting, same
illumination in all directions.
 For this scheme, flourescent lights are used.

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DESIGN OF INDOOR LIGHTING SCHEMES
I. Adequate illumination
II. Uniform light distribution all over the working
plane.
III. Light of suitable colour.
IV. Minimum hard shadow and glare.

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Types of Lamps
Electric lamps :-
A. Incandescent lamps
B. Discharge lamps
Incandescent lamps:-
1. Vacuum lamps
2. Gas filled lamps

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1. Vacuum lamps
 Current is passed through a filament
Temperature of wire increased
Heat energy is emitted
Higher amount of light radiated
Thus, filament made up of Tungsten
Used for below 40W

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2.Gas filled lamps
 The bulb filled with an inert gas-mostly N2 ,Ar.
 This reduces the evaporation of metal from the
filament.
 Use coiled filaments.
 Gas prevents arcing between two coils of spiral
filament.
 Low initial cost, low energy consumption &
convenience.
 Used for 40W-500W.

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Halogen lamps
n vary from 1 to ?00, it depends on surface material being simulated
If a small amount of halogen vapour is added to iodine gas, a
part of the evaporated tungsten is restored to the filament by
means of chemical reaction.
Reduces blackening caused by deposits of evaporated
tungsten.
Advantages :-
I. Life is almost double that of conventional tungsten
lamp.
II. Almost no blackening.
III. Better colour.
IV. Reduced dimensions.

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Dischrge lamps
I. High and low pressure mercury lamps
II. Sodium lamps
III. Neon lamps

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1. High & low pressure mercury lamps
Under low pressure, mercury lamps emit UV
radiation.
The pressure is increased we get light having
bluish tinge.
These lamps were widely used earlier, but now
a days it replace by the sodium vapour lamps.

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2. Sodium Vapour Lamps
Efficiency=40–50 lumens per Watt
Average life=about 3000 hours
Not affected by voltage variations
Glass tube is made up of chemical resistant to
withstand the chemical reaction of hot Na.
Must operated at horizontal position to keep
the sodium uniform throughout.
Need safety otherwise sodium may spread
and catch fire.

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3. Neon tube
• Widely used for decoration & ads purposes.
• Can be bent into desirable shape.
• Made to emit different colours like orange, red,
etc. by mixing chemicals with neon gas.
• Length of glass tube=upto 7-8 m
• Electrodes at two ends.
• Operating temperature=573 K
• Also known as Cold Cathode Discharge Lamps.

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Fluorescent Tubes/Lamps
 Tubes are filled with argon gas at low pressure
and one or two drops of mercury.
 Inner surface has thin fluorescent coating.
 Different colours depending upon different
coating material.
 When charge is pass through the tube, Mercury
vapour emits UV radiations and coating reflect it
& convert into visible light.
 CFL=Compact Fluorescent Lamp

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Conti…
 Properties of CFL:-
1. Compact in size, saves space compared to FL.
2. Saves 70-80% energy as compared to
incandescent bulbs.
3. Suitable for pendant luminairs.
4. Life of CFL=about (10*incandescent lamps).
5. Starting & working is flicker free.
 CFL is used where continuous economic
lighting is required.

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Industrial Lightings
 Industrial adequate illumination, providing
amenities to the workers & increasing
productivity ,avoiding mishaps & accidents.
 200 Lumens/ M2
= day-light
 Light of suitable colour must be distributed all
over the working plane.
 Take care of avoid glare.
 In large machine shopes, the height of light
must be above level of machines.
 In such places, in addition to the main lighting,
side lighting is also used.

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Cont…
 Lamps should be mounted in deep reflectors to
avoid glare.
 Ceilings and walls if coated with light coloured
paints will also help for better illumination.

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Street Lighting
 Mercury & Sodium lamps are
suitable for this purpose.
 Initial cost high, power
consumption low.
 economical compared to
filament lamps.
 illumination required depends
upon the class of street.
 used for clearly visible traffic,
surrounding ,obstructions on road.
 Also for attractive look of area.

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Conti…
Class Case of road illumination
(lux)
Class A1 Important roads
with heavy traffic
30
Class A2 Main roads with
mixed traffic, city,
streets etc.
15
Class B1 Roads like shopping
streets localized
traffic routes etc.
8
Class B2 Secondary roads
with light traffic, by
lanes, etc.
4

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Reference:-
Images :-www.Google.com
Slide templates :-http:xpowerpoint.com
Reference book :-
ELEMENTS OF ELECTRICAL
ENGINEERING
J.N.Swamy
N.V.Sinha
Mahajan publication(2nd Edition)

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