IlluminationLighting The World

Siddharth N. Joshi

GCET, VVNagar Mechanical (F.Y) 2015-16

Illumination… Natural Illumination:• Sources of light existing naturally in the

environment.• E.g. Sun, Stars, etc. Artificial Illumination:• Produced Electrically.• Steady output, aesthetic appearance,

clean, reliable and low-in-cost.

Terms To Keep In Mind… Light: Electromagnetic Energy radiated

from a hot body or substance. Luminous Flux: Light energy emitted

per unit time. UNIT: Lumens Luminous Intensity: Intensity of

emission of luminous flux. UNIT: Candela

Illumination: Phenomenon of light falling on any surface.

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.

• Used for general outdoor lighting.

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.

Semi-Indirect Lighting… 60%-90% of the total light flux is thrown

upwards to the ceiling for diffused reflection by using inverted reflectors.

Used for indoor light decorations.

Indirect Lighting… More than 90% of the total light flux is

thrown upwards to the ceiling for diffused reflection by bowl reflectors.

Used in cinemas, hotels, theatres, etc.

General Lighting… Causes diffused and glare-less lighting, same

illumination in all directions.

For this scheme, fluorescent lights are used.

Indoor Lighting Schemes… Aspects to be kept in mind:

• Adequate illumination

• Uniform light distribution all over the working plane.

• Light of suitable color.

• Minimum hard shadow and glare.

Types Of Lamps… Electric lamps :-• Incandescent lamps• Discharge lamps

Incandescent lamps:-• Vacuum lamps• Gas filled lamps

Vacuum Lamps:• Current is passed through FILAMENT.• Lamps are used below 40 W.• Higher amount of light radiated.• Heat energy is emitted, as wire glows.

Gas Filled Lamps:

• The bulb filled with an inert gas-mostly N2 ,Ar.• Used for 40W-500W.• Low initial cost, low energy consumption &

convenience.• Use coiled filaments.

Discharge Lamps… High & Low Pressure Mercury Lamps:

• Under low pressure, mercury lamps emit UV radiation.

• The pressure is increased we get light having bluish tinge.

• Replaced by Sodium Vapour Lamps.

Sodium Vapour lamps:

• Must operated at horizontal position to keep the sodium uniform throughout.

• Efficiency=40–50 lumens per Watt• Average life=about 3000 hours

• Not affected by voltage variations

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.

• Operating temperature=573 K• Thus, are known as Cold Cathode Discharge

Lamps.

CFLs…

Compact Fluorescent Lamps. Compact size, saves space. Saves 70-80% energy. Life Is 10 times as compared to

incandescent lamps. Starting and working is flicker-free.

Industrial Lightings… Provides amenities to the workers &

increasing productivity ,avoiding accidents.

200 Lumens/ m2 = day-light. Light of suitable colour must be

distributed all over the working plane.

In large machine shops, the height of light must be above level of machines.

Industrial lighting…

Street Lighting… Mercury & Sodium lamps are suitable for this

purpose.

Initial cost high, power consumption low.

Economical compared to filament lamps.

Used for clearly visible traffic, surrounding ,obstructions on road.

Also for attractive look of area

Street Lighting…

Illumination Of Street Lighting…

Sr. No

Class Of The Street Illumination (lux)

1. A1: Imp. Roads with heavy traffic 30

2. A2: Main roads with Mix Traffic, city streets, etc.

15

3. B1: Roads like shopping streets, Localized Traffic routes, etc.

8

4. B2: Secondary Roads with Light Traffic, By-Lanes, etc.

4

References: Images from Google.

Reference Text: Elements Of Electrical Engineering--- J. N. Swamy

N. V. Sinha (8th Edition)

ThAnK YoU