ILLUMINATION

8/26/2011 1

• ARC LAMPS

• INCANDESCENT LAMPS

• GASEOUS DISCHARGE LAMPS

• FLUORESCENT LAMPS

SOURCES OF LIGHT

8/26/2011 2

ARC LAMPS

8/26/2011 3

• Very efficient source of light

• Electric current is allowed to flow between

electrodes

• Electrodes are drawn apart

• The arc maintains the current

• Arc temperature – several thousand Celsius

• Outer envelope temperature – 500 degree

celsius

ARC LAMPS

8/26/2011 4

ELECTRIC ARC

8/26/2011 5

PARTS OF AN ARC LAMP• IGNITER

• connected parallel to the electrodes

• interrupts current after ignition

• BALLAST• connected series to the lamp

• helps to increase the voltage on current interruption

• builds up the potential across the rods

• the arc strikes between the rods

• ROD SHAPED ELECTRODES• solenoid based control is used to move them apart

• arc is maintained between the rods by the ballast8/26/2011 6

• CARBON ARC LAMP

• FLAME ARC LAMP

• MAGNETIC ARC LAMP

TYPES OF AN ARC LAMP

8/26/2011 7

• One of the earliest types

• Used in Cinema projectors & search lamps

• Arc is produced by incandescence principle

• Initially rods are joined together and a low voltage of 45V

is applied

• When the rods are moved apart an arc is formed

• Carbon particles migrate from positive to negative

• Positive rod – crater

• Negative rod – pointed pencil

8/26/2011 8

CARBON ARC LAMP

• Oxidation takes place – positive crater is bigger

• So the cross section – twice of negative

• In ac supply the rods are of same size

• Carbon is consumed regularly and hence replacement /

adjustment of the gap is required regularly

• Automatic device is used to feed carbon

• A series resistance is used to stabilize the arc

• Hence overall luminous efficiency decreases due to

resistive losses

8/26/2011 9

CARBON ARC LAMP

• Positive crater gives 85% light at a temperature of 3500o C

• Negative rod gives 10% light at a temperature of 2500 o C

• Efficiency of the lamp is 12 lumens/watt

• The voltage drop across the arc is about 60 V and supply

voltage is 100 V.

8/26/2011 10

CARBON ARC LAMP

CARBON ARC LAMP

8/26/2011 11

CONTROL FOR CARBON ARC LAMP

8/26/2011 12

• Principle is same as Carbon Arc Lamp

• Electrodes - 5-15% fluoride & 85 – 95% Carbon

• Core type carbon electrodes with cavities filled with fluoride are used

• Fluoride • Radiates light from a very high heated arc stream

• Vaporizes along with carbon

• Fluoride vapour produces high luminous intensities

• Flame materials – different colours

• Owing to non-appealing colours – not most widely used

• Luminous efficiency is around 8 lumen per watt

8/26/2011 13

FLAME ARC LAMP

SAMPLE ARC LAMPS

Krypton arc lamp

Carbon arc lamps

8/26/2011 14

SAMPLE ARC LAMPS

Xenon arc lamp

Mercury arc lamp8/26/2011 15

MAGNETIC ARC LAMPS

• Positive electrode – Copper

• Negative electrode – Magnetic oxide of Iron

• Arc strikes similar to the above two

• Very rarely used

8/26/2011 16

INCANDESCENT

LAMPS

8/26/2011 17

WHAT IS INCANDESCENCE?

METAL FILAMENT

Temperature rise

Red Hot

Higher wave length(Hot)

HEAT

White Hot

Lower wave length(Hot + Light)

188/26/2011

HEAT

• Electric current passed through a thin metallic

filament

• At low temperature radiates heat energy

• At very high temperature radiates heat and

light

• Higher the temperature higher is the luminous

flux

INCANDESCENT LAMPS

8/26/2011 19

INCANDESCENT LAMPS• Glass globe completely evacuated

– To prevent OXIDATION– To prevent CONVECTION CURRENT– To prevent REDUCTION IN

TEMPERATURE

• Filament – Carbon– Tantalum – Osmium– Tungsten

• Properties of filament– High melting point– Low vapor pressure – High resistivity– Low temperature co-efficient – Ductility– Sufficient mechanical strength

8/26/2011 20P.Raja, Assistant Professor, EEE, NITT

• Carbon Filament

– Melting point – 3500°C

– Starts vaporizing very fast beyond 1800°C

– Temperature co-efficient is negative

– Takes more current from the mains

– Low operating temperature

– Efficiency is low – 3.5 lumen per watt

8/26/2011 21

INCANDESCENT LAMPS

• Tantalum Filament

– Melting point – 2800°C

– Efficiency is low – 5 lumen per watt

• Osmium Filament

– Very rare and expensive metal

– Melting point is 2600°C

– Efficiency is low – 5 lumen per watt

8/26/2011 22

INCANDESCENT LAMPS

• Tungsten Filament – Melting point – 3400°C– High resistivity – Low temperature co-efficient – Low vapour pressure – Ductile and mechanically strong to withstand vibrations – Hot resistance is 15 times as that of cold resistance – Inrush current reaches maximum in 0.003 sec and reaches

normal operating value in 0.2 sec– Efficiency is good – 10 lumen per watt– Spectrum has – red and yellow dominant radiation and

less of blue and violet radiations

8/26/2011 23

INCANDESCENT LAMPS

• EVAPORATION– Blackens the bulb– Reduces the diameter of the filament – Increases the resistance – Draws less current and operated at lower temperature – Luminous output reduces

• DECREASE IN EFFICIENCY– Power consumption and current drawn decreases in the

same rate of the age of the lamp– Total depreciation of the lamp is around 15 % over the

useful range – Efficiency decreases four times as the fast and light output

decreases five times fast 8/26/2011 24

AGEING EFFECT IN

INCANDESCENT LAMPS

• OPERATES AT UNITY POWER FACTOR

• AVAILABLE IN VARIOUS SHADES AND SHAPES

• GOOD RADIATION CHARACTERISTICS IN LUMINOUS RANGE

• DIRECT OPERATION ON STANDARD DISTIBRUTION VOLTAGE

• NO EFFECT ON SURROUNDING AIR TEMPERATURE

8/26/2011 25

ADVANTAGES OF

INCANDESCENT LAMPS

8/26/2011 26

CHARACTERISTICS OF

INCANDESCENT LAMPS

PERCENTAGE NORMAL VOLTAGE

PERCENTAGE POWER CONSUMPTION, EFFICIENCY, LUMEN OUTPUT & LIFE

POWER CONSUMPTION

EFFICIENCY

LIFE

LUMEN OUTPUT

GAS FILLED LAMPS

8/26/2011 27

• Metal filaments upto 2000°C – in vacuum

• Inert gases reduce the chances of evaporation at higher temperatures- Argon & Krypton

• Nitrogen is added to avoid arc effect

• Krypton is best suited but very expensive

• Coiled coil filaments are used – slow rate of evaporation

• Hot gas carries the tungsten vapour and creates black spot

• Getters – absorb the evaporated Tungsten

• Collector grid – connected to lead wires

• Efficiency of coiled coil bulbs – 12 lumen per watt

• Low wattage – vacuum types

• Medium wattage – gas filled types

8/26/2011 28

GAS FILLED LAMPS

• Regenerative cycle – helps to retain the vaporized

tungsten onto the filament

• No blackening of lamps

• No depreciation of lumen output

• High operating temperature with increased luminous

efficiency – 22 to 33 lumen per watt

• Reduced dimensions of the lamps

• Long life – 2000 hours

• Better colour effect

8/26/2011 29

HALOGEN FILLED LAMPS

• Available upto 5kW

• Outdoor illumination

• Gardens

• Sport halls

• Fountains

• Car parks

• Air-port runways

• Factories

• Photo film and cinema studios

8/26/2011 30

APPLICATIONS OF

HALOGEN LAMPS

GASEOUS

DISCHARGE LAMPS

8/26/2011 31

• An electric current is passed through a gas or vapour

which renders it luminous beyond IGNITION

VOLTAGE

• The colour of the light depends on the medium

– Neon – orange – red

– Mercury always bluish

– Sodium vapour – Orange yellow

• Superior to filament lamps in efficiency and colour

8/26/2011 32

DISCHARGE LAMPS

PRINCIPLE OF OPERATION

• Ignition voltage across the electrodes causes discharge inthe gas medium

• Electro-magnetic radiation occurs

• Wavelength of the radiation depends on

– the gas

– operating pressure

– metal vapour used

• Possesses negative resistance characteristics

• Choke or a ballast used limits the current and to build theinitial voltage

• To improve the power factor a condenser is used

8/26/2011 33

DISCHARGE LAMPS

• High initial cost

• Poor power factor

• Starting problem

• Requires starters/ transformers

• Time required to reach full brilliancy

• Lamp with negative resistance – need ballast

• Flickering

• Suitable for particular position

8/26/2011 34

DEMERITS OF

DISCHARGE LAMPS

• Discharge lamps

– produces same light as that of the gas or vapour inside

– Sodium , Mercury and Neon vapour lamps

• Fluorescent lamps

– Discharge through vapours produce UV rays

– UV rays cause fluorescence in certain materials like PHOSPHORS

– They absorb UV rays and radiate visible light

– Fluorescent Mercury vapour tube

8/26/2011 35

TYPES OF

DISCHARGE LAMPS

SODIUM VAPOUR

LAMP

8/26/2011 36

• Bulb – Metallic Sodium

– Neon gas

– Two sets of electrodes connected to a base

• Neon helps to initiate discharge and increase heat

• Discharge envelope is of U shape

• Lamp is operated horizontally to enable uniform spread of Sodium

• Suitable only for alternating current and hence choke control becomes inevitable

8/26/2011 37

SODIUM VAPOUR

DISCHARGE LAMP

• A tapped transformer is preferred with an open circuited voltage of 470 / 480 V

• Initial glow is due to discharge through neon gas as the Solid sodium deposits on the walls when OFF

• Initial glow is hence Red –orange colour

• Lamp comes to rated operation in 15 minutes

• Efficiency – 40 to 50 lumen per watt

8/26/2011 38

SODIUM VAPOUR

DISCHARGE LAMP

SODIUM VAPOUR LAMP

8/26/2011 39

• High way lighting

• Rail yards

• Storage yards

• Gardens

8/26/2011 40

APPLICATIONS

ADVANTAGES

• Average life – 3000 hours

• Depreciation is 15% after this period

• Available in 45, 60, 85 and 140 watt ratings

8/26/2011 41

SPECTRUM OF SODIUM

VAPOUR LAMP

8/26/2011 42

OFFICE BUILDING

LIGHTED WITH SVL

MERCURY VAPOUR

LAMP

8/26/2011 43

MERCURY VAPOUR LAMP

8/26/2011 44

• Outer Bulb – Ordinary glass– Partially or completely evacuated to avoid

convection – Absorbs harmful UV rays

• Inner tube (bulb) – Made of hard glass / Quartz– Constitutes Argon & Mercury

• Two main electrodes– Made of helical Tungsten wire

• Starting / Auxiliary electrode• Choke to improve the voltage • Capacitor to improve the power factor 8/26/2011 45

MERCURY VAPOUR LAMP - MA

8/26/2011 46

MERCURY VAPOUR LAMP

PRINCIPLE OF WORKING

• When switch is closed and sufficient voltageapplied between auxiliary and nearby mainelectrode Argon starts discharge ( it conductsbefore mercury is vapourized)

• This enables the main discharge to commence

• Heat of electrodes evaporates the mercury

• The vapour pressure increases and the luminosityincreases

• Lamp requires 4 – 5 minute to attain fullbrightness

• Will not restart until it is cooled (because ofpressure)

• It takes 3 – 4 min to restart8/26/2011 47

• This lamp must be hung vertically(arc burningthe inner tube)

• Street lighting and outdoor lighting (where colourof light is not important blue- green)

• Operating temperature – 600°C

• Lamp efficiency – 30-40 lumen / watt

• Manufactured rating – 250 & 400 W for 200-250 V

• Gives greenish blue colour

• Applications – Industrial lighting , Railway yards, ports , work area, any outdoor lighting

8/26/2011 48

PRINCIPLE OF WORKING

• Similar to the previous type in working principle

• Choke is not used

• Outer tube has a Tungsten filament in series with the discharge tube

• Initially starts as a Incandescent lamp

• Glow is due to filament incandescence

• This warms the discharge tube

• After a threshold temperature filament is partially cut

• Voltage across discharge tube increases

• Complete discharge starts progressing8/26/2011 49

MERCURY VAPOUR LAMP - MAT

• Filament radiates RED color

• Discharge though Mercury gives BLUE color

• The filament resistance improves the power factor

• No capacitor is required

• Manufactured rating – 300 & 500 W

8/26/2011 50

MERCURY VAPOUR LAMP - MAT

• Low wattage lamps – 80 & 125 Watt

• High vapour pressure

• Filament radiates RED color 5 -10 atm

• Resistance series with the starting electrode is large

• Outer bulb is of Quartz or hard glass to withstand pressure

8/26/2011 51

MERCURY VAPOUR LAMP - B

• Additional Iodides are added with Mercury vapour

• Colour characteristic is improved

• Efficiency – 75 -90 lumen per watt

• Separate ignition device is required

• Suitable for outdoor lighting like Flood lighting , public lighting and industrial lighting

8/26/2011 52

MERCURY IODIDE LAMP

MERCURY VAPOUR LAMP

8/26/2011 53

8/26/2011 54

MERCURY VAPOUR LAMP

8/26/2011 55

NEON VAPOUR LAMP

8/26/2011 56

• GLASS BULB

– Filled with Neon gas

– Small percentage of Helium

– Emits Orange pink colour light

• Electrodes are made of purely IRON

• Efficiency – 15 – 40 lumen per watt

• Discharge of gas takes place like an arc

• To limit the current high resistance is connected in series

to the electrodes

• Power consumption – 5 W

• Applications – Indicator lamps , night lamps , DC main

polarity identification and NEON TUBES8/26/2011 57

NEON VAPOUR LAMP

8/26/2011 58

NEON TUBES • Length of 9 m

• Possess –• Two electrodes made of Iron, steel or Copper

• Orange – red – blue – green colors

• 10 – 15 – 20 – 30 mm diameters

• 25 – 35 – 60 – 150 mA current ratings

• Voltage – 300 – 1000 V per meter of tube length

• Ignition voltage – 1.5 times the above

• Operating voltage – 6000 volt

• High voltage – transformer with high leakage reactance –drooping characteristics

• Step up transformers with tapings are required

• Connections between letters are made of Nickel wires

• Power factor is very low and capacitors are used on the low voltage side of the transformers

8/26/2011 59

DEMERITS

• Flicker may occur due to

– Low voltage on the transformer secondary

– Reduction of gas pressure

• Requires frequent cleaning

• Maintenance of the transformer and its tapings

• Resonance problem

FLUORESCENT

LAMPS

8/26/2011 60

• Tubes of various lengths

• Many different colours are possible to be produced

• High luminous intensity without very high rise in

temperature

• Minimal glare is possible

• Efficiency – 40 lumen per watt

• The glass tube – 25 mm in diameter & 0.38 – 1.52 m

length

• Inner layer of the tube is coated with a thin layer of

fluorescent material in the form of powder

8/26/2011 61

FLUORESCENT LAMP

• Phosphors

– Zinc Silicate , Cadmium Silicate and Calcium Tungstate

– Converts the short –wave invisible radiations to visible light

– Coated along the sides of the discharge tube

• Contains Argon along with Mercury

• Electrodes are coated with electron emissive materials

• Starting switch is present

• Stabilizing choke is connected in series

• Power factor improvement capacitor is used

8/26/2011 62

FLUORESCENT LAMP

• A – Discharge tube

• B – AC supply

• C – Starter

• D – Bimetallic strip

• E – Capacitor

• F – Filament electrode

• G – Ballast

8/26/2011 63

CIRCUIT DIAGRAM

• Based on inelastic scattering of electrons

• Incident electron collides with an atom

• Kinetic energy ejects the outer shell electron to ahigher energy level

• Higher energy is unstable and emits photons

• Photons emitted are in Ultra violet wavelengths –253.7 and 185 nm

• Phosphors in the coating absorb these UV photonsand this jump emits lower energy photons in thevisible spectrum

• Avalanche effect is actually responsible for the furtherionization of the vapour

8/26/2011 64

BASIC PRINCIPLE OF OPERATION

8/26/2011 65

COMPONENTS OF LAMP

ELECTRODES FILAMENT

8/26/2011 66

COMPONENTS OF LAMP

STARTERS IRON BALLAST

ELECTRONIC BALLAST

• Thermal type starter is a current operated device

– Two metallic strips

– A heater coil

• Contacts are in contact when the lamp is OFF

• When supply is ON, the two electrodes get connectedin series with the bimetallic strip

• Relatively large current flows rising to incandescence

• Heater element heats up and break the bimetallic strip

• This current interruption causes a voltage surge

• Arc is established between the electrodes

• Gas in the discharge tube gets ionized8/26/2011 67

PRINCIPLE OF THERMAL STARTER

• Glow type starter is a voltage operated device

– two bimetallic electrodes enclosed in a bulb

– bulb - with Helium and Hydrogen mixture

• Contacts are open in normal condition

• When supply is ON, bimetallic strip causes a smallglow discharge

• Bimetallic strip heats up and bend and makecontact

• Large current flows through the end electrodes

• Temperature rises to incandescence

• Gas in the discharge tube gets ionized8/26/2011 68

PRINCIPLE OF GLOW STARTER

• Used for rapid or instant mode of start

• Supplied with ac voltage which is internally converted to dc

• This is then converted back to ac but with high frequency

• Types

– Oscillator start type

– Programmed start type

8/26/2011 69

ELECTRONIC CHOKE

• Oscillator type

– Has an oscillator and LC resonant circuit

– When turned ON oscillator starts and LC charges

– After a short time the voltage across the filaments reach 1 kV

– Process is too fast to pre heat the cathodes

– Lamp starts at cold start instantly

– Positive temperature co-efficient thermistors are used to delay the start of the discharge

8/26/2011 70

ELECTRONIC CHOKE

• Programmed type – Output frequency starts above the resonant frequency

– After heating the cathode the operating frequency falls down

– When the frequency touches resonant frequency voltage becomes maximum

– Lamp starts glowing

– If the lamp does not start the electronic circuit stops the ballast operation

– Micro-controller based – DIGITAL BALLASTS • Auto tube detection

• Auto checking of the filaments

• Auto tube replacement detection

• Automatic control on the ballast based on the impinging sunlight

• Possible with freq > 20kHz

• Increases the lamp efficiency and hence life

8/26/2011 71

ELECTRONIC CHOKE

• After few seconds the strip cools down

• As the bimetallic strip opens it creates a momentaryhike in potential due to the series choke

• This increase in potential is enough for the dischargethrough mercury

• The starter ceases to glow as the voltage is low now

• A small capacitor placed in the starter bulb suppressesthe arcing and radio interference

• Avalanche effect maintains the further glow of thelamp

8/26/2011 72

PRINCIPLE OF OPERATION

• A Ballast resistance is connected in series to thechoke to limit the current

• On systems below 220 V initiation of discharge ispossible only with thermal starters

• Mercury tends to vaporize and migrate towardsnegative terminal – bulb becomes dark nearpositive electrode

• Reversing switch is needed

• No power factor correction and stroboscopic effectproblems

• Efficiency is low and life of the bulb decreases(80% )8/26/2011 73

STEPS TO PONDER ON DC SUPPLY

• Direct radiation form the bulb to the antenna

• Line radiation from the supply line to the antenna

• Line – feed back through the line from the lamp to

the radio

8/26/2011 74

RADIO – INTERFERENCE IS DUE TO

• At usual alternating supply the discharge getsextinguished 100 times per second

• For normal operation this effect is notnoticeable to the human eyes

• But when moving bodies are illuminated bythese lamps they seem to have jerk ormoving slower than actual speed

8/26/2011 75

STROBOSCOPIC EFFECT

• Day light – Industrial applications – High illumination level – 1000 lux or more

• Warm – white – Street lighting applications – Illumination level is low – 10 lux

• Warm – white deluxe – Large rooms – shops, restaurants and dwelling houses– Goes hand in hand with incandescent lighting

• White – Offices, drawing rooms, schools and factories – Good supplement of day light

• White Deluxe– Offices , schools and shops where colour rendition is important

8/26/2011 76

COLOUR OF FLUORESCENT LIGHT

• Emission Mix– Sputtering decreases life– Severe if operated for less than three hours – Method of start influences – Cold start on lost emission mix over heats the bulb– Ends become black as an indication

• Ballast electronics– At higher ambient temperature ballast life reduces – This increases sputtering of emission mix– In CFL lamps capacitor comes in parallel to the

discharge on ignition – poor choice of capacitor reduces life

8/26/2011 77

USEFUL LAMP LIFE

• Phosphor– Lost on an average in 25,000 hours – Process is slow– Bulb becomes dim and inefficient

• Loss of mercury– Slowly absorbed by glass, phosphors and electrodes – Glow is due to base gas present in addition to Hg– Pinkish glow continues – Also occurs due to asymmetrical waveforms – Mercury in the form of amalgum takes time to vaporize

• Burned filaments – Open circuit is created – Difficult to ignite the mercury vapour

8/26/2011 78

USEFUL LAMP LIFE

• Average lamp life – 7500 hours

– For three burning hours per switching

• Actual life – 5000 – 10000 hours

– Depends on operating conditions

• Depreciation limit – 4000 hours

– Depreciation is 15-20 %

– Suggested to replace lamps once in 4000-5000 hours

8/26/2011 79

USEFUL LAMP LIFE

8/26/2011 80

CHARACTERISTICS OF

FLUORESCENT LAMPS

PERCENTAGE NORMAL VOLTAGE

PERCENTAGE POWER CONSUMPTION, EFFICIENCY, LUMEN OUTPUT

POWER CONSUMPTION

EFFICIENCY

LUMEN OUTPUT

100%

100%

90%

80%

90%

110%

PERFORMANCE OF

FLUORESCENT LAMPS

• Effect of voltage variation is less markedcomparatively

• Life and performance are adversely affected bylow and high voltages

• Increased voltage over heats electrodes andleads to evaporation of emissive materials

• Reduced voltage reduces the current causingsputtering

• Best performance – 20 – 25 deg Celsius

8/26/2011 81

POINTS TO PONDER

• Lamp should start with little blinking

• Blinking indicates

– a defective starter

– a defective tube

– low voltage

• Correct voltage must be ensured

• Starter should be replaced every time when thebulb is replaced

• Frequent switching operations should be avoided

8/26/2011 82

SYMPTOMS POSSIBLE CAUSES REMEDIES

Blinking ON and OFF 1. Low voltage 2. Loose contact 3. Defective starter / tube4. Wrong connection

1. Change ballast 2. Check connections3. Replace starter4. Replace tube

END OF A TUBE REMAIN LIGHTED

1. Short circuited starter 1. Replace starter

FAILURE OF LAMP TO LIGHT UP

1. Defective tube / starter / choke

2. Defective / loose holders

1. Replace the defective part 2. Check the connection

BLACKENING OF THE TUBE ENDS

1. Too low / high voltage 2. Mercury deposits at the

end

1. Adjust ballast 2. Gets corrected when

made to remain lighted

BURN OUT ELECTRODES 1. Control unit / choke short Test with a new choke

DARK STREAKES ALONG TUBE 1. Mercury globules Rotate the tube through 180°

SNAKING SPIRALLY 1. Insufficient heating 2. Wrong tapings on ballast

Replace ballast

8/26/2011 83

COMPARISON OF TUNGSTEN AND

FLUORESCENT LAMPS

TUNGSTEN LAMPS

1. Voltage fluctuation influences illumination

2. Luminous efficiency increases with voltage

3. Gives light close to natural

4. Efficiency of colouredfilament is poor

5. Heat radiation is considerable

6. Ageing effect is serious

7. Maintenance cost is more

8. Life – 1000 hours

FLUORESCENT LAMPS

1. Effect of voltage fluctuation is less upon lumens produced

2. Luminous efficiency increases with wattage and length of tube

3. Colour rendering is defective

4. Efficiency is high and different colours are possible

5. Heat radiation is low

6. Ageing effect is not very serious

7. Maintenance cost is low

8. Life – 7500 hours8/26/2011 84

T5 FLUORESCENT LAMPS

• Thinner

• More efficient

• Gives higher intensity of light

• Diameter is five times one eight of an inch

• Better optical control and fixture efficiency

8/26/2011 85

COMPARISON OF T5 WITH T8 & T12

8/26/2011 86

COLOR RENDERING INDEX LUMEN PER WATT CO-EFFICIENT OF UTILIZATION

T12 = 62CRI T12 = 78LPW T12 = .46CU

T8 = 85CRI T8 = 92LPW T8 = .76CU

T5 = 85CRI T5 = 103LPW T5 = .90CU

T5 IS 51% MORE EFFICIENT THAN T12 AND T8 40 % MORE EFFICIENTT5 IS 3-4 TIMES THE COST OF T12 BUT T8 IS 20% MORE COSTLIER

8/26/2011 87

DESIGN OF

LIGHTING SCHEMES

8/26/2011 88

• To provide adequate illumination

• To provide uniform distribution of light over the working plane

• To provide suitable colour

• To avoid glare and hard shadows

8/26/2011 89

MAIN OBJECTIVES

FACTORS TO BE CONSIDERED

• Illumination level

• Uniformity of illumination

• Colour of light and surrounding walls

• Shadows

• Glare

• Mounting height

• Spacing of luminaries

• Favorable level of brightness

– Should minimum fatigue

– Should give maximum output in terms of quality and quantity

• Degree of illumination depends on

– Size of the object to be seen

– Distance of the object from the observer

– Contrast between the object and the background

– Time duration for which the objects are viewed

8/26/2011 90

ILLUMINATION LEVEL

8/26/2011 91

ILLUMINATION LEVELLOCATION ILLUMINATION LEVEL in LUX

Entrance hallways 100

Living room, Study room, General utility room 300

Dining room 150

Games or recreation rooms, Stairs, Bathroom 100

Sewing like works 700

Kitchen, Laundry , Workshop 200

Garage 70

• Visual performance is best if the brightness ratio is not greater than 3:1

• This is achieved by combining general lighting with localized lighting

• Particularly has weightage in Factory lighting

8/26/2011 92

UNIFORMITY OF ILLUMINATION

• Hard and aharp shadows are avoided through– Large number of small luminaries

– Mounting height not less than 2.5 m

– Using wide surfaces for sources

– Indirect lighting schemes

8/26/2011 93

SHADOWS

GLARE • Mounting height should be above the ordinary range

of vision

• Metal reflectors are provided as a rim around the reflectors

• Direct lighting – In large rooms - Luminaries are mounted close to ceiling

• This helps to avoid glare

• Level of mounting is above the range of vision

– In small rooms with high ceilings• Filament bulbs with focusing reflectors are preferred

• Mounting height is preferred high

• Indirect / Semi direct lighting – Mounting height from floor can be low

• Enhances uniform illumination

• Minimum of 2.5m should be there between the floor and luminaries

• Size of the object to be seen

– Distance of the object from the observer

– Contrast between the object and the background

– Time duration for which the objects are viewed8/26/2011 94

MOUNTING HEIGHT

• Direct AND Semi-direct lighting – SHR depends on the candle power distributed

– For fluorescent luminaries – unity

– Tungsten lamps – 0.6

• Indirect / Semi direct lighting – Horizontal spacing between rows should be

approximately equal to the height of the ceiling form the working area

– SHR <= 1.5

– Two luminaries can even be connected together

8/26/2011 95

SPACING OF LUMINARIES

LIGHTING SCHEMES

• STREET LIGHTING

• FACTORY LIGHTING

• FLOOD LIGHTING

8/26/2011 96

STREET LIGHTING

8/26/2011 97

• To make the traffic visible

– To promote safety

– To promote convenience

• To enhance the community value of the streets

• To make the street safe place to travel

• To make the street attractive

8/26/2011 98

MAIN OBJECTIVES

DESIGN PRINCIPLES• Diffusion Principle

• Specular Reflection Principle

• Light is uniformly distributed over a stipulatedarea

• The observer cannot see the source but only thereflected surface

• Glare is totally avoided

• Lamps are provided with suitable reflectors

• Reflectors are cut – off between 30° - 45 °

• Road surface appears bright

• Over certain portions are illuminated by twolamps

8/26/2011 99

DIFFUSION PRINCIPLE

• Reflectors are curved upwards

• Light is reflected by a very large angle ofincidence

• Pedestrians can see the object in closeproximity

• But motorists experience glare

• Comparatively more economical

8/26/2011 100

SPECULAR REFELCTION

PRINCIPLE

8/26/2011 101

SPECULAR

REFLECTION

PRINCIPLE DIFFUSION

PRINCIPLE

• Important shopping centers and junction likeplaces – 30 lumen / m2

• Sub urban illumination - 4 lumen / m2

• Average well lighted street – 15 lumen / m2

• Spacing between lamps – 50 m

• Mounting height – 8 m

• Lamp posts bust be placed at the junction of roads

• Mercury and Sodium vapour lamps are preferred• Low power consumption

• Mono-chromatic nature is not objected

8/26/2011 102

ILLUMINATION DETAILS

LAMP POST DESIGN

8/26/2011 103

8/26/2011 104

• Case (i)

– Residential neighbourhood

• Case (ii)

– Intersection of residential buildings

• Case (iii)

– Downtown commercial area

• Case (iv)

DESIGN DETAILS

8/26/2011 105

RESIDENTIAL NEIGHBOURHOOD

SINGLE LAMP

8/26/2011 106

8/26/2011 107

INTERSECTION IN RESIDENTIAL OR

COMMERCIAL AREA

8/26/2011 108

INTERSECTION IN RESIDENTIAL

OR COMMERCIAL AREA

8/26/2011 109

INTERSECTION IN RESIDENTIAL

OR COMMERCIAL AREA

DOWNTOWN COMMERCIAL AREA

8/26/2011 110

MAIN ROADS

8/26/2011 111

8/26/2011 112

RESIDENTIAL ROAD WITH

UNDERGROUND UTILITY

STREET LIGHTING

8/26/2011 113

8/26/2011 114

ILLUMINATION LEVELCLASSIFICATION TYPE OF STREET ILLUMINATION LEVEL

in LUX

CLASS A1 Important traffic roads with fast traffic

30

CLASS A2 Other main roads 15

CLASS B1 Secondary roads – sub urban 8

CLASS B2 Secondary roads with light traffic

4

SOLAR STREET LIGHTING

8/26/2011 115

FACTORY LIGHTING

8/26/2011 116

• Adequate illumination on the working plane

• Good distribution of light

• Simple and easily cleaned fittings

• Avoid glare

8/26/2011 117

MAIN OBJECTIVES

EFFECTS OF EFFECTIVE LIGHTING

• Productivity of labour increases

• Quality of work is improved

• Accidents are reduced

• Work stoppages are reduced

• Number of lamps is decided so that to produceuniformly distributed light

• Adjustable fittings are provided for intenseillumination

• Deep reflectors are used to avoid glare– Diffusing fittings– Concentrating reflectors– Angle reflectors– Enclosed diffusing fittings– Standard industry fittings

• Auxiliary lighting is desirable• Emergency lighting completely isolated from main

supply8/26/2011 118

DESIGN ISSUES

• Discharge Lamps

– Mercury discharge

• Fluorescent Lamps

– Lamps with colour on par with the daylight

– Absence of glare

8/26/2011 119

TYPES OF LAMPS

ROLE OF REFLECTORS

8/26/2011 120

LUMINARIES

8/26/2011 121

LUMINARIES

8/26/2011 122

LUMINARIES

8/26/2011 123

8/26/2011 124

SHADOW FREE LIGHTING

FLOOD LIGHTING

8/26/2011 125

• To enhance beauty of a monument

• To illuminate advertisement boards

• To illuminate show cases

• To illuminate railway yards , stadiums, parks etc.

• To illuminate construction sites, quarries etc.

8/26/2011 126

MAIN OBJECTIVES

8/26/2011 127

LIGHTING REQUIREMENTS

• Light is focused orthogonally to the focused item

• Shadows are strictly prohibited

• Projectors should not be visible to the viewers

• Lamp posts are placed at a distance not more than 60

meters

8/26/2011 128

TYPES OF PROJECTORS

• Narrow beam projectors

• 12 – 25 °

• Distance beyond 70 meters

• Medium angle projectors

• 25 – 40 °

• Distance 30 – 70 meters

• Wide angle projectors

• 40 -90 °

• Distance – less than 30 meters

• Decide the illumination level

– Standard requirement based on application

• Decide the type of the projector

– Beam size

– Light output

• Number of projectors

– N = ( A * E * Df * WLF) / (Uf* Wattage * Efficiency)

8/26/2011 129

LIGHTING DESIGN ISSUES

• Gas filled tungsten Lamps

– High wattage lamps

– 250, 500, 1000 watt lamps are used in projectors

– Wide angle projectors

• Projector lamps

– Lamps with bunched filaments

• LED lamps

8/26/2011 130

TYPES OF LAMPS

8/26/2011 131

8/26/2011 132

8/26/2011 133

HOUES WIRING

8/26/2011 134

BASIC CIRCUIT

8/26/2011 135

TUBE LIGHT CONNECTION

8/26/2011 136

MULTIPLE LIGHTS

8/26/2011 137

TWO WAY SWITCH

8/26/2011 138

8/26/2011 139

TWO WAY SWITCH

ENERGYMETER CONNECTION

8/26/2011 140

ADDITIONAL BULB

8/26/2011 141

SOCKET CONNECTION

8/26/2011 142