The gas filled tube (bulb or burner)The gas filled tube (bulb or burner) Coiled glass coated with phosphorusCoiled glass coated with phosphorus Mercury vapor filled insideMercury vapor filled inside

Electronic ballastElectronic ballast circuit boards with rectifiercircuit boards with rectifier A filter capacitorA filter capacitor Two switching transistor as high Two switching transistor as high

frequency resonant series DC to AC.frequency resonant series DC to AC. Integrated CFLsIntegrated CFLs

tube + ballast + Edison screwtube + ballast + Edison screw In a single unit.In a single unit.

CFLs are produced for both AC CFLs are produced for both AC and DC, later are popular in and DC, later are popular in recreational vehicle, off-the grid recreational vehicle, off-the grid housing, solar panels etc.housing, solar panels etc.

Working of FLsWorking of FLs Starting of Fluorescent Starting of Fluorescent

LampLamp When the lamp first turns on, When the lamp first turns on,

the path of least resistance is the path of least resistance is through the bypass circuit, through the bypass circuit, and across the and across the starter switchstarter switch

• Current passes through the Current passes through the electrodes on both ends of the electrodes on both ends of the tube. These electrodes are tube. These electrodes are simple simple filamentsfilaments

• Electricity heats up the Electricity heats up the filaments. This boils off filaments. This boils off electrons from the metal electrons from the metal surface, sending them into the surface, sending them into the gas tube, ionizing the gas.gas tube, ionizing the gas.

How light is emittedHow light is emitted Ionized electrons will migrate Ionized electrons will migrate

through the Argon gas from through the Argon gas from one end of the tube to the one end of the tube to the other, this changes some of other, this changes some of the the mercurymercury in the tube from in the tube from a liquid to a gasa liquid to a gas

some of them some of them collidecollide with with gaseous mercury atoms, gaseous mercury atoms, bumping electrons up to bumping electrons up to higher energy levelshigher energy levels

Electrons returning to their Electrons returning to their original energy level, release original energy level, release light photons in UV range.light photons in UV range.

PhosphorsPhosphors are substances are substances that give off visible light that give off visible light when they are exposed to UV when they are exposed to UV light. light.

The ballastThe ballast negative resistance in conduction through gasesnegative resistance in conduction through gases If the current in a fluorescent light isn't controlled, If the current in a fluorescent light isn't controlled,

it can it can blow outblow out the various electrical components the various electrical components Thus ballast is needed to control the current flow Thus ballast is needed to control the current flow

which is either of the opposing device R,L or C.which is either of the opposing device R,L or C. Magnetic ballast – uses inductorMagnetic ballast – uses inductor Electronic ballast – produces high frequency A.C Electronic ballast – produces high frequency A.C

and high peak voltageand high peak voltage• ballastballast constantly channels current through both constantly channels current through both

electrodes difference between the two electrodes, electrodes difference between the two electrodes, establishing a voltage across the tube.establishing a voltage across the tube.

• Less bulky inductor is needed for high frequency A.C Less bulky inductor is needed for high frequency A.C

LifespanLifespan• 8 to 15 times more average life8 to 15 times more average life• Cfl-6000 and 15000 hours and IL- 750 Cfl-6000 and 15000 hours and IL- 750

or 1000 hoursor 1000 hours• Depends on operating voltage, Depends on operating voltage,

manufacturing defects, exposure to vol. manufacturing defects, exposure to vol. spikes, mech. Shock, freq. of cycling on spikes, mech. Shock, freq. of cycling on and off, lamp orientation and operating and off, lamp orientation and operating temperatures.temperatures.

• for 5 min. on-off life reduces to 85%, it for 5 min. on-off life reduces to 85%, it is suggested don’t switch off if leaving is suggested don’t switch off if leaving for 15 min.for 15 min.

CFLs V/s IncandescentCFLs V/s Incandescent Energy EfficiencyEnergy Efficiency

• For a given light output CFL uses 20%to 30% For a given light output CFL uses 20%to 30% of the power of equivalent IL.of the power of equivalent IL.

Energy efficiency contd.Energy efficiency contd.

Table showing electrical power Table showing electrical power equivalent for different lampsequivalent for different lamps

Electrical power equivalents for differing lamps

Compact Fluorescent (W)

Incandescent (W)

Luminous (lumens)

9–13 40 450

13–15 60 800

18–25 75 1,100

23–30 100 1,600

30–52 150 2,600

Figure showing energy Figure showing energy consumption from different light consumption from different light bulbs.bulbs.

CFLs V/s IncandescentCFLs V/s Incandescent Embodied EnergyEmbodied Energy

• While CFLs require more energy in While CFLs require more energy in manufacturing than incandescent lamps manufacturing than incandescent lamps

• this embodied energy is more than offset by the this embodied energy is more than offset by the fact that they last longer and use less energy.fact that they last longer and use less energy.

CostCost• While the purchase price of an integrated CFL is While the purchase price of an integrated CFL is

typically 3 to 10 times greater than that of an typically 3 to 10 times greater than that of an equivalent incandescent lampequivalent incandescent lamp

• the extended lifetime and lower energy use will the extended lifetime and lower energy use will more than compensate for the higher initial cost more than compensate for the higher initial cost

CFLs V/s IncandescentCFLs V/s Incandescent

Starting TimeStarting Time• Incandescent reach full brightness a fraction of Incandescent reach full brightness a fraction of

a second after being switched on. As of 2009, a second after being switched on. As of 2009, CFLs turn on within a second, but may still take CFLs turn on within a second, but may still take time to warm up to full brightnesstime to warm up to full brightness

• Some CFLs are marketed as "instant on" and Some CFLs are marketed as "instant on" and have no noticeable warm-up period, but others have no noticeable warm-up period, but others can take up to a minute to reach full brightness, can take up to a minute to reach full brightness, or longer in very cold temperatures.or longer in very cold temperatures.

• Some that use a mercury amalgam can take up Some that use a mercury amalgam can take up to three minutes to reach full output.to three minutes to reach full output.

Luminous efficacyLuminous efficacy Luminous efficacy is the measure of the lamp’s ability

to convert input electric power, in watts, into output luminous flux, in lumens, and is measured in lumens per watt (lm/w).

The luminous flux of a light source is the electromagnetic radiation within the visible part of the electromagnetic spectrum multiplied by the sensitivity of man’s eyes to that part of the light from the source.

A typical CFL is in the range of 17 to 21% efficient at A typical CFL is in the range of 17 to 21% efficient at converting electric power to radiant power based on converting electric power to radiant power based on 60 to 72 lumens per watt source efficacy 60 to 72 lumens per watt source efficacy

The luminous efficacy of CFL sources is typically 60 to The luminous efficacy of CFL sources is typically 60 to 72 lumens per watt, versus 8 to 17 lm/W for 72 lumens per watt, versus 8 to 17 lm/W for incandescent lamps. incandescent lamps.

Ave. Lm/Watt Ave. Lm/Watt

Life, Hrs

IncandescentIncandescent 1414 10001000

FTLFTL 5050 50005000

High Lumen High Lumen FTLFTL

9090 15000-15000-1800018000

CFLCFL 6060 8000-8000-1000010000

LEDLED 150150 5000050000

HalogenHalogen 2020 2000-2000-40004000

HPSVHPSV 9090 6000-6000-1200012000

LPSVLPSV 150150 6000-6000-1200012000

Every extra phosphor added Every extra phosphor added to the coating mix causes a to the coating mix causes a loss of efficiency and loss of efficiency and increased cost.increased cost.

Good quality consumer CFLs Good quality consumer CFLs use three or four part use three or four part phosphors to achieve a phosphors to achieve a 'white' light with a CRI 'white' light with a CRI (color rendering index) of (color rendering index) of around 80.around 80.

Color temperature can be Color temperature can be indicated in Kelvin or mired indicated in Kelvin or mired (1 million divided by the (1 million divided by the color temperature in Kelvin).color temperature in Kelvin).

a CFL with a CRI of 83 and a a CFL with a CRI of 83 and a color temperature of 4,700 K color temperature of 4,700 K would be given a code of would be given a code of 847 847

Color temperature Kelvin mired

'Warm white' or 'Soft white'

≤ 3,000 K ≥ 333 M

'White' or 'Bright White' 3,500 K 286 M

'Cool white' 4,000 K 250 M

'Daylight' ≥ 5,000 K ≤ 200 M

Health issuesHealth issues• According to Scientific Committee on Emerging and

Newly Identified Health Risks (SCENIHR) CFLs UV radiation cause skin diseases.

Mercury emissionMercury emission• CFLs contain 3-4mg of mercury• Coal fired power plants produce mercury

Broken and discarded lampsBroken and discarded lamps• crushing in a machine that uses negative pressure crushing in a machine that uses negative pressure

ventilation and a mercury-absorbing filter or cold trapventilation and a mercury-absorbing filter or cold trap • The crushed glass and metal is stored in drums, ready for The crushed glass and metal is stored in drums, ready for

shipping to recycling factories.shipping to recycling factories.

SizeSize• CFL light output is roughly proportional to CFL light output is roughly proportional to

phosphor surface area phosphor surface area End of lifeEnd of life

• In addition to the wear-out failure modes, the In addition to the wear-out failure modes, the electronic ballast may fail.electronic ballast may fail.

Incandescent replacement wattage Incandescent replacement wattage inflationinflation• Replaces Less lumen producing Incandescent Replaces Less lumen producing Incandescent

lamplamp

Design and application Design and application issues contd.issues contd.

DimmingDimming• The dimming range of CFLs is usually between The dimming range of CFLs is usually between

20% and 90% but now come with 2% and 20% and 90% but now come with 2% and 100%100%

• Below lower limit flickering, above higher limit Below lower limit flickering, above higher limit full 100% light.full 100% light.

• Using regular CFLs with a dimmer is Using regular CFLs with a dimmer is ineffective at dimming, can shorten bulb life ineffective at dimming, can shorten bulb life and will void the warranty of certain and will void the warranty of certain manufacturersmanufacturers

Design and application Design and application issues contd.issues contd.

Perceived coldness of low intensity CFLPerceived coldness of low intensity CFL• When a CFL is dimmed the color temperature (warmth) stays the When a CFL is dimmed the color temperature (warmth) stays the

samesame

• other light sources (such as the sun or incandescent) other light sources (such as the sun or incandescent) where color gets warmer as the light source gets where color gets warmer as the light source gets dimmer dimmer

Infrared signals distortionInfrared signals distortion• Electronic devices operated by infrared remote control Electronic devices operated by infrared remote control

can interpret the infrared light emitted by CFLs as a can interpret the infrared light emitted by CFLs as a signal signal

Audible noiseAudible noise• CFLs, much as other fluorescent lights, may emit a CFLs, much as other fluorescent lights, may emit a

buzzing sound, where incandescent normally do notbuzzing sound, where incandescent normally do not

Design and application Design and application issues contd.issues contd.

IridescenceIridescence• Fluorescent lamps can cause window film to exhibit Fluorescent lamps can cause window film to exhibit

iridescence. This phenomenon usually occurs at nightiridescence. This phenomenon usually occurs at night Outdoor use/cold weather useOutdoor use/cold weather use

• . CFLs are available with cold-weather ballasts, which . CFLs are available with cold-weather ballasts, which may be rated to as low as −23 °C (−10 °F )may be rated to as low as −23 °C (−10 °F )

UV emission effect on paints and textiles.UV emission effect on paints and textiles.• Can damage paintings and textiles which have light-Can damage paintings and textiles which have light-

sensitive dyes and pigments, polymer degradation.sensitive dyes and pigments, polymer degradation. Power factor and Total harmonic disturbance Power factor and Total harmonic disturbance

(T.H.D)(T.H.D)

Traditional, electromagnetic Traditional, electromagnetic equipment will draw sinusoidal equipment will draw sinusoidal current from a sinusoidal current from a sinusoidal voltage. voltage.

But electronic equipment, But electronic equipment, which converts ac power to dc which converts ac power to dc power does not draw current power does not draw current for the entire voltage waveform for the entire voltage waveform interval. interval.

The resulting current The resulting current irregularities can cause irregularities can cause disturbances, such as impulses disturbances, such as impulses and voltage loss, on the power and voltage loss, on the power distribution system distribution system

What Is THD ?What Is THD ? HarmonicsHarmonics

• distortion of the supplied waveform distortion of the supplied waveform • caused by "non-linear," (distorted) loads, which caused by "non-linear," (distorted) loads, which

include motor controls, compact fluorescent lamps include motor controls, compact fluorescent lamps etc.etc.

• High harmonics increase line losses and decrease High harmonics increase line losses and decrease equipment lifetime. equipment lifetime.

Harmonic distortionHarmonic distortion • Refers to the difference between the shape of the Refers to the difference between the shape of the

current wave drawn by a device, and the shape of current wave drawn by a device, and the shape of the voltage wave supplied to that device.the voltage wave supplied to that device.

Total harmonic distortion (THD)Total harmonic distortion (THD) • Measures the degree to which the input is Measures the degree to which the input is

distorted, and is the relative value of all the distorted, and is the relative value of all the harmonics combined, as a percentage of the harmonics combined, as a percentage of the fundamental current.fundamental current.

What is Power Factor ?What is Power Factor ? Power factorPower factor is a measure of how the current is is a measure of how the current is

being used to transmit power.being used to transmit power. When a load draws current that is not "in phase" When a load draws current that is not "in phase"

with the voltage waveform, or draws a current that with the voltage waveform, or draws a current that differs from the sinusoidal waveform provided by differs from the sinusoidal waveform provided by the utility, the power factor is less than 1 the utility, the power factor is less than 1

Poor power factor causes inefficiency in the delivery Poor power factor causes inefficiency in the delivery of electricity to the end-user, requiring more energy of electricity to the end-user, requiring more energy to compensate for losses on the line to compensate for losses on the line

For example, a load with a power factor of .5 will For example, a load with a power factor of .5 will require twice as much current as a load with a require twice as much current as a load with a power factor of 1 for the same amount of usable power factor of 1 for the same amount of usable power. power.

A low power factor is a power drain that decreases A low power factor is a power drain that decreases system efficiency system efficiency

THD and Power Factor of THD and Power Factor of CFLsCFLs