169788209 illumination basic and schemes uep in eee

8/10/2019 169788209 Illumination Basic and Schemes Uep in Eee

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Illumination Basic & Scheme

Utilization of Electrical Energ


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Topics

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1. Introduction2. Nature of light

3. Terms used in illumination

4. Law of illumination5. Electrical methods of producing light

6. Sources of light

7. Arc lamps

8. Filament lamps

9. Gaseous discharge lamps


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Topics

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10. Sodium vapor lamp11. Mercury vapor lamp

12. Fluorescent tube

13. Neon lamp14. Halogen lamp

15. Compact fluorescent lamp

16. Candle power and its measurement

17. Lighting scheme

18. Street light

19. Flood lighting


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Introduction

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As we know that almost all human activities depends onlight. Sun is a prime natural source of light butartificial lighting plays almost main role in our dailylife. These artificial lights are produced by

mechanical lamps and electrical lamps.But due to poor performance the mechanical light are

totally replaced by electrical lights. The electricallighting are mainly used for decorative purpose,

advertising, traffic control , medical field and streetlighting etc.


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Lighting energy consumption

20-45% in commercial buildings

3-10% in industrial plants

Significant energy savings can be

realized with a minimal capital

investment

Background


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Light: electromagnetic waves in space

Light is emitted through:

a) Incandescence

b) Electric discharge

c) Electro luminescence

d) Photoluminescence

Basic Theory


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Electrical Lighting

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Electrical lighting has following advantages :1. Cleanliness

2. Easy to control

3.Economical

4. Easy to handle

5. Steady output

6. Better reliability

7. Suitable for almost all purposes etc.


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Sensitivity of Human Eye

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As we know natural light consists of seven colorshaving different wavelengths. The average humaneye is most sensitive to a wave length of 5500 0A.

The relative sensitivity of eye for a particular wavelength is the visual effect produced by the light onthe average human eye as compared with the effectof light having wave length 5500 0A on human eye.


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Sensitivity of Human eye

This is also

known asRelativeluminosity

Factor.

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Terms used in Illumination

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1. Light2. Luminous flux

3. Lumen

4.Plane angle

5. Solid angle

6. Steradian

7. Candle power

8. Luminous intensity reduction factor

9. Glare

10. Lamp efficiency


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light

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That part of radiant energy froma hot body which produced the

visual sensation on human eyeis called light.


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Luminous Flux

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The total quantity of radiant energy per secondresponsible for visual sensation from a luminousbody is called Luminous Flux.

It is represented as F of and measured inlumens.

Lumen

1 lumen = the photometric equivalent of the watt

1 lumen = luminous flux per m2 of a sphere with 1 mradius and a 1 candela isotropic light source at thecentre

1 watt = 683 lumens at 555 nm wavelength


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Lumen

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It is the unit of luminous flux. Onelumen is defined as the luminous

flux emitted per unit solid anglefrom a point source of one candlepower.

Lux

metric unit of measure for illuminance on a surface: 1 lux = 1

lumen / m2


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Plane Angle

The angle subtended

at a point by twoconverging lineslying in the sameplane is called planeangle. It is measuredin radians and equal

to the ratio of thelength of the arc tooits radius,

= arc/ radius

= l/ r radians

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Solid Angle

The angle subtended

by the partial surfacearea of a sphere at itscentre is called assolid angle. It ismeasured insteradians and equal

to the ratio of area ofthe surface to thesquare of radius ofsphere,

= area of surface/square of radius

= A/ r2 steradians

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Steradian

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the unit of solid angle. One steradian isdefined as the solid angle that issubtended at the centre of a sphere byits surface having area equal to radiussquare,

= surface area/ (radius)2

= r 2/ r2= 1 steradian


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Candle Power

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The light radiating capacity of asource is called its candle power. Thenumber of lumens given out by asource per unit solid angle in a givendirection is called its candle power. Itis denoted by C.P.

Total flux emitted = CP X solid angle

= 1 X 4= 4 lumens

= 4lumens


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Luminous Intensity

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Luminous intensity in any particular direction is theluminous flux emitted by the source per unit solid anglein that direction.

It is denoted by I and its unit is candela or candle power

(CP) . Luminous intensity of source in a particular direction,

I = /

Luminous intensity (I)

measured in Candela (cd)

Luminous flux (lm)

4 x luminous intensity


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Reduction Factor

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reduction factor of a source of light isthe ratio of its mean spherical candlepower to its mean horizontal candle

power.

Reduction factor = MSCP/ MHCP


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Illumination

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When light falls on a surface, itbecomes visible, the phenomenon iscalled as illumination.

It is defined as luminous flux falling ona surface per unit area. It is denotedby E and measured in lumen per

square meter or meter- candle.

E = / A lux


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Lux

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One meter candle or lux is defined asthe illumination produced by a

uniform souce of one CP on the innersurface of a sphere of radius onemeter.


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Glare

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In the human eye, the opening of pupil is controlled byits iris which depends upon the intensity of lightreceived by the eye. If the eye is exposed to a very

bright source of light, the pupil of the eye contracts

automatically in order to reduce the amount of lightadmitted and prevent damage to the retina. This effectis called glare.

Glare is defined as the brightness within the field of

vision of such a character so as to cause discomfortand interference in vision.


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Lamp Efficiency

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It is defined as the visible radiations emitted by it inlumens per watt.

Usually, the light sources do not radiate energy only inthe visible spectrum. The radiant energy is alsoaccompanied with infrared and ultra violetradiations.

Sun light produces majority of radiations in the visiblespectrum. The tungsten lamp produces smallradiations so its efficiency is very poor.


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Lamp efficiency

The efficiencyof fluorescentlamp is morethan tungsten

lamp.

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Reflection Factor

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Whole of the light incident on a reflecting surface isnot reflected. Some portion of it is absorbed by the

surface.The ratio of the reflected light to the incident light is

called reflection factor.


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Law of Illumination

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The illumination on a surface depends upon theluminous intensity, distance between the source and

surface and the direction of rays of light. It isgoverned by following laws :

1. Inverse square law

2. Lambertscosine law


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Inverse Square Law

It states that

the illuminationof a surface isinverselyproportional tothe square ofthe distance ofthe surfacefrom thesource.

E 1/d2

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The inverse square lawDefines the relationship between

illuminance from a point source and

distance

E = I / d2

E1 d12 = E2 d22

E = Iluminance

I = Luminous intensity

d = distance


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Lamberts Cosine Law

This law states

that theillumination onany surface isproportional tothe cosine of

angle between thedirection of theincident flux andperpendicular tothe area.

E = 1/d2cos

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Electrical method of producing Light

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Following are the methods of producing light :

1. By developing arc between two electrodes

2. By passing a current through a filament3. By electric discharge through vapors or gases


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Types of Lighting Systems

Incandescent lamps

Tungsten Halogen Lamps

Fluorescent lamps

High pressure sodium lamps

Low pressure sodium lamps

Mercury vapour

Metal halide

Blended

LED lamps

HID lamps


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Arc Lamp

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The principle of an arc lamp is that when twoelectrodes carrying current are separated through asmall distance, an arc is struck between them. Thearc lamps were used in the past for street lighting

purposes but now a day these are used whenextreme brightness is required.

Most commonly use arc lamp is

Carbon Arc Lamp


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Carbon Arc Lamp

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This is the oldest type of lamp and is still being employedin cinema projectors and search lights. It consists of twohard carbon rods (Electrodes). The diameter of +veelectrode is double to that of ve electrode. The ve

electrode is generally fixed and +ve electrode is placed inadjustable holder and the process is manually orautomatic. The arc consists of carbon vapors surroundedby orange red zone of burning carbon and pale greenflames.


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Carbon Arc Lamp

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When the lamp is OFF, the two electrodes are touching eachother due to spring pressure on +ve electrode. When thesupply is ON a large current is flow through electrodes. Thetemperature of carbon electrode is increased and thus the +ve

electrode is pulled away against its spring pressure through asmall distance by coil and thus an arc is struck betweenelectrodes. This arc is maintained by transfer of carbonparticles from one electrode to other electrode.


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Carbon Arc Lamp

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These particles travel from +ve electrode to veelectrode, thus after sometime of operation +veelectrode become hollow and ve become pointed.Thats why +ve electrode is made double than ve

electrode.In carbon arc lamp 85 % of light is given by +ve

electrode which produces high intensity light and only10 % by ve electrode and 5 % by air. The temperature

of +ve electrode is 4000 oC and that of ve electrode isabout 2500 oC. The luminous efficiency of such lampsis about 9 lumen/watt.


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ARC Lamps

For maintaining thearc, a minimumvoltage required isgiven by :

V = (39 + 28 L ),where L is length ofarc in centimeter.

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Filament or Incandescent Lamp

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Working Principle :As we know when a room heater is

switched On , it gives out red lightwith heat at the workingtemperature of 750 oC and at this

temperature the radiations aremostly in infra red regions. Thisworking principle is used todevelop the filament lamp.

When an electric current ispassed through a finemetallic wire , it raises thetemperature of wire. At lowtemperature only heat is

produced but at highertemperature lightradiations goes onincreasing. As filamentlamp consists of fine wire

of high resistive materialplaced in an evacuatedglass bulb. This type oflamps are operated at thetemperature of 2500 oC .


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Filament or Incandescent Lamp

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Emit radiation mainly in

the visible region

Bulb contains vacuum or

gas filling Efficacy: 12 lumen / Watt

Color rendering index: 1A

Color temperature: 2500

2700 K

Lamp life


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Filament Lamp

A tungsten filamentis enclosed inevacuated glass

bulb but to improveits performancesome chemical likeargon or nitrogengas are filled.

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Tungsten-Halogen Lamps Tungsten filament and a halogen gas

filled bulb

Tungsten atoms evaporate from the hotfilament and move to cooler wall of bulb

Efficacy: 18 lumens/Watt

Color rendering index: 1A

Color temperature: warm

Lamp life < 4000 hrs

Tungsten halogen lamps

Advantages:

More compact

Longer life

More and whiter light

Disadvantages:

Cost more

Increased IR and UV

Handling problems


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Properties of Metal for Filament

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1. High melting point : so that it can be operated at hightemperature.

2. High specific resistance : so that it produces moreheat.

3. Low temperature coefficient : so that filamentresistance may not change at operating temperature.

4. Low vapor pressure ; so that it may not vaporize

5. High ductile : so that it may withstand mechanicalvibrations


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Sodium Vapor Lamp

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This lamp consists of discharge tube made from specialheat resistance glass, containing a small amount ofmetallic sodium, neon gas and two electrodes. Neongas is added to start the discharge and to develop

enough heat to vaporised sodium. A long tube isrequired to get more light. To reduce overalldimensions of the lamp, the tube is generally bentinto U-shape .


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Sodium Vapor Lamp

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Working Principle :An electric discharge lamps require a high voltage at

staring and low voltage during operation. So atstarting a voltage of 450 V is applied across the lamp

to start the discharge. After 10 to 15 minutes, thevoltage falls to 150 V because of low power factor. Toimprove the power factor a capacitor is connectedacross the supply. The color of light produce is

yellowish.


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Sodium Vapor Lamp

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High Pressure Sodium (HPS) Lamps

Used in outdoor and industrial applications

Consist of: ballast, high- voltage electronic starter,

ceramic arc tube, xenon gas filling, sodium, mercury

No starting electrodes

High efficacy: 60 80 lumen/Watt

Color rendering index: 1 - 2 Color temperature: warm

Lamp life < 24,000 hrs


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Low Pressure Sodium (LPS) Lamps

Commonly included in the HID family

Highest efficacy: 100 - 200 lumen/Watt

Poorest quality light: colors appear black, white

or grey shades

Limited to outdoor applications

Efficacy: Color rendering index: 3

Color temperature: yellow

Lamp life < 16,000 hours

M V L


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Mercury Vapor Lamp

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On the basis of pressure inside the discharge tube, themercury vapor lamps are classified as high pressureMercury Vapor Lamp and low pressure Mercury VaporLamp. High pressure M.V. Lamps are of following

types :1. M.A. type : these are operated at 220 -250 V A.C.

main and made in 250 W and 400 W.

2. M.A.T. type : these are made in 300 and 500 W and

operated at 200 -250 V A.C. as well as D.C.

3. M.B. type : This is operated at 200 250 V A.C. andmade in 80 W and 125 W.

Mercury Vapor Lamp


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Mercury Vapor Lamp

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Construction :

It consists of hard glass tube enclosed in outer bulbof ordinary glass. The space between two bulbs arecompletely evacuated to prevent heat loss byconvection from inner bulb. The outer bulb absorbsharmful ultra violet rays. The inner bulb containsargon gas with certain quantity of mercury. Inaddition with two electrodes on starting electrodehaving high resistance in series also provided. The

main electrodes are made of tungsten wire in helicalshape. The lamp has screwed cap and connected tosupply with choke. A capacitor is connected acrosssupply to improve power factor.

Mercury Vapor Lamp


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Mercury Vapor Lamp

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Working Principle :

When the supply is switched ON, full voltage isapplied across main and starting electrodes. Thisvoltage breaks down the gap and discharge through

argon gas takes place. As the lamp warms up,mercury is vaporized , which increase the vaporpressure. This discharge takes the shape of intensearc. After 5 minutes, the lamp gives full light.

It gives greenish blue color light .

this lamp is always suspended vertically, other wiseinner glass tube may break due to excessive heat.


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Oldest HID lamp

Consists of: arc tube with mercury and argon gas and

quartz envelope, third electrode, outer phosphor coated

bulb, outer glass envelope

Long life and low initial costs

Very poor efficacy: 30 65 lumens/Watt

Color rendering index: 3

Color temperature: intermediate

Lamp life: 16000 24000 hours

Mercury Vapor Lamps

Mercury Vapor Lamp


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Mercury Vapor Lamp

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Fluorescent Tube

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Working :A choke is connected in series with the tube whichact as a blast and provide a high voltage at startingglow in the tube. During running condition the

same choke absorbs some supply voltage andremain a voltage of 110 V across the tube. Acapacitor is connected to improve the power factor.


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Fluorescent Tube

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it is a low pressure mercury vapor lamp. It consists ofa glass tube 25 mm in diameter and 0.6 m, 1.2 m and1.5 m in length. The tube contains argon gas at lowpressure about 2.5 mm of mercury. At the two ends,

two electrodes coated with some electron emissivematerial are placed.


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Fluorescent Lamps

3 5 times as efficient as standard incandescent

lamps and last 10 20 times longer

Electricity passes through a gas or metallic vapor

and causes radiation

Fluorescent tubes are hot cathode lamps


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Fluorescent Tube

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The colors produce by this tubes are as :Material Color

Zinc silicate Green

Calcium tungsten BlueCadmium borate Pink

Calcium Holo phosphate White or day light

Magnesium tungsten Bluish white


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Fluorescent Tube

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Fluorescent Lamps

Different types (T12,

T10, T8 and T5)

differing in diameter

and efficiency

Most efficient at

ambient temperature

of 20-30 oC,

Compact fluorescent

lamps (CFL) have

much smaller

luminaries

Features:Halo-phosphate

Efficacy80 lumens/Watt (HF

gear increases this by 10%)

Color Rendering Index2-3

Color TemperatureAny

Lamp Life7-15,000 hours

Tri-phosphor

Efficacy90 lumens/Watt

Color Rendering Index1A-1B

Color TemperatureAny

Lamp Life7-15,000 hours

d f l b


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Advantages of Fluorescent Tube

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1. Voltage fluctuation has very small effect on lightoutput.

2. The luminous efficiency is more as length of rodis more.

3. It gives light close to natural light.

4. Heat radiations are negligible.

i d f l b


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Disadvantages of Fluorescent Tube

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1. Its brightness is less.

2. Initial cost is more

3. Overall maintenance cost is high.


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N L


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Neon Lamp

These lamps are operated at a very low

temperature of about 200 oC thats whythese are called cold cathode dischargelamps.

Two electrodes are housed at the two ends

of the tube which contain neon gas. Theelectrodes are made of iron or nickelcylinder without any coating andpractically they do not emit electrons. It

gives red light whereas with mixture ofmercury and argon it gives bluish greencolor. Voltage require for starting andoperation is 10000 V. This high voltage isobtained from transformer.

N L


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Neon Lamp

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Working :

When the supply is switched ON at primary side oftransformer, a voltage of 10000 V develops across

secondary side which come across two electrodes. Atthis voltage a discharge occurs in neon gas.

Different colors can be obtained by changing theconstituents of gases and mercury filled in the tubes.

N L


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Neon Lamp

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N L


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Neon Lamp

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Applications :Neon lamps are generally used for advertising. Most of

letters having two ends at which electrodes areplaced. In letter having more than two ends , thetube path is repeated for some portion.

H l L


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Halogen Lamp

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Halogen lamp is a special type of tungsten filamentlamp which was developed in 1959, in this lams, asmall amount of halogen vapor is added to the

inert gas of the bulb. Its glass bulb is small in sizeand mechanically strong. It operates at hightemperature of 3000 oC .

H l L


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Halogen Lamp

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When the supply is given to thelamp, a filament glows andproduce light. The halogen inaddition to inert gas causes

the evaporated tungsten toresettle back on the filamentduring cooling, thats whylamp can be operated at high

temperature. It provides highintensity light.

H l L


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Halogen Lamp

Ad t f H l L


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Advantages of Halogen Lamp

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1. It is smaller in size.2. It does not need any blast.

3. Good colors can be obtained.

4. Excellent optical control.5. Gives same output throughout life

6. It has long life

Di d t f H l L


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Disadvantages of Halogen Lamp

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1. During maintenance the handling of lamp isdifficult.

2. Radiant heat is more which heats the surroundings.

3. Operating temperature is high which effects its life.

Compact fluorescent Lamp( CFL)


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The compact fluorescent lamps are

becoming more and morepopular now a days because oftheir low power consumption,low running cost, longer life,attractive look, smooth light

and low maintenance. Theselamps are available in differentsizes and designs. They havesingle rod, double rod, triplerod or spiral rod. These lamps

are available in differentpower rating e.g. 5, 7, 9, 11, 18and 24 watt 220 V



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It is basically a low pressure mercuryvapor lamp having two electrodescoated with electron emissive

material placed in a glass tube. Thetube is coated internally with somefluorescent material in the form of

powder. In the tube one drop ofmercury and argon gas is filled at lowpressure.

Advantage of CFL


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Advantage of CFL

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1. Low energy consumption.2. Low maintenance cost

3. It stars instantly

4. It does not heat the surroundings

5. Excellent color properties

6. Low operating cost7. More life

Applications of CFL


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Applications of CFL

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The compact size, longer life, lowrunning and maintenance cost,instant glow makes these lamps

suitable for all places whereuniform illumination is required.

It is used in offices, shops, hotels,

hospitals, cinema halls, residentialbuildings etc.


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C i l


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Comparing lamps

Type of Lamp

Lum /Watt Color

Rendering

Index

Typical Appl icat ion

Life

(Hours)

RangeAvg.

Incandescent 8-18 14 Excellent Homes, restaurants, general

lighting, emergency lighting

1000

Fluorescent Lamps

46-60

50

Good w.r.t.coating

Offices, shops, hospitals,homes

5000

Compact fluorescent lamps

(CFL)

40-70 60 Very good Hotels, shops, homes, offices 8000-10000

High pressure mercury (HPMV) 44-57 50 Fair General lighting in factories,

garages, car parking, flood

lighting

5000

Halogen lamps 18-24 20 Excellent Display, flood lighting, stadium

exhibition grounds,

construction areas

2000-4000

High pressure sodium (HPSV)

SON

67-121 90 Fair General lighting in factories,

ware houses, street lighting

6000-12000

Low pressure sodium (LPSV)

SOX

101-

175

150 Poor Roadways, tunnels, canals,

street lighting

6000-12000

Energy Efficiency Opportunities


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High Efficiency Lamps & Luminaries

Examples (9 75% savings):

Metal halide lamps to replace mercury /

sodium vapor lamps

HPSV lamps where color rendering is

not critical

LED panel indicator lamps to replace

filament lamps

Luminaries with mirror optics instead of

conventional painted ones




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Reduction of

Lighting Feeder

Voltage

Can save

energy

Provided drop

in light output

is acceptable

Percentage

Supply voltage percentage

1) Lamp current 2) Circuit power, 3) Lamp power,

4) Lamp output 5) lamp voltage 6) lamp efficiency

Effect of voltage variation of

fluorescent tube light parameters

1

2

3

4

5

6

12

3

4

5

6

6


Measurement of Candle Power


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Measurement of Candle Power

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The candle power of a source in anygiven direction is measured by

comparing it with a standard orsubstandard source with the help ofan optical instrument called

PHOTOMETER.

Photometer


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Photometers are mostly based on inverse square law ofillumination and may be classified as stationary andportable photometers.

The stationary photometers are usually installed in a

dark room with dead black walls and ceiling in orderto eliminate error due to reflected light.

The portable photometers are direct readinginstruments used to measured illumination inhouses, offices , commercial and industrial places.

Lighting Schemes


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g g

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Lighting schemes are classified accordingto the location, requirement andpurpose etc. are as under :

1. Direct lighting2. Indirect lighting

3. Semi direct lighting4. Semi indirect lighting

5. General lighting

Direct Lighting


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g g

As is clear from the name, in this system almost

90 to 95 % light falls directly on the object orthe surface. The light is made to fall upon thesurface with the help of deep reflectors. Suchtype of lighting scheme is most used in

industries and commercial lighting. Althoughthis scheme is most efficient but it is liable tocause glare and shadows.


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Indirect Lighting


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In this system, the light does not fall directly on the surface butmore than 90 % of light is directed upwards by usingdiffusing reflectors. Here the ceiling acts as a source oflight and this light is uniformly distributed over the surfaceand glare is reduced to minimum. It provides shadow lessillumination which is useful for drawing offices and

composing rooms. It is also used for decoration purposesin cinema halls, hotels etc.


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Semi direct Lighting


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Semi direct Lighting

This is also an efficient system of lighting and chancesof glare are also reduced. Here transparent typeshades are used through which about 60 % light isdirected downward and 40 % is directed upward.

This also provides a uniform distribution of lightand is best suited for room with high ceilings.

S i i di t Li hti


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Semi indirect Lighting

In this system about 60 to 90 % of total light isthrown upward to the ceiling for diffusedreflection and the rest reaches the working plane

directly. A very small amount of light is absorbedby the bowl. It is mainly used for interiordecoration.

General Lighting


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General Lighting

This system employs such type of luminaries, shadesand reflectors which give equal illumination in allthe directions.

Design of Indoor Light Scheme


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Design of Indoor Light Scheme

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While designing a good lighting schemes, thefollowing points must be kept in mind :

1. It should provide adequate illumination.

2. It should provides uniformly distributed light all

over working plane.3. It should avoid glare and shadows as far as

possible.

4. It should provide light of suitable colors.

Factors required for Light Scheme


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Factors required for Light Scheme

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The following factors are required to be consideredwhile designing the lighting scheme :

1. Illumination level

2. Quality of light

3. Co efficient of utilization4. Depreciation factor

5. Space height ratio

Illumination Level


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Illumination Level

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This is the most vital factor in deciding the numberand wattage of luminaries so that we are able tosee and recognize the object properly. Colors of the

body have the property of reflecting the light indifferent proportions, degree of illumination, itsdistance from the viewer, contrast between theobject to be seen and its surroundings.

Illumination Level


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Illumination Level

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Type of work recommended illumination level

Offices 100-400 lumens/ meter square

Schools 250-400 lumens/ meter square

Industry 1000 lumens/ meter square

Shops 250-500 lumens/ meter square

Hotels 80-100 lumens/ meter square

Hospitals 250-3500 lumens/ meter square

Quality of Light


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Quality of Light

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This means that the illumination should not beharmful to the viewers. It should be glare free,shadow less and contrast free. Direct glare fromthe source of light is most common factor.Presence of polished and glassy surface will causeindirect glare unless diffused light is used. Hardand long shadows can be avoided by using a largenumber of lamps and adjusting the mounting

height.

Co efficient of Utilizationor


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Utilization Factor

A surface to be illuminated receive light either directlyfrom the lamps or reflected from the ceiling and

walls or both. In this case, the total flux reachingthe surface will never be equal to the flux emitted

by the lamp, due to absorption by reflectors,ceiling and walls.

total lumens emitted by the source

Usually it varies from 0.5 to 0.8.

Depreciation Factor


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Depreciation Factor

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The total flux emitted by the source and its fitting maybe reduced due to deposition of dust upon thesurfaces. Similarly quantity of light reflected fromthe ceiling and walls also decreases with thepassage of time. This is called as depreciationfactor.

Usually it varies from 1.3 to 1.6.

Space Height Ratio


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Space Height Ratio

The ratio of space (horizontal distance ) between the two

adjacent lamps to the vertical height of the lamps abovethe working plane is called space height ratio.

So the distance between the lamps is not too much. Anideal scheme could be when there is large number of

small size lamps are used also it increases the cost ofinstallation. So the space height ratio is 1 to 1.5.


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Lighting Maintenance


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Light levels decrease >50% due to aging lampsand dirt on fixtures, lamps and room surfaces

Maintenance options:

Clean equipment

Replace lenses

Keep spaces bright and clean

Re-lamping


105/106

11/03/2013


106/106

Thank You

169788209 illumination basic and schemes uep in eee

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