Unit 2 ppt.pdf

Presentation
on
UTILIZATIONAND TRACTION
Department of Electrical Engineering
Madan Mohan Malaviya University of Technology,
Gorakhpur
Presented by- Dr. A. K. Pandey ( Professor & HEED)
1

TOPICS
Various definitions, Laws of illumination, requirements of good lighting, Design of
indoor lighting and outdoor lighting systems, Refrigeration systems, domestic
refrigerator, water cooler, Types of air conditioning, Window air conditioner

What is light ?
➢Light is the form of electromagnetic energy radiated from a body which is capable of
being perceived by the human eye.
➢Light can be described by – a vibratory motion, which is transmitted in the form of
waves through space. Visible light travels in the form of transverse waves of
electromagnetic oscillations.
Spectrum of Electromagnetics waves

Wavelength and colour of light

DEFINATIONS:
PLANE ANGLE:
➢A plane angle is subtended at a point is enclosed by two straight lines lying in the
same plane. Its magnitude is given by,
𝜃 =
𝐴𝑟𝑐
𝑅𝑎𝑑𝑖𝑢𝑠
radians
The largest angle subtended at a point is 2𝜋 radians.
SOLID ANGLE:
➢A solid is the generated by the surface passing through the point in space and the
periphery of the area.
➢It is denoted by ɷ, expressed in steradians and is given by the ratio of the area of the
surface to the square of the distance between the area and the point.

𝝎 =
𝑨𝒓𝒆𝒂
𝑹𝒂𝒅𝒊𝒖𝒔𝟐 =
𝑨
𝒓𝟐
The largest value is 4𝜋 ste-radians.
RELATIONSHIP BETWEEN 𝝎 AND 𝜽:
Consider a curved surface of a spherical segment ABC of height h and radius r (shown
in fig.)
Surface area of segment ABC = 2𝜋rh
Here, h (BD) = OB – OD = r – r cos
𝜃
2
= r(1- cos
𝜃
2
)
Surface area of segment ABC = 2𝜋𝑟2
(1- cos
𝜃
2
)

Solid angle, 𝜔 =
𝑺𝒖𝒓𝒇𝒂𝒄𝒆 𝑨𝒓𝒆𝒂
𝑹𝒂𝒅𝒊𝒖𝒔𝟐 =
2𝜋𝑟2(1− cos 𝜃
2
)
𝑟2
𝜔 = 2𝜋 (1- cos
𝜃
2
)
LIGHT:
The radiant energy from a hot body which produces the visual sensation upon the
human eye is called light. It is denoted by the symbol Q, expressed in lumen-hours (
analogous to watt-hours).
LUMINOUS FLUX:
The total quantity of light energy emitted per second from a luminous body is called
luminous flux. It is represented by the symbol F and measured in lumens.
LUMINOUS INTENSITY:
Luminous intensity in a given direction is the luminous flux emitted by the source per
unit solid angle.
It is denoted by the symbol I and is measured in ‘candela’ or lumens/steradian, I =
𝐹
𝜔

LUMEN:
➢It is the unit of luminous flux and is defined as the amount of luminous flux given out
in a space represented by one unit solid angle by a source having an intensity of one
candle power in all directions.
i.e. Lumens = Candle power(C.P.)×Solid angle(𝜔).
Total lumens given out by source of one candela is 4𝜋 lumens.
CANDEL POWER:
➢It is defined as the number of lumens emitted by a source in a unit solid angle in a
given direction. It is denoted by symbol C.P.
𝐶. 𝑃. =
𝐿𝑢𝑚𝑒𝑛𝑠
𝜔

ILLUMINATION:
➢It is the luminous flux received by a surface per unit area. It is denoted by symbol E
and is measured in ‘lumens per square meter’ or ‘lux’ or meter-candle.
➢ Illumination differs from light very much, though generally these terms are used
more or less synonymously.
➢ Strictly speaking light is the cause and illumination is the result of the light on the
surfaces on which it falls.
➢ Thus illumination makes surfaces more or less bright with a certain colour And it is
this brightness and colour which the eyes sees and interprets as something useful or
pleasant.

BRIGHTNESS (or Luminance):
➢Brightness of a surface is defined as the luminous intensity per unit projected area of
the surface in the given direction.
➢It is denoted by the symbol L.
When a surface of area A has an effective
luminous intensity of I candelas in a 𝜃
to the normal ( shown in fig.) then the
brightness of that surface,
L =
𝐼
𝐴 𝑐𝑜𝑠𝜃
(Cd/𝑚2
)
Relation between I, L and E:
➢Consider a uniform diffuse spherical source with radius r meters and luminous
intensity I candela. Then,
L=
𝑰
𝝅𝒓𝟐
And, E =
𝑰
𝟒𝝅𝒓𝟐 × 𝟒𝝅 =
𝑰
𝒓𝟐 = 𝝅𝑳

Mean Horizontal Candle Power (M.H.C.P.):
It is defined as the mean of candle power in all directions in horizontal plane containing
the source of light.
Mean Spherical Candle Power (M.S.C.P.):
It is defined as the mean of candle powers in all directions and in all planes from the
source of light.
Mean Hemi-spherical Candle Power:
It is defined as the mean of all candle powers in all directions above or below the
horizontal plane passing through the source of light.
Reduction factor:
It is the ratio of mean spherical candle power to its mean horizontal candle power, i.e.
Reduction Factor =
𝑴𝑺𝑪𝑷
𝑴𝑯𝑪𝑷
.

Lamp efficiency:
It is defined as the ratio of the luminous flux to the power input.
It is expressed in lumens per watt.
Specific consumption:
It is defined as the ratio of power input to the average candle power.
It is expressed in watts per candle.
Space – height ratio:
It is defined as the ratio of horizontal distance between adjacent lamps and height of
their mountings.
Utilization factor(U.F.):
The ratio of total lumens reaching the working plane to total lumens given out by the
lamp is called utilization factor (or co-efficient of utilization).
Maintenance factor:
It is the ratio of illumination under normal working condition to illumination when the
things are perfectly clean.

Depreciation Factor:
This is the merely the reverse of the maintenance factor.
➢ It is defined as the ratio of initial metre –candles to the ultimate maintained metre-
candles on the working plane.
➢ Its value is more than unity.
Waste light factor:
➢Whenever, a surface is illuminated by a number of sources of light, there is always a
certain amount of waste of light.
➢The effect is taken into account by multiplying the theoretical value of lumens
required by 1.2 for rectangular areas. 1.5 for irregular areas and objects such as
statues, monuments etc.

Absorption factor:
➢In the places where atmosphere is full of smoke fumes, such as in foundries, there is
possibility of absorption of light.
➢The ratio of total lumens available after absorption to the total lumens emitted by the
source of light is called as ‘absorption factor’.
➢ Its value varies 1 for clean atmosphere to 0.5 for foundries.
Beam factor:
➢The ratio of the lumens in the beam of a projector to the lumens given out by lamps is
called as beam factor.
Glare:
➢ The brightness within the field of vision of such a character as to cause annoyance,
discomfort, interference with vision or eye- fatigue is called as glare.

Reflection factor:
➢When a ray of light imposes on a surface it is reflected from the surface at an
angle of incidence, as shown in fig.
A certain portion of incident light is absorbed by the surface.
➢ The ratio of reflected light to the incident light is called as reflection factor.
➢ It is always less than unity.

Laws of illumination:
➢The illumination (E) of a surface depends upon the following factors( The source is
assumed to be a point source) –
➢E is directly proportional to the luminous intensity (I) of the source.
➢ In other words, E∝ 𝐼.
Inverse Square Law:
➢The illumination of a surface is inversely proportional to the square of the distance
of the surface from the source.
In other words, E ∝
1
𝑟2 .

Proof:
Consider surface areas 𝐴1 and 𝐴2 at the distances 𝑟1 and 𝑟2 respectively from the point
source S of luminous intensity I and normal to the rays as shown in fig.
➢ Let the solid angle be 𝜔
Total luminous flux radiated
𝐹 = 𝐼𝜔 lumens.
➢ Illumination of the surface area 𝐴1
𝐸1 =
𝐼𝜔
𝐴1
=
𝐼𝜔
𝜔𝑟12 =
𝐼
𝑟12 lumens per unit area,
Similarly, illumination for area 𝐴2,
𝐸2 =
𝐼𝜔
𝐴2
=
𝐼𝜔
𝜔𝑟22 =
𝐼
𝑟22 lumens per unit area.

➢Hence, the illumination of a surface is inversely proportional to the square of the
distance between the surface and the light source provided.
Inverse square law

Lambert’s Cosine Law:
➢According to this law, E is directly proportional to the cosine of the angle made by
the normal to the illuminated surface with the direction of the incident flux.

➢ Let F be the flux incident on the surface area A when in the position 1 as shown in
the figure. When the surface is turned back through an angle 𝜃, then flux incident on
it is F cos𝜃.
➢Hence, illumination of the surface when in position 1 is
𝐸1 =
𝐹
𝐴
➢ But when in position 2,
𝐸2=
𝐹𝑐𝑜𝑠𝜃
𝐴
Therefore, 𝐸2 = 𝐸1𝑐𝑜𝑠𝜃
➢ Combining all these factors together, we get
𝐸 =
𝐼𝑐𝑜𝑠𝜃
𝑟2
➢ The unit is lumens per unit area.

Polarcurves:
➢The luminous intensity is most lamps or sources of light is not the same in all
directions. Because of their un-symmetrical shapes.
➢Often it is necessary to know the distribution of light in all directions to ascertain
how the candle power of light source varies in different directions.
➢The luminous intensity in all the directions can be represented by polar curves.
Horizontal polar curve:
➢ If the luminous intensity i.e., candle power is measured in horizontal plane about a
vertical axis and plotted between C.P. and angular position, horizontal polar curve is
obtained.

➢Polar curve for horizontal plane is shown below-
Vertical polar curve:
If the candle power is measured at angular position in a vertical plane, called vertical
polar curve is obtained.

➢The figure shows the vertical polar curve-
The polar curves are used to determine the following:
➢The mean horizontal candle power (M.H.C.P.) and mean spherical candle power
(M.S.C.P.).
➢The actual illumination of a surface by employing the candle power in that particular
direction as read from the vertical polar curve in illumination calculations.

REFRIGERATION
➢Refrigeration is the science of producing and maintaining temperature below that of
the surrounding atmosphere.
➢This means removing heat from the substance to be cooled.
➢Before the advent of mechanical refrigeration water was kept cool by storing it in
semi-porous jugs so that water could seep through and evaporate.
➢The equipment required to maintain the system at low temperature is called as
refrigerating system.

Applications:
➢Ice making.
➢Transportation of food above and below freezing.
➢Industrial air-conditioning.
➢Comfort air-conditioning.
➢Chemical and related industries.
➢Medical and surgical aids.
➢Processing food products and beverages.
➢Manufacturing and treatment of metals.
➢Plumbing.
➢Building construction.

Refrigeration systems:
➢Ice refrigeration system
➢Air-refrigeration system
➢Vapor compression refrigeration system
➢Vapor absorption refrigeration system
➢Thermoelectric refrigeration
➢Mixed refrigeration system

Domestic refrigeration:
Construction
A domestic refrigerator consists of the following two main parts-
1. The refrigerator system
2. The insulated cabinet.
Electric circuit of refrigerator
▪ Lamp and switch
▪ Thermostat switch
▪ Thermal overload release
▪ Starting relay
▪ Motor

Electric circuit of refrigerator

Typesofairconditioning
Central air conditioning:-
This is the most common type of cooling system as it is the most preferable for larger
homes due to its ability to cool efficiently. Central air conditioners circulate cool air
through supply and return ducts. Supply ducts and registers, which are in the wall or
floors, carry cooled air into the home. Then, once the air becomes warm it circulates
back into the supply ducts and registers where it will then be transported back to the air
conditioner.
Ductless, mini-split air conditioner:-
Ductless, mini-split systems are most common in parts of the home that have been
retrofitted. Like central air conditioning systems, these systems have an outdoor
compressor/condenser and an indoor handling unit.
Window air conditioner:-
Think of a window air conditioner as a compact unit, cooling only one particular room.
Also known as a “unitary unit,” this system is installed in the window of room Window
units cool a room be emitting the warm air out the back of it and blowing cool air into
it. These types of units are best for those who live in small spaces.
Portable air conditioner:-
Portable air conditioners are considered as the next generator of window units. This
type of air conditioning unit takes in air from the room and cools it, then directs it back
into the room.
10/17/2020 32

Hybridairconditioners:-
➢ Like hybrid cars, hybrid heat pump systems alternate between burning fossil fuels and
using electricity to run.
➢ The system intelligently chooses between the two energy sources in order to save money
and energy.
Geothermal heating & cooling:-
➢ Geothermal energy is sustainable, energy-efficient, and has a long lifespan. Since the
ground temperature below us remains a fairly consistent 55 degrees no matter how hot or
cold it is in the atmosphere, geothermal technology is able to extract the heat from below
and transfer it into your home.
Window air conditioners
10/17/2020 33
➢ Window air conditioner (WAC) is a type of AC that's installed into a window of a
room and designed to cool that specific room. An evaporator coil cools the interior
while a condenser coil releases hot air outside. Window air conditioners work by
removing both heat and humidity, in addition some models can heat a room.
➢ Window air conditioner is a most economical choice for cooling. It is much easier to
install than high-wall or central air conditioner. Room air conditioners can also be
built into the wall for a more permanent installation.

Watercooler
➢A water dispenser, known as water cooler (if used for cooling only), is
a machine that cools or heats up and dispenses water with a refrigeration unit.
➢It is commonly located near the restroom due to closer access to plumbing. A drain
line is also provided from the water cooler into the sewer system.
➢Water dispensers come in a variety of form factors, ranging from wall-mounted to
bottle filler water dispenser combination units, to bi-level units and other formats.
➢They are generally broken up into two categories: point-of-use (POU) water
dispensers and bottled water dispensers.
➢POU water dispensers are connected to a water supply, while bottled water dispensers
require delivery (or self-pick-up) of water in large bottles from vendors. Bottled
water dispensers can be top-mounted or bottom-loaded, depending on the design of
the model.
10/17/2020 34

DESIGNOFINDOORLIGHTSCHEME
When designing indoor lighting for energy efficiency, consider some basic design
principles and methods:-
Energy-efficient lighting design principles include the following:
➢More light is not necessarily better: light quality is as important as quantity
➢Match the amount and quality of light to the performed function
➢Install task lights where needed and reduce ambient light elsewhere
➢Use energy-efficient lighting components, controls, and systems
➢Maximize the use of daylighting.
Here are some basic methods for achieving energy-efficient indoor lighting:
➢Install fluorescent or LED light fixtures for all ceiling- and wall-mounted fixtures that
will be on for more than 2 hours each day, such as kitchen and living room,
bathroom, hallway, and other higher-demand locations.
➢Consider installing fluorescent or LED fixtures, rather than using fluorescent or LED
replacement lamps in incandescent fixtures.
➢Use CFLs or LEDs in portable lighting fixtures that are operated for more than 2
hours a day.

When designing outdoor lighting, consider the purpose of the lighting along with basic
methods for achieving energy efficiency.
Outdoor lighting for homes generally serves one or more of three purposes:-
➢Aesthetics: Illuminate the exterior of the house and landscape
➢Security: Illuminate the grounds near the house or driveway
➢Utility: Illuminate the porch and driveway to help people navigate safely to and from
➢ the house.
Here are some basic methods for achieving energy-efficient outdoor lighting:
➢Security and utility lighting does not need to be bright to be effective.
➢Use LED or fluorescent lights unless incandescent lights are automatically controlled
to be on for just a few minutes each day.
➢Consider flood lights with combined photosensors and motion sensors in the place of
other security lighting options.
➢Make sure outdoor light fixtures have reflectors, deflectors, or covers to make more
efficient use of the light source and help reduce light pollution.
➢Use timers and other controls to turn decorative lighting on and off.
➢Use outdoor solar lighting where applicable.
OUTDOORLIGHTINGDESIGN

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