Electric Power Automation &

Utilization
Day 7
Part 2
#1) Two sources of luminous intensity 200 candela and 250 candela are
mounted at 8m and 10m respectively above floor. Horizontal distance
between the lamp posts is 40m. Calculate the illumination on floor at the
middle of the two posts.
Solution:

P
#1) Two sources of luminous intensity 200 candela and 250 candela are
mounted at 8m and 10m respectively above floor. Horizontal distance
between the lamp posts is 40m. Calculate the illumination on floor at the
middle of the two posts.
Solution:

P
#1) Two sources of luminous intensity 200 candela and 250 candela are
mounted at 8m and 10m respectively above floor. Horizontal distance
between the lamp posts is 40m. Calculate the illumination on floor at the
middle of the two posts.
Solution:

P
 ILOs – Day 7
 Understand and apply the concepts of lighting design
 List the properties of good lighting
 Discuss the advantages of good lighting
 Describe the factors affecting good lighting design
 Realize the illumination level desired at different locations
 Design lighting systems
 Street light
 Factory light
 Flood light
Lighting Design
 Lighting Design
 The lighting scheme should be such that:
 It should be able to provide sufficient illumination.
 It should be able to provide the uniform distribution of light throughout
the working plane.
 It should be able to produce the light of suitable color
 It should be able to avoid glare and hard shadows as much as possible
 Properties of good lighting
 A good lighting scheme should have the following properties.
 Lighting scheme should be able to produce sufficient light
 It should not produce any glare in the eyes
 It must be installed at a place so that it gives uniform light
 It should have suitable shades and reflectors
 It should be of correct colour as needed
 Advantages of good lighting
 Good lighting scheme
 Increases the production rate in workshop
 Reduces the probability of accidents
 It will not cause strain to eyes
 Reduces the wastage or loss of material
 It increases the interior decoration of buildings
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
Illumination level desired
 Illumination level desired
 The intensity of illumination required on the surface depends on the
type of work being done
 Illumination level desired
 The intensity of illumination required on the surface depends on the
type of work being done
 For each type of work, there is a range of brightness that causes
minimum fatigue and gives maximum output in terms of quality and
quantity
 Moving objects and the objects that are seen for longer duration
require more illumination than those for stationary object and casual
work
Illumination level desired
Occupancy Illumination
(Lux)
1 Covered areas
1. Proof reading 100 – 200
2. Drawing and exhibition 50 – 100
3. Museum 30 – 60
4. Bed room and waiting room 15 - 30

5. Railway platform 5 – 10
Illumination level desired
Occupancy Illumination
(Lux)
2 Offices, hotels and restaurants
1. Reception, dining room, and bedroom, 150–200
lounges, stairs
2. Accounts and writing desks 300–400

3 Power station
1. Boiler house, turbine stage, transformer, 100 - 150
and switch gear chamber
2. Control room 200–300
Illumination level desired
Occupancy Illumination
(Lux)
4 Sports area
1. Boxing rings 2000 - 3000
2. Race tracks 180 - 300
3. Football ground 100 - 200
4. Tennis court 300–400
5. Stadium 200–300
Illumination level desired
Occupancy Illumination
(Lux)
5 Industrial purpose
1. Very fine work, e.g. assembly of precision 1200 - 1500
instruments
2. Fine work – radio and telephone 500 – 700
equipment
3. Medium work – Lathe, machine parts, 200 – 300
engine, vehicle assembly
4. Rough work – frame assembly of heavy 100 - 150
machine
5. General factory lighting 20 - 40
Illumination level desired
Occupancy Illumination
(Lux)
6 Schools and colleges
1. Classroom, laboratories, library, lecture 1200 - 1500
hall, and workshop
2. Drawing rooms, art rooms 500 – 700
3. Common rooms, canteen and stairs 200 – 300

7 Shops
1. General areas 200 – 400
2. Stock area 100 – 200
3. Shop window Special lighting
Illumination level desired
Occupancy Illumination
(Lux)
8 Houses
1. General living room 100 – 150
2. Study room 250 – 300
3. Kitchen, bathroom, bedroom 100 - 150

9 Hospitals
1. Waiting rooms, wards 100 – 150
2. Dispensaries, diagnostic laboratories 250 – 300
3. Operation table Special lighting
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
Size and colour of the room
 Size and colour of the room
 The luminous flux emitted from the source will not be completely
utilized at the workplace
 A portion of flux will be lost in the lamp fitting, some other will be
absorbed, and the rest of it is reflected
 This absorption and reflection are depending upon the size and colour
of the walls and ceiling
 Illumination in any room depends greatly upon the reflected light
from the walls and ceiling
 White colour walls and ceiling reflect more light as compared to
coloured ones
 This is taken into account by a factor known as the “utilization factor”
or “coefficient of utilization” (UF)
Coefficient of utilization of different fittings
Utilization factor
Big rooms with light Small rooms
Sl Type of fitting
coloured walls and with dark walls
ceilings and ceilings
1 Standard direct reflectors 0.64 0.24
Coefficient of utilization of different fittings
Utilization factor
Big rooms with light Small rooms
Sl Type of fitting
coloured walls and with dark walls
ceilings and ceilings
2 Fluorescent lamp fittings 0.75 0.33
Coefficient of utilization of different fittings
Utilization factor
Big rooms with light Small rooms
Sl Type of fitting
coloured walls and with dark walls
ceilings and ceilings
3 Semi-direct fittings 0.56 0.20
Coefficient of utilization of different fittings
Utilization factor
Big rooms with light Small rooms
Sl Type of fitting
coloured walls and with dark walls
ceilings and ceilings
4 Enclosed sphere or diffusing 0.56 0.15
fittings
Coefficient of utilization of different fittings
Utilization factor
Big rooms with light Small rooms
Sl Type of fitting
coloured walls and with dark walls
ceilings and ceilings
4 Indirect fittings 0.4 0.1
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
Mounting height and the space of
fitting
 Mounting height and the space of fitting
 In general lighting, the illumination at any point should not vary
throughout the room
 The lamp fittings for general lighting should be in such a way that the
illumination received from each fitting overlaps with the other
 In order to provide adequate illumination over the working plane, the
distance between the source fittings or the spacing should not exceed
more than 1.5 times the mounting height (height above the working
plane)
Mounting height and the space of fitting
(S)
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
 Factors affecting lighting design
 While designing a lighting scheme, the following factors should be
taken into consideration:
 Illumination level desired
 Size and colour of the room
 Mounting height and the space of fitting
 Conditions of use
Conditions of use
 Conditions of use
 Conditions of use of the light fitting vary with different types of
installations
 Dust and dirt of the surroundings may get deposited in the light fittings
and hence deteriorate the lamp efficiency
 If regular periodic cleaning is adopted, and assuming good atmospheric
conditions, the value of “maintenance factor (MF)” may be taken as 0.8
 But for dusty and dirty atmosphere, the factor may be as low as 0.4
 Another term “depreciation factor (DF)” is also used which is the
reciprocal of maintenance factor
Lighting design

Street lighting
Factory lighting
Flood lighting
Street lighting design
 Street lighting
 Main objectives of street lighting are:
 To make the traffic and obstructions of the road clearly visible in order to
promote safety and convenience
 Illuminated environment for quick movement of the vehicles
 Reducing the risk of night-time accidents
 Assisting in the protection of buildings/property (discouraging
vandalism)
 Discouraging crime
 To enhance the community value of the street, and creating a secure
environment for habitation
 To make the street more attractive
 Street lighting
 General principles for street lighting:
 Diffusion principle
 Specular reflection principle
Diffusion principle
 Diffusion principle
 In this method, lamps fitted with suitable reflectors are employed
 Design of the reflectors are such that they direct the light downwards
and spread as uniformly as possible over the road surface
 Diffusion principle
 In order to avoid glaring the drivers’ eyes, the reflectors are made to
have cut-off between 300 – 450 so that the light filament is not visible
except when the viewer is directly underneath it

Unusable candle
power ‘glare’
30 - 450

Area of usable
candle power
 Diffusion principle
 The rough surface of the road causes diffused reflection of a certain
proportion of the incident light in the direction of the observer
 Thereby the road surface appears to be bright to the observer

 Illumination at any point on the road surface is calculated by applying

inverse square law or point-by point method
Specular reflection principle
 Specular reflection principle
 In case of specular reflection principle, the reflectors are curved
upward so that the light is thrown on the road at a very large angle of
incidence causing specular reflection from smooth surface
 Specular reflection principle
 In this case, the observer can see the objects that are even 30 meters
away
 Due to obstruction, the reflected rays will be cut-off from reaching
the observer
 The obstacle thus looks dark against the bright background road
surface

Obstruction Vehicle
 Specular reflection principle
 This method of street lighting is only suitable for straight sections of
the road
 It is more economical than the diffusion method of street lighting
 However, it has the demerit that it produces glare for the motorists

A dry asphalt road When wet, water fills in the

diffuses incident light crevices, resulting in specular
reflection and glare
Road characetristics
Road characteristics

Types Recommended
of Road Recommended Height of pole
Road Characteristics Illumination
Important Traffic
Routes Carrying Fast
Traffic

A [ National highways 20 to 30 lux 7.5 m to 10 m

or state highways or
called interstate
highways, express
ways or motor ways]
Road characteristics

Types Recommended
of Road Recommended Height of pole
Road Characteristics Illumination
Main road carrying
mixed traffic like
city, main roads
B including cycles. 15 to 20 lux 7.5 m to 10 m
[ Trunk road or major
road in a city, like
EM bypass]
Road characteristics

Types Recommended
of Road Recommended Height of pole
Road Characteristics Illumination
Secondary roads with
considerable traffic
C like slow-moving 10 to 12 lux 7 m to 8 m
vehicles, shopping
streets
Road characteristics

Types Recommended
of Road Recommended Height of pole
Road Characteristics Illumination

D 6 to 9 lux Less than 7.5 m

Residential and
unclassified roads
Road characteristics - summary
Types Recommended
of Road Recommended Height of pole
Road Characteristics Illumination
A National highways 20 to 30 lux 7.5 m to 10 m

B Main road 15 to 20 lux 7.5 m to 10 m

C Secondary roads 10 to 12 lux 7 m to 8 m

D Residential 6 to 9 lux Less than 7.5 m

Street light arrangements
 Street light arrangements
 There are four basic types of street lighting layout arrangements used
for streets or highways illumination
 Single Side Pole Layout
 Both Side Staggered Pole Layout
 Both Side opposite Pole Layout
 Twin-central Pole Layout
 Single Side Pole Layout
 Arrangement:
 All luminaries are located on one side of the road
 Road Width:
 For narrower roads.
 Pole Height:
 The installation height of the lamp be equal to or less than the effective
width of the road surface.
 Single Side Pole Layout
 Advantage:
 These are of low manufacturing cost
 Disadvantage:
 The brightness (illuminance) of the road on the side where the lamp is
not placed is lower than the on which side the light pole is placed
 Both Side Staggered Pole Layout
 Arrangement:
 The luminaires are placed alternately on each side of the road in a “zig-
zag” or staggered fashion.
 Road Width:
 For Medium Size roads.
 Pole Height:
 The installation height of the lamp
is equal or 1.5 time the effective
width of the road
 Both Side Staggered Pole Layout
 Advantage:
 This type of arrangement is better than single side arrangement.
 Disadvantage:
 Their longitudinal luminance uniformity is generally low and creates an
alternating pattern of bright and dark patches
 However, during wet weather they cover the whole road better than
single-side arrangements.
 Both Side opposite Pole Layout
 Arrangement:
 The luminaries located on both sides of the road opposite to one another.
 Road Width:
 For Medium Size roads.
 Pole Height:
 The installation height of the lamp will be 2 to 2.5 time the effective
width of the road
 Both Side opposite Pole Layout
 Advantage:
 Opposite arrangements may provide slightly better lighting under wet
conditions.
 Disadvantage:
 If the arrangement is used for
a dual carriageway with a
central reserve (wide divider),
or if the divider includes other
significant visual obstructions
(such as trees or screens), it
effectively becomes two
single-sided arrangements and
must be treated as such
 Twin-central Pole Layout
 Arrangement:
 The luminaries are mounted on a T-shaped pole in the middle of the
divider of the road.
 When the divider is not too wide, both luminaires can contribute to the
luminance of the road surface on either lane.
 Road Width:
 For Large Size roads.

 Pole Height:
 The installation height of the
lamp be equal to the effective
width of the road
 Twin-central Pole Layout
 Advantage:
 This arrangement generally more efficient than opposite arrangements
 Disadvantage:
 Can only be installed on roads having wide enough divider
 Far edge of load not enough illuminated during wet seasons
Mounting height and spacing
 Mounting height and spacing
 Normal spacing for standard street light poles if 50 meters with a
mounting height of 8 meters
 W = Road width (8 m)
 H = Pole height (8 m)
 S = Spacing (40 m)
 OH = Overhang (1.5 m)
 Q = Tilt angle
Types of lamps for street lighting
 Types of lamps for street lighting
 For street lighting purposes, mercury vapour and sodium discharge
lamps have been found to have certain advantages
 Most important of these is the low power consumption for a given
amount of light
 Nowadays, however LED lamps have overtaken as more energy
efficient option

Mercury vapor Sodium vapor LED

Factory lighting
 Factory lighting
 In an industrial establishment, an adequate amount of light produces
the following good effects:
 The productivity of labour is increased
 Number of work stoppages are reduced (less fatigue)
 The quality of work is improved
 Accidents are reduced
 An effective factory lighting should provide the following:
 Adequate illumination over the working place
 Good distribution of light
 Simple and easily cleaned fittings
 Avoid glare (from the lamp itself or from any polished surface)
 Factory lighting
 In factories and workshops, the usual scheme is to mount number of
lamps at sufficient height so that uniform distribution of light over the
working plane is obtained
 Factory lighting
 In factories and workshops, the usual scheme is to mount number of
lamps at sufficient height so that uniform distribution of light over the
working plane is obtained
 Factory lighting
 On some precision working points, fairly intense illumination is
needed
 For this purpose, local lighting can be provided by means of adjustable
fittings attached to the machine or bench in question or mounted on
portable fittings
 Such lamps should be mounted in deep reflectors to avoid glare
 Factory lighting
 It is also necessary to provide auxiliary lighting from sources other
than the main electric supply
 Preferably from batteries or small diesel generator sets
 These act as backup during main supply failure or similar emergencies
 Factory lighting locations
 Interior lighting:
 Interior lighting of the production plant, research and development, and
office interior lighting.

 Outdoor device lighting:

 Lighting for various outdoor devices
such as:
 Chimneys
 Tanks
 reaction towers of petrochemical
companies
 Ladders
 Furnaces
 platforms of metallurgical companies
 gas tanks of power stations.
 Factory lighting locations
 Station yard lighting:
 Illumination of stations
 railway marshaling stations
 parking lots
 open storage yards
 outdoor test yards and etc

 Underground lighting:
 Lighting basements
 cable tunnels
 integrated pipe corridors
 tunnels
 Factory lighting locations
 Evacuation lighting:
 The lighting is effectively identified and used in the evacuation passages in
the factory buildings.
 Guard lighting:
 The lighting set up along the perimeter of the factory area and around
guard areas of key places
 Factory lighting locations
 Obstacle lighting:
 There are super tall buildings and structures in the factory area, such as
chimneys, etc.
 According to the regional aviation conditions, the signs need to be
installed according to relevant regulations
Factory Brightness (Lux) Level
Industrial Lighting Lux Level
Area inside Factory Standard Suggestion
Factory Aisle 50 to 100 lux

Goods Storage 150 to 300 lux

Office 200 to 300 lux

Production Line 500 to 750 lux

Quality Control 600 to 900 lux

Precise Mechanical Works 800 to 1000 lux

Flood lighting
 Flood lighting
 The flooding of a large surface with light from powerful projectors is
called flood lighting
 It may be employed for the following purposes:
 To enhance beauty of ancient monuments at night
 To illuminate advertisement boards and show-cases
 To illuminate railway yards, sports stadiums, construction sites, ports
 Flood lighting
 The flooding of a large surface with light from powerful projectors is
called flood lighting
 It may be employed for the following purposes:
 To enhance beauty of ancient monuments at night
 To illuminate advertisement boards and show-cases
 To illuminate railway yards, sports stadiums, construction sites, ports
 Flood lighting
 The flooding of a large surface with light from powerful projectors is
called flood lighting
 It may be employed for the following purposes:
 To enhance beauty of ancient monuments at night
 To illuminate advertisement boards and show-cases
 To illuminate railway yards, sports stadiums, construction sites, ports
 Flood lighting
 A special reflector and housing is employed in floodlighting in order
to concentrate the light emitted from the lamp into a relatively
narrow beam, which is known as floodlight projector
 This projector consists of a reflecting surface that may be a silvered
glass or chromium plate or stainless steel
 The efficiency of silvered glass and polished metal are 85–90% and
70%, respectively
 Usually metal reflectors are robust; therefore, they can be preferred