Project Report On Lighting Design

Project Report On
Lighting Design
Submitted To
Dezyne E’ cole College
Towards The
Partial Fulfillment
Of
Interior Design NSQF Level 6
By
Aashish Jain
Dezyne E’ Cole College
106/10 Civil Lines, Ajmer
www.dezyneecole.com
2015-2018

ACKNOWLEDGEMENT
I am Aashish Jain, student of Interior Design Department of Dezyne E’ cole College would like
to express my gratitude to each and every person who has contributed in stimulating
suggestions and encouragement which really helped me to coordinate my project.
I also thank Dezyne E’ cole College who provided insight and expertise that greatly
assisted the project. Also, A special thanks to my teachers, parents and colleagues who have
supported me at every step. Not to forget, the Almighty who blessed me with good health
because of which I worked more efficiently and better.

SYNOPSIS
This is an Assignment where after learning about the lighting aspects used in designing, We
have made a report on the reasons for using lights in design and how a light is distributed in
different direction when fixed. The various types of lights, the bulbs and their bases used in
them and the different colour temperatures. We learnt about the Colour Rendering Index and
its impact on design, usage of coloured filters when using lighting design. Along with this we
have studied about the LED and its benefits and why it is being commonly used in today’s era.
The various types of light controls like baffles and louvers are used and also about the light
dimmers. This assignment is a learning assignment created during our period of study which we
used while creating spaces of commercial interest.

What is Lighting?
Why do we need it?

Light is defined as the electromagnetic radiation with wavelengths between 380 and 750 nm
which is visible to the human eye. The main source of light on earth is the sun.
Lighting or illumination is the deliberate use of light to achieve A practical or aesthetic effect.
Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as
natural illumination by capturing daylight. Day lighting (using windows, skylights, or light shelves)
is sometimes used as the main source of light during daytime in buildings. This can save energy in
place of using artificial lighting, which represents A major component of energy consumption in
buildings. Proper lighting can enhance task performance, improve the appearance of an area,
or have positive psychological effects on occupants. During the daytime, we can use sunlight to
see things and do our work but during the night time we need artificial lights to help us in seeing
things. Light plays an important role in Commercial spaces as well as in Residential spaces.

Perception of the world around us is based not on the quantity of light entering the eye, but on
the quantity of contrast. What we perceive as light is a narrow band of electromagnetic energy,
ranging from ranging from approximately 380 nanometers (nm) to 760 nm. Only wavelengths in
this range stimulate receptors in the eye that permit vision these wavelengths are called visible
energy even though we cannot directly see them. We can see different objects only in the
presence of light. When a white light beam is passed through a prism, a band of seven colors are
formed is known as spectrum of white light. Actually when a beam of light falls on an object from
the source of light then this light gets reflected in all directions after striking that object. The
reflected light then reaches our eyes and we become able to see that object.
Electromagnetic Spectrum

Types of Lights
used in
Commercial and Residential Design?

There are basically three types of lighting which are used in Commercial and Residential Design
and these are as follows:
General Lighting:
General lighting provides an area with overall illumination. Also known
as ambient lighting, general lighting should provide a comfortable level
of brightness, enabling you to perform tasks and move about safely.
General lighting for indoors can be accomplished with a chandeliers,
ceiling or wall-mounted fixtures, recessed or track lights, and with floor
and table lamps. General lighting fixtures outside your home can
include spotlights, hanging fixtures, post lanterns, wall lighting, and
recessed fixtures used in overhanging structures.
Task Lighting:
Task lighting helps you perform specific tasks and activities such as
reading, writing, sewing, cooking, homework, or balancing your
checkbook. Task lighting is usually achieved with recessed and track
lighting, pendant lighting, portable lamps, or desk lamps. Task lighting
should be free of distracting glare and shadows and should be bright
enough to prevent eyestrain. It’s useful to have task lighting on controls
that are separate from the general lighting.
Accent Lighting:
Accent lighting is the use of a concentrated light on an area or subject
to create a visual point of interest. Accent lighting is often used to
spotlight architectural features, paintings, plants, sculptures or
collectables. Accent lighting adds an extra dimension to a room, and
proper use of accent lighting can help make a room look larger.

• Cove lighting-
Cove lighting is located in a ledge,
shelf or recess high up on a wall,
and the light is bounced toward
the ceiling or upper wall.
• Soffit lighting-
Soffit lighting is located in a soffit or
cornice near the ceiling, and the
light radiates downward, washing
the wall with light.
• Valance lighting-
Valance lighting is located in a
wood, metal or glass valance
(horizontal shield) mounted above
a window or high on the wall, and
the light bounces both upward and
downward.
• Recessed lighting-
Installed above the ceiling, a
recessed lighting sends a relatively
narrow band of light in one
direction; it can be used to provide
ambient, task or accent lighting.
• Wall washers-
Wall washing is a technique
typically used to light flat walls. You
get a nice, even distribution
of light from floor to ceiling, bringing
your attention to a large, smooth
vertical surface.
• Spotlights-
A lamp projecting a narrow, intense
beam of light directly on to a place
or person, especially a performer
on stage.

• Chandeliers-
Suspended from the ceiling,
chandeliers direct their light
upward, typically over A table. They
can enhance the decorative style
of a room. Chandeliers provide
ambient lighting.
• Wall Sconces-
Surface-mounted to the wall,
sconces can direct light upwards or
downwards, and their covers or
shades can add A stylistic touch to
a room. Wall sconces provide
ambient or task lighting.
• Tracklights-
Mounted or suspended from the
ceiling, track lighting consists of a
linear housing containing several
heads that can be positioned
anywhere along a track; the
direction of the heads is adjustable
also. Track lighting is often used for
task or accent lighting.
• Pendant lighting-
Suspended from the ceiling, a
pendant light directs its light down,
typically over a table or kitchen
island. A pendant can enhance
the decorative style of a room.
Pendants can provide ambient or
task lighting.

Ways of Light distribution
through Light and Fixtures?

Brightness versus Luminance
Brightness is the subjective
sensation that occurs in the
consciousness of a human
observer.
Luminance is the objective
measurement of intensity per unit
of projected area.
Distribution of Light
A luminaire (lighting fixture) emits light in one of three
directions- downward, upward or multidirectional- and
in one of two distributions-concentrated or diffuse.
Downward light from a properly designed luminaire has
a restricted angular spread; direct glare is prevented by
both this restricted and the shape of the human
eyebrow. Upward light usually covers a large area of
the ceiling; the light reflected from the ceiling is of low
luminance and is unlikely to cause distracting glare.
Multidirectional light is emitted in all directions, but it
cannot emit much of its output sideways without
causing objectionable glare.
Glare versus Sparkle
Excessive contrast or luminance is
distracting and annoying. This
negative side of brightness is
called glare. In the extreme,
glare cripples vision by destroying
the ability to see accurately. The
glare is of two types i.e. direct
and reflected.
The principle difference between
glare and sparkle is the
relationship between the area
and magnitude of luminance in
the field of view. Large areas of
luminance are distracting and
disconcerting; relatively small
areas of similar or higher intensity
are points of sparkle and
highlight that contribute to
emotional excitement and visual
interest. They are of three types
i.e. direct, reflected and
transmitted.
The seven directions and distribution of light.

• Concentrated downward distribution
Luminaires with narrow beam-spreads that lack an upward component
of light produce a concentrated downward distribution. When located
in low ceilings, concentrated downward beams-with spreads 30 degree
or less- create areas of high luminance on the floor with dark areas in
between.
• Diffuse downward distribution
Luminaires with diffuse beam-spreads and a downward distribution
produce diffuse downward light. It spreads from 80-120 degrees-offer a
more practical light distribution for many purposes. A luminaire with 100
degrees beam-spread, emitting most of its light below A cut-off angle of
40 degree from horizontal is offered by most well designed downlights.
• Concentrated upward distribution
A concentrated upward distribution directs light toward the ceiling. With
light directed upward and the downward component removed, the
ceiling becomes visually prominent. It also becomes a secondary light
source because of its reflective properties. When mounted in close
proximity to the surface being lighted, concentrated upward beams
create isolated areas of high luminance.

• Multidirectional concentrated distribution
Multidirectional distribution created with concentrated beam-spreads is
called multidirectional concentrated. It is also called semi direct if 60-90%
of the lumens are directed downward, and semi indirect if 60-90% of the
lumens are directed upward.
• Direct/indirect distribution
Luminaires that deliver both direct and indirect components of diffuse
light, but no side lighting is called direct/indirect distribution. They
provide efficient use of light on work surfaces while relieving contrast by
reflecting light from the ceiling plane.
• Diffuse upward distribution
A diffuse upward distribution directs light towards the ceiling and the
upper side walls. This technique is to create uniform ceiling luminance for
the prevention of glare in areas with video display terminals and to
emphasize structural form or decorative detail on or near the ceiling
plane.

• Multidirectional diffuse distribution
Multidirectional diffuse/general diffuse distribution is produced by
luminaries that deliver both upward and downward components of light.
These luminaries emit light in several directions at the same time- toward
the ceiling and walls as well as toward the floor. The reflected light from
the ceiling and the inter-reflection of light in the space diffuse the
downward distribution, reducing shadow and contrast and creating a
uniform, high-brightness interior.

The Colour temperature of a light source is the temperature of an ideal black-body radiator that
radiates light of comparable colour to that of the light source. Colour temperature is a
characteristic of visible light that has important applications in lighting, photography, etc.. In
practice, colour temperature is meaningful only for light sources that do in fact correspond
somewhat closely to the radiation of some black body, i.e., Those on a line from reddish/orange
via yellow and more or less white to bluish white; it does not make sense to speak of the colour
temperature of, Ex. A green or a purple light. Colour temperature is conventionally expressed
in kelvins, using the symbol K, A unit of measure for absolute temperature. Colour temperatures
over 5000 K are called cool colours (bluish white), while lower color temperatures (2700–3000 K)
are called warm colours (yellowish white through red). Warm in this context refers to radiated
heat flux rather than temperature; the spectral peak of warm-coloured light is closer to infra-red
and most natural warm-coloured light sources emit significant infra-red radiation.

Interior Spaces with different Colour temperature.

What is
Colour Rendering Index?

A COLOUR RENDERING INDEX (CRI) is a quantitative measure of the ability of a light source to
reveal the colors of various objects faithfully in comparison with an ideal or natural light source.
The CRI of a light source does not indicate the apparent color of the light source; that
information is under the rubric of the correlated color temperature (CCT). The CRI is determined
by the light source's spectrum. If the colour temperature of a given source is 5000K or less, the
reference source is the blackbody radiator at the nearest colour temperature. If it is above 5000K
then it is nearest simulated daylight source. The comparison is expressed as an ra on a scale of 1-
100, which indicates how closely the given light source matching the colour-rendering ability of
the reference light source. is an average of the colour rendering ability of eight test colours;
better performance at some wavelengths is concealed when average with poorer performance
at other wavelengths.
Colour Rendering Index of common lighting sources.

Incandescent lamps emit energy in a smooth curve beginning with a small amount of deep blue
radiation in the near ultraviolet range and increasing into the deep-red portion of the spectrum.
It complements the appearance of warm colours and human faces. Incandescent lamps enjoy
one slight advantage over other lamps in colour rendering-not because they render colours
more naturally but because more than a century of use has established them as a norm.
Tungsten-halogen lamps (3000k) have more blues and less red energy than standard
incandescent lamps; they appear whiter than the slightly yellowish standard incandescent lamps
(2700K). All incandescent and tungsten – halogen lamps are assigned a CRI of 100
Parts of an Incandescent Lamp

A-Arbitrary (With Familiar Teardrop Shape)
AR-Aluminum Reflector
B-Flame (Smooth)
C-Cone Shape
CA-Candle
F-Flame (Irregular)
G-Globe Shape
GT-Globe–tubular
MR-Multifaceted Mirror-reflector
P-Pear Shape
PAR-Parabolic Aluminized Reflector
PS-Pear–straight Neck
R-Reflector
S-Straight Side
T-Tubular
The family of large lamps
contains about hundred
combinations of glass quartz
shapes and sizes. These
variations are designated by a
two-part abbreviation: the first
part, one or more letters,
indicates the shape of the bulb
and second part, a number
which says the diameter of the
bulb in eighths of an inch.

Incandescent lamps have a base at one end, although some tubular lamps have bases at both
ends. All bases conduct current from the electrical supply into the lamp; most bases also support
the lamp physically, but many kinds of PAR lamps can be supported by their bulbs. The most
frequently used is the medium base; its name describes its size. Smaller lamps have smaller bases,
including bayonet, bipin, candelabra, intermediate, miniature, mini-candelabra (“mini-can”),
twist-and-lock (TAL), and two-pin bases. Larger lamps have larger bases, including mogul screw
and medium and mogul bipost bases. The bipin and bipost bases orient the filament position,
providing rotational alignment for optical control. Bayonet and prefocus medium and mogul
bases also locate the filament in the exact predetermined position required for optical
instruments and searchlights.

R Lamps
In reflector (R) lamps, the bulb is
shaped into a reflecting contour;
the inner surface is coated with
vaporized silver. The lamps are
available in spot or flood beam-
spreads. Spot lamps have a light
frost on the inside front of the
bulb; flood lamps have a heavier
frosting to increase the spread of
the beam. As with non-directional
and semi-directional
incandescent lamps, the glass
bulbs of most R lamps are made
of blown lime glass. This “soft”
glass is intended only for indoor
use. Some wattages are available
in a “hard,” heat-resistant glass for
areas where contact with
moisture is a possibility, but these
lamps still require protection from
rain. All R lamps emit a substantial
percentage of light outside the
principal beam. Unless
intercepted by an auxiliary
reflector, this light is usually lost
due to absorption within the
luminaire; in most luminaires, R
lamps are inefficient.
PAR Lamps
Parabolic aluminized reflector (PAR) lamps are made of
low-expansion, heat-resistant borosilicate glass that is
pressed rather than blown. This method of construction
allows great precision in shaping the reflector of the bulb
and in the configuration of the lens, as well as in the
positioning of the filament. The combined precision of these
factors accounts for the superior beam control and greater
efficacy that are characteristic of PAR lamps. PAR lamps
were originally designed for outdoor applications and are
sometimes still referred to as “outdoor” lamps because they
are weather-resistant. Over the years their use indoors has
grown rapidly wherever efficacy and precise beam control
are desired. PAR lamps are available with beam spreads
that range from 3° (very narrow spot, or VNSP) to 60° (very
wide flood, or VWFL). The initial beam is formed by the
shape of the reflector and the position of the filament. The
configuration of the lens modifies that beam: a light stipple
smoothens the narrow beam for a spot lamp; “prescription”
lenses similar to those of car headlights provide the wider
beam distributions of flood lamps. In cool-beam PAR lamps,
a reflective dichroic coating replaces the bright aluminum
used on the reflector surface of standard PAR lamps. Visible
wavelengths (light) are reflected forward into the beam
while infrared wavelengths (heat) pass through the back of
the bulb. About two-thirds of the heat energy in the beam
is removed; light output and distribution are unchanged.
These lamps were originally developed to light perishable
foods.

In electric discharge lamps, light is produced by the passage of an electric current through a
vapor or gas, rather than through a tungsten wire as in Incandescent Lamps.
A fluorescent lamp is a low-pressure mercury arc discharge source. Its operation relies on an
electrical arc passing between two cathodes, one at either end of a glass tube. Fluorescent
lamps require A ballast to provide the proper starting voltage and regulate the lamp operating
current.
When the voltage difference between the two cathodes is sufficient to strike an arc, an
electric current passes through mercury vapor within the bulb. As the arc current passes through
the vapor, it causes changes in the energy levels of electrons in the individual mercury ions. As
the electrons change levels, they release several wavelengths of visible and ultraviolet energy.
This radiation strikes the tube wall, where it causes phosphor material to fluoresce (become
luminous) and emit light
Components of a Fluorescent Lamp

Preheat fluorescent lamp dia. and bases
Instant-start lamp dia. and bases
Rapid-start lamp dia. and bases

Compact fluorescent lamps provide high efficacy, a CRI of 82, and 10,000- to 20,000-hr lives in a
single-ended, multi-tube fluorescent lamp. They operate in the preheat and rapid-start circuit
modes; many have a starter built into the lamp base. Compact fluorescent lamps have
significantly higher lumen output per unit length than conventional small fluorescent lamps. This is
the result of high phosphor loading, which is necessary because of their small diameter and
sharp-concerned, multi-tube bulb shape. As with all fluorescent lamps, compact ones require a
ballast in order to start and operate properly.
The compact lamp use the same high –colour-rendering rare-earth phosphors as the t5 and t8
lamps mentioned earlier. Colour temperature varies according to the relative balance among
the phosphors. The 2700K colour temperature is often used to stimulate the colour of standard
incandescent lamps; 3000K is compatible with tungsten-halogen and linear, straight tube 3000k
fluorescent lamps; 3500k and 4100k are compatible with straight tube 3500k and 4100k
fluorescent lamps, respectively.
Twin-tube CFL Quad-tube CFL Triple-tube CFL ‘Long’ CFL Non-modular, self-
Ballasted, CFL

Coloured fluorescent lamps emit only a particular portion of the spectrum; the colour is
determined by the selection of the phosphors used. Different mixtures of phosphors composition
produce different colours of light. In a few cases, additional filtering is required to absorb
mercury radiations that will otherwise desaturate the colour. For red and deep blue lamps, a filter
coating is applied to the outside bulb wall. The gold fluorescent lamp achieves its colour by
subtraction, because no phosphors emit mainly yellow light. A yellow filter coating on the inside
of the tube absorbs the unwanted wavelengths from a warm-white phosphor. Whenever
subtractive filtering is used, luminous efficacy is reduced. Black light fluorescent lamps use a
special phosphor that emits primarily near-ultraviolet energy, plus a small amount of visible blue
light. Coloured fluorescent lamps vary widely in lumen output. For example, twenty-five red
lamps are required to equal the lumen output of one green lamp. Different colours of light have
different degrees of effectiveness in attracting attention; this is independent of brightness
intensity.

A Colour filter is a sheet of transparent material that modifies A light beam by selective
absorption of some colours in relation to others. A neutral filter absorbs all wavelengths equally
and merely serves to reduce the intensity of a beam of light without changing its colour. Colour
filters are usually designed for incandescent lamps. Other types of light sources, lacking a truly
continuous spectrum, are seldom used with coloured filters. The various kinds of colour filters
available are as follows:
• Gelatin filters (gels):
The are thin, coloured, transparent plastic sheets available in a wide variety of colours as well as
multicoloured and diffusing sheets. Deeper saturation are obtained by using more than one
thickness. They have short service life because their colour fades rapidly due to light and heat
transmit.
• Coloured plastic panels:
They are available for use with fluorescent lamps but are unsatisfactory for use with hot
incandescent filaments.
• Coloured glass filters:
They can withstand the heat of incandescent lamps, come smooth, stippled, prismatic or split;
they are highly stable.
• Interference filters:
It consist of one or more layers of ultrathin film coating on clear glass that reflect rather than
absorb the unwanted wavelengths. The number and thickness of the film coatings determine the
transmission because unwanted wavelengths are not absorbed, interference filters remain cool.
• Broadband/dichroic filter:
They are designed to reflect a portion of the spectrum; infrared or ultraviolet or both. They are
also called dichroic because they transmit one colour and reflect the complimentary colour.

Interference Filter
Coloured Plastic Panels
Gelatin Filter Coloured Glass Filter
Dichroic Filter

An LED lamp is a light-emitting diode (LED) product which is assembled into a lamp (or light
bulb) for use in lighting fixtures. LED lamps have a lifespan and electrical efficiency which are
several times greater than incandescent lamps, and are significantly more efficient than
most fluorescent lamps. LEDs use only about 10% of the energy an incandescent lamp
requires. Like incandescent lamps and unlike most fluorescent lamps (eg. Tubes and compact
fluorescent lamps or Cfls), LEDs come to full brightness without need for a warm-up time; the
life of fluorescent lighting is also reduced by frequent switching on and off. The initial cost of
LED is usually higher. Degradation of LED dye and packaging materials reduces light output to
some extent over time.

• Light colour:
‘White LED’ light is produced by Led lights that deliver blue light which is then ‘shifted’ into the
broader spectrum by phosphors. This is much the same as the way fluorescent technology
produces ‘white’ light. LED lamps are usually available in a variety of colour-temperatures.
• Light output:
Light output is the main aspect of LED performance that is still developing. LED technology will
increasingly provide lighting solutions as light output and efficacy improves.
• Heat production:
LED lights generate very little heat when compared to other light sources. However, minimizing
the temperature at the internal junction between the power supply and the LED material is
critical to ensure long LED life.
• Glare:
Glare can be a problem with LED lights because of the small size of each light in relation to the
amount of light they produce.
• Operating Life:
The operating life of LEDs can easily exceed 50,000 hours. Compared to other light sources,
LEDs very rarely fail. Only the luminous flux is slightly reduced over the operating period. In
practice, LEDs are virtually service-free during their entire period of use, depending on the
particular application.

• They require less energy to power, LEDs will save you electricity.
• Compared to incandescent bulbs, LED lights will save you around 80% of electrical power.
• In comparison with a halogen lamp, there is a 75% saving on electricity.
• They contain no hazardous solids, liquids or gases – which can be harmful to the environment.
• LED Lights are available in a number of different colours and shades that can define the style,
setting and ambience you desire.
• There is no high-powered discharge that can have a detrimental effect on the eyes.
• LEDs use direct light meaning there is no light pollution.
• LEDs have no UV light, eradicating the possibility of skin damage.
• They are easy to install – simply screw on.
• LEDs have a thick epoxy which makes them incredibly durable and pretty much impossible to
break.
• They have the ability to be dimmed
• They can last up to 50,000 hours
• LEDs immediately switch-on with no warm-up time
• LEDs last 2400% longer than regular halogen bulbs

Quality lighting is an important aspect of our daily life, and is often taken for granted. Light
control is the ability to regulate the level and quality of light in a given space for specific tasks
or situations. Controlling light properly not only enhances the experience, it helps to save
energy by using light when and where it is needed most. Light control mainly have two
purposes: (1) To direct the light where it is wanted and (2) To block light where it is unwanted-
to shield the lamp from viewing angles that would otherwise cause glare. The control of light
direction is accomplished by three methods: reflection, transmission and refraction.

Baffles and Louvers shield glare at normal viewing angles, thereby contributing to visual
comfort. Baffles provide shielding in one direction, along a single axis. For small-aperture
luminaires, a baffle around the perimeter provides shielding from all directions. Louvers are a
series of baffles or shielding elements placed in a geometric pattern to provide shielding from
many directions with minimum interference to the desired beam distribution. Baffles and
Louvers conceal the light source from direct view within this specified zone, horizontal work
surfaces are still directly exposed to the source. The mirrored image of the light source
becomes a source of reflected glare from glossy paper, photographs, objects behind glass,
and polished tabletops.
Baffles and louvers may be black or made from reflective and transmitting materials. The
intensity of light directed toward the eye is determined by the luminance of these surfaces.
The choice of materials is based on various considerations including visual comfort and design
harmony with the space. To achieve concurrent glare control and lamp concealment with
minimal change in the diffuse beam, use open louvers, or plastic or glass with a slight degree
of diffusion. Whether the beam is modified by diffuse reflection or by diffuse transmission, the
distribution of light is the same.
Baffles Louvers

Baffles used in Interior space.
Louvers used in Interior space.

A dimmer provides variation in the intensity of an electric light source. Full-range dimming is the
continuous variation of lighting intensity from maximum to zero without visible steps. All
dimming systems operate on one of two principles for restricting the flow of electricity to the
light source: (1) varying the voltage or (2) varying the length of time that the current flows
during each alternating current cycle. There are 3 types of dimmers which are as follows:
• Resistance Dimmers:
Resistance Dimmers were the first dimming method; they were used mainly in theatres in the early part of the
twentieth century. A resistance dimmer, or “rheostat,” controls voltage by introducing into the circuit a
variable length of high resistance wire. The longer the length of the wire, the greater the resistance, the lower
the voltage, and the lower the intensity of the lamp. In order to absorb a sufficient amount of energy, the
resistance wire must be quite long; for this reason it is often coiled. Current flows into one end of the coil and
an arm slides along the resistance wire in increments. Dimming is thus achieved in a series of steps, often a
minimum of 110 to appear “flicker-less.” A large drawback to this kind of dimmer is that the portion of the
current that would otherwise produce light is instead converted to heat. Also, no savings in energy is realized:
although light output is reduced, connected wattage remains unchanged. In addition, these dimmers are
bulky; consequently, they are no longer used.
• Autotransformer Dimmers:
Autotransformer dimmers avoid these problems by using an improved method of dimming. Instead of
converting the unused portion of the current into heat, the autotransformer changes the standard-voltage
current into low-voltage current, with only a 5 percent power loss. A transformer has two coils of wire; the ratio
of the number of turns in one coil to the other produces the ratio of the voltage change induced by the
transformer. An autotransformer is simply a variable transformer: the primary coil remains fixed, while the
number of turns in the secondary coil is varied by a rotating arm that controls successive turns of the coil.
Because electrical power can be drawn from different points along the secondary coil, different voltages are
achieved from the same transformer. Because autotransformers do not convert energy to heat as light
intensity is reduced, they are therefore cooler and more compact than resistance dimmers. Autotransformer
dimmers are widely available in sizes up to many thousands of watts.

• Solid-State Dimmers:
Solid-state dimmers are predominant today; they use the second of the two methods of limiting current flow.
A power control device— such as a silicon-controlled switch (SCS) under 6 kW, or a silicon-controlled rectifier
(SCR) over 6 kW—allows electric current to flow at full voltage, but only for a portion of the time. This causes
the lamp to dim just as if less voltage were being delivered.
Resistance dimmer. Autotransformer dimmer.
Solid-state dimmer.

Project Report On Lighting Design

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