LIGHT SOURCES The Incandescent Filament Lamp
a. Construction This lamp is consists simply
• Electrical Lighting had its real beginning in
of a tungsten filament inside a gas-filled,
about 1870 with the development of
sealed glass envelope as shown in figure
commercially usable arc lamps and was
below, Current passing through the high
given a greater impetus nine years later by
resistance filament causes the familiar
Edison’s first practical incandescent lamp.
blackening of the bulbs and eventual
• Todays electric light source fall into three filament rupture and lamp failure.
generic classifications. a. The incandescent
Lamp, including tungsten-halogen types b.
The gaseous discharge lamp, which includes
the well-known fluorescent neon, and
mercury lamps. c. The electroluminescent
source.
• The efficiency of a light is termed its
efficacy and its measured lumen per watt.
Incandescent Lamp
Incandescent Lamps are available in
many bulbs and base types and special
designs for particular application.
Legend:
A. Standard Shape
L. . reflector
B,E flame shape
Characteristics of Outdoor Illumination M. straight
a. Factors C,D cone shape
The most prominent characteristic of N. Tubular
daylight is its variability. Obviously, the F. Globe
source of all daylight is the sun. The level of G. Combination of a and f
H. Pear shape
exterior illumination, at a particular place I. Arbitrary designation
and time, depends on: J. pear shape
1. Altitude and azimuth (latitude, date , K. Parabolic aluminized reflector
time of the day)
2. Weather conditions (clouds, cover, fog)
3. Effects of local terrain (natural, man-
made obstructions and reflections)
Factors in Interior daylighting
a. Horizontal and vertical surfaces
b. Window Details
c. Surface Reflections
d. Glare and Heat Control.
Incandescent Lamp
, These are made in “R” and PAR
shapes and contain reflective coating
on the side of the glass envelope; this
gives the entire lamp accurate light
beam control. Both types are
available in narrow or wide beam
design. Commonly called spot and
b. OPERATING CHARACTERISTICS flood, respectively. R Lamps are
generally made in soft glass
These are the critically dependent on the envelopes for indoor use. Whereas
voltage at the lamps; therefore, the life, PAR lamps are hard glass, suitable for
output, and efficiency of a lamp can be exterior application.
markedly altered by even a small change
in operating voltage, as illustrated by
this example.
Burning a 120V lamp at 125 V (104.2%
means approximately: 16% more light
(lumens) 7% more power consumption
(watts) 8% higher efficacy (lumens per
watt) 42 % less life (hours)
Burning a 120V lamp at 115 V (95.8%
means approximately: 15% less light
(lumens) 7% less power consumption
(watts) 8% lower efficacy (lumen per
watt) 72 % more life (hours)
b. INTERFERENCE (DICHROIC)
FILTERS
C. OTHER CHARACTERISTICS
Since filters had been previously use
1. Lumen Maintenance : light output
only in specialized applications such
decreases slowly with lamp life as the
as projection lamps to remove heat
bulb blackens. Position during burning
from light beam, are now available in
and bulb temperature affects this
lamps, the basic filter is a thin film
characteristics.
that operates on the interference
2. Color: white, with large, yellow –red
principle rather than absorption, thus
component and therefore highly flatter
the surface remains relatively cool.
ring to the skin. Since color depends on
temperature, high voltage lamp are
c. LOW VOLTAGE LAMPS
bluer, lower wattage lamp are yellower.
These lamps, in PAR shape and for 6-
Dimmed lamps give yellow-red light.
V operation, are available in
3. Surroundings: Generally impervious
extremely narrow beam spread (5 10
to external heat and cold or humidity,
degree) for special precision control
starting completely unaffected.
floodlighting. The low voltage makes
4. Lamp Efficiency: since incandescent
their application to exterior work
lamps produce light as a by-product of
simplier.
heat, they are inherently inefficient.
Efficiency increases with wattage ,
d. KRYPTON GAS
varying from 8% for a 25W lamp to 13%
This gas in lamps in place of the
for 1000 W unit.Thus a 100W lamp
usual nitrogen-argon mixture
produces the same 1750 lm as two 60 W
conducts heat more slowly from the
lamps, representing 20% increase in
filament and results in approximately
efficacy.
10% higher efficacy, longer life, and a
smaller envelope. The cost premium
SPECIAL INCANDESCENT LAMPS
for krypton lamps is approximately
INCLUDING TUNGSTEN -HALOGEN
50% . Application are in long-life
a. Reflector Lamps
a. Construction This lamp is consists simply
• Electrical Lighting had its real beginning in
of a tungsten filament inside a gas-filled,
about 1870 with the development of
sealed glass envelope as shown in figure
commercially usable arc lamps and was
below, Current passing through the high
given a greater impetus nine years later by
resistance filament causes the familiar
Edison’s first practical incandescent lamp.
blackening of the bulbs and eventual
• Todays electric light source fall into three filament rupture and lamp failure.
generic classifications. a. The incandescent
Lamp, including tungsten-halogen types b.
The gaseous discharge lamp, which includes
the well-known fluorescent neon, and
mercury lamps. c. The electroluminescent
source.
• The efficiency of a light is termed its
efficacy and its measured lumen per watt.
Incandescent Lamp
Incandescent Lamps are available in
many bulbs and base types and special
designs for particular application.
Legend:
A. Standard Shape
L. . reflector
B,E flame shape
Characteristics of Outdoor Illumination M. straight
a. Factors C,D cone shape
The most prominent characteristic of N. Tubular
daylight is its variability. Obviously, the F. Globe
source of all daylight is the sun. The level of G. Combination of a and f
H. Pear shape
exterior illumination, at a particular place I. Arbitrary designation
and time, depends on: J. pear shape
1. Altitude and azimuth (latitude, date , K. Parabolic aluminized reflector
time of the day)
2. Weather conditions (clouds, cover, fog)
3. Effects of local terrain (natural, man-
made obstructions and reflections)
Factors in Interior daylighting
a. Horizontal and vertical surfaces
b. Window Details
c. Surface Reflections
d. Glare and Heat Control.
Incandescent Lamp
, These are made in “R” and PAR
shapes and contain reflective coating
on the side of the glass envelope; this
gives the entire lamp accurate light
beam control. Both types are
available in narrow or wide beam
design. Commonly called spot and
b. OPERATING CHARACTERISTICS flood, respectively. R Lamps are
generally made in soft glass
These are the critically dependent on the envelopes for indoor use. Whereas
voltage at the lamps; therefore, the life, PAR lamps are hard glass, suitable for
output, and efficiency of a lamp can be exterior application.
markedly altered by even a small change
in operating voltage, as illustrated by
this example.
Burning a 120V lamp at 125 V (104.2%
means approximately: 16% more light
(lumens) 7% more power consumption
(watts) 8% higher efficacy (lumens per
watt) 42 % less life (hours)
Burning a 120V lamp at 115 V (95.8%
means approximately: 15% less light
(lumens) 7% less power consumption
(watts) 8% lower efficacy (lumen per
watt) 72 % more life (hours)
b. INTERFERENCE (DICHROIC)
FILTERS
C. OTHER CHARACTERISTICS
Since filters had been previously use
1. Lumen Maintenance : light output
only in specialized applications such
decreases slowly with lamp life as the
as projection lamps to remove heat
bulb blackens. Position during burning
from light beam, are now available in
and bulb temperature affects this
lamps, the basic filter is a thin film
characteristics.
that operates on the interference
2. Color: white, with large, yellow –red
principle rather than absorption, thus
component and therefore highly flatter
the surface remains relatively cool.
ring to the skin. Since color depends on
temperature, high voltage lamp are
c. LOW VOLTAGE LAMPS
bluer, lower wattage lamp are yellower.
These lamps, in PAR shape and for 6-
Dimmed lamps give yellow-red light.
V operation, are available in
3. Surroundings: Generally impervious
extremely narrow beam spread (5 10
to external heat and cold or humidity,
degree) for special precision control
starting completely unaffected.
floodlighting. The low voltage makes
4. Lamp Efficiency: since incandescent
their application to exterior work
lamps produce light as a by-product of
simplier.
heat, they are inherently inefficient.
Efficiency increases with wattage ,
d. KRYPTON GAS
varying from 8% for a 25W lamp to 13%
This gas in lamps in place of the
for 1000 W unit.Thus a 100W lamp
usual nitrogen-argon mixture
produces the same 1750 lm as two 60 W
conducts heat more slowly from the
lamps, representing 20% increase in
filament and results in approximately
efficacy.
10% higher efficacy, longer life, and a
smaller envelope. The cost premium
SPECIAL INCANDESCENT LAMPS
for krypton lamps is approximately
INCLUDING TUNGSTEN -HALOGEN
50% . Application are in long-life
a. Reflector Lamps
