INFRA-RED lamps are designed for
heating rather than lighting. The filament operates at a lower temperature around 2200 degrees
Celsius. About 86% of the input energy is produced as radiant energy.
Figure 4.15 shows lamp shapes similar to reflector lamps but made from hard glass.
They are used to provide radiant heating for people and industrial processes. Red fronted versions
reduce the lamp brightness where it may cause discomfort.
Figure 4.15. Infra-red lamps.
Lamp Operating Characteristics
There are four main characteristics:
-
Efficacy - defines light output per
unit of power input (lumens/watt).
-
Lumen Maintenance - defines how
light output decreases as lamp ages.
-
Mortality - defines average lamp
life expectancy.
-
Colour Rendering - defines how the
lamps affect colour perception.
The following comparison illustrates this point:
|
Lamp type
|
Light Output
(Lumens)
|
Efficacy
(lumens/watt)
|
|
100W gls
|
1350
|
13.5
|
|
100W Double Life
|
1200
|
12.0
|
|
100W Pluslife
|
1050
|
10.5
|
Lamp Mortality
Lamp mortality defines how long lamps are expected to last. It is expressed as RATED AVERAGE
LIFE in hours of operation. Lamps usually fail when the filament breaks due to evaporation or
physical shock. There is a choice of lamp life for incandescent lamps to suit different
installations where access or maintenance cost can vary.
-
gls 1000 hours
-
Double Life 2000 hours
-
Pluslife 3000 hours
Compared with other lamp types,
incandescent lamps have a relatively short rated average life.
|
