Satco Products HID Lamps, Catalog

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HID Basics
HOW IT WORKS
The operational concept behind HID lamps
is very similar to that of fluorescent lamps.
Electrodes are positioned at either end of a
tube, whose chamber is filled with gas and
metals such as mercury. An electrical charge
passes from one electrode to the other. In
fluorescent lamps, this charge creates
ultraviolet (UV) light, which converts to visible
light once it passes through the phosphors
on the tube’s interior.
In an HID lamp, the electrical arc, gasses
and metals are contained in what is known
as the arc tube. The arc tube is made from
either quartz (used in mercury vapor and
metal halide lamps) or transparent ceramic
(used in high-pressure sodium lamps because of
their high temperature). All arc tubes are housed
within a larger outer glass envelope.
Unlike fluorescent lamps, the arc tube of HID lamps is
filled with gas at a very high rate of pressure (up to 50
psi). This allows the electrical arc created by the electrodes to
operate in the visible part of the spectrum, producing usable light
without the addition of phosphors.
Like fluorescents, HID lamps require a ballast to control the electrical current
in the arc tube. Certain HID lamps also require an ignitor, which produces a
high voltage to pulse the arc tube, allowing the arc to strike.
The biggest difference in HID lamps is the fact that they need a start-up time to reach their full brightness. This usually takes
five to 10 minutes, during which time the lamp will flicker until the metal inside fully vaporizes and the lamp reaches is full
operating temperature.
Visible Light
Electrode
Arc Tube
Filled with
Gasses &
Metals
Starting
Electrode
(Probe)
New HID lamps require a “burn in” period of
approximately 100 hours before the lamp will
reach its true specified color. Until this process is
completed, lamps can be unstable and vary in
color.
As HID lamps age, chemical changes occur that
cause color shifting. The shifts vary depending
on the lamp type.
Standard probe start
lamps tend to shift
color about twice as
much as pulse start
lamps. Results vary
from lamp to lamp.
It is recommended
to conduct a group
relamping once it
is determined that
a lamp or group of
lamps is changing
color or failing. This
way, the area being
illuminated will main-
tain an even balance
of color and light.
FACT:
HID lamp color is
rated in kelvins and
is reffered to as its
Correlated Color
Temperature (CCT).
FACT:
Colors are created
by using different
arc tube designs
and changing the
mixture of chemicals
within the tube.
Burning
Positions
Certain HID lamps have been
designed to operate in a specific
position to achieve targeted life
or performance goals. These
examples illustrate these burning
positions
Vertical
BU-HOR
Vertical
BD-ONLY
Vertical
BU-ONLY
Universal
U
Horizontal
HOR
Double Ended
HOR
105º
15º 15º
15º 15º
15º
15º
15º
15º
4º
4º
4º
4º