| Glossry
of Terms |
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Arc
Tube : A completely sealed quartz or ceramic
tube where the electrical discharge (arc) occurs
and light is generated. |
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Correlated
Color Temperature (CCT) : The perceived "color"
of the light emitted by a lamp expressed in kelvin
(K) units. |
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Current
Crest Factor : The ratio of the peak-to-rms
value of lamp current ; metal halide magnetic ballast
values range from 1.5 to 1.8 |
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Economic
Life : The number of hours a group of lamps
will burn before if is economically and aesthetically
advisable to group relamp (typically 60% to 75%
of rated life). |
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Efficacy
(Lamp) :A ratio of lamp lumens to lamp power,
measured in lumens per watt (LPW). |
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HID
: High intensity discharge lamps; includes metal
halide, mercury vapour and high pressure sodium. |
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Lamp
voltage : The RMS voltage at which lamps operate
when they are fully warmed up. |
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Lamp
Power : The Power Consumed by a lamp after warm-up,
measured in watts. |
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Lamp
Regulation : The ratio of lamp power to lamp
voltage often expressed in graphical format. |
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Line
Regulation : The ratio of lamp power to ballast
input voltage often expressed as a percentage. |
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Lumens
: A measurement of light; takes into account
the human eye sensitivity curve so that more weight
is given to the yellow-green part of the light spectrum
(photopic). |
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Lumen
Maintenance : The lumen output of a lamp at
a given operating time or a percentage of 100 hour
lumens at that time. |
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Lumens
Per Watt (LPW) |
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Maximum
Overall Length (MOL) : The maximum allowable
distance from the top of the glass bulb to the end
of contact of the base. |
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Mean
Lumens : Light output at 40% of rated lamp life. |
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Starting
Pulse :A high-voltage, low-energy pulse superimposed
on the open circuit voltage of some HID ballasts
to aid in starting a lamp. |
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Warm-Up
Time :The amount of time from ignition of the
lamp to 90% of full light output. |
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Watts
:A measure of energy (in joules) being used
or emitted each second. |