Crestron electronic Green Light GLPS-HSW-FT - Manual (Page 80)

Crestron Commercial Lighting Design Guide
76
Appendix C – Glossary of Lighting Ter
m
s
FOOT CANDLE (FC): The English unit of measurement of the illuminance
(or light level) on a surface. One foot candle is equal to one lumen per
square foot
FORWARD PHASE DIMMING: Rather than attempting to restrict the
amplitude of the current flowing through a lamp, as in other forms of
dimming, forward phase control works by switching off the beginning
part of each cycle of the alternating current supply
FOUR-WIRE 10V ANALOG SIGNAL DIMMING: Two power wires (switched
hot and neutral) and two additional control wires that are connected to a
low-voltage circuit. Note: these ballasts do not turn on and off like DALI
ballasts, so in addition to the low-voltage-level control circuit, they must
also have a line-voltage switch. Zero to ten-volt control is a low-voltage
DC dimming method. Power wires are rated Class 1 and control wires
are rated Class 2. This separation allows multiple circuits to use the
same dimming signal without additional power equipment
G
GLARE: The effect of brightness or differences in brightness within the
visual field sufficiently high to cause annoyance, discomfort or loss of
visual performance
H
HALOGEN: (SEE TUNGSTEN HALOGEN LAMP)
HARMONIC DISTORTION: A harmonic is a sinusoidal component of a
periodic wave having a frequency that is a multiple of the fundamental
frequency. Harmonic distortion from lighting equipment can interfere
with other appliances and the operation of electric power networks. The
total harmonic distortion (THD) is usually expressed as a percentage of
the fundamental line current. THD for 4-foot fluorescent ballasts usually
range from 20% to 40%. For compact fluorescent ballasts, THD levels
greater than 50% are not uncommon
HID: Abbreviation for high intensity discharge. Generic term describing
mercury vapor, metal halide, high-pressure sodium, and (informally)
low-pressure sodium light sources and luminaires
HIGH BAY: Pertains to the type of lighting in an industrial application
where the ceiling is 20 feet or higher. Also describes the application
itself
HIGH OUTPUT (HO): A lamp or ballast designed to operate at higher
currents (800 mA) and produce more light.
HIGH POWER FACTOR: Ballast with a 0.9 or higher rated power factor,
which is achieved by using a capacitor.
HIGH PRESSURE SODIUM LAMP: A high intensity discharge (HID) lamp
whose light is produced by radiation from sodium vapor (and mercury)
HOT RESTART or HOT RESTRIKE: The phenomenon of re-striking the arc
in an HID light source after a momentary power loss. Hot restart occurs
when the arc tube has cooled a sufficient amount
I
IESNA: Abbreviation for Illuminating Engineering Society of North
America.
ILLUMINANCE: A photometric term that quantifies light incident on a
surface or plane. Illuminance is commonly called light level. It is
expressed as lumens per square foot (foot candles), or lumens per
square meter (lux)
INDIRECT GLARE: Glare produced from a reflective surface.
INSTANT START: A fluorescent circuit that ignites the lamp instantly with
a very high starting voltage from the ballast. Instant start lamps have
single-pin bases
L
LAMP CURRENT CREST FACTOR (LCCF): The peak lamp current divided
by the RMS (average) lamp current. Lamp manufacturers require <1.7
for best lamp life. An LCCF of 1.414 is a perfect sine wave
LAMP LUMEN DEPRECIATION FACTOR (LLDF): A factor that represents
the reduction of lumen output over time. The factor is commonly used as
a multiplier to the initial lumen rating in illumination calculations, which
compensates for the lumen depreciation. The LLD factor is a
dimensionless value between 0 and 1
LAY-IN-TROFFER: A fluorescent fixture; usually a 2' x 4' fixture that sets
or "lays" into a specific ceiling grid
LED: Abbreviation for light emitting diode. Consumes low wattage and
has a rated life of greater than 80 years. Increasingly popular as
production costs are decreasing.
LENS: Transparent or translucent medium that alters the directional
characteristics of light passing through it. Usually made of glass or
acrylic
LIGHT LOSS FACTOR (LLF): Factors that allow for a lighting system's
operation at less than initial conditions. These factors are used to
calculate maintained light levels. LLFs are divided into two categories,
recoverable and non-recoverable. Examples are lamp lumen
depreciation and luminaire surface depreciation
LIFE-CYCLE COST: The total costs associated with purchasing,
operating, and maintaining a system over the life of that system
LOUVER: Grid type of optical assembly used to control light distribution
from a fixture. Can range from small-cell plastic to the large-cell
anodized aluminum louvers used in parabolic fluorescent fixtures
LOW POWER FACTOR: Essentially, an uncorrected ballast power factor of
less than 0.9 (SEE NPF)
LOW-PRESSURE SODIUM: A low-pressure discharge lamp in which light
is produced by radiation from sodium vapor. Considered a
monochromatic light source (most colors are rendered as gray)
LOW-VOLTAGE LAMP: A lamp (typically compact halogen) that provides
both intensity and good color rendition. Lamp operates at 12V and
requires the use of a transformer. Common lamps are MR11, MR16, and
PAR36
LOW-VOLTAGE SWITCH: A relay (magnetically-operated switch) that
allows local and remote control of lights, including centralized time clock
or computer control
LUMEN: A unit of light flow, or luminous flux. The lumen rating of a lamp
is a measure of the total light output of the lamp
LUMINAIRE: A complete lighting unit consisting of a lamp or lamps, along
with the parts designed to distribute the light, hold the lamps, and
connect the lamps to a power source. Also called a fixture
LUMINAIRE EFFICIENCY: The ratio of total lumen output of a luminaire
and the lumen output of the lamps, expressed as a percentage. For
example, if two luminaires use the same lamps, more light will be
emitted from the fixture with the higher efficiency.