Terms for Lighting
Glossary
Ampere
A unit expressing
the rate of flow of electric current.
Amperes(Design)
The approximate
current which the lamp will draw at design
volts
ANSI (American
National Standards Institute)
The organization
that develops voluntary guidelines and produce
performance standards for the electrical and
other industries.
Arc (electric) -- The visible light, or spark, produced when electricity jumps through air or a gas. Heat is produced also. Switches wear out because each time a switch is opened, a brief arc occurs and the switch contacts suffer a small amount of heat damage.
Arc Light -- Generally refers to a carbon arc lamp. Some of the first streetlights were carbon arc lights. The carbon arc lamp had the electricity jumping between a pair of carbon rods since these did not melt as metal electrodes did given the heat produced. (The carbon rod ends did evaporate gradually so arc streetlights required maintenance in the form of frequent rod replacement. Arc lights still used for theater spotlights today have automatic means of moving the rod ends back together as they wore away.) Mercury and sodium lights are technically arc lights since they contain small arcs passing through mercury or sodium vapor, respectively.
Average Rated
Life
An average rating,
in hours, indicating when 50% of a large group
of lamps have failed, when operated at nominal
lamp voltage and current; manufacturers use 3
hours per start for fluorescent lamps and 10
hours per start for HID lamps when performing
lamp life testing procedures; every lamp type
has a unique mortality curve that depicts its
average rated life. For PHOTO-OPTIC lamps
average rated life refers to the operating
period after which on statistical average, 50%
of the lamps will perform within their specified
values.
Ballast -- A coil of wire and/or related electronic components used to limit the amount or electric current flowing through a lamp. Almost all lamps other than incandescent lamps used in street lighting require ballasts. A device used with
an electric-discharge lamp to obtain the
necessary circuit conditions (voltage, current
and waveform) for starting and operating; all
fluorescent and HID light sources require a
ballast for proper operation. Ballasts have two
primary functions: 1) start the lamp and 2)
control operation of the lamp once it has
started. High frequency electronic ballasts
operate lamps more efficiently (30 - 40% at
equivalent light output) and eliminate the hum
and visible flicker normally associated with
standard magnetic ballasts. Electronic ballasts
also typically have better power quality than
magnetic ballasts (higher power factor and lower
THD).
Ballast Efficacy
Factor (BEF)
Relative light
output (ballast factor) divided by input power
(watts). Used to measure the level of efficiency
of similar ballast models. For example, the
OSRAM SYLVANIA QT2X32IS which has a ballast
factor of 0.90 and input watts of 59 (BEF=1.53),
is more efficient than competitors' electronic
ballasts with ballast factor of 0.875 and input
watts of 62 (BEF=1.41).
Ballast factor (BF)
Relative light
output as compared to a reference ballast (i.e.
BF of 0.90 would yield 90% of a lamp's rated
lumens. The measured ability of a particular
ballast to produce light from the lamp(s) it
powers; ballast factor is derived by dividing
the lumen output of a particular lamp/ballast
combination by the lumen output of the same
lamp(s) on a reference ballast.
Ballast
life
OSRAM SYLVANIA
ballasts are designed to have a life expectancy
of 60,000 hours. To maximize life, ambient
temperature should be kept as low as possible.
It is also important to maintain effective
dissipation of heat using the lighting fixture
as a heatsink for the ballast enclosure.
Ballast
losses
Power consumed by a
ballast that dissipates as heat instead of being
converted into light. Electronic ballasts
operate more efficiently than magnetic or hybrid
ballasts. A typical ballast loss for a standard
two lamp magnetic ballast is 20 watts, which an
electronic equivalent would only be 7 watts.
Ballast
types
There are three
types of lighting ballasts: 1) Magnetic: an
inefficient device that uses a core and coil
assembly transformer to perform the minimum
functions required to start and operate the
lamp; 2) Hybrid or "low frequency electronic":
essentially a magnetic ballast with a few
electronic components that switch off voltage to
the lamp coil once the lamp has started. A
minimal increase in efficiency is obtained via
more expensive magnetic core material and the
absence of power to the lamp coils during
operation; 3) High frequency electronic: a
ballast that operates lamps at frequencies above
20,000 Hz. Maximum efficiency is obtained
through the use of electronic circuitry and
optimum lamp operating characteristics.
Base The lamp
base mechanically holds the lamp in place in the
application. The lamp base directly or
indirectly (via a cable or lead-in wires)
conducts electricity from the circuit to the
lamp and can be designed to dissipate heat. Lamp
bases should be operated within specified
temperature range.
Beam
angle
Also called the beam
spread; the angular dimension of the cone of
light from reflectorized lamps encompassing the
central part of the beam out ot the angle where
the intensity is 50 percent of maximum.
Bulb
Hard, soft or quartz
glass enclosure, which can contain a vacuum,
elemental inert gas or metal and a means of
light generation (filament or electrodes).
Candela (cd)
The unit of measure
indicating the luminous intensity (candlepower)
of a light source in a specific direction; any
given light source will have many different
intensities, depending upon the direction
considered.
Candlepower
distribution
A curve that
represents the variation in luminous intensity
(expressed in candelas) in a plane through the
light center of a lamp or luminaire; each lamp
or lamp/luminaire combination has a unique set
of candlepower distributions that indicate how
light will be spread.
Center Beam
Candlepower (CBCP)
The intensity of
light produced at the center of a reflector
lamp, expressed in candelas.
Color rendering
index (CRI)
The Color Rendering
Index (CRI) measures the effect a light source
has on the perceived color of objects and
surfaces. High CRI lights makes virtually all
colors look natural and vibrant. Low CRI causes
some colors to appear washed out or even to take
on a completely different hue.
Color temperature (CT)
Color temperature,
which is measured in Kelvin, indicates whether a
lamp has a warm, midrange or cool color
appearance. "Warm" light sources have a low
color temperature (2000-3000K) and feature more
light in the red/orange/yellow range. Light with
a higher color temperature (>4000K) features
more blue light and is referred to as "cool."
Compact
fluorescent lamps
Compact fluorescent
lamps employ small diameter tubes that are bent
so they begin and end in a ceramic base. This
allows them to be produced in a wide variety of
configurations, greatly extending the
applications for fluorescent lighting.
Correlated Color
Temperature (CCT)
A specification of
the color appearance of a lamp, relating its
color to that of a reference source heated to a
particular temperature, measured in degrees
Kelvin (K); CCT generally measures the "warmth"
of "coolness" of light source appearance.
Current
A measure of the
flow of electricity, expressed in amperes
(A).
Curvalume
Brand name of
SYLVANIA's line of U-shaped fluoresent lamps,
available in T-8 and T-12 versions.
Cutoff -- Refers to the aiming of light down onto the street and reducing of light that can be seen from above. Full cutoff refers to streetlights that direct no light above their mounting level. Non-cutoff refers to streetlights with little or no aiming of light. Semi-cutoff refers to streetlights with a reflector that aims most of the light downward.
Décor
Decorative lamps,
such as candelabra or post lights, in a variety
of shapes and bases.
Description
See ordering
abbreviation.
Dime -- A temporary insulating device the size and shape of a coin that is placed between a pair of metal strips specifically intended to hold it and which metal strips if they touched would short out or bypass one lamp in a series circuit. When subjected to a certain voltage kick occurring if the lamp burns out, the dime burns through and becomes an alternate current path for the purpose of keeping the rest of the lamps in the circuit operating. Once in awhile the dime (and also the shunt inside a miniature Christmas tree lamp that performs the same function) fails to work and it is then necessary to go from lamp to lamp to find the burned out one.
Double-ended
Lamps that have two
bases opposite one another for series electrical
connection, mechanical mounting and heat
dissipation.
Dulux(R)
Brand name of
SYLVANIA's line of compact fluorescent
lamps.
Efficacy
The rate at which a
lamp is able to convert power (watts) into light
(lumens). A watt of electricity is the amount of
power in and a lumen or light is the amount of
power out. Represented in lumens per watt and
found by dividing the light output in lumens by
the electrical power input (to the lamp). Also
see LPW performance.
Electronic
ballasts
The electric arc in
any fluorescent system is generated by a
ballast. The ballast starts the lamp, then
limits its operating current and provides power
factor correction. Modern electronic ballasts
perform these functions with great efficiency
and provide other control functions as well.
Electronic
Control Systems
See Ballast
End Foot Candles
(EFC)
A measure of that
portion of the total light output of a T-2 lamp
that passes through a .250" orifice placed at
the end of the lamp.
Energy
A measure of work
done by an electrical system over a given period
of time, often expressed in kilowatt-hours
(kWh).
Envelope -- Another term for the glass or quartz bulb part of a lamp. Mercury and high pressure sodium lamps have a small inner envelope to contain the arc, maintain proper pressure of the mercury or sodium vapor, and maintain the proper temperature using a small enclosed space. The outer envelope absorbs harmful ultraviolet light or converts it to visible light using a layer of phosphors, limits the cooling down of the inner bulb, and provides safety from the high temperature of the inner bulb.
External Wiring -- Refers to streetlights where the current carrying wires emerge from the luminare and are strung through the air or along insulators mounted on the bracket arm.
Filament
A tungsten wire
purposely positioned inside a lamp bulb, that
when heated electrically generates radiation in
the visible, infrared and ultraviolet ranges.
Tungsten material replaced carbon almost
universally, as it has great tensible strength,
and is very durable. However, the basic reason
for its selection as the best filament material
is the fact that it can be burned very near its
melting point without evaporating rapidly. Lamp
filaments are offered in a variety of designs
optimized for specific applications.
Fixture
see Luminaire.
Floodlight
A reflectorized lamp
whose emitted beam pattern is enlarging. Also a
luminaire consisting of lamp and reflector at
fixed distance providing a wide field of
illumination.
Fluorescent -- Emitting light of one color or a range of colors (usually human visible) when light of another color (usually ultraviolet) is shone upon it. The fluorescent lamp would give off no more than a dim bluish glow plus produce a lot of ultraviolet light mostly absorbed by the glass tube were it not for the fluorescent material (called phosphors) coating the inside of the tube. Mercury vapor lamps also produce ultraviolet light and are often coated with phosphors so they give off white light for more natural looking illumination in addition to the bright bluish (green-purple) glow of the mercury arc.
Fluorescent
lamp
High efficiency lamp
that uses an electric discharge through
low-pressure mercury vapor to produce
ultra-violet (UV) energy. The UV excites
phosphor materials applied as a thin layer on
the inside of a glass tube that makes up the
structure of the lamp. The phosphors transform
the UV to visible light.
Foot-candle -- Level of illumination (or amount of brightness) at any given spot on a one square foot area evenly illuminated by one lumen. A unit of
illuminance equal to 1 lumen per square
foot.
Frequency
The number of times
per second that an alternating current system
reverses from positive to negative and back to
positive, expressed in cycles per second or
hertz (Hz).
Fusing
All OSRAM SYLVANIA
Quicktronic ballasts contain inherent electrical
protection. Although there is no need to
externally fuse the ballast, should code or
regulation require one, 3 amp slow blow fuses
are recommended.
Glare
Excessive brightness
that may be caused by either direct of indirect
viewing of a light source.
Glow to arc
transition
In order to achieve
full rated lamp life, a ballast should start a
lamp so that the time from when the lamp begins
to glow to the time the lamp arc strikes should
be as short as possible. OSRAM SYLVANIA instant
start ballasts typically accomplish this task
within 50 msec.
Grounding
The ballast case and
fixture must always be grounded. The grounding
helps assure safety, proper lamp starting, and
acceptable EMI/RFI performance.
Halide Lamp -- A mercury lamp containing chemical compounds involving halogens so that the light produced is whiter compared with the green-purple glow from a pure mercury vapor lamp.
Halogen -- One of the chemical elements chlorine, fluorine, bromine, or iodine. Halogen lamp -- An incandescent lamp whose bulb is filled with one or a mixture of halogens in order to cause material naturally evaporating from the filament to tend to redeposit on the filament and thus make the filament last longer.
Halogen
lamps
(Tungsten-halogen
lamp) high pressure lamps containing halogen
gases which allow the filaments to operate at
higher temperatures and higher efficacies.
Halogen lamps use a filament, but since it is
sealed in a pressurized capsule containing
halogen gas, the lamp provides brighter, whiter
light with better color characteristics, longer
service life and improved energy efficiency.
Harmonic
An electrical
frequency that is an integer multiple of the
fundamental frequency; for example, if 60 Hz is
the fundamental frequency, then 120 Hz is the
second harmonic and 180 Hz is the third
harmonic; some electronic devices, such as
ballasts or power supplies, can cause harmonic
distortion, directly affecting power
quality.
Head -- Generally, the part of the luminaire that holds the lamp socket and mounting hanger or collar. When the mounting collar is part of or attached directly to the reflector housing, as in a clamshell style, that assembly has been referred to as either the head or the body.
HID (High Intensity Discharge) -- Generally refers to a mercury, mercury & metal halide, or sodium lamp. The electric arc ,or discharge, passing through mercury vapor, sodium vapor, etc. produces an intensely bright glow.
High-intensity
discharge (HID) lamps
In HID lamps, an arc
passing between two cathodes in a pressurized
tube cause various metallic additives to
vaporize and release large amounts of light. All
HID lamps offer outstanding energy efficiency
and service life. Metal halide lamps also offer
good to excellent color rendering index
(CRI).
Hot
ignition
The restarting of a
previously operating lamp shortly after
turn-off. Hot ignition is a high performance
feature in many OSRAM discharge lamp types.
Illuminance
Light arriving at a
surface, expressed in lumens per unit area; 1
lumen per square foot equals 1 footcandle, while
1 lumen per square meter equals 1 Lux.
Incandescent -- Being so hot as to give off light (glow). The principle behind the incandescent electric lamp is to maintain a component (the filament) in a white-hot glowing state by the use of electricity flowing through it. What Thomas Edison spent a long time in accomplishing was finding a material for the filament that lasted a reasonably long time without burning out and that could be kept hot enough to give off at least yellowish-white light which requires a higher temperature than giving off red light. Still higher temperatures result in a whiter light tending towards blue, which is more desirable for indoor photography. Lamps operating this hot have a much shorter lifetime due to accelerated evaporation of their filaments..
Incandescent
lamps
A light source that
generates light utilizing a think filament wire
(usually tungsten) heated to white heat by an
electric current passing through it. Regular
incandescent lamps produce light by passing an
electric current through a filament in a vacuum
or gas-filled bulb. They provide low initial
cost, good color rendition and excellent optical
control.
Instant start (IS) vs. rapid start (RS)
Instant start (high
voltage is applied across the lamp with no
preheating of the cathode) is the most energy
efficient starting method for fluorescent lamp
ballasting. IS ballasts use 1.5 to 2 watts less
per lamp than rapid start ballast (low voltage
is applied to the cathodes prior to lamp
ignition and is maintained throughout
operation). Other IS ballast benefits typically
include parallel lamp circuitry, longer remote
wiring distance, easier installation due to less
complicated wiring, and capability to start
lamps at 0 degrees (versus 50 degrees F for
rapid start).
Internal Wiring -- Refers to streetlights where the current carrying wires pass through a hollow bracket arm and on into the luminaire.
K-factor
A measurement that
quantifies the effect of non-linear equipment,
such as lighting ballasts, on an electrical
system. Lighting systems should be designed so
that the transformer rating is sufficient for
the ballast used (typically K-factor <4). All
OSRAM SYLVANIA ballasts meet this
specification.
Lamp
Manufactured light
source; synonymous with light bulb; the three
broad categories of electric lamps are
incandescent, fluorescent and high-intensity
discharge.
Lamp Current
Crest Factor (LCCF)
The ratio of peak
lamp current to the RMS (average) lamp current.
Lamp manufacturers require a LCCF of less than
1.70 in order to achieve full lamp life. Values
less than 1.70 do not achieve higher than rated
lamp life.
Lamp
Disposal
When disposing of
spent lamps, always consult federal, state,
local and/or provincial hazardous waste disposal
rules and regulations to ensure proper
disposal.
Lamp (electric) -- Correctly, the item commonly referred to as a light bulb or fluorescent tube.
Lamp
flicker
High frequency
electronic ballasts provide a minimal level of
lamp flicker. Lamp flicker from magnetic
ballasts can cause eye fatigue for some
people.
Lamp Fuse
OSRAM requires that
all PHOTO OPTIC lamps be fused in their
applications to prevent lamp over-powering.
Certain lamps contain their own internal fuse.
Please ensure lamps in your specific application
are fused with respect to their power
source.
Light
Radiant energy that
is capable of producing a visual sensation.
Light
bulb
see Bulb
Light Center
Length (LCL)
The distance from a
specified reference point on a lamp base to its
light center, typically expressed in inches.
Linear
fluorescent lamps
In a fluorescent
lamp, an electric arc passing between cathodes
in a tube excites mercury vapor and other gases
and produces UV radiant energy. A phosphor
coating on the tube then converts this energy to
visible light. Fluorescent lamps are very energy
efficient and provide a wide range of color
responses.
LPW
performance
Lumens Per Watt. The
number of lumens produced by a lightsource for
each watt of electrical power supplied to the
light source. Also see Efficacy.
Lumalux
Plus(TM)
Brand name of
SYLVANIA's line of high-pressure sodium (HPS)
lamps. These lamps are extremely energy
efficient, ideal for street lighting and other
non-color critical applications. This family
also includes Lumalux Plus(TM)/ECO(TM)
Lumen -- Unit of measure of illumination, equal to the amount of light that comes out of the hole resulting from cutting 1 square foot of surface area from a two foot diameter (one foot radius) opaque non-reflecting sphere at the center of which is a candle of certain defined characteristics burning under certain defined conditions. (A dinner table candle is roughly equivalent but I do not know the standard candle's exact measurements, wax material, wick length, or the other defined conditions.) A sphere two feet in diameter has approximately 12 square feet of surface area and the total light emitted by the candle is therefore around 12 lumens. Since the candle itself blocks some of the light, the amount of useful light from the candle is more like ten lumens, which many published references use as the definition of one candlepower.
Lumens
A unit of luminous
flux; overall light output; quantity of light,
expressed in lumens. For example, a dinner
candle provides about 12 lumens and a 60-watt
soft white incandescent lamps provides about 840
lumens.
Lumen
depreciation
The decrease in
lumen output of a light source over time; every
lamp type has a unique lumen depreciation curve
(sometimes called a lumen maintenance curve)
depicting the pattern of decreasing light
output.
Lumen-second: -- One lumen for a period of one second, or two lumens for a period of one half second, etc. (and then perhaps the light is turned off). For photography, if the light is dimmer, one can leave the shutter open longer, thus the usefulness of talking about a given light intensity for a given period of time. A peanut sized photoflash lamp (now obsolete) which burns fine zirconium wire in a clear glass oxygen filled bulb was rated at 8000 lumen seconds. Since the flash lasts for about 1/50 of a second, the brightness of the light, if it was sustained, comes out to 8000 x 50, or 400000 lumens which is equal to the light of twenty 400 watt mercury streetlights.
Luminaire -- The "streetlight itself" not counting the pole or bracket arm. It consists of at least the head, lamp socket, reflector if any, refractor or glass cover if any, and lamp. Sometimes it contains a ballast and/or photocontrol.
Luminaire
A light fixture; the
complete lighting unit, including lamp,
reflector, ballast, socket, wiring, diffuser and
housing.
Luminance (L)
Light reflected in a
particular direction; the photometric quantity
most closely associated with brightness
perception, measured in units of luminous
intensity (candelas) per unit area (square feet
or square meters).
Lux, or Meter-candle (lx) -- Level of illumination at any given spot given one lumen as it evenly illuminates one square meter (10-3/4 square feet) of area. A unit of luminance
equal to 1 lumen per square meter.
Mantle -- A mesh or similar component in a gas or oil lamp that more or less covers the flame. Its purpose is to be the light emitting component by becoming white hot (incandescent), while not cutting off the oxygen supply or significantly detracting from the burning of the flame. A gas or oil flame does not give off much light by itself, and when the fuel-air proportions are set for maximum light output, a lot of smoke and carbon deposits result. Instead the flame is adjusted for maximum heat and the mantle is placed over it. Much research went into the design of mantles both long ago for gas streetlights and in recent years for equipment such as Coleman lanterns. A mantle had to be of a material that would last a reasonable length of time in a white hot condition without disintegrating. (The same properties plus the ability to conduct electricity but not the being in the presence of oxygen were necessary for an incandescent electric lamp filament.) A typical mantle is the burned out remains of a small cloth bag. It is typically supplied and sold unburned for ruggedness during installation. After the bag is burned at the first usage, the ash skeleton remains intact because of the chemicals the bag was soaked in, but it is still very brittle and fragile. When a hole develops in the mantle as it eventually burns away or is mishandled, the flame burning characteristics or air/fuel mixture may be upset so as to cause additional loss of light output. Therefore the mantle needs periodic replacement. (See, also, Wick.)
Maximum Overall
Length (MOL)
The total length of
a lamp, from top of bulb to bottom of base,
typically expressed in inches.
Mean Spherical
Candela (MSCD)
The average value of
the luminous intensity of a light source in all
directions. To convert MSCD to Lumens, multiply
by 4?(12.57).
MTBF - Mean Time
Between Failures A calculation of ballast
life based on thermal conditions, component
values, and circuit characteristics used to
develop relative predictions of ballast life.
OSRAM SYLVANIA uses methodology that typically
provides a 1:10 actual life prediction based on
MTBF calculations.
Medium
pin
Referring to the
lamp base pin diameters. Often referencing
fluorescent lamps (T-8F and T-12F).
Metalarc(R)
Brand name of
SYLVANIA's line of metal halide lamps -- the
most energy efficient source of white light
available today. This family also includes
Metalarc Pro-Tech(R), Pulse Start and Super
Saver lamps.
Multiple -- Parallel, q.v.
NEMA -- National Electric Manufacturers' Association, a group of industry representatives who set standards (not always adhered to) for various types of electrical equipment including streetlights and traffic signals. Standards included dimensions (streetlight components), weights, current consumption, and behavior (traffic signal controllers).
Non-drip candle -- Wax that drips from a candle and accumulates at the base is difficult to re-use as fuel and is therefore wasted. A "non-drip" candle has an outer layer of wax that melts at a higher temperature. As the candle burns, an equilibrium is maintained where a pool of melted wax is held in place at the top by the not yet melted outer edge. This pool both feeds the wick and keeps the outer layer from getting too hot and melting. Then as the melted wax is consumed and the level drops, the top outer edge no longer has enough melted wax lapping around to help dissipate the heat of the flame. It finally melts, commingles with the pool of melted wax, and feeds the flame. If the flame is buffeted by too many air currents, it will get too close to the outer wax edge, melt it, and allow wax to drip. If the top of the candle is thinner, it is more likely to drip because the outer edge is closer to the flame. If a candle is very thick, the flame will burn down inside and the outer walls are too far from the flame to ever melt and be consumed as fuel. One way to avoid wasting the leftover wax is to melt it in a pot and make new candles from it by hand dipping. Walkways are sometimes illuminated in a decorative fashion using candles placed in paper bags. So long as the flame does not get too close to it, the paper bag won't catch fire.
Nominal
watts
Represents the rated
wattage consumption period. Represents the
energy used to produce light. Watts= Volts x
Amperes. Also see Watt.
Ohm's Law -- The relationship between voltage, current, and resistance that is always true; voltage equals current times resistance, or current equals voltage divided by resistance, or resistance equals voltage divided by current. Click here for a more involved discussion.
Parallel or Multiple (as opposed to series) -- Refers to an electric circuit where current can flow to and from each lamp or device without having to flow through another device. No device or lamp is dependent on the integrity of any other (as in Christmas tree lights) in order to operate.
Operating
Position
All OSRAM
PHOTO-OPTIC lamps must be operated within the
specified operational positions (base, filament,
electrodes).
Ordering
abbreviation
Provides a shorthand
description of the lamp, using a unique code
which can be used when ordering a lamp if you do
not know the item number. An example would be:
CF15EL/R30/830/MED, which translates to a
15-watt Soft White Dulux EL reflector electronic
self-ballasted compact fluorescent lamp.
Parallel vs.
series
Ballasts with
parallel lamp circuitry have the benefit of
companion lamps remaining lit, even if one of
the lamps operated by the ballast should fail.
Systems with series lamp wiring (magnetic
ballasts and many competitors' electronic types)
result in all lamps operated on the ballast
going out if one should fail.
PAR lamps
Usually halogen
lamps, means parabolic reflector lamps. A
lamp fixed within a parabolic reflector, a lamp
system that can use incandescent, halogen and
HMI lamp types. Numeric portion of PAR
description indicates actual parabolic reflector
diameter size in 1/8th inch units (example: PAR
64 is a lamp whose diameter is 64/8th inch or 8
inches). Example: PAR 36, 38, 46, 56 and
64 types.
Photocontrol -- The device, usually cylindrical and the size of a tin can, that contains a light sensitive element and other electromechanical or electronic components to turn lights on at night and off during the day.
Photo-Optic
lamps
Photo-Optic lamps
employ a variety of technologies to meet the
very precise levels of performance required by
the entertainment industry, science, medicine
and other high-tech fields.
Power
The rate at which
energy is taken from an electrical system or
dissipated by a load, expressed in watts; power
that is generated by a utility is typically
expressed in volt-amperes.
Power
factor
A measure of the
effectiveness with which an electrical device
converts volt-amperes to watts; devices with
power factors (0.90) are "high power factor"
devices.
Quicktronic(R)
Brand name of
SYLVANIA's line of high frequency electronic
ballasts -- the industry's broadest selection of
instant start electronic ballasts. These
ballasts ensure proper operating conditions and
reduce energy consumption without sacrificing
light output.
Reflector -- Any polished or light colored object intended to aim (by "bouncing") light in a desired direction as opposed to just block or absorb it.
Refractor -- A transparent panel or dish which also serves as a lamp cover and which has molded ridges to aim by bending (refract) light in desired directions. For street lighting, the ideal is a choice of refractors to produce reasonably uniformly lit areas of specific shapes and sizes. Were it not for the desire to redirect the light, streetlights would have been equipped with simple flat plain glass lamp covers.
Relamp -- Change a light bulb, as in the joke, "how many (xxx) does it take to ... ?"
Remote Ballast -- Refers to streetlight where the ballast is mounted on the pole or in the pole base. Early ballasts for high wattage mercury lamps were heavy, sometimes over thirty pounds, so mounting them in the luminaire was not practical at first.
Reflectance (icon)
The percentage of
light reflected back from a surface, the
difference having been absorbed or transmitted
by the surface. See Reflection.
Reflection
If a light ray
strikes a mirror- life surface, it is reflected.
The angle of incidence equals the angle of
reflection; this is called specular reflection.
When a ray strikes a mat surface, light is
reflected uniformly in all directions. This is
called diffuse reflection. With the reflectors
the rays of light are pencilled in the proper
direction. See Reflectance.
Reflector
An optical device to
reflect light. PHOTO-OPTIC reflector lamps
utilize ellipsoidal (converging light rays) or
parabolic (collimating light rays) reflectors.
Dichroic coated reflectors are designed to
reflect visible light and pass through unwanted
infrared wavelengths.
Resistance (R)
A measure of
resistance to flow of current, expressed in
ohms.
Series -- Refers to an electrical circuit comparable to most Christmas tree lights, where when one lamp is removed, the entire string goes dark. In reality, both with modern Christmas lights and now rarely found series streetlight circuits, there are devices in or at each lamp that bypass a burned out lamp to keep the rest of the lights on, and which work most of the time but are not perfect.
Single
pin
Single pins have a
mini can or D.C. bay base whereas bi- pin lamps
have a bi- pin base.
Single-ended
Lamps having a
single lamp base or point of electrical
connection.
Spectral Power
Distribution (SPD)
A curve illustrating
the distribution of power produced by the lamp,
at each wavelength across the spectrum.
Spotlight
A luminaire using
halogen/incandescent or a high intensity
discharge (HID) lamp that produces a narrow beam
angle designed to illuminate a specifically
defined area.
Total harmonic
distortion (THD)
Excessive THD
(defined by ANSI as greater than 32%) may cause
adverse effects to the electrical system. THD
levels below 20% provide optimal system
compatibility, but levels below 10% may not add
any practical benefit. 10% THD types may also
introduce excessive in-rush current unless
circuitry is added that limits in-rush
levels.
TCLP Test
(Toxicity
Characteristic Leaching Procedure), Federal EPA
regulations (RCRA of 1990) have define a TCLP
test to determine whether wastes are to be
treated as hazardous or non-hazardous.
Tungsten Halogen Cycle
Halogen light
sources utilizing the halogen regenerative cycle
to prevent blackening of the lamp envelope
during life.
Voltage (E)
A measure of
electrical potential, expressed in volts
(V).
Watt
A unit of electrical
power. Lamps are rated in watts to indicate
power consumption. Also see Nominal watts.
Wavelength (icon)
Distance between two
successive points of a periodic wave; the
wavelengths of light are typically expressed in
nanometers (nm), or billionths of a meter.
Wick -- A long, porous, usually fibrous, component in an oil lamp or candle through which the fuel soaks and rises to feed the flame at a controlled rate. If the wick goes dry, it itself burns away if it is not made of a fireproof material such as fiber glass. Materials through which the fuel or melted wax cannot soak fast enough therefore don't make good wicks. In the case of a candle, as the wax is consumed and the candle shortens, the flame gets taller as the exposed wick lengthens and more smoke is given off. Eventually the wick gets so long that the melted wax soaking it is used up before it gets to the top of the wick and the end of the wick then burns away. To reduce smoke, modern candles have wicks that tend to curl as the wax around them is melted by the flame. When this wick has reached the length where the end goes dry, it points sideways and keeps the flame from getting too tall. Also because the outer sides of the flame are hotter, the wick end burns away faster. (See, also, Mantle.)
Working
Distance
As a function of an
elliptical reflector, light is collected and
converged into a specific area a certain
distance in front of the lamp. Lamp alignment
can be provided for specific illumination and
color qualities at the designated area.
Glossary courtesy of
Sylvania
Lighting and DIS Group Inc. |
