lighting jargon de mystified - bluff your way in lighting with this simple guide to the technical...

Lighting Jargon De-mystified

A simple guide to what lighting people actually mean when they talk

about this sort of stuff

BALLASTIn a fluorescent lighting system, the ballast regulates the current to the lamps and provides sufficient voltage to start the lamps.

Without a ballast to limit its current, a fluorescent lamp connected directly to a high voltage power source would rapidly and uncontrollably increase its current draw. Within a second the lamp would overheat and burn out.

During lamp starting, the ballast must briefly supply high voltage to establish an arc between the two lamp electrodes. Once the arc is established, the ballast quickly reduces the voltage and regulates the electric current to produce a steady light output.

Lighting jargon de-mystified

Breeam ratingBreeam stands for the Building Research Establishment Environmental Assessment Method and it’s the industry’s leading environmental rating system for buildings. More than 200,000 buildings have been assessed and awarded a Breeam rating. Breeam evaluates design, construction and use.

B

CANDELAA candela is the luminous intensity emitted

by a light source in a particular direction weighted by the sensitivity of the human eye to different wavelengths. One candle

has an approximate intensity of one candela.


CCeramic lampsCeramic metal halide (CMH) lamps combine high output with great colour rendering and good efficiency. They produce light by passing an electric arc through a mixture of gases. In a metal halide lamp the compact arc tube contains a high-pressure mixture of argon, mercury and a variety of metal halides.

CFLPopularly referred to as energy-saving lamps, compact fluorescent lamps have a poor image because of perceived deficiencies in colour, power and the time it takes for them to reach full output. But massive improvements have been made in all these areas thanks to substantial investment by the big lamp manufacturers.

CHROMATICITYChromaticity is an

objective specification of the quality of a colour

regardless of its luminance as determined by its hue

and colourfulness. It is the quality of a colour or light with reference to its purity

and its dominant wavelength.


CColour temperatureColour temperature describes whether a light source appears ‘warm’ or ‘cool’ – indicated by the correlated colour temperature (CCT). Lamps with a warm appearance have a CCT of 2700-3000K and are considered appropriate for domestic settings; cooler lamps might be 4000K and are used more often in offices and shops.

CRIShort for colour-rendering index, CRI is the ability of a light source to show the

colours of objects accurately. The higher the CRI on a 1-100 scale, the more

accurately the lamp will render colours. Lamps with poor colour rendering will

distort some colours. CRI only works for approximately white sources and

doesn’t actually tell you which colours a light source renders well or badly.

DALIThe Digital Addressable Lighting

Interface is a protocol for lighting controls and dimming agreed by

major manufacturers. It is set out in the technical standard IEC

62386 and promoted by a Dali working group set up by

manufacturers and institutions.


D


EEfficacySpecific luminous efficacy indicates the efficiency with which electrical energy is converted to light, i.e. how much luminous flux is produced using electric input power (W) supplied to the light source. The unit is lumen per watt (lm/W).

Fluorescent lightsA fluorescent lamp or tube is a very low pressure mercury-vapour gas-discharge lamp that uses fluorescence to produce visible light. The electric current (in the gas) excites mercury vapour which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the bulb to fluoresce, producing visible light.

The luminous efficacy of a compact fluorescent light bulb is about 60 lumens per watt, four times the efficacy of a typical incandescent bulb.

For conventional tube fluorescent lamps the fitting is more costly because it requires a heavy ballast to regulate the current through the lamp, but the lower energy cost typically offsets the higher initial cost.


F

HEAT SINKHeat sinks are used with high-power semiconductor devices such as light

emitting diodes (LEDs), where the heat dissipation ability of the basic device is insufficient to moderate its temperature. A heat sink is designed to maximize

its surface area in contact with the cooling medium surrounding it, such as the air. In general, the more surface area a heat sink has, the better it works,

hence many of them feature arrays of fins.


H

Halogen lightThe halogen lamp is also known as a quartz halogen and tungsten halogen lamp. It is an advanced form of incandescent lamp. The filament is composed of ductile tungsten and located in a gas filled bulb just like a standard tungsten bulb, however the gas in a halogen bulb is at a higher pressure (7-8 ATM). The glass bulb is made of fused quartz, high-silica glass or aluminosilicate. This bulb is stronger than standard glass in order to contain the high pressure. This lamp has been an industry standard for work lights and film/television lighting due to compact size and high lumen output.


HHIDHigh-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. Varieties of HID lamp include:

Mercury-vapour lampsMetal-halide (MH) lampsCeramic MH lampsSodium-vapour lamps/high pressure sodiumXenon short-arc lamps

IncandescentAn incandescent light produces light with a filament wire heated to a high

temperature by an electric current passing through it, until it glows. The hot filament is protected from oxidation with a glass or quartz bulb that is filled

with inert gas or evacuated. The light bulb is supplied with electrical current by feed-through terminals or wires embedded in the glass.

Most bulbs are used in a socket which provides mechanical support and electrical connections. Incandescent bulbs are much less efficient than most

other types of electric lighting and convert less than 5% of the energy they use into visible light – they’re really heaters that give off light as a by-product.


I

Induction lightingInduction lighting is a form of light created by filling the inside of a bulb with mercury gas and exciting it with electricity. When this excitation occurs, ultra violet radiation is emitted that then converts into visible light. The phosphor coating inside the bulb determines the colour of light that is emitted. Since induction lamps do not contain electrodes, which can eventually burn out, they last much longer than fluorescent lamps.


I

IP ratingAn IP (index of protection) rating tells

you the level of protection that a luminaire or other piece of equipment

provides against things getting in – including dust, dirt and water as well as hands and fingers. For example, a fitting rated IP22 is protected against insertion of fingers and will not be damaged by

exposure to dripping water.

kWhThe kilowatt-hour is a

unit of energy equal to 1,000 watt-hours.

That’s what a 1,000W device uses in one hour – or what a 1W device uses in 1,000 hours. It’s the ‘unit’ that shows up on your electricity bill.


KKelvinThe light colour of a light source determines the atmosphere in the room. It is defined by the colour’s temperature of artificial light source, expressed in Kelvin (K). Low temperatures create warm lighting, high temperatures, in turn, create a colder-looking environment.


L

LuxLux is the international unit of illuminance – a measure of how much luminous flux (in lumens) is spread over a given area (in square metres). In other words, it tells you how much light is hitting a surface. 1lm/m2 equals 1lx.

Li-FiLight fidelity is visual light technology that uses light from LED luminaires to transmit data. It uses invisible modulations in the light from the LED fittings to provide a fast, reliable wireless internet connection.

L70L70 is a term used to specify a lumen maintenance factor for a light source.

Lumen maintenance compares the amount of light emitted by a source

when it is new with the amount emitted at a specific time in the

future. The L70 figure is the time taken for the light emitted by the

source to drop to 70 per cent of its ‘as new’ value. L50 and L80 are also used

within the lighting industry.


L

LIGHT ENGINEAn LED light engine is a combination of one or more LED modules together with the associated electronic control gear (ECG), also known as an LED driver. An LED module contains one or more LEDs, together with further components, but excluding the ECG.

LEDLight emitting diodes (LEDs) are based on solid-state semi-conductor technology and are the most efficient white light source. Having no air, glass or fragile filaments, LEDs are extremely resistant to shock and vibration. They deliver big energy savings, good colour rendering, dimmability and a long life which reduces maintenance needs.

LED driverAn LED driver is a self-contained power supply that has outputs matched to the electrical characteristics of your LED or array of LEDs. There are currently no industry standards, so understanding the electrical characteristics of your

LED or array is critical in selecting or designing a driver circuit. Drivers should

be current-regulated (deliver a consistent current over a range of load

voltages).

LeniThe Lighting Energy Numeric Indicator – a measure of the energy predicted to be used by the lights in a building, taking into account daylight, occupancy, operating hours and controls. Leni is much more nuanced as a predictor of energy use than simply measuring the efficiency of luminaires. Leni knows, for example, that a building in John O’Groats will have to use a little more lighting energy than an identical building at Land’s End, because the availability of daylight will differ.


LLORLight output ratio – the percentage of

light emitted from the light source that makes it out of the luminaire. A LOR of 70 means 30 per cent of the light from the lamp is lost inside the reflector and light fitting. There is some debate about

how to apply LOR to LED luminaires because of the directional nature of the

light they emit.

LumenThe lumen is the international unit of luminous flux. One lumen is the amount of light emitted per second in a solid angle of one steradian from a one candela light source. (A steradian is a solid angle at the centre of a sphere subtending a section on the surface equal in area to the square of the radius of the sphere.)


MMETAL HALIDEA metal halide lamp is a type of high-intensity discharge lamp that produces light by an electric arc through a gaseous mixture of vaporised mercury and metal halides. Metal halide lamps have high luminous efficacy of around 75 - 100 lumens per watt (about twice that of mercury vapour lights and 3 to 5 times that of incandescent lights) and produce an intense white light.

Mercury VapourThe mercury vapour lamp is a high intensity discharge lamp. It uses an arc through vaporised mercury in a high pressure tube to create very bright light directly from its own arc. While it has good efficiency and better colour rendering than HPS street lights which have a better lm/w rating, the lamp requires a warm-up time to start and even then produces a greenish tinge.


OOLEDShort for organic light-emitting diode, a display device that sandwiches carbon-based films between two charged electrodes, one a metallic cathode and one a transparent anode, usually being glass. When voltage is applied to the OLED cell, the injected positive and negative charges recombine and create electro luminescent light. It is beginning to replace LCD technology in handheld devices such as PDAs and cellular phones because the technology is brighter, thinner, faster and lighter than LCDs, uses less power, offers higher contrast and is cheaper to manufacture.

PIRShort for passive infrared, PIR sensors are electronic sensors that measure infrared light radiating from objects in their field of view. Sometimes known as proximity sensors, they can detect heat from objects that is undetectable by mere humans. When combined with lighting they can be used to deliver the light only when needed, for example, with street lights which would otherwise be in full use throughout the night even when there is no one in the vicinity.


P

SONHigh pressure sodium lamps (commonly called SON lamps) are gas discharge lamps that use sodium vapour in an excited state to produce light. They are

often used for street lighting. SONs produce a yellow light and have poor colour rendering, but they are efficient, often reaching efficacies of about 100lm/W.

Higher-powered 600W versions can reach an efficacy of 150lm/W.


S


W

WEEEWaste electrical and electronic equipment. This includes old fridges and fax machines as well as lamps and luminaires. An EU directive defines WEEE and sets out how you are and aren’t allowed to dispose of it. Recycling schemes such as Lumicom and Recolight help manufacturers of lighting products comply.

White lightWhite light is the name given to what the human eye sees when all the colours that make up the visible light spectrum are combined. Incandescence, which is visible light created from heat, is the greatest known generator of white light. Objects with lower temperatures emit infrared radiation, which cannot be seen, but as an object gets hotter, the wavelengths get shorter and brighter, moving through red to yellow to white; these white lights are visible to the human eye. In addition to the sun and the common light bulb, molten materials, such as metal or glass, also glow incandescently.


XXENONA xenon arc lamp is a specialised type of gas discharge lamp that produces light by passing electricity through ionised xenon gas at high pressure. It produces a bright white light that closely mimics natural sunlight.

Xenon arc lamps are used in movie projectors in theatres, in searchlights and for specialised uses in industry and research to simulate sunlight.

In order to achieve maximum efficiency, the xenon gas inside short-arc lamps is maintained at an extremely high pressure — up to 30 atmospheres (440 psi / 3040 kPa) — which poses safety concerns. As lamps age, the risk of failure increases, so bulbs being replaced are at the greatest risk of explosion. Because of the danger, some lamps, especially those used in IMAX projectors, require the use of full-body protective clothing.

ZhagaZhaga (not an acronym) is an industry-wide co-operation

to standardise specifications for the interfaces of LED light engines. The aim is to enable interchangeability between products made by diverse manufacturers by defining interfaces for a variety of application-specific

light engines. Currently all Zhaga members are manufacturers.


ZZIGBEE

ZigBee is a global specification for digital radio communication that is suitable for

applications that require a low data rate, long battery life and secure

networks. Among those applications is lighting control. No special devices are needed to connect equipment to the

lighting network. ZigBee is simpler and cheaper to implement than other

wireless networks such as Bluetooth.

lighting jargon de mystified - bluff your way in lighting with this simple guide to the technical...

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