Lamp (electrical component)
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A lamp, in technical usage, is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a ceramic or metal base, which makes an electrical connection in the socket of a light fixture. This connection may be made with a threaded base, two metal pins, or a "bayonet mount." Re-lamping is the replacement of only the removable lamp in a light fixture.
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[edit] Types of lamp
[edit] Incandescent light bulb
The incandescent light bulb was the first type of modern electric light, introduced in the early 19th Century. It is now being banned in some countries because it is inefficient at converting electricity to light. About 90% of the energy input is released as heat. This excess heat is then dumped into the air which, in warm climates, must then be cooled by ventilation or air conditioning, resulting in more energy consumption. However, in northern climates where heating and lighting is required during the cold and dark winter months, this technology can be considered efficient.
Halogen lamps were introduced as an improvement to incandescent bulbs. Visible light output of these lamps is about 15% of the energy input, instead of 10%, allowing them to produce a total of about 50% more light using the same amount of electrical power. The bulb capsule is under high pressure instead of a vacuum or low-pressure noble gas. Good halogen bulbs produce a "cool white" color temperature approaching the appearance of sunlight at noon, while regular incandescent bulbs produce warm light with a warm yellow color temperature.
Halogen lamps are usually much smaller than standard incandescents and burn with a hotter filament temperature, which results in a very hot surface. For this reason, a fused-quartz "capsule" is used to enclose the filament, which is sealed behind an additional layer of glass. This is a safety precaution, because halogen "bulbs" can explode if broken while operating or by coming into contact with water or oily residue from fingerprints. The risk of burns or fire is also greater than other bulbs, leading to their prohibition in some places.
[edit] Fluorescent lamp
Fluorescent lamps have an efficiency of about 40%, meaning that for the same amount of light generated, they use ¼ the power and produce 1/6 the heat of a regular incandescent. Fluorescents were limited to linear and a round "circleline" lamp until the 1980s, when the compact fluorescent lamp (CFL) was invented. CFLs can have a built-in electrical ballast which fit into a standard screw base, or make use of a remote ballast. Compact and linear fluorescent lamps last far longer than incandescents, but do have some starting trouble in very cold weather when installed outside.
Fluorescents most often come in cool white (CW), with some home bulbs being a warm white (WW), which has a pinkish color. In between there is an "enhanced white" (EW), which is more neutral. There is also a very cold daylight white (DW). Compact fluorescent lamps are usually considered warm white, though many have a yellowish cast like an incandescent. "Warm" and "cool" are entirely relative terms and almost arbitrary so color temperature and the color rendering index (CRI) are used as absolute scales of color for fluorescents, and sometimes for other types of lighting.
[edit] HID lamp
High-intensity discharge lighting first came about with the mercury-vapor streetlights, and later the high-pressure sodium ones with their characteristic orange color. Modern ones are metal halide, used in everything from headlights to floodlights, and with a more pleasant color balance. Like fluorescents, all HID bulbs require a ballast, but they also require a few minutes (or seconds for headlights) to warm up after "igniting". HID bulbs are over 60% and up to 80% efficient.
[edit] LED lamp
University researchers have made recent advances in the production of white light-emitting diodes (LEDs) which lead to the introduction of Solid State Lighting (SSL) fixtures made for general illumination. Before this time, colored LEDs were used as indicator lights for electronic devices. These lamps are still more expensive than other lamps, but they last an extremely long time, up to 100,000 hours (compared to around 10,000 for fluorescent and 1,000 for incandescent). It appears that for now these will be most useful and cost-effective in smaller applications, starting with nightlights and flashlights. Colored LEDs can also be used for accent lighting, and even in fake ice cubes for drinks at parties. They are also being increasingly used as Christmas lights. White LEDs are about the same efficiency as fluorescent lamps, while red ones can be up to 90% efficient.
LED technology is useful for lighting designers because of its low power consumption, low heat generation, instantaneous on/off control, continuity of color throughout the life of the diode and relatively low cost of manufacture. In the last few years, software has been developed to merge lighting and video by enabling lighting designers to stream video content to their LED fixtures, creating low resolution video walls.
[edit] Arc lamp
An arc lamp consists of two electrodes which are separated by a gas, including neon, argon, xenon, sodium, metal halide, and mercury. Very high voltage is needed to "ignite" or "strike" the arc. This requires an electrical circuit sometimes called an "igniter", which is part of a larger circuit called the "ballast". After the arc is struck, the internal resistance of the lamp drops to a very low level that would allow an instantly-destructive high current to flow if the ballast were not present to limit it to the lamp's normal operating current. The ballast is typically designed to maintain safe operating conditions and constant light output over the life of the lamp.
[edit] Lamp circuit symbols
In circuit diagrams lamps usually are shown as symbols. For example, an electrician would not want to have to keep on drawing out light bulbs so symbols are used instead. There are two main types of symbols, these are:
The X in a circle, which usually represents a bulb not to be mixed up with an L.E.D.
The semi-circled dent in a circle, which usually represents standard filament lamps.
[edit] See also
[edit] External links, references, resources
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Lighting and Lamps
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|---|---|---|
| Incandescent: | Conventional - Halogen - Parabolic aluminized reflector (PAR) | |
| Fluorescent: | Compact fluorescent (CFL) - Linear fluorescent - Induction lamp | |
| Gas discharge: | High-intensity discharge (HID) - Mercury-vapor - Metal-halide - Neon - Sodium vapor | |
| Electric arc: | Arc lamp - HMI - Xenon arc - Yablochkov candle | |
| Combustion: | Acetylene/Carbide - Candle - Gas lighting - Kerosene lamp - Limelight - Oil lamp - Safety lamp - Petromax - Rushlight | |
| Other types: | Sulfur lamp - Light-emitting diode (LED) - LED lamp (SSL) - Plasma - Electroluminescent wire - Chemiluminescence - Deuterium arc lamp - Radioluminescence | |
