Design, technical parameters and types of incandescent lamps. History of incandescent lamps

incandescent lamp

Incandescent lamp- electric light source, in which the filament body (refractory conductor), placed in a transparent vessel evacuated or filled with an inert gas, is heated to a high temperature due to the flow of electric current through it, as a result of which it emits in a wide spectral range, including visible light . The filament currently used is mainly a tungsten-based alloy helix.

Operating principle

The lamp uses the effect of heating the conductor (incandescent body) when an electric current flows through it ( thermal effect of current). The temperature of the heating body rises sharply after the current is turned on. The filament body radiates electromagnetic thermal radiation in accordance with Planck's law. The Planck function has a maximum whose position on the wavelength scale depends on temperature. This maximum shifts with increasing temperature towards shorter wavelengths (Wien's displacement law). To obtain visible radiation, it is necessary that the temperature be on the order of several thousand degrees. At a temperature of 5770 (the temperature of the surface of the Sun), light corresponds to the spectrum of the Sun. The lower the temperature, the lower the proportion of visible light, and the more "red" the radiation appears.

Part of the electrical energy consumed by the incandescent lamp converts into radiation, part is lost as a result of heat conduction and convection processes. Only a small fraction of the radiation lies in the visible light region, the bulk is in the infrared radiation. To increase the efficiency of the lamp and obtain the maximum "white" light, it is necessary to increase the temperature of the filament, which in turn is limited by the properties of the filament material - the melting point. A temperature of 5771 K is unattainable, because at this temperature any known material melts, breaks down and ceases to conduct electricity. In modern incandescent lamps, materials with maximum melting points are used - tungsten (3410 ° C) and, very rarely, osmium (3045 ° C).

Color temperature is used to evaluate this quality of light. At typical incandescent temperatures of 2200-3000 K, a yellowish light is emitted, different from daylight. Warm in the evening< 3500 K) свет более комфортен и меньше подавляет естественную выработку мелатонина , важного для регуляции суточных циклов организма и нарушение его синтеза негативно сказывается на здоровье.

In normal air at these temperatures, tungsten would instantly turn into an oxide. For this reason, the filament body is placed in a flask, from which air is pumped out during the manufacture of the lamp. The first were made by vacuum; At present, only low-power lamps (for general-purpose lamps - up to 25 W) are made in a vacuum flask. The flasks of more powerful lamps are filled with an inert gas (nitrogen, argon or krypton). The increased pressure in the bulb of gas-filled lamps sharply reduces the rate of evaporation of tungsten, which not only increases the service life of the lamp, but it is also possible to increase the temperature of the incandescent body, which makes it possible to increase efficiency and bring the emission spectrum closer to white. The bulb of a gas-filled lamp does not darken as quickly due to the deposition of material from the filament body, as with a vacuum lamp.

Design

The design of a modern lamp. In the diagram: 1 - flask; 2 - the cavity of the flask (vacuum or filled with gas); 3 - glow body; 4, 5 - electrodes (current inputs); 6 - hooks-holders of the body of heat; 7 - lamp leg; 8 - external link of the current lead, fuse; 9 - base case; 10 - base insulator (glass); 11 - contact of the bottom of the base.

The designs of incandescent lamps are very diverse and depend on the purpose. However, the filament body, bulb and current leads are common. Depending on the characteristics of a particular type of lamp, filament holders of various designs can be used; lamps can be made without a base or with bases of various types, have an additional outer bulb and other additional structural elements.

In the design of general-purpose lamps, a fuse is provided - a ferronickel alloy link welded into the gap of one of the current leads and located outside the lamp bulb - usually in the leg. The purpose of the fuse is to prevent the bulb from breaking when the filament breaks during operation. The fact is that in this case an electric arc arises in the rupture zone, which melts the remnants of the thread, drops of molten metal can destroy the glass of the bulb and cause a fire. The fuse is designed in such a way that when the arc is ignited, it is destroyed by the arc current, which significantly exceeds the rated current of the lamp. The ferronickel link is located in a cavity where the pressure is equal to atmospheric pressure, and therefore the arc is easily extinguished. Due to their low efficiency, they have now been abandoned.

Flask

The flask protects the body of heat from the effects of atmospheric gases. Bulb dimensions are determined by the deposition rate of the filament material.

Gas medium

The flasks of the first lamps were evacuated. Most modern lamps are filled with chemically inert gases (except for low power lamps, which are still made vacuum). The heat loss arising in this case due to thermal conductivity is reduced by choosing a gas with a large molar mass. Mixtures of nitrogen N 2 with argon Ar are the most common due to their low cost, pure dried argon is also used, less often krypton Kr or xenon Xe (molar masses: N 2 - 28.0134 / mol; Ar: 39.948 g / mol; Kr - 83.798 g/mol; Xe - 131.293 g/mol).

Halogen lamp

The filament body of the first lamps was made of coal (sublimation temperature 3559 ° C). Modern lamps use almost exclusively tungsten filaments, sometimes osmium-tungsten alloy. To reduce the size of the filament body, it is usually given the shape of a spiral, sometimes the spiral is subjected to repeated or even tertiary spiralization, receiving, respectively, a bi-spiral or a tri-spiral. The efficiency of such lamps is higher due to a decrease in heat loss due to convection (the thickness of the Langmuir layer decreases).

Electrical parameters

Lamps are made for various operating voltages. The current strength is determined by Ohm's law ( I=U/R) and power according to the formula P=U I, or P=U²/R. Since metals have low resistivity, a long and thin wire is needed to achieve such resistance. The thickness of the wire in conventional lamps is 40-50 microns.

Since the filament is at room temperature when turned on, its resistance is an order of magnitude less than the operating resistance. Therefore, when turned on, a very large current flows (ten to fourteen times the operating current). As the filament heats up, its resistance increases and the current decreases. Unlike modern lamps, early incandescent lamps with carbon filaments, when turned on, worked on the opposite principle - when heated, their resistance decreased, and the glow slowly increased. The increasing resistance characteristic of the filament (as the current increases, the resistance increases) allows the use of an incandescent lamp as a primitive current stabilizer. In this case, the lamp is connected in series to the stabilized circuit, and the average value of the current is chosen so that the lamp works half-heartedly.

In flashing lamps, a bimetallic switch is built in series with the filament. Due to this, such lamps independently work in a flickering mode.

plinth

In the USA and Canada, other socles are used (this is partly due to a different voltage in the networks - 110 V, so other sizes of socles prevent accidental screwing in of European lamps designed for a different voltage): E12 (candelabra), E17 (intermediate), E26 (standard or medium ), E39 (mogul). Also, similarly to Europe, there are plinths without thread.

Nomenclature

According to their functional purpose and design features, incandescent lamps are divided into:

• general purpose lamps(until the mid-1970s, the term "normal lighting lamps" was used). The most massive group of incandescent lamps designed for general, local and decorative lighting purposes. Since 2008, due to the adoption by a number of states of legislative measures aimed at reducing the production and limiting the use of incandescent lamps in order to save energy, their output began to decline;
• decorative lamps produced in curly flasks. The most common are candle-shaped flasks with a diameter of approx. 35 mm and spherical with a diameter of about 45 mm;
• local lighting lamps, structurally similar to general-purpose lamps, but designed for low (safe) operating voltage - 12, 24 or 36 (42) V. Scope - manual (portable) lamps, as well as local lighting lamps in industrial premises (on machine tools, workbenches and etc., where an accidental lamp strike is possible);
• illumination lamps produced in colored flasks. Purpose - illumination installations of various types. As a rule, lamps of this type have low power (10-25 W). Flasks are usually colored by applying a layer of inorganic pigment to their inner surface. Lamps with flasks painted on the outside with colored varnishes (colored zaponlak) are less commonly used, their disadvantage is the rapid fading of the pigment and shedding of the varnish film due to mechanical influences;
• mirrored incandescent lamps have a flask of a special shape, part of which is covered with a reflective layer (a thin film of thermally sprayed aluminum). The purpose of mirroring is the spatial redistribution of the luminous flux of the lamp in order to use it most efficiently within a given solid angle. The main purpose of mirror LNs is localized local lighting;
• signal lamps used in various lighting devices (means of visual display of information). These are low power lamps designed for a long service life. Today they are being replaced by LEDs;
• transport lamps- an extremely wide group of lamps designed to work on various vehicles (cars, motorcycles and tractors, airplanes and helicopters, locomotives and wagons of railways and subways, river and sea vessels). Characteristic features: high mechanical strength, vibration resistance, the use of special socles that allow you to quickly replace lamps in cramped conditions and, at the same time, prevent lamps from spontaneous falling out of their sockets. Designed to be powered by the on-board electrical network of vehicles (6-220 V);
• projector lamps usually have high power (up to 10 kW, lamps up to 50 kW were previously produced) and high luminous efficiency. Used in lighting devices for various purposes (lighting and light-signal). The filament of such a lamp is usually laid more compactly due to a special design and suspension in the bulb for better focusing;
• lamps for optical instruments, which include mass-produced until the end of the 20th century. lamps for film projection equipment have compactly stacked spirals, many are placed in specially shaped flasks. Used in various devices (measuring instruments, medical equipment, etc.);

Special Lamps

Incandescent switch lamp (24V 35mA)

Invention history

Lamp Lodygin

Thomas Edison lamp with carbon fiber filament.

• In 1809, the Englishman Delarue builds the first incandescent lamp (with a platinum spiral).
• In 1838, the Belgian Jobar invents the charcoal incandescent lamp.
• In 1854, the German Heinrich Göbel developed the first "modern" lamp: charred bamboo thread in an evacuated vessel. In the next 5 years, he developed what many call the first practical lamp.
• In 1860, the English chemist and physicist Joseph Wilson Swan demonstrated the first results and received a patent, but difficulties in obtaining a vacuum led to the fact that Swan's lamp did not work long and inefficiently.
• On July 11, 1874, Russian engineer Alexander Nikolaevich Lodygin received a patent number 1619 for a filament lamp. As a filament, he used a carbon rod placed in an evacuated vessel.
• In 1875, V.F. Didrikhson improved Lodygin's lamp by pumping air out of it and using several hairs in the lamp (in the event of one of them burning out, the next one turned on automatically).
• English inventor Joseph Wilson Swan received a British patent in 1878 for a carbon fiber lamp. In his lamps, the fiber was in a rarefied oxygen atmosphere, which made it possible to obtain very bright light.
• In the second half of the 1870s, the American inventor Thomas Edison conducted research work in which he tried various metals as a thread. In 1879 he patents a platinum filament lamp. In 1880, he returned to carbon fiber and created a lamp with a lifespan of 40 hours. At the same time, Edison invented the household rotary switch. Despite such a short lifespan, his lamps are replacing the gas lighting used until then.
• In the 1890s, A. N. Lodygin invents several types of lamps with filaments made of refractory metals. Lodygin suggested using tungsten filaments in lamps (these are used in all modern lamps) and molybdenum and twisting the filament in the form of a spiral. He made the first attempts to pump air out of the lamps, which kept the filament from oxidizing and increased their service life many times over. The first American commercial lamp with a tungsten filament was subsequently produced under Lodygin's patent. He also made gas-filled lamps (with carbon filament and nitrogen filling).
• Since the late 1890s, lamps have appeared with an incandescent filament made of magnesium oxide, thorium, zirconium and yttrium (Nernst lamp) or a filament of metal osmium (Auer lamp) and tantalum (Bolton and Feuerlein lamp)
• In 1904, the Hungarians Dr. Sandor Just and Franjo Hanaman received a patent for the use of tungsten filament in lamps No. 34541. In Hungary, the first such lamps were produced, which entered the market through the Hungarian company Tungsram in 1905.
• In 1906, Lodygin sold a patent for a tungsten filament to General Electric. In the same 1906, in the USA, he built and put into operation a plant for the electrochemical production of tungsten, chromium, and titanium. Due to the high cost of tungsten, the patent only finds limited application.
• In 1910, William David Coolidge invents an improved method for producing tungsten filament. Subsequently, the tungsten filament displaces all other types of filaments.
• The remaining problem with the rapid evaporation of a filament in a vacuum was solved by an American scientist, a well-known specialist in the field of vacuum technology Irving Langmuir, who, working since 1909 at General Electric, introduced the filling of lamp bulbs with inert, more precisely, heavy noble gases (in in particular - argon), which significantly increased their operating time and increased light output.

efficiency and durability

Durability and brightness depending on operating voltage

Almost all of the energy supplied to the lamp is converted into radiation. Losses due to heat conduction and convection are small. For the human eye, however, only a small range of wavelengths of this radiation is available. The main part of the radiation lies in the invisible infrared range and is perceived as heat. The efficiency of incandescent lamps reaches its maximum value of 15% at a temperature of about 3400. At practically achievable temperatures of 2700 (a typical 60 W lamp), the efficiency is 5%.

As the temperature rises, the efficiency of the incandescent lamp increases, but at the same time its durability is significantly reduced. At a filament temperature of 2700, the lamp life is approximately 1000 hours, at 3400 only a few hours. As shown in the figure on the right, when the voltage is increased by 20%, the brightness doubles. At the same time, the lifetime is reduced by 95%.

Reducing the supply voltage, although it lowers the efficiency, but increases the durability. So lowering the voltage by half (for example, when connected in series) reduces the efficiency by about 4-5 times, but increases the lifetime by almost a thousand times. This effect is often used when it is necessary to provide reliable emergency lighting without special requirements for brightness, for example, in stairwells. Often, for this, when powered by alternating current, the lamp is connected in series with a diode, due to which the current flows into the lamp only during half the period.

Since the cost of electricity consumed during the service life of an incandescent lamp is ten times higher than the cost of the lamp itself, there is an optimal voltage at which the cost of the luminous flux is minimal. The optimal voltage is slightly higher than the nominal voltage, therefore, ways to increase durability by lowering the supply voltage are absolutely unprofitable from an economic point of view.

The limited lifetime of an incandescent lamp is due, to a lesser extent, to the evaporation of the filament material during operation, and to a greater extent, inhomogeneities arising in the filament. Uneven evaporation of the filament material leads to the appearance of thin areas with increased electrical resistance, which in turn leads to even greater heating and evaporation of the material in such places. When one of these constrictions becomes so thin that the filament material at that point melts or completely evaporates, the current is interrupted and the lamp fails.

The greatest wear of the filament occurs when the lamp is suddenly energized, therefore, it is possible to significantly increase its service life using various kinds of soft start devices.

A tungsten filament has a cold resistivity that is only 2 times higher than that of aluminium. When a lamp burns out, it often happens that the copper wires that connect the base contacts to the spiral holders burn out. So, a conventional 60 W lamp consumes over 700 W at the time of switching on, and a 100-watt lamp consumes more than a kilowatt. As the spiral warms up, its resistance increases, and the power drops to the nominal value.

To smooth peak power, thermistors with a strongly falling resistance as they warm up, reactive ballast in the form of a capacitance or inductance, dimmers (automatic or manual) can be used. The voltage on the lamp increases as the spiral warms up and can be used to shunt the ballast with automatics. Without turning off the ballast, the lamp can lose from 5 to 20% of the power, which can also be beneficial for increasing the resource.

Low-voltage incandescent lamps at the same power have a longer resource and light output due to the larger cross section of the incandescent body. Therefore, in multi-lamp fixtures (chandeliers), it is advisable to use the series connection of lamps for a lower voltage instead of the parallel connection of lamps for mains voltage. For example, instead of six 220V 60W lamps connected in parallel, use six 36V 60W lamps connected in series, that is, replace six thin spirals with one thick one.

Below is an approximate ratio of power and luminous flux for ordinary transparent pear-shaped incandescent lamps popular in Russia, E27 base, 220V.

Varieties of incandescent lamps

Incandescent lamps are divided into (arranged in order of increasing efficiency):

• Vacuum (the simplest)
• Argon (nitrogen-argon)
• Krypton (approximately +10% brightness from argon)
• Xenon (2 times brighter than argon)
• Halogen (filler I or Br, 2.5 times brighter than argon, long service life, do not like under-burning, as the halogen cycle does not work)
• Dual bulb halogen (more efficient halogen cycle due to better heating of the inner bulb)
• Xenon-halogen (filler Xe + I or Br, the most efficient filler, up to 3 times brighter than argon)
• Xenon-halogen with an IR reflector (since most of the lamp radiation is in the IR range, the reflection of IR radiation into the lamp significantly increases efficiency; they are made for hunting lamps)
• Incandescent with a coating that converts infrared radiation into the visible range. Lamps with a high-temperature phosphor are being developed, which, when heated, emit a visible spectrum.

Advantages and disadvantages of incandescent lamps

Advantages:

• excellence in mass production
• low cost
• small size
• lack of control gear
• insensitivity to ionizing radiation
• purely active electrical resistance (unit power factor)
• quick start up
• low sensitivity to power failures and power surges
• the absence of toxic components and, as a result, the absence of the need for an infrastructure for the collection and disposal
• the ability to work on any kind of current
• voltage polarity insensitivity
• the possibility of manufacturing lamps for a wide variety of voltages (from fractions of a volt to hundreds of volts)
• no flicker when operating on alternating current (important in enterprises).
• no hum when operating on alternating current
• continuous emission spectrum
• pleasant and habitual spectrum
• resistance to electromagnetic impulse
• the ability to use brightness controls
• not afraid of low and high ambient temperatures, resistant to condensate

Flaws:

Import, purchase and production restrictions

Due to the need to save energy and reduce carbon dioxide emissions into the atmosphere, many countries have introduced or are planning to introduce a ban on the production, purchase and import of incandescent lamps in order to force them to be replaced with energy-saving (compact fluorescent, LED, induction, etc.) lamps.

In Russia

According to some sources, in 1924 an agreement was reached between the cartel members to limit the life of incandescent lamps to 1000 hours. At the same time, all cartel lamp manufacturers were required to maintain strict technical documentation for compliance with measures to prevent lamps from exceeding the 1000-hour cycle of lamp life.

In addition, the current Edison base standards were developed by the cartel.

see also

Notes

1. Lamps with white LEDs suppress the production of melatonin - Gazeta.Ru | The science
2. Buy Tools, Lighting, Electrical and DataComm Supplies at GoodMart.com
3. Photo lamp // Photo-cinema technique: Encyclopedia / Editor-in-chief E. A. Iofis. - M .: Soviet Encyclopedia, 1981.
4. E. M. Goldovsky. Soviet cinematography. Publishing House of the Academy of Sciences of the USSR, Moscow-Leningrad. 1950, C. 61
5. The history of the invention and development of electric lighting
6. David Charles. King of Invention Thomas Alva Edison
7. Electrotechnical encyclopedia. The history of the invention and development of electric lighting
8. A. de Lodyguine, U.S. Patent 575,002 "Illuminant for Incandescent Lamps". Application on January 4, 1893 .
9. G.S. Landsberg. Elementary textbook of physics (Russian). Archived from the original on June 1, 2012. Retrieved April 15, 2011.
10. en: Incandescent light bulb
11. [Incandescent lamp]- an article from the Small Encyclopedic Dictionary of Brockhaus and Efron
12. The History of Tungsram (PDF). Archived(English)
13. Ganz and Tungsram - the 20th century. (unavailable link - story) Retrieved October 4, 2009.
14. A. D. SMIRNOV, K. M. ANTIPOV Reference book energy. Moscow, Energoatomizdat, 1987.
15. Keefe, T.J. The Nature of Light (2007). Archived from the original on June 1, 2012. Retrieved November 5, 2007.
16. Klipstein, Donald L. The Great Internet Light Bulb Book, Part I (1996). Archived from the original on June 1, 2012. Retrieved April 16, 2006.
17. black body visible spectrum
18. See luminosity function.
19. Incandescent lamps, characteristics. Archived from the original on June 1, 2012.
20. Taubkin S. I. Fire and explosion, features of their expertise - M., 1999 p. 104
21. On September 1, the sale of 75-watt incandescent lamps will cease in the EU.
22. The EU limits the sale of incandescent lamps from September 1, the Europeans are unhappy. Interfax-Ukraine.
23. Medvedev proposed to ban "light bulbs Ilyich", Lenta.ru, 02.07.2009.
24. Federal Law of the Russian Federation dated November 23, 2009 No. 261-FZ “On Energy Saving and Improving Energy Efficiency and on Amendments to Certain Legislative Acts of the Russian Federation”.
25. Sabotage the veto , Lenta.ru, 28.01.2011.
26. "Lisma" started production of a new series of incandescent lamps, SUE RM "LISMA".
27. The need for inventions is cunning: 95W ​​incandescent lamps appeared on sale, EnergoVOPROS.ru.
28. http://russeca.kent.edu/InternationalBusiness/Chapter09/t09p23.html Restrictive Technology Transfer Business Practices (RCTs)

An incandescent lamp uses the effect of heating an incandescent body when an electric current flows through it ( thermal effect of current). The temperature of the incandescent body rises after the electrical circuit is closed. All bodies whose temperature exceeds the temperature of absolute zero emit electromagnetic thermal radiation in accordance with Planck's law. The spectral power density of radiation (Planck's function) has a maximum, the wavelength of which on the wavelength scale depends on temperature. The position of the maximum in the emission spectrum shifts with increasing temperature towards shorter wavelengths (Wien's displacement law). To obtain visible radiation, it is necessary that the temperature of the radiating body exceed 570 ° C (the temperature at which the red glow visible to the human eye in the dark begins). For human vision, the optimal, physiologically most convenient, spectral composition of visible light corresponds to the radiation of an absolutely black body with a surface temperature of the Sun's photosphere of 5770 . However, no solids are known that can withstand the temperature of the solar photosphere without destruction, so the operating temperatures of incandescent lamp filaments lie in the range of 2000-2800 ° C. The incandescent bodies of modern incandescent lamps use refractory and relatively inexpensive tungsten (melting point 3410 ° C), rhenium (melting point about the same, but higher strength at threshold temperatures) and very rarely osmium (melting point 3045 ° C). Therefore, the spectrum of incandescent lamps is shifted to the red part of the spectrum. Only a small fraction of electromagnetic radiation lies in the visible light region, the main share falls on infrared radiation. The lower the temperature of the incandescent body, the smaller the fraction of energy supplied to the heated wire is converted into useful visible radiation, and the more “red” the radiation appears.

To assess the physiological quality of fixtures, the concept of color temperature is used. At typical incandescent temperatures of 2200-2900 K, a yellowish light is emitted, different from daylight. Warm in the evening< 3500 K) свет более комфортен для человека и меньше подавляет естественную выработку мелатонина , важного для регуляции суточных циклов организма (нарушение его синтеза негативно сказывается на здоровье).

In atmospheric air at high temperatures, tungsten is rapidly oxidized to tungsten trioxide (forming a characteristic white coating on the inner surface of the lamp when it loses its tightness). For this reason, the tungsten filament body is placed in a sealed flask, from which, during the manufacture of the lamp, air is evacuated and filled with an inert gas - usually argon. In the early days of the lamp industry, they were made with evacuated bulbs; At present, only low-power lamps (for general-purpose lamps - up to 25 W) are made in a vacuum flask. The flasks of more powerful lamps are filled with an inert gas (nitrogen, argon or krypton). The increased pressure in the bulb of gas-filled lamps reduces the rate of evaporation of the tungsten filament. This not only increases the life of the lamp, but also allows the temperature of the filament body to rise. Thus, the light efficiency increases, and the emission spectrum approaches white. The inner surface of the bulb of a gas-filled lamp darkens more slowly when the filament material is sprayed during operation, as with a vacuum lamp.

All pure metals and many of their alloys (particularly tungsten) have a positive temperature coefficient of resistance, which means that electrical resistivity increases with increasing temperature. This feature automatically stabilizes the lamp's electrical power consumption to a limited level when connected to a (low output impedance) source, allowing lamps to be connected directly to electrical distribution networks without the use of current-limiting reactive or active bipolar ballasts, which economically distinguishes them from gas discharge fluorescent lamps . For a filament of a lighting lamp, the resistance in a cold state is typically 10 times less than when heated to operating temperatures.

It takes at least 7 metals to craft a regular light bulb.

Design

The designs of lamps are very diverse and depend on the purpose. However, the filament body, bulb and current leads are common. Depending on the characteristics of a particular type of lamp, filament holders of various designs can be used. Hooks-holders of the incandescent body of incandescent lamps (including general purpose incandescent lamps) are made of molybdenum. Lamps can be made without bases or with bases of various types, have an additional outer bulb and other additional structural elements.

In the design of general-purpose lamps, a fuse is provided - a ferronickel alloy link welded into the gap of one of the current leads and located outside the lamp bulb - usually in the leg. The purpose of the fuse is to prevent the bulb from breaking when the filament breaks during operation. The fact is that in this case an electric arc arises in the rupture zone, which melts the remains of the thread, drops of molten metal can destroy the glass of the bulb and cause a fire. The fuse is designed in such a way that when the arc is ignited, it is destroyed by the arc current, which significantly exceeds the rated current of the lamp. The ferronickel link is located in a cavity where the pressure is equal to atmospheric pressure, and therefore the arc is easily extinguished. Currently, the use of fuses is abandoned due to their low efficiency.

Flask

The flask protects the body of heat from the effects of atmospheric gases. Bulb dimensions are determined by the deposition rate of the filament material.

Gas medium

The flasks of the first lamps were evacuated. Most modern lamps are filled with chemically inert gases (except for low power lamps, which are still made vacuum). The heat loss arising in this case due to thermal conductivity is reduced by choosing a gas with a large molar mass. Mixtures of nitrogen N 2 with argon Ar are the most common due to their low cost, pure dried argon is also used, less often krypton Kr or xenon Xe (molar masses: N 2 - 28.0134 / mol; Ar: 39.948 g / mol; Kr - 83.798 g/mol; Xe - 131.293 g/mol).

Since the filament is at room temperature when turned on, its resistance is an order of magnitude less than the operating resistance. Therefore, when turned on, a very large current flows through the filament body (ten to fourteen times the operating current). As the filament heats up, its resistance increases and the current decreases. Unlike modern lamps, early incandescent lamps with carbon filaments, when turned on, worked on the opposite principle - when heated, their resistance decreased, and the glow slowly increased.

The increasing characteristic of the resistance of the filament (resistance increases with increasing current) allows the use of an incandescent lamp as a primitive current stabilizer. In this case, the lamp is connected in series to the stabilized circuit, and the average value of the current is chosen so that the lamp works half-heartedly.

In flashing lamps, a bimetallic switch is built in series with the filament. Due to this, such lamps independently work in a flickering mode.

plinth

In the USA and Canada, other socles are used (this is partly due to a different voltage in the networks - 110 V, so other sizes of socles prevent accidental screwing in of European lamps designed for a different voltage): E12 (candelabra), E17 (intermediate), E26 (standard or medium ), E39 (mogul). Also, similarly to Europe, there are plinths without thread.

Varieties

Incandescent lamps are divided into (arranged in order of increasing efficiency):

• Vacuum (the simplest)
• Argon (nitrogen-argon)
• Krypton
• Xenon-halogen with an IR reflector (since most of the lamp radiation is in the IR range, the reflection of IR radiation into the lamp significantly increases efficiency; they are made for hunting lamps)
• Incandescent with a coating that converts infrared radiation to the visible range. Lamps with a high-temperature phosphor are being developed, which, when heated, emit a visible spectrum.

Nomenclature

According to their functional purpose and design features, incandescent lamps are divided into:

• general purpose lamps(until the mid-1970s, the term "normal lighting lamps" was used). The most massive group of incandescent lamps designed for general, local and decorative lighting purposes. Since 2008, due to the adoption by a number of states of legislative measures aimed at reducing the production and limiting the use of incandescent lamps in order to save energy, their output began to decline;
• decorative lamps produced in curly flasks. The most popular are candle-shaped flasks with a diameter of about 35 mm and spherical flasks with a diameter of about 45 mm;
• local lighting lamps, structurally similar to general-purpose lamps, but designed for low (safe) operating voltage - 12, 24 or 36 (42) V. Scope - manual (portable) lamps, as well as local lighting lamps in industrial premises (on machine tools, workbenches and etc., where an accidental lamp strike is possible);
• illumination lamps produced in colored flasks. Purpose - illumination installations of various types. As a rule, lamps of this type have low power (10-25 W). Flasks are usually colored by applying a layer of inorganic pigment to their inner surface. Lamps with flasks painted on the outside with colored varnishes (colored zaponlak) are less commonly used, their disadvantage is the rapid fading of the pigment and shedding of the varnish film due to mechanical influences;
• mirrored incandescent lamps have a flask of a special shape, part of which is covered with a reflective layer (a thin film of thermally sprayed aluminum). The purpose of mirroring is the spatial redistribution of the luminous flux of the lamp in order to use it most efficiently within a given solid angle. The main purpose of mirror LNs is localized local lighting;
• signal lamps used in various lighting devices (means of visual display of information). These are low power lamps designed for a long service life. Today they are being replaced by LEDs;
• transport lamps- an extremely wide group of lamps designed to work on various vehicles (cars, motorcycles and tractors, airplanes and helicopters, locomotives and wagons of railways and subways, river and sea vessels). Characteristic features: high mechanical strength, vibration resistance, the use of special socles that allow you to quickly replace lamps in cramped conditions and, at the same time, prevent lamps from spontaneous falling out of their sockets. Designed to be powered by the on-board electrical network of vehicles (6-220 V);
• projector lamps usually have high power (up to 10 kW, lamps up to 50 kW were previously produced) and high luminous efficiency. Used in lighting devices for various purposes (lighting and light-signal). The filament of such a lamp is usually stacked due to the special design and the suspension in the bulb is more compact for better focusing;
• lamps for optical instruments, which include mass-produced until the end of the 20th century. lamps for film projection equipment have compactly stacked spirals, many are placed in specially shaped flasks. Used in various devices (measuring instruments, medical equipment, etc.);

Special Lamps

• switch lamps- a kind of signal lamps. They served as indicators on switchboards. They are narrow long miniature lamps with smooth parallel contacts, which makes it easy to replace them. Options were produced: KM 6-50, KM 12-90, KM 24-35, KM 24-90, KM 48-50, KM 60-50, where the first number means the operating voltage in volts, the second - the current strength in milliamps;
• photo lamp, chimney lamp- a kind of incandescent lamp, designed to operate in a strictly normalized forced voltage mode. Compared to conventional ones, it has an increased light output (up to 30 lm / W), a short service life (4-8 hours) and a high color temperature (3300-3400K, compared to 2700K). In the USSR, photolamps with a power of 300 and 500 watts were produced. As a rule, they have a frosted flask. At present (XXI century) they have practically fallen into disuse, due to the emergence of more durable devices of comparable and higher efficiency. In photo labs, such lamps were usually powered in two modes:
• Projection lamps- for dia- and film projectors. They have increased brightness (and, accordingly, increased filament temperature and reduced service life); usually the thread is placed so that the luminous area forms a rectangle.
• Double filament lamps. In a car, a headlight lamp may have one thread for high beam, another for dipped beam, or, for example, one thread for a parking light, another for a brake light. In addition, such lamps may contain a screen that, in low beam mode, cuts off rays that could dazzle oncoming drivers. In an airplane, the landing and taxiing headlight has a main thread, on which the lamp works without external cooling, and an additional one, switched on together with the main one, allowing you to get more powerful light, but only with external cooling - blown by an oncoming air stream. The stars of the Moscow Kremlin use specially designed double-filament lamps, both filaments are connected in parallel.
• headlamp. A lamp of a complex special design used on moving objects, the figured bulb of which is made in the form of a part of the headlight housing with a reflector. Structurally, it contains a filament (s), a reflector, a diffuser, fasteners, terminals, etc. Headlight lamps are widely used in modern automotive technology and have been used in aviation for quite a long time.
• Fast response incandescent lamp, an incandescent lamp with a thin filament - was used in optical sound recording systems by modulating the brightness of the source and in some experimental models of the Phototelegraph. Due to the small thickness and mass of the filament, applying a voltage modulated by a signal of the audio frequency range (up to about 5 kHz) to such a lamp led to a change in brightness in accordance with the instantaneous signal voltage . Since the beginning of the 21st century, they have not been used due to the presence of much more durable solid-state light emitters and much less inertial emitters of other types.
• heating lamps- the main source of heat in the fusing units of laser printers and copiers. The cylindrical lamp is fixedly mounted inside a rotating metal shaft, against which paper with toner is pressed. Due to the heat transferred from the shaft, the toner is melted and pressed into the paper structure.
• Special spectrum lamps. Used in a variety of technologies.

Invention history

A burned-out lamp, the bulb of which has retained its integrity, and the filament has collapsed in only one place, can be repaired by shaking and turning so that the ends of the filament are reconnected. With the passage of current, the ends of the filament can fuse and the lamp will continue to work. In this case, however, the fuse that is part of the lamp may fail (melt / break off).

Advantages and disadvantages of incandescent lamps

Advantages

• low price
• small size
• low sensitivity to power failures and power surges
• instant ignition and re-ignition
• invisibility of flicker when operating on alternating current (important in enterprises)
• Possibility to use brightness controls

• a pleasant and familiar spectrum in everyday life; The emission spectrum of an incandescent lamp is determined solely by the temperature of the working fluid and does not depend on any other conditions, which follows from the principle of its operation. It does not depend on the materials used and their purity, is stable over time and has 100% predictability and repeatability. This is also important in large installations and in luminaires with hundreds of lamps: it is not uncommon to see when using modern phosphor or LED lamps they have a different color shade within a group. This reduces the aesthetic perfection of the installations. If one lamp fails, it is often necessary to replace the entire group, but even when installing lamps from the same batch, spectrum deviation occurs
• high color rendering index, Ra 100
• continuous radiation spectrum
• sharp shadows (as in sunlight) due to the small size of the radiating body
• not afraid of low and high ambient temperatures, resistant to condensate
• excellence in mass production
• the possibility of manufacturing lamps for a wide variety of voltages (from fractions of a volt to hundreds of volts)
• the absence of toxic components and, as a result, the absence of the need for an infrastructure for the collection and disposal
• lack of control gear
• the ability to work on any kind of current
• voltage polarity insensitivity
• purely active electrical resistance (unit power factor)
• no buzz when operating on alternating current (due to the absence of electronic ballast, driver or converter)
• does not create radio interference during operation
• resistance to electromagnetic impulse
• insensitivity to ionizing radiation

Flaws

Production

Import, purchase and production restrictions

In connection with the need to save energy and reduce carbon dioxide emissions into the atmosphere, many countries have introduced or are planning to introduce a ban on the production, purchase and import of incandescent lamps in order to force them to be replaced with energy-saving (compact fluorescent, LED, induction, etc.) lamps.

In Russia

On July 2, 2009, at a meeting in Arkhangelsk of the Presidium of the State Council on Increasing Energy Efficiency, President of the Russian Federation Dmitry A. Medvedev proposed to ban the sale of incandescent lamps in Russia.

On November 23, 2009, D. A. Medvedev signed the law “On Energy Saving and Increasing Energy Efficiency and on Amending Certain Legislative Acts of the Russian Federation”, previously adopted by the State Duma and approved by the Federation Council. According to the document, from January 1, 2011, the sale of electric incandescent lamps with a power of 100 W or more is not allowed in the country, and it is also prohibited to place orders for the supply of incandescent lamps of any power for state and municipal needs; From January 1, 2013, a ban may be introduced on electric lamps with a power of 75 W or more, and from January 1, 2014 - with a power of 25 W or more.

This decision is controversial. In support of it, obvious arguments are given for saving electricity and pushing the development of modern technologies. Against - the consideration that the savings on replacing incandescent lamps are completely negated by the ubiquitous obsolete and energy-inefficient industrial equipment, power lines that allow high energy losses, as well as the relatively high cost of compact fluorescent and LED lamps, which are inaccessible to the poorest part of the population. In addition, there is no well-established system for the collection and disposal of used fluorescent lamps in Russia, which was not taken into account when the law was adopted, and as a result, mercury-containing fluorescent lamps are thrown out uncontrollably. Most consumers are not aware of the presence of mercury in a fluorescent lamp, as it is not indicated on the packaging, and instead of "fluorescent" it says "energy saving". At low temperatures, many "energy-saving" lamps are unable to start. Fluorescent energy-saving lamps are not applicable in spotlights of directional light, since the luminous body in them is ten times larger than the incandescent filament, which does not allow narrow focusing of the beam. Due to their high cost, “energy-saving” lamps are more often the subject of theft from public places (for example, entrances of residential buildings), such thefts cause more significant material damage, and in the event of vandalism (damage to a fluorescent lamp out of hooligan motives), there is a danger of contamination of the premises with mercury vapor .

incandescent lamp is an electrical light source that emits light flow as a result of the heating of a conductor made of refractory metal (tungsten). Tungsten has the highest melting point of all pure metals (3693 K). The filament is in a glass flask filled with an inert gas (argon, krypton, nitrogen). inert gas protects the filaments from oxidation. For incandescent lamps of low power (25 W), vacuum flasks are made that are not filled with an inert gas. The glass bulb prevents the negative effects of atmospheric air on the tungsten filament.

To calculate the illumination of a room, you can use the calculator for calculating the illumination of a room.

Varieties of incandescent lamps.

Incandescent lamps are divided into:

• vacuum;
• Argon (nitrogen-argon);
• Krypton (+10% brightness from argon);
• Xenon (2 times brighter than argon);
• Halogen (composition I or Br, 2.5 times brighter than argon, high service life);
• Halogen with two flasks (improved halogen cycle due to better heating of the inner flask);
• Xenon-halogen (composition Xe + I or Br, up to 3 times brighter than argon);
• Xenon halogen with IR reflector;
• Incandescent with a coating that converts infrared radiation to the visible range. (new)

Advantages and disadvantages of incandescent lamps.

Advantages:

• low cost;
• instant ignition when turned on;
• small overall dimensions;
• wide power range.

Flaws:

• high brightness (negatively affects vision);
• short service life - up to 1000 hours;
• low efficiency. (only a tenth of the electrical energy consumed by the lamp is converted into visible light flux) the rest of the energy is converted into heat.

Characteristics of incandescent lamps.

Light flow is a physical quantity that characterizes the amount of "light" power in the corresponding radiation flux.

Light output- this is the ratio of the light flux emitted by the source to the power consumed by it, measured in lumens per watt (lm / W). It is an indicator of the efficiency and economy of light sources.

Lumen- This is a unit of measurement of the luminous flux, a luminous quantity.

Luminous flux and luminous efficiency of incandescent lamps.

Comparative table of the ratio of luminous flux to power consumption of various types of lamps.

Characteristics of different types of lamps in terms of light transmission.

• LN- incandescent lamps;
• GLN- halogen lamps;
• CFL- compact fluorescent lamps;
• MGL- metal halide lamps;
• LL- fluorescent lamps;
• LEDs- LED lamp.

Characteristics of various types of incandescent lamps.

Lamp voltage - U, Volt;

Lamp power - W, W;

Luminous flux - Lm, Lumen.

General purpose incandescent lamps (standard).

General purpose incandescent lamps (minions).

General purpose incandescent lamps (mirror).

General purpose incandescent lamps (opaque).

Schemes for switching on incandescent lamps.

Wiring diagram for switching on a single-lamp luminaire with a socket.

Schematic diagram of the inclusion of one lamp with a switch and a socket.

Parsing the structure of an incandescent lamp (Figure 1, a) we find that the main part of its design is the filament body 3 , which, under the action of an electric current, is heated up to the appearance of optical radiation. This is actually based on the principle of operation of the lamp. The fastening of the filament body inside the lamp is carried out using electrodes 6 , usually holding its ends. Through the electrodes, an electric current is also supplied to the filament body, that is, they are still internal links of the conclusions. With insufficient stability of the filament body, use additional holders 4 . The holders are soldered onto the glass rod 5 , called a rod, which has a thickening at the end. The stem is associated with a complex glass part - a leg. Leg, it is shown in Figure 1, b, consists of electrodes 6 , plates 9 , and stem 10 , which is a hollow tube through which air is pumped out of the lamp bulb. Common interconnection of intermediate outputs 8 , rod, plate and stem forms a spatula 7 . The connection is made by melting glass parts, during which an exhaust hole is made. 14 connecting the internal cavity of the exhaust tube with the internal cavity of the lamp bulb. For supplying electric current to the filament through the electrodes 6 apply intermediate 8 and external findings 11 connected to each other by electric welding.

Figure 1. The device of an electric incandescent lamp ( a) and its legs ( b)

To isolate the filament body, as well as other parts of the light bulb from the external environment, a glass bulb is used. 1 . The air from the inner cavity of the flask is pumped out, and instead an inert gas or a mixture of gases is pumped in. 2 , after which the end of the stem is heated and sealed.

For supplying electric current to the lamp and fixing it in an electric cartridge, the lamp is equipped with a base 13 , the attachment of which to the neck of the flask 1 carried out with the help of base mastic. Solder the lamp leads to the corresponding places of the base 12 .

The light distribution of the lamp depends on how the filament body is located and what shape it is. But this applies only to lamps with transparent flasks. If we imagine that the filament is an equally bright cylinder and project the light emanating from it onto a plane perpendicular to the largest surface of the luminous filament or spiral, then the maximum luminous intensity will be on it. Therefore, in order to create the desired directions of light forces, in various designs of lamps, the filaments are given a certain shape. Examples of filament shapes are shown in Figure 2. A straight, non-spiralized filament is almost never used in modern incandescent lamps. This is due to the fact that with an increase in the diameter of the filament, heat loss through the gas filling the lamp decreases.

Figure 2. The design of the heating body:
a- high-voltage projection lamp; b- low-voltage projection lamp; in- providing an equally bright disk

A large number of heating bodies are divided into two groups. The first group includes filaments used in general purpose lamps, the design of which was originally conceived as a radiation source with a uniform distribution of light intensity. The purpose of designing such lamps is to obtain maximum luminous efficiency, which is achieved by reducing the number of holders through which the filament is cooled. The second group includes the so-called flat filaments, which are made either in the form of parallel spirals (in high-power high-voltage lamps) or in the form of flat spirals (in low-power low-voltage lamps). The first design is made with a large number of molybdenum holders, which are fastened with special ceramic bridges. A long filament is placed in the form of a basket, thereby achieving a large overall brightness. In incandescent lamps intended for optical systems, the filaments must be compact. To do this, the filament body is rolled into a bow, double or triple helix. Figure 3 shows the luminous intensity curves generated by filaments of various designs.

Figure 3. Luminous intensity curves for incandescent lamps with different filaments:
a- in a plane perpendicular to the axis of the lamp; b- in a plane passing through the axis of the lamp; 1 - ring spiral; 2 - straight spiral; 3 - spiral located on the surface of the cylinder

The required luminous intensity curves of incandescent lamps can be obtained by using special flasks with reflective or diffusing coatings. The use of reflective coatings on an appropriately shaped bulb allows for a considerable variety of luminous intensity curves. Lamps with reflective coatings are called mirrored (Figure 4). If it is necessary to ensure particularly accurate light distribution in mirror lamps, flasks made by pressing are used. Such lamps are called lamps-headlights. Some designs of incandescent lamps have metal reflectors built into the bulbs.

Figure 4. Mirrored incandescent lamps

Materials used in incandescent lamps

Metals

The main element of incandescent lamps is the filament body. For the manufacture of a heating body, it is most advisable to use metals and other materials with electronic conductivity. In this case, by passing an electric current, the body will heat up to the required temperature. The material of the heating body must satisfy a number of requirements: have a high melting point, plasticity, which allows drawing wires of various diameters, including very small ones, a low evaporation rate at operating temperatures, which leads to a high service life, and the like. Table 1 shows the melting points of refractory metals. The most refractory metal is tungsten, which, along with high ductility and low evaporation rate, ensured its widespread use as the filament of incandescent lamps.

Table 1

Melting point of metals and their compounds

The evaporation rate of tungsten at temperatures of 2870 and 3270°C is 8.41×10 -10 and 9.95×10 -8 kg/(cm²×s).

Of other materials, rhenium can be considered promising, the melting point of which is slightly lower than that of tungsten. Rhenium lends itself well to mechanical processing in a heated state, is resistant to oxidation, and has a lower evaporation rate than tungsten. There are foreign publications on the production of lamps with a tungsten filament with rhenium additives, as well as coating the filament with a layer of rhenium. Of non-metallic compounds, tantalum carbide is of interest, the evaporation rate of which is 20–30% lower than that of tungsten. An obstacle to the use of carbides, in particular tantalum carbide, is their brittleness.

Table 2 shows the main physical properties of an ideal filament made of tungsten.

table 2

Main physical properties of tungsten filament

An important property of tungsten is the possibility of obtaining its alloys. Details from them retain a stable shape at high temperatures. When the tungsten wire is heated, during the heat treatment of the filament and subsequent heating, a change in its internal structure occurs, called thermal recrystallization. Depending on the nature of the recrystallization, the filament body may have greater or lesser dimensional stability. The nature of recrystallization is influenced by impurities and additives added to tungsten during its manufacture.

The addition of thorium oxide ThO 2 to tungsten slows down the process of its recrystallization and provides a fine crystalline structure. Such tungsten is strong under mechanical shock, however, it sags strongly and is therefore not suitable for the manufacture of filaments in the form of spirals. Tungsten with a high content of thorium oxide is used for the manufacture of gas discharge lamp cathodes due to its high emissivity.

For the manufacture of spirals, tungsten is used with an additive of silicon oxide SiO 2 together with alkali metals - potassium and sodium, as well as tungsten containing, in addition to those indicated, an additive of aluminum oxide Al 2 O 3. The latter gives the best results in the manufacture of coils.

The electrodes of most incandescent lamps are made of pure nickel. The choice is due to the good vacuum properties of this metal, which releases the gases sorbed in it, high current-carrying properties, and weldability with tungsten and other materials. The malleability of nickel makes it possible to replace welding with tungsten by compression, which provides good electrical and thermal conductivity. Vacuum incandescent lamps use copper instead of nickel.

Holders are usually made of molybdenum wire, which retains its elasticity at high temperatures. This makes it possible to maintain the filament body in a stretched state even after it has expanded as a result of heating. Molybdenum has a melting point of 2890 K and a temperature coefficient of linear expansion (TCLE) in the range from 300 to 800 K equal to 55 × 10 -7 K -1 . Molybdenum is also used to make bushings in refractory glass.

The terminals of incandescent lamps are made of copper wire, which is butt welded to the inputs. Low-power incandescent lamps do not have separate leads; their role is played by elongated inputs made of platinum. To solder the leads to the base, tin-lead solder of the POS-40 brand is used.

glass

Bars, plates, stems, flasks and other glass parts used in the same incandescent lamp are made of silicate glass with the same temperature coefficient of linear expansion, which is necessary to ensure the tightness of the welding points of these parts. The values ​​of the temperature coefficient of linear expansion of lamp glasses must ensure that consistent junctions are obtained with the metals used to make the bushings. The most widely used glass brand SL96-1 with a temperature coefficient equal to 96 × 10 -7 K -1 . This glass can operate at temperatures from 200 to 473 K.

One of the important parameters of glass is the temperature range within which it retains its weldability. To ensure weldability, some parts are made of SL93-1 glass, which differs from SL96-1 glass in chemical composition and a wider temperature range in which it retains weldability. Glass brand SL93-1 is distinguished by a high content of lead oxide. If it is necessary to reduce the size of the flasks, more refractory glasses are used (for example, grade SL40-1), the temperature coefficient of which is 40 × 10 -7 K -1 . These glasses can operate at temperatures from 200 to 523 K. The highest operating temperature is SL5-1 quartz glass, incandescent lamps from which can operate at 1000 K or more for several hundred hours (the temperature coefficient of linear expansion of quartz glass is 5.4 × 10 -7 K -1). Glasses of the listed brands are transparent for optical radiation in the wavelength range from 300 nm to 2.5 - 3 microns. Transmission of quartz glass starts from 220 nm.

Inputs

The bushings are made of a material that, along with good electrical conductivity, must have a thermal coefficient of linear expansion, which ensures that consistent junctions are obtained with glasses used for the manufacture of incandescent lamps. Consistent junctions are called junctions of materials, the values ​​of the thermal coefficient of linear expansion of which in the entire temperature range, that is, from the minimum to the glass annealing temperature, differ by no more than 10 - 15%. When soldering metal into glass, it is better if the thermal coefficient of linear expansion of the metal is slightly lower than that of glass. Then, when cooled, soldered glass compresses the metal. In the absence of a metal having the required value of the thermal coefficient of linear expansion, it is necessary to produce non-matched solder joints. In this case, the vacuum-tight connection of metal with glass over the entire temperature range, as well as the mechanical strength of the soldered joint, are ensured by a special design.

A matched junction with SL96-1 glass is obtained using platinum bushings. The high cost of this metal led to the need to develop a substitute, called "platinum". Platinite is a wire made of an iron-nickel alloy with a temperature coefficient of linear expansion smaller than that of glass. When a copper layer is applied to such a wire, it is possible to obtain a highly conductive bimetallic wire with a large temperature coefficient of linear expansion, depending on the layer thickness of the superimposed copper layer and the thermal coefficient of linear expansion of the original wire. It is obvious that such a method of matching the temperature coefficients of linear expansion allows matching mainly in terms of diametrical expansion, leaving the temperature coefficient of longitudinal expansion inconsistent. To ensure better vacuum density of junctions of SL96-1 glass with platinite and enhance wettability over a layer of copper oxidized over the surface to cuprous oxide, the wire is covered with a layer of borax (sodium salt of boric acid). Sufficiently strong solder joints are provided when using platinum wire with a diameter of up to 0.8 mm.

Vacuum-tight soldering into SL40-1 glass is obtained using molybdenum wire. This pair gives a more consistent seal than SL96-1 glass with platinum. The limited use of this solder is due to the high cost of raw materials.

To obtain vacuum-tight bushings in quartz glass, metals with a very low thermal coefficient of linear expansion are required, which do not exist. Therefore, I get the desired result thanks to the input structure. The metal used is molybdenum, which has good wettability with quartz glass. For incandescent lamps in quartz bulbs, simple foil bushings are used.

gases

Filling incandescent lamps with gas allows you to increase the operating temperature of the filament body without reducing the service life due to a decrease in the rate of sputtering of tungsten in a gaseous medium compared to sputtering in a vacuum. The spray rate decreases with increasing molecular weight and filling gas pressure. The pressure of the filling gases is about 8 × 104 Pa. What gas to use for this?

The use of a gaseous medium leads to heat losses due to heat conduction through the gas and convection. To reduce losses, it is advantageous to fill the lamps with heavy inert gases or their mixtures. These gases include air-derived nitrogen, argon, krypton and xenon. Table 3 shows the main parameters of inert gases. Nitrogen in its pure form is not used because of the large losses associated with its relatively high thermal conductivity.

Table 3

Basic parameters of inert gases

Despite a whole list of shortcomings identified when compared with other sources of artificial light, incandescent lamps remain in demand both in the domestic sphere and in industrial sectors.

Cheap and easy to use devices do not want to give up their positions, although a huge number of more economical and "long-lasting" substitutes have appeared on the market - for example, LED lamps.

What is the main secret of their success and why are they still popular? We will consider these issues in our article, referring to the technical characteristics of conventional light bulbs, their main types. We will also consider the advantages and disadvantages and give recommendations for choosing a traditional light bulb.

Until recently, incandescent lamps (LN) were used everywhere and now they are still being bought - they can work both “at full strength”, brightly illuminating the room, and reduce the brightness with the help of. Due to the prevalence of traditional light bulbs among the population, many are familiar with their design features.

Moreover, they often had to “get acquainted” due to the failure of the light source: the tungsten filament burned out, the glass burst or the bulb flew out of the base.

Some manufacturers have used more reliable and proven materials and treated the production of incandescent bulbs so responsibly that their products have been working for several decades. But this is more an exception than a rule - today there are no guarantees for a long service life.

Schematic representation of a lamp showing the main details. The design of the artificial light source has not changed much since the invention, only the materials and composition of the gas filling the flask have been improved.

The main active element is the so-called filament body, fixed on the holders and attached to the electrodes. At the moment of connecting the electricity, a voltage passes through it, causing both heating and glow. In order for the radiation to become visible, the heating temperature must reach 570 °C.

Tungsten is recognized as the most resistant metal to high temperatures. It begins to melt when heated to 3422 ° C. To maximize the radiation area, but reduce the volume of the filament body inside the glass bulb, it is twisted into a spiral.

The usual comfortable light of a yellow hue, which creates coziness in the house and is visually “warm”, occurs when the thread is heated to 2830-2850 ° C

To protect tungsten from the oxidation process characteristic of metals, air is pumped out of the flask and replaced with a vacuum or gas (krypton, argon, etc.). Vacuum filling technology is outdated; for household lamps, a mixture of nitrogen and argon or krypton is most often used.

As a result of testing, the minimum duration of lamp burning was revealed - 1 thousand hours. But, given the random reasons that disable devices ahead of time, it is assumed that the standards apply to only 50% of the products from each batch. The operating time of the second half may be longer or shorter - depending on the conditions of use.

Types and features of the use of LN

Qualitative characteristics and marking of tungsten bulbs are regulated GOST R 52712-2007. According to the type of filling of the flask, LN devices are divided into vacuum and gas-filled varieties.

The former serve less due to the inevitable evaporation of the tungsten filament. In addition, tungsten vapors are deposited on the glass envelope of the vacuum source, which significantly reduces the transparency and the ability of the glass to transmit light. They are produced with a monospiral, in the nomenclature designation they are assigned the letter AT.

In gas-filled devices, the disadvantages of vacuum bulbs are minimized. The gas reduces the evaporation process and prevents the tungsten from settling on the walls of the flask. Gas-filled monospiral species are designated by the letter G, and light bulbs with a double-wound helix, i.e. bispiral, marked with a letter B. If the bispiral variety has the nomenclature BC, which means that krypton was used in its filling.

In GLN halogen bulbs, bromine or iodine is added to the glass bulb filler, due to which the evaporating tungsten atoms, after evaporation, return back to the filament. Halogens are produced in two formats: in the form of quartz tubes with a long spiral or in a capsule version with a compact working element.

In state standards, the division into groups occurs according to the scope, but other characteristics are also affected. Let's assume that at the same level, "LN electric miniature" are considered ( LN mn) and "LN infrared mirror" ( ZK– devices with concentrated light distribution, ZD- with an average) - as you can see, different criteria are chosen to designate the categories.

There are groups that can be attributed to the most popular:

• general purpose;
• for vehicles;
• searchlights;
• miniature, etc.

Consider the scope and features of various categories, which in some cases may overlap.

Especially for fans of traditional light bulbs, filament devices based on LEDs are produced, similar in shape, but favorably differing in their characteristics.

If you choose a device of lower power, then the luminous flux will be weaker, if you choose a larger one, then you risk the integrity of the shades - they can be deformed due to the high heating temperature.

In addition to the technical characteristics, it is worth paying attention to the quality of the workmanship of the lamp. Preference should be given to products with a wide base contact, a soldered conductor, and a stably fixed filament.

Conclusions and useful video on the topic

Even more informative and interesting information about the production, use and disadvantages of incandescent lamps - in videos shot by experts and amateurs.

Interesting Incandescent Facts:

Considering that we use lighting all the time, and there are usually more than a dozen light bulbs in the house, habits should be reconsidered. Many users have long switched to more reliable, economical, safe LED lamps.

Have you noticed errors or inaccuracies in the material presented? Or do you want to supplement this article with useful recommendations? Write to us about it, please, in the comment block.

If you prefer to use traditional light bulbs instead of more economical energy-saving ones and want to share your opinion on them, write your point of view on the advisability of using conventional light bulbs under this article.