Ultra-high pressure arc lamps. Mercury lamps. How does a mercury lamp work, its advantages and disadvantages

High-pressure mercury arc lamps (HALVs)

DRL250 lamp on a homemade test bench

For general lighting of workshops, streets, industrial enterprises and other facilities that do not have high requirements for color rendering quality, high-pressure mercury lamps of the DRL type are used.

Device

DRL lamp device

The DRL lamp (see figure on the right) has the following structure: a glass cylinder 1, equipped with a threaded base 2. In the center of the cylinder there is a quartz burner (tube) 3 filled with argon with the addition of a drop of mercury. Four-electrode lamps have main cathodes 4 and additional electrodes 5, located next to the main cathodes and connected to the cathode of the opposite polarity through an additional carbon resistor 6. Additional electrodes make it easier to ignite the lamp and make its operation more stable.

Recently, DRL lamps have been manufactured as three-electrode lamps, with one starting electrode and a resistor.

Ignition of a DRL400 lamp at home

Operating principle

In a burner made of durable, refractory, chemically resistant transparent material, in the presence of gases and metal vapors, a discharge glow occurs - electroluminescence.

When voltage is applied to the lamp between the closely spaced main cathode and an additional electrode of reverse polarity at both ends of the burner, gas ionization begins. When the degree of gas ionization reaches a certain value, the discharge moves to the gap between the main cathodes, since they are included in the current circuit without additional resistance, and therefore the voltage between them is higher. Stabilization of parameters occurs 10-15 minutes after switching on (depending on the ambient temperature - the colder it is, the longer the lamp will light up).

An electrical discharge in a gas creates visible white without the red and blue components of the spectrum and invisible ultraviolet radiation, causing a reddish glow of the phosphor. These glows are summed up, resulting in a bright light that is close to white.

When the mains voltage changes by 10-15% up or down, the working lamp responds with a corresponding increase or loss of luminous flux by 25-30%. If the voltage is less than 80% of the mains voltage, the lamp may not light up, but may go out when lit.

When burning, the lamp becomes very hot. Due to its peculiarity, the DRL lamp must cool down after turning off before turning it on again.

Traditional areas of application of DRL lamps

Lighting of open areas, industrial, agricultural and warehouse premises. Wherever this is due to the need for great energy savings, these lamps are gradually being replaced by low-pressure lamps (lighting of cities, large construction sites, high production workshops, etc.).

Arc mercury metal halide lamps (MAH)

The abbreviation “DRI” stands for “arc mercury with radiating additives (metal iodides and bromides).” Along with mercury, sodium, thallium and indium iodides are introduced into these lamps, due to which the light output significantly increases (it is approximately 70 - 95 lumens/W and higher) with a fairly good color of the radiation. The lamps have ellipsoidal and cylindrical bulbs. A quartz or ceramic cylindrical burner is placed inside the flask, where a discharge occurs in vapors of metals and their iodides. Service life - up to 8-10 thousand hours.

Modern DRI lamps use mainly ceramic burners, which are more resistant to reactions with their functional substance, due to which over time the burners darken much less than quartz ones. However, the latter are also not discontinued due to their relative cheapness.

Another difference between modern DRIs is the spherical shape of the burner, which makes it possible to reduce the decline in light output, stabilize a number of parameters and increase the brightness of the “point” source. There are two main versions of these lamps: with sockets E27, E40 and soffit - with sockets like Rx7S and the like.

To ignite DRI lamps, a breakdown of the interelectrode space with a high voltage pulse is required. In “traditional” circuits for switching on these vapor light lamps, in addition to the inductive ballast choke, a pulsed ignition device is used - IZU.

By changing the composition of impurities in DRI lamps, it is possible to achieve “monochromatic” glows of various colors (violet, green, etc.) Thanks to this, DRIs are widely used for architectural lighting. DRI-12 lamps (with a greenish tint) are used on fishing vessels to attract plankton.

Arc mercury metal halide lamps with a mirror layer (DRIZ)

It is a regular DRI lamp, part of the bulb of which is partially covered from the inside with a mirror reflective layer, due to which such a lamp creates a directed flow of light. Compared to the use of a conventional DRI lamp and a mirror spotlight, losses are reduced by reducing reflections and light transmission through the lamp bulb.

Mercury-quartz ball lamps (MSB)

High-pressure mercury-quartz lamps (PRK, DRT)

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Low and high pressure mercury gas discharge lamps of various modifications are used everywhere today. They are installed on the streets and roads of populated areas, perform the functions of architectural lighting, illuminate train stations, markets, highway overpasses, bridges and many other objects.

Low-pressure mercury lamps illuminate the buildings of schools, hospitals, kindergartens, administrative buildings, and shopping malls. They are popular in the housing and communal services sector for lighting entrances, basements, strollers and utility rooms. Powerful devices are installed in courtyards and playgrounds. Categories of narrow focus lamps are used for medical, forensic, agricultural livestock purposes and help in bird breeding.

Despite the disadvantages, mercury devices also have a number of advantages. Until some time, they were the most economical and reliable for consumers of different levels. But scientific developments and their improvement are constantly moving forward. And now, mercury-based devices are being replaced in orderly rows by sodium and LED lamps of the new generation. In the meantime, 70% of the space around us is illuminated by gas-discharge lamps.

Types of mercury lamps and the specifics of their operation

Lamps of this type are produced with a power from 8 to 1000 W and are divided into 2 groups:

general purpose;
highly specialized applications.

By internal filling pressure:

low pressure lamps (mercury vapor pressure > 100 Pa)
high pressure lamps (partial pressure value = 100 kPa);
ultra-high pressure lamps (value = 1 MPa and< 1 МПа).

High pressure mercury instruments

A mercury gas discharge lamp (MDL) operates on the principle of optical radiation generated from mercury vapor by a gas discharge.

Until 1970, lamps had only 2 electrodes. This made lighting the light bulbs difficult and the devices themselves unreliable. Then another pair of electrodes was added, located next to the main ones and connected to the opposite ones through resistors - current limiters.

When switched on, small discharges heat the gas and transfer to the main arc. Such a connection system also depends on the temperature of the surrounding space, so it is impossible to determine with accuracy after what period of time the light passes from glowing to arcing. Probably 1.5 to 8 minutes.

To ensure normal “entry” into the light mode, a regulating device is needed - a throttle. It partially absorbs the voltage from the network and creates an even background necessary for the lamps to work. Recently, lighting devices for DRL lamps have replaced the choke in their configuration with ballasts - a new generation ballast electronic ballast. The introduction of ballasts helped reduce the noise of lamps and improve the quality of light. Ignition time has been reduced to a minimum.

The lamp includes:

glass flask;
base;
a glass quartz tube containing argon gas and mercury vapor under pressure. The inside of the bulb is coated with phosphor to improve the quality of the light flux;
limiting resistor;
main electrode;
additional electrode.

Arc metal halide (MAH) a lamp with emissive additives that increase the efficiency of light transmission. In DRIs, not quartz, but ceramic burners are often installed, and a choke is included in the circuit. Power varies from 125 to 1000 W. Thanks to the added elements - metal halides, the lamp can emit different colors.

Metal halide lamp (DRIZ) with a mirror layer. These mercury devices have a special base and one side is coated with a mirror layer, which makes it possible to obtain a directed light flux.

Mercury-tungsten arc lamp (MAT) does not require ballasts due to the presence of a tungsten spiral. This high-pressure mercury lamp is also distinguished by the fact that its bulb, in addition to mercury vapor, is filled with a mixture of nitrogen and argon. Tungsten lamps produce bright, pleasant light and are the most durable.

Mercury-quartz (straight) bulb (PRK) or high-pressure tubular mercury arc lamp (HART). They have cylindrical flasks with electrodes located at the ends.

Mercury-quartz ball lamp (DSH). Distinctive features: spherical bulb and high level of lighting brightness along with ultraviolet radiation. The lamp operates under very high pressure with a cooling system.

High pressure mercury ultraviolet lamp (DRUF, DRUFZ) Made from uviol black glass. Another option for creating such bulbs is to use europium-doped strontium borate to coat the inside of the bulb. They practically do not produce visible light.

Low pressure mercury instruments

A fluorescent mercury lamp is a gas-discharge lamp and is designed on the same principle as high-pressure lamps.

Compact fluorescent lamp (CFL) appeared on the territory of our country in 1984. Such devices were initially equipped with standard types of bases with electric ballasts mounted inside.

Therefore, in view of the energy-saving characteristics declared by the manufacturer, KKL models quickly appeared in many apartments. Unlike other types of mercury fluorescent lamps, compact devices light up immediately and operate silently. The flickering frequency of such light bulbs is perceptible to the human eye, but not as clearly as in the case of other gas-discharge lamps.

Linear mercury-containing lamp presented in the form of a long flask with two electrodes at the ends, filled with gas and mercury vapor. The flask itself is coated inside with a phosphor. When the lamp is turned on, an electric arc discharge occurs, the filling of the lamp heats up to the required level, and the device flares up at full power.

In this case, the phosphor absorbs ultraviolet radiation emitted during operation. If you supplement the chemical composition of the phosphor with various additives, you can thus change the color of the light flux. Linear lamps differ in the types of base and diameter of the devices.

Low Pressure Quartz Mercury Arc Fluorescent Lamp produces powerful ultraviolet radiation. Used for disinfection of drinking water and air. Produces ozone in increased concentration. Requires further ventilation of the room.

Germicidal lamp Made from uviol glass. There is another technology when the inner surface of the flask is treated with a special chemical composition (see DRUF). Producing powerful ultraviolet radiation, the lamp does not emit too much ozone. Therefore, there may be people in the room where the device is used.

Areas of application of lamps containing mercury

DRL - mercury arc fluorescent lamps - are used to illuminate roads, stations, bridges, passages, squares, courtyards and other objects.

DRI lamps are used to organize outdoor lighting of streets, squares, parks, outdoor sports grounds, fairs, markets, etc. The ability to change the chemical composition to increase the spectrum of glow colors allows the use of metal halide lamps in architectural lighting.

Sailors on fishing boats use lamps with a greenish glow to attract plankton. Ultraviolet radiation, creating color temperature, brightness and a bluish glow all contribute to the growth of plants or even corals.

DRIZ lamps are relevant in areas with poor visibility, and tungsten devices are installed on construction sites, parking lots, and open warehouses.

Mercury-quartz and DRT devices are used in the medical field. Germicidal ultraviolet irradiators are used to disinfect water, food or air. During the period of burning of such lamps, a large concentration of ozone is formed in the air, so the rooms in which processing or other work with the device takes place must be provided with good ventilation to ventilate the space. Lamps are also used for photochemical technologies and photopolymerization of dyes and varnishes.

High-pressure mercury ultraviolet lamps are used to catch insects, taking into account the specifics of their visual apparatus. Lamps are used during performances, holidays, and carnivals.

Devices with DRUF lamps help in the work of experts and forensic scientists, indicating subtle traces of organic origin.

Linear fluorescent lamps have been widely used for lighting various public organizations and buildings for many years. After the appearance of models with sockets of standard sizes, light bulbs began to be used in houses and apartments.

A low-pressure bactericidal lamp is used for external and internal disinfection. Used indoors and for medical purposes.

Advantages of mercury gas discharge lamps

compactness of lamps;
fairly high light output 50 -60 lm/W;
efficiency is 5-7 times higher than incandescent lamps;
Durability - 10,000-15,000 thousand hours with proper use;
The heating of the housing is significantly lower than incandescent lamps;
Ability to reproduce different colors;
Work at high and low temperatures from +50 to -40.

For DRV lamps:

the possibility of replacing incandescent lamps for street lighting;
Possibility of operation without special start-up control equipment.

Disadvantages of mercury-containing arc lamps

operation on alternating current (except RDV);
switching on through ballast (except RDV);
sensitivity to network fluctuations;
unsatisfactory color rendering;
flicker that tires the eyes;
long period from switching on to the upper level of lamp light (except CFL);
after turning off until the next turn on, there is a long cooling period for the lamp (except CFL);
from the 2nd half of the service life, a decrease in light output;
Hazard class 1 due to mercury content in the structure.

For DRV lamps:

fragility of tungsten filament.

Disposal of lamps containing mercury

All lamps that contain mercury have a hazard class of 1. This means that after the end of their service life, such a device cannot simply be thrown into the trash. Moreover, it is unacceptable to get rid of a broken or cracked lamp in this way.

Only organizations that have a license for this activity can store, transport and dispose of devices with hazard class 1. It is clear that every person will not look for the coordinates of such a company. For this purpose, places for temporary storage of such lamps are provided in any locality.

The management organization that services your home is authorized to allocate such reception premises for citizens. After consulting with the public about opening hours, you can simply take your faulty appliances there. If the lamp is damaged, it must be placed in a bag, sealed tightly and handed over to a collection point.

The recycling process occurs in various, rather labor-intensive ways: amalgamation, demercurization, high-temperature firing or others.

The high-pressure mercury lamp is gradually becoming a thing of the past. The fight to preserve the environment is gaining momentum. They were replaced by sodium gas-discharge devices. More and more LED lamps that are safe, economical, durable and provide excellent illumination are appearing in homes and cities. But nothing happens suddenly. And it depends on each person which “tomorrow” will replace “today.” Take care of the earth and appreciate what you have now.

High-pressure mercury lamps are still produced by the domestic industry due to their low cost, good color rendering and efficiency. There are many different types of drl lamps for them. The abbreviation DRL stands for “high pressure mercury arc lamp”. This light source belongs to hazard class 1 equipment due to its mercury content. Street lamps on poles are in most cases equipped with these lamps.

Main design elements

The base is the part of the lamp through which supply voltage is supplied to it. On the base there are two leads from the electrodes, one of which is soldered to the threaded part, and the second to the lower end point. Through the contacts of the socket, electricity from the network is transferred to the lamp. The base is the contacting part. DRL 400 lamps with E40 sockets can be easily installed in any lamp equipped with the appropriate sockets.

The burner is a sealed tube, inside of which there are 2 electrodes at opposite ends. Two of them are main, two are incendiary. An inert gas is pumped inside the burner and a drop of mercury is placed in a strictly dosed amount. The burner material is chemically resistant and refractory.

The outer shell is made of glass with a burner mounted inside it. The volume is filled with nitrogen. To convert the radiation of a quartz burner, a phosphor coating is used on the inner surface of the flask. In addition, two limiting resistors for igniting electrodes are installed inside this flask.

The first DRL burners were equipped with two electrodes. To light a lamp, it was necessary to have a high-voltage pulse source in the switching circuit, which had a service life shorter than that of the lamp. Subsequently, the production of such lamps was discontinued and their production began in a four-electrode design, which did not require third-party pulse devices.

A four-electrode DRL lamp consists of a bulb, a threaded base and a quartz burner mounted on the lamp leg, filled with argon with the addition of mercury. There are 2 electrodes on each side of the burner: the main one and the igniter located next to it. To limit the current on the electrodes in the lamp, current-limiting resistances are provided, which are located in the outer bulb.

DRL 400 is widely used in lighting networks.

Principle of operation

After connecting the lamp to the power supply, conditions are created at both ends of the burner for a glow discharge to occur between the main and ignition electrodes. The launch of this process occurs due to the small distance between them. To break through this gap, a lower voltage is required than to break through the gap between the main electrodes. The current in this section is limited by resistances installed in the circuit of additional electrodes in front of the discharge tube.

After achieving a sufficient degree of ionization in the burner, a glow discharge is ignited in the main gap, which then turns into an arc.

When the lamp is turned off, the mercury in the burner is present in liquid or spray form. After ignition of the discharge between the main and ignition electrodes, the temperature in the burner rises and the mercury gradually evaporates, thereby improving the quality of the discharge in the main discharge gap. After all the mercury has passed into the vapor state, the lamp begins to operate in nominal mode with standard luminous efficiency.

The combustion lasts about ten minutes. After turning off the DRL lamp, turning it on again is possible only after it has cooled and the mercury has returned to its original form.

The most widely used lamps are those with DRL 250, since lamps with such parameters are necessary both for lighting inside and outside buildings.

The external appearance of these devices is subject to increased requirements for exposure to climatic factors.

Street lamps on poles are classified as outdoor lamps.

Luminaires for DRL lamps have a fairly wide range.

Models intended for indoor use are resistant to high humidity and dust.

Due to the tightness of the housing, DRL street lamps can withstand exposure to rain and snow. They successfully withstand strong gusts of wind.

Luminaires with DRL lamps use heat-resistant wires and connectors of reliable quality.

Where are lamps used?

Designed for lighting industrial and agricultural enterprises; areas outside buildings; for all objects in which there is an urgent need to use economical lighting systems. Used to illuminate streets and construction sites. In factories, workshops and warehouses, as well as other facilities where good color rendering is not needed.

Storage and disposal

Due to the fact that DRL lamps contain mercury, storing these products with broken and cracked bulbs in rooms that have not been prepared for this is strictly prohibited. At enterprises, a separate isolated zone with hermetically sealed containers should be allocated for these purposes. The storage time for such waste is allocated until it is removed from the zone for further destruction.

) - arc mercury phosphor high pressure lamp. This is one of the types of electric lamps that is widely used for general lighting of large areas such as factory floors, streets, playgrounds, etc. (where there are no special requirements for the color rendering of lamps, but high luminous efficiency is required from them). DRL lamps have a power of 50 - 2000 W and are initially designed to operate in AC electrical networks with a supply voltage of 220 V (frequency 50 Hz). To match the electrical parameters of the lamp and the power source, almost all types of mercury lamps that have a falling external current-voltage characteristic need to be used ballast(PRA), which in most cases is used as a choke connected in series with the lamp.

Device

The first DRL lamps were made with two electrodes. To ignite such lamps, a source of high-voltage pulses was required. The device used was PURL-220(Starting device for mercury lamps for voltage 220 V). The electronics of those times did not allow the creation of sufficiently reliable ignition devices, and the composition PURL included a gas discharger, which had a service life shorter than that of the lamp itself. Therefore, in the 1970s. industry gradually stopped producing two-electrode lamps. They were replaced by four-electrode ones, which do not require external ignition devices.

Now, regarding the device of the DRL lamp. A mercury arc lamp (MAL) consists of three main functional parts:

base;
quartz burner;
glass flask.

Base designed to receive electricity from the network by connecting the lamp contacts (one of which is threaded and the other is point-type) with the socket contacts, after which alternating electricity is transferred directly to the electrodes of the DRL lamp burner itself.

Quartz burner is the main functional part of the DRL lamp. It is a quartz flask with 2 electrodes on each side. Two of them are basic and two are additional. The burner space is filled with inert gas “argon” (to isolate heat exchange between the burner and the medium) and a drop of mercury.

Glass flask- this is the outer part of the lamp. A quartz burner is placed inside it, to which conductors are connected from the contact base. Air is pumped out of the flask and nitrogen is pumped into it. And one more important element that is located in the glass flask is 2 limiting resistances (connected to additional electrodes). The outer glass bulb is coated with phosphor on the inside.

Operating principle

The burner (RT) of the lamp is made of a refractory and chemically resistant transparent material (quartz glass or special ceramics), and is filled with strictly dosed portions of inert gases. In addition, metallic mercury is introduced into the burner, which in a cold lamp has the form of a compact ball, or settles in the form of a coating on the walls of the flask and (or) electrodes. The luminous body of the RLVD is a column of arc electric discharge.

The process of igniting a lamp equipped with igniting electrodes is as follows.

Mains voltage is supplied to the lamp; it is supplied to the gap between the main and additional electrodes, which are located on one side of the quartz burner, and to the same pair located on the other side of the burner. The second gap between which the mains voltage is concentrated is the distance between the main electrodes of the quartz burner, located on its opposite sides.

The distance between the main and additional electrodes is small, this makes it possible to easily ionize this gas gap when voltage is applied. The current in this section is necessarily limited by resistances located in the chain of additional electrodes before the entrance of the wire conductors into the quartz burner. After ionization has occurred at both ends of the quartz burner, it is gradually transferred to the gap between the main electrodes, thereby ensuring further combustion of the DRL lamp.

The maximum combustion of the DRL lamp occurs after about 7 minutes. This is due to the fact that in a cold state, the mercury in the quartz burner is in the form of droplets or deposits on the walls of the flask. After starting, the mercury slowly evaporates under the influence of temperature, gradually improving the quality of the discharge between the main electrodes. After all the mercury has turned into vapor (gas), the DRL lamp will reach its nominal operating mode and maximum light output. It should also be added that When the DRL lamp is turned off, it is impossible to turn it on again until the lamp has completely cooled down. This is one of the disadvantages of the llama, since it becomes dependent on the quality of the power supply.

The DRL lamp is quite sensitive to temperature and therefore its design includes an external glass bulb. It performs two functions:

Firstly, serves as a barrier between the external environment and the quartz burner, preventing the burner from cooling (the nitrogen inside the flask prevents heat exchange);
Secondly, since during an internal discharge not the entire visible spectrum is emitted (only ultraviolet and green), the phosphor lying in a thin layer on the inside of the glass bulb converts ultraviolet into a red spectrum.

As a result of the combination of blue, green and red radiation, the white glow of the DRL lamp is formed.

The four-electrode lamp is connected to the mains via a choke. The choke is selected in accordance with the power of the DRL lamp. The role of the inductor is to limit the current feeding the lamp. If you turn on a lamp without a choke, it will instantly burn out because too much electric current will pass through it. It is advisable to add to the connection diagram capacitor(not electrolytic). It will affect reactive power, and this will save electricity twice.

Choke DRL-125 (1.15A) = capacitor 12 uF. (not less than 250 V.)
Choke DRL-250 (2.13A) = capacitor 25 uF. (not less than 250 V.)
Choke DRL-400 (3.25A) = capacitor 32 uF. (not less than 250 V.)

Advantages:

high luminous efficiency (up to 60 lm/W)
compactness, with high unit power
ability to work at negative temperatures
long service life (about 15 thousand hours)

Flaws:

low color rendering
light pulsation
criticality to network voltage fluctuations

The DRL lamp contains droplets of mercury inside; if the quartz flask breaks, the mercury vapor will disperse in a room of 25 square meters. Handle the DRL lamp with care.

High pressure discharge lamps

High-pressure lamps, compared to fluorescent lamps, have significantly smaller dimensions and a higher unit power. High-pressure mercury lamps with the same power as fluorescent lamps (for example, 40, 80 W) have a length that is almost 10 times shorter. Small dimensions and high pressure in them determined the temperature of the discharge tube - 700...750°C. Therefore, the discharge tube of the lamps is made of quartz glass or special ceramics, which has high transparency in the visible region of the spectrum. .

One of the first to be developed was a high-pressure lamp of the DRT type. Lamp designation: D - arc, P - mercury, T - tubular; the next number corresponds to the lamp power. The former name of the lamp was PRK (direct mercury-quartz). The DRT lamp is intended for ultraviolet irradiation of young animals, chickens, eggs before incubation, grain seeds, etc. It is used in a set of irradiation installations of various types.

The DRT lamp is a straight tube made of quartz glass, at the ends of which tungsten electrodes are soldered. A small

Fig.1.26. Switching circuits: a) - DRT lamps; b) - DRL lamps; EL - lamp; L - throttle, SB - push-button switch; CI, C2, SZ - capacitors; R - resistor

the amount of mercury and inert gas - argon. For ease of fastening to the fittings, the lamp is equipped with clamps with holders at the edges, which are connected to each other by a metal strip used to facilitate ignition of the lamp. The DRT lamp is connected to the electrical network in series with the inductor L according to a resonant circuit (Fig. 1.26a). As a result of the resonance formed when capacitor C2 is turned on briefly, the voltage across inductor L and capacitor C2 increases by approximately 2 times compared to the supply voltage. This provides an arc discharge in the lamp. A metal strip connected through a small capacitor C3 facilitates breakdown of the lamp. Capacitor C1 increases the power factor of the circuit to 0.92...0.95.

The electrical energy supplied to the DRT lamp is converted in the following way: ultraviolet radiation is 18%, infrared radiation is 15%, visible light is 15%, losses are 52%. However, the DRT lamp is used primarily as a source of ultraviolet radiation. Table 1.9 shows the characteristics of DRT lamps.

Table 1.9 - High-pressure mercury arc lamps DRT

The radiation flux of DRT lamps depends on the ambient temperature. At high temperatures, the transparency of quartz glass deteriorates, which determines the reduction in especially ultraviolet radiation and the shelf life of the lamp.

The DRL mercury arc lamp is intended for outdoor lighting, indoor spaces and objects where high quality color rendering is not required. It can be recommended for lighting livestock and other agricultural buildings; with special irradiators, it is used to irradiate seedlings in greenhouses, as it has photosynthetically active radiation with a wavelength = 580...700 nm (orange-red part of the radiation spectrum).

The energy balance of the DRL lamp: ultraviolet radiation is practically absent, visible radiation is 17%, infrared radiation is 14%, heat loss is 69%. The color of the total radiation is close to white. The share of red radiation is 6...15%. The percentage of red radiation content is indicated when marking lamps in brackets. The brightness of DRL lamps is almost 10 times higher than the brightness of low-pressure fluorescent lamps.

The design of the DRL lamp is shown in Fig. 1.27. A quartz tube (burner) 3 is placed in a flask 1, the inner surface of which is coated with a thin layer of phosphor 2. The phosphor layer converts the ultraviolet radiation of the tube into light suitable for lighting. Two main tungsten electrodes 4, coated with an activated layer and connected to the base 7, and two additional (ignition) electrodes 5 are soldered into the quartz tube. The tube contains a small amount of mercury (40...60 mg). After pumping out the air from the outer flask 1, it is filled with argon under a pressure of 2.5...4.5 kPa.

This design allows you to light a four-electrode lamp from a 220 V power supply without a special ignition device (Fig. 1.26b). The presence of a choke and a capacitor in the circuit makes it possible to reduce fluctuations in the light flux and increase the power factor. In this case, the ballast consumes about 10% of the rated power of the lamp. When the lamp is connected to the network in series with the inductor, the discharge initially occurs between the adjacent main and additional electrodes. The resulting ionization of the discharge gap leads to the occurrence of a discharge between the main electrodes, after which the additional electrodes stop working.

The presence of 1 argon under pressure in the outer flask allows you to keep the phosphor coating in working condition for a long time. Heating of the outer bulb during lamp operation is 220... 280°C. The optimal ambient temperature for lamp operation is 25...40°C. The burning period of the DRL lamp lasts 5...10 minutes. The characteristics of DRL lamps are given in table. 1.10.

General purpose lighting metal halide lamps of the DRI type (mercury arc lamps with emitting additives) have, depending on the composition of the additives, a different emission spectrum that provides high quality color rendering and a higher luminous efficiency than that of DRL lamps. Structurally, the lamps differ from DRL lamps in the shape of the outer bulb, which does not have a phosphor coating, and in the absence of additional ignition electrodes in the discharge tube.

Therefore, they are included in the network according to a circuit containing special pulsed ignition devices - IZUs, which generate high-voltage pulses with a voltage of 2...6 kV.

To improve the spectral composition of visible radiation, compounds of the halogen group are added to the lamp tube: sodium iodides, scandium, bromides of rare earth metals. The characteristics of DRI lamps are given in table. 1.11.

In table 1.11 also shows the characteristics of DRIZ lamps for lighting dry, dusty and damp rooms and DRISH lamps for illuminating objects during color television filming and broadcasts (Ш - designation of a wide spectrum).

DRLF high-pressure mercury-quartz lamps are designed for plant irradiation based on DRL lamps. A special feature of these lamps is the special composition of the phosphor, which provides a radiation spectrum that is most conducive to the passage of physiological processes in plants. This radiation is in the wavelength range from 350 to 750 nm with a predominance of orange-red and blue-violet rays.

In their design and electrical parameters, DRLF lamps are similar to DRL lamps, however, they have a glass bulb that can withstand splashes of cold water when heated. The lamps are connected to the electrical network in the same way as DRL lamps.

Lamp designations: D - arc, R - mercury, L - fluorescent, F - with increased phyto-efficiency. The most widely used lamps are DRLF-400 and DRLF-1000 with a power of 400 and 1000 W with a phytoflux of 12,800 and 90,000 mft, respectively.

Table 1.10 - DRL high-pressure mercury lamps

Lamp type	Lamp power, W	Lamp voltage, V	Luminous flux, lm	Luminous efficacy, lm/W	Service life, h
DRL-50(15)				33,7
DRL-80(15)
DRL-125(6)				41,9
DRL-125(15)				44,8
DRL-250(6)-4
DRL-250(14)-4
DRL-400(10)-3				57,5
DRL-400(12)-4
DRL-700(6)-3
DRL-700(12)-3				58,5
DRL-1000(6)-2
DRL-1000(12)-3				58,5
DRL-2000(12)-2

The DRV-750 mercury-tungsten arc lamp is designed for additional irradiation of plants in greenhouses. Its main advantage, compared with DRLF lamps, is the absence of ballasts, as a result of which the metal consumption of the irradiation installation is reduced, the load on the roof of the greenhouse is reduced, and the maneuverability of mobile irradiation systems is improved. The lamp is made in the form of a flask in which a mercury burner is mounted together with an incandescent filament. The flask itself is made of heat-resistant glass and is designed to withstand splashes of cold water.

Table 1.11 - Arc mercury metal halide lamps for external and internal lighting DRI

Lamp type	Lamp power, W	Lamp voltage, V	Luminous flux, lm	Luminous efficacy, lm/W	Service life, h
DRI-125
DRI-175				68,5
DRI-250
DRI-1000-5
DRI-400-5
DRI-700
DRIZ-250-2				54,8
DRIZ-400-3
DRISH-2500-2
DRISH-4000-2

Has a specular or diffuse reflector. The filament is a ballast resistance and at the same time a source of radiation that enhances the red part of the spectral characteristics of the lamp.

As a result, the DRV-750 lamp is a source of mixed radiation with a predominance of orange-red and blue-violet rays.

A modernization of the DRV lamp is the mercury-tungsten lamp DRVL. It also has a tungsten spiral installed in the space between the discharge tube and the outer bulb, connected in series with the discharge tube and acting as a ballast resistance. In this ballast, approximately half of the lamp power is lost. This reduces the effective efficiency of mercury-tungsten lamps by 1.5...2 times compared to DRL and DRT lamps.

Arc mercury-tungsten erythema lamps with a diffuse reflector of the DRVED type are designed for complex exposure to radiation of a part of the spectrum with wavelengths from 280 to 5000 nm. The outer bulb of these lamps is made of special uviol glass that transmits ultraviolet radiation. The service life of DRVED type lamps is determined mainly by the service life of the tungsten filament - 3000...5000 hours.

Arc mercury fluorescent lamps DRF-1000 and DRF-2000 with increased phyto-output are intended for completing vegetation lighting systems used to create a light regime in climatic chambers and cabinets for the selection of various plants. The lamps have a large luminous flux and high luminous efficiency. The design and characteristics are similar to DRL lamps, but they differ in the phosphor composition and have a bulb made of tungsten heat-resistant glass that can withstand splashes of cold water. Disadvantages include the large mass of ballasts and power factor correction devices.

In the group of high-pressure discharge lamps, sodium lamps of the HPS type (sodium arc tubular) are distinguished by a higher light efficiency and a slightly more elongated outer bulb compared to a DRL lamp. The discharge tube of regular cylindrical shape is made of translucent ceramic (polycrystalline aluminum) or transparent tubular single crystal (leucosapphire). These materials are resistant to prolonged exposure to sodium vapor at temperatures up to 1600°C. The total transmittance of visible radiation is 90...95%. However, 70% of the radiation is in the zone 560...610 nm of yellow-orange color, which causes color distortion. Therefore: HPS lamps are mainly used for outdoor lighting. HPS lamps are connected to the electrical network according to a circuit similar to that of DRI lamps.

The characteristics of high-pressure sodium lamps HPS are given in table. 1.12.

Xenon arc tube lamps (AKsT) are used relatively little in agriculture due to the complexity of their operation. The lamps are carried out in one quartz discharge flask (DKsT) and in two water-cooled flasks (DKsTV).

In the spectrum of DKsT lamps without water cooling there is an excess of ultraviolet radiation. This drawback is corrected in lamps of the DKsTL type, the bulbs of which are made of quartz glass with alloying (A) additives. In the visible region of the spectrum, the radiation of xenon lamps approaches that of the sun. For DKsTV type lamps, the share of visible radiation is only 10...12% of their power. These types of lamps are produced, as a rule, with high unit power - from 1000 to 12000 W with a luminous efficiency of 24...40 lm/W. The service life is 500...1500 hours, which is due to the significant surface temperature of the discharge tube (750...800°C).

Table 1.12 - DnaT high-pressure sodium lamps

Lamp type	Lamp power, W	Lamp voltage, V	Luminous flux, lm	Luminous efficacy, lm/W	Life time
DNAT-70
DNAT-100
DNAT-150
DNAT-250-4		97,5
DNAT-250-7		97,5
DNAT-360
DNAT-400-4		102,5		117,5
DNAT-400-7		102,5

A feature of most high-pressure discharge lamps is the flare-up mode, which occurs within 5...10 minutes after the lamp is ignited. For mercury and sodium lamps it lasts longer than for xenon lamps. During the combustion process, all parameters of the lamp change. For example, the current in mercury lamps exceeds the rated value by 1.5...2 times. As it heats up, the vapor pressure inside the lamp increases, which is accompanied by a decrease in current and an increase in the radiation flux; with increasing pressure, the ignition voltage of the lamp increases. Therefore, re-ignition of an extinguished lamp is possible only after it has cooled, therefore, after reducing the ignition voltage. Mains voltage fluctuations have little effect on the luminous output of lamps, but large voltage deviations have a significant effect. Lamps must be used in the position specified by the manufacturer. When operating installations with high-pressure discharge lamps, significant pulsation of light fluxes should be taken into account and measures should be taken to reduce them.

Control questions

1. What is called an artificial source of optical radiation?

2. What main types of optical radiation sources do you know?

3. What is called an ideal emitter?

4. Name three classes of filament bodies.

5. How does the conversion of electricity occur? energy into optical radiation?

6. Define Kirchhoff's law.

7. Define Stefan Boltzmann's law.

8. Write Planck's law.

9. Define Wien's displacement law.

10. What are the main design elements of a general purpose incandescent lamp?

11. How does a linear halogen incandescent lamp work?