Mercury discharge lamps are an electric light source that uses a gas discharge in mercury vapor to generate optical radiation. Mercury vapor lamps are a type of gas discharge lamp. For the name of all types of such light sources in domestic lighting technology, the term "discharge lamp" (RL) is used, included in the International Lighting Dictionary, approved by the International Commission on Lighting. This term should be used in technical literature and documentation.
Depending on the filling pressure, a low pressure RL is distinguished ( RLND), high pressure (RLVD) and ultra-high pressure (RLSVD).
TO RLND include mercury lamps with a partial pressure of mercury vapor in a steady state of less than 100 Pa. For RLVD this value is about 100 kPa, and for RLSVD - 1 MPa or more.
RLVD are subdivided into lamps of general and special purpose... The first of them, which include, first of all, the widespread DRL lamps, are actively used for outdoor lighting, but they are gradually being replaced by more efficient sodium and metal halide lamps. Special-purpose lamps have a narrower range of applications, they are used in industry, agriculture, medicine.
High pressure mercury lamps type DRL
DRL (Dugovaya Rmulberry Lluminescent) - the designation RLVD adopted in domestic lighting engineering, in which, to correct the color luminous flux, aimed at improving color rendering, the radiation of a phosphor deposited on the inner surface of the bulb is used.
For general lighting of workshops, streets, industrial enterprises and other facilities that do not impose high requirements on the quality of color rendering and premises without the constant presence of people.
Arc mercury metal halide lamps (DRI)
Lamps DRI (Dugovaya Rmulberry with ANDradiant additives) is structurally similar to DRL, however, strictly metered portions of special additives - halides of some metals (sodium, thallium, indium, etc.) are additionally introduced into its burner, due to which the light output significantly increases (about 70 - 95 lm / W and above) with a sufficiently good chromaticity of the radiation. Lamps have ellipsoidal and cylindrical bulbs, inside which a quartz or ceramic burner is located. Service life - up to 8 - 10 thousand hours.
In modern DRI lamps, mainly ceramic burners are used, which are more resistant to reactions with their functional substance, due to which, over time, burners darken much less than quartz ones. However, the latter are also not removed from production because of their relative cheapness.
Another difference between modern DRI is the spherical shape of the burner, which allows 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 E27, E40 socles; soffit - with plinths like Rx7S and similar.
To ignite the DRI lamps, a breakdown of the interelectrode space with a high voltage pulse is required. In the "traditional" schemes for switching on these steam lamps, in addition to an inductive ballast choke, a pulsed ignitor is used - IZU.
By changing the composition of impurities in DRI lamps, it is possible to achieve "monochromatic" glow of various colors (purple, green, etc.). Due to this, DRI is widely used for architectural illumination. DRI lamps with an index "12" (with a greenish tint) are used on fishing vessels to attract plankton.
Arc mercury metal halide lamps with a mirror layer (DRIZ)
Lamps DRIZ (Dugovaya Rmulberry with ANDradiant additives and Zmirror layer) is an ordinary 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 stream of light. Compared to the use of a conventional DRI lamp and a mirror spotlight, losses are reduced by reducing re-reflections and light transmission through the lamp bulb. High focusing accuracy of the torch is also obtained. In order to change the direction of radiation after screwing the lamp into the cartridge, DRIZ lamps are equipped with a special base.
Mercury-quartz ball lamps (DRSH)
Lamps DRSH (Dcoal Rmulberry Shary) are ultra-high pressure mercury arc lamps with natural cooling. They are spherical and emit strong ultraviolet radiation.
High pressure mercury-quartz lamps (PRK, DRT)
High pressure mercury arc lamp type DRT (Dcoal Rmulberry Tcorrugated) represent a cylindrical quartz flask with electrodes soldered at the ends. The flask is filled with a metered amount of argon, in addition, metallic mercury is introduced into it. Structurally, DRT lamps are very similar to DRL burners, and their electrical parameters are such that they allow the use of DRL ballasts of appropriate power to turn on. However, most DRT lamps are made in a two-electrode design, therefore, special additional devices are required to ignite them.
The first developments of DRT lamps, which bore the original name PRK (Pstraight Rhere- TOvarzovaya), were performed by the Moscow Electric Lamp Plant in the 1950s. In connection with the change in the regulatory and technical documentation in the 1980s. PRK designation was changed to DRT.
The existing range of DRT lamps has a wide power range (from 100 to 12000 W). Lamps are used in medical equipment (ultraviolet bactericidal and erythemal irradiators), for disinfection of air, food products, water, for photopolymerization of varnishes and paints, exposure of photoresists and other photophysical and photochemical technological processes. Lamps with a power of 400 and 1000 W were used in theatrical practice to illuminate decorations and costumes painted with fluorescent paints. In this case, the lighting devices were equipped with UVS-6 ultraviolet glass filters, which cut off the hard UV and almost all visible radiation of the lamps.
An important disadvantage of DRT lamps is the intense formation of ozone during their combustion. If for bactericidal installations this phenomenon usually turns out to be useful, then in other cases the concentration of ozone near the light device can significantly exceed the permissible sanitary standards. Therefore, rooms in which DRT lamps are used must be adequately ventilated to remove excess ozone. In small quantities, ozone-free DRT lamps are manufactured, the bulb of which has an outer coating of quartz doped with titanium dioxide. Such a coating practically does not transmit the ozone-forming line of resonance radiation of mercury at 253.7 nm.
Emission spectrum
Mercury vapors emit the following spectral lines used in gas discharge lamps:
The most intense lines are at 184.9499, 253.6517, 435.8328 nm. The intensity of the remaining lines depends on the mode (parameters) of the discharge.
Ultra-high pressure arc lamps (LSVD) include lamps operating at a pressure of 10 × 10 5 Pa and above. At high pressures of a gas or metal vapor, with a strong approach of the electrodes, the near-cathode and near-anode discharge regions contract. The discharge is concentrated in a narrow spindle-shaped region between the electrodes, and its brightness, especially near the cathode, reaches very high values.
This arc discharge is an indispensable light source for projector and projector types, as well as for a number of special applications.
The use of mercury vapor or inert gas in lamps gives them a number of features. Obtaining mercury vapor at an appropriate pressure, as can be seen from the examination of high pressure made in the article "", is achieved by dosing mercury in the lamp bulb. The discharge ignites as a low pressure mercury discharge at ambient temperature. Then, as the lamp burns up and heats up, the pressure increases. The working pressure is determined by the steady-state temperature of the bulb, at which the electric power supplied to the lamp becomes equal to the power dissipated in the surrounding space by radiation and heat transfer. Thus, the first feature of ultra-high pressure mercury lamps is that they are fairly easy to ignite but have a relatively long burn-up period. When they go out, reignition can be carried out, as a rule, only after complete cooling. When the lamps are filled with inert gases, the discharge after ignition almost instantly enters a steady state. Ignition of a discharge in a gas at high pressure presents certain difficulties and requires the use of special igniting devices. However, after extinguishing, the lamp can be re-lit almost instantly.
The second feature that distinguishes an ultra-high pressure mercury discharge with a short arc from the corresponding gas discharge is its electrical mode. Due to the large difference between the potential gradients in mercury and inert gases at the same pressure, the combustion voltage of such lamps is significantly higher than with gas filling, due to which, at equal powers, the current of the latter is much higher.
The third significant difference is the emission spectrum, which in gas-filled lamps corresponds in spectral composition to daylight.
These features have led to the fact that arc lamps are often used for filming and film projection, in simulators of solar radiation and other cases when correct color rendering is required.
Lamp device
The spherical shape of the lamp bulb is selected to ensure high mechanical strength at high pressures and small distances between the electrodes (Figure 1 and 2). The quartz glass spherical flask has two diametrically located long cylindrical legs, in which the inputs connected to the electrodes are sealed. A long leg is necessary to remove the lead from the hot bulb and prevent it from oxidizing. Some types of mercury lamps have an additional ignition electrode in the form of a tungsten wire soldered into the bulb.
Figure 1. General view of ultra-high pressure mercury-quartz lamps with a short arc of various power, W:
and - 50; b - 100; in - 250; r - 500; d - 1000
Figure 2. General view of xenon ball lamps:
and - constant current lamp with a power of 100 - 200 kW; b - 1 kW AC lamp; in - AC lamp with a power of 2 kW; r - constant current lamp with a power of 1 kW
Electrode designs differ depending on the type of current that powers the lamp. When working on alternating currentfor which mercury lamps are intended, both electrodes have the same design (Figure 3). They differ from the electrodes of tubular lamps of the same power in greater massiveness, due to the need to reduce their temperature.
Figure 3. Electrodes for short arc AC mercury lamps:
and - for lamps up to 1 kW; b - for lamps up to 10 kW; in - solid electrode for high-power lamps; 1
- core from tornated tungsten; 2
- tungsten wire sheathing coil; 3
- oxide paste; 4
- getter; 5
- base made of sintered tungsten powder with addition of thorium oxide; 6
- forged tungsten part
When the lamps are on direct current important is the position of the lamp burning, which should be only vertical - anode upwards for gas lamps and preferably anode downwards for mercury lamps. The location of the anode at the bottom reduces the stability of the arc, which is important, due to the counterflow of electrons directed downward and hot gases rising upward. The upper position of the anode forces to increase its dimensions, since in addition to its heating due to the higher power dissipated at the anode, it is additionally heated by a stream of hot gases. For mercury lamps, the anode is placed at the bottom in order to provide more uniform heating and, accordingly, reduce the burn-up time.
Due to the small distance between the electrodes, mercury ball lamps can operate on alternating current from a mains voltage of 127 or 220 V. The working pressure of mercury vapor in lamps with a power of 50 - 500 W, respectively (80 - 30) × 10 5, and in lamps with a power of 1 - 3 kW - (20 - 10) × 10 5 Pa.
Ultra-high-pressure lamps with a ball bulb are most often filled with xenon due to the convenience of its dosage. The distance between the electrodes is 3 - 6 mm for most lamps. Xenon pressure in a cold lamp (1 - 5) × 10 5 Pa for lamps with a power of 50 W to 10 kW. Such pressures make ultra-high-pressure lamps explosive even when not in operation and require special enclosures for their storage. Due to the strong convection, the lamps can only work in an upright position, regardless of the type of current.
Radiation lamps
High brightness of mercury ball lamps with a short arc is obtained due to an increase in the current and stabilization of the discharge at the electrodes, which prevent the expansion of the discharge channel. Depending on the temperature of the working part of the electrodes and their design, different brightness distributions can be obtained. When the temperature of the electrodes is insufficient to provide the arc current due to thermionic emission, the arc contracts at the electrodes into bright luminous points of small sizes and takes on a spindle shape. The brightness near the electrodes reaches 1000 Mcd / m² and more. The small size of these areas leads to the fact that their role in the total radiation flux of lamps is insignificant.
When the discharge contracts at the electrodes, the brightness increases with an increase in pressure and current (power) and with a decrease in the distance between the electrodes.
If the temperature of the working part of the electrodes ensures the receipt of the arc current due to thermionic emission, then the discharge seems to spread over the surface of the electrodes. In this case, the brightness is more evenly distributed along the discharge and still increases with increasing current and pressure. The radius of the discharge channel depends on the shape and design of the working part of the electrodes and is almost independent of the distance between them.
The light output of lamps increases with an increase in their power density. With a spindle-shaped discharge, the light output has a maximum at a certain distance between the electrodes.
Radiation of mercury ball lamps of the DRSh type has a line spectrum with a strongly pronounced continuous background. The lines are greatly expanded. There is no radiation with wavelengths shorter than 280 - 290 nm at all, and due to the background, the proportion of red radiation is 4 - 7%.
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| Figure 4. Distribution of brightness along ( 1 ) and across ( 2 ) axis of discharge of xenon lamps |
The discharge cord of dc xenon ball lamps, when operating in a vertical position with the anode up, has the shape of a cone, resting with its tip on the tip of the cathode and expanding upward. A small cathode spot of very high brightness is formed near the cathode. The distribution of brightness in the discharge cord remains the same when changing the discharge current density in a very wide range, which makes it possible to construct uniform curves of the brightness distribution along and across the discharge (Figure 4). The brightness is directly proportional to the power per unit length of the arc discharge. The ratio of the luminous flux and luminous intensity in a given direction to the arc length is proportional to the ratio of the power to the same length.
The emission spectrum of ultrahigh pressure xenon ball lamps differs little from the emission spectrum.
Powerful xenon lamps have a rising current-voltage characteristic. The slope increases with increasing electrode spacing and pressure. The anode-cathode potential drop for short-arc xenon lamps is 9-10 V, with the cathode being 7-8 V.
Modern ultra-high pressure ball lamps are produced in various designs, including those with collapsible electrodes and water cooling. The design of a special metal collapsible lamp-lamp of the DKsRM55000 type and a number of other sources used in special installations has been developed.
DRL type mercury lamps
The quartz burner considered in the article "Operation of the DRL lamp" is strongly influenced by the external environment, on which the cooling conditions depend. The stability of the lamp with such a burner is ensured by placing it inside the outer bulb. The inner surface of the outer bulb is covered with a layer of phosphor, which, due to the absorption of the ultraviolet part of the radiation of the mercury discharge, adds to the visible radiation of this discharge the missing radiation in the red region of the spectrum. To ensure cooling of the quartz burner not only by radiation, but also by convection and heat transfer, the outer bulb is filled with gas, which must be inert with respect to the phosphor and lamp mounting parts. A mixture of argon and nitrogen is used as the filling gas.
The device of the DRL lamp is shown in Figure 1. The lamps are connected to the network using threaded socles, similar to those used for incandescent lamps: E27 - for lamps with a power of up to 250 W and E40 - for lamps of higher power. To facilitate ignition, the lamp is made with a three- or four-electrode. In the latter, the main and auxiliary electrodes are connected through resistors.
The shape and size of the outer bulb and the position of the burner in it are chosen so that all the ultraviolet radiation of the burner falls on the phosphor layer and during and during the lamp operation the phosphor layer has the optimum temperature for its operation.
Heating of the outer flask occurs due to the absorption of a part of the discharge radiation by a layer of phosphor applied to it and glass, as well as heat transfer through the inert gas filling the flask. Cooling is carried out by radiation from the heated glass and heat transfer through the ambient air.
The uniformity of the surface temperature of the flask can be achieved if, neglecting in the first approximation the convection of the inert gas filling the flask, it is made in the form of a surface providing uniform irradiation. Calculations show that the central part of the flask should have a surface close to an ellipsoid of revolution, with a major axis coinciding with the axis of the burner. The convection correction forces the diameter of that part of the bulb, which turns out to be at the top when the lamp is operating, to slightly increase. Since the lamps are practically operated in any position, no amendments are made to the shape of the bulb.
In a number of lamp designs, the bulb acts as an optical element that redistributes the luminous flux. In this case, the shape and size of the bulb must be calculated, as is done for luminaires, and its thermal regime must also be taken into account in the calculation.
Various types of phosphors are used to correct the color of DRL lamps. The use of a phosphate-vanadate-yttrium phosphor instead of magnesium fluorogermanate made it possible to improve the parameters of DRL lamps.
The use of a phosphor deposited on the inner wall of the outer bulb, on the one hand, leads to the addition of missing red radiation in the spectrum, and, on the other hand, causes the absorption of part of the visible radiation in this layer. With increasing thickness of the phosphor layer, the radiation flux of the lamp has a maximum at a certain layer thickness, while the luminous flux of the discharge passing through the phosphor layer gradually decreases. To solve the problem of the optimal thickness of the phosphor layer and a general assessment of its effectiveness for the characteristics of DRL lamps, the concept of "red ratio" was introduced. The red ratio is the percentage ratio of the red luminous flux added by the phosphor to the total luminous flux of the lamps. Obviously, the best will be the phosphor and such a layer that, when creating a red ratio sufficient to ensure correct color rendering, provide the maximum luminous flux of the lamp as a whole, that is, the greatest luminous efficiency.
The red ratio is usually expressed as a percentage by dependence
where φ (λ) - spectral flux density of the lamp radiation; V (λ) is the relative sensitivity of the eye.
The red ratio for DRL-type lamps with the optimal phosphor thickness of fluorogermanate and magnesium arsenate reaches 8%, and the luminous flux is 87% of the luminous flux of the lamp without phosphor. The use of orthophosphate-zinc phosphors with the addition of strontium makes it possible to obtain a luminous flux 15% higher than the luminous flux of a lamp without a phosphor, and r cr \u003d 4 - 5%.
During the ignition of the lamps, cathode sputtering of the active substance of the cathode and the rod part of the electrode takes place. In the steady-state mode of combustion on an alternating current, due to re-ignition of the discharge in each half-period, the sputtering of the rod part of the electrode continues. This deteriorates over time the emission properties of both parts of the electrodes, respectively, the voltage required to ignite the lamps increases. The sputtering of the electrodes simultaneously leads to the absorption of molecules of the inert gas filling the lamp, the initial pressure of which was chosen from the conditions for the ignition of the discharge. These processes lead to the formation on the walls of the burner of a dark coating of particles of sputtered electrodes, which absorbs radiation, especially its ultraviolet component, and the red ratio decreases. Ignition interruption determines the full service life of DRL lamps, and the standardized decrease in luminous efficiency determines their useful service life.
 |
| Figure 2. Construction details of the high pressure mercury lamp burner: 1 - main electrode; 2 - molybdenum foil bushings of the main electrode and the ignition electrode; 3 - additional resistor in the ignition electrode circuit; 4 - ignition electrode circuit |
The conventional designation of DRL lamps is deciphered as follows: D - arc, R - mercury, L - luminescent. The numbers after the letters correspond to the lamp power in watts, then the red ratio in percentage is given in brackets and the development number is given through a hyphen. The vast majority of DRL lamps are produced with four-electrode, that is, with additional electrodes to facilitate ignition (see Figure 2). Such lamps are lit directly from the mains voltage. A small part of DRL lamps are made of two-electrode type; special ignition devices are used to ignite them.
DRL lamps are used in outdoor lighting installations and for lighting high premises of industrial enterprises, where strict requirements are not imposed on the quality of color rendering.
The influence of the ambient temperature affects primarily the ignition voltage of the lamps. At negative temperatures, ignition of DRL-type lamps is difficult, which is associated with a significant decrease in the pressure of mercury, as a result of which ignition occurs in pure argon and requires higher voltages than in the presence of mercury vapor. According to GOST 16354-77, DRL lamps of all powers must ignite at a voltage of no more than 180 V at an ambient temperature of 20 - 40 ° C; at a temperature of -25 ° C, the ignition voltage of lamps increases to 205 V, at -40 ° C, the ignition voltage for lamps with a power of 80 - 400 W is not more than 250 V, with a power of 700 and 1000 W - 300 V. For the light and electrical parameters of lamps of the DRL type the change in external temperature has practically no effect. Table 1 shows the parameters of DRL lamps. The lamps are available in two versions with a red ratio of 6 and 10%.
Table 1
Basic parameters of DRL lamps in accordance with GOST 16357-79
| Lamp type | Power, W | Working voltage, V | Current, A | Luminous flux, lm | Dimensions, mm | Average service life | |
| outer bulb diameter | full length | ||||||
| DRL80 (6) -2 DRL125 (6) -2 DRL250 (6) DRL400 (6) -2 DRL700 (6) -2 DRL1000 (6) -2 DRL2000 (6) | 80 125 250 400 700 1000 2000 | 115 125 130 135 140 145 270 | 0,80 1,15 2,13 3,25 5,40 7,50 8,00 | 3400 6000 13000 23000 40000 57000 120000 | 81 91 91 122 152 181 187 | 165 184 227 292 368 410 445 | 10000 10000 12000 15000 15000 15000 6000 |
Mercury-tungsten lamps
Difficult ignition of DRL lamps at subzero temperatures, the use of inductive ballasts, and the need to correct the color of the radiation led to the creation of high-pressure lamps with ballast in the form of an incandescent lamp filament. Note that the large power losses in the active ballast, which is the filament, in comparison with the losses in the inductive ballast, are compensated by the simplicity of the active ballast with the possibility of simultaneously obtaining the missing red radiation with its help.
By placing a ballast filament in an external flask in which a quartz burner is placed to reduce the dependence of its parameters on the external temperature, it was possible to obtain a lamp suitable for direct connection to the network. The design of such a lamp is shown in Figure 3. Placing the filament inside the lamp bulb has the added benefit of shortening the burn-up period by heating the burner with radiation from the coil.
The main thing when calculating lamps of mixed light, as mercury-tungsten lamps are sometimes called, is the choice of the parameters of the filament. The power of the filament is selected based on the condition for stabilizing the mercury discharge. the luminous efficacy of the filament has to be reduced in order to obtain a sufficiently red ratio, while at the same time the filament service life is commensurate with the service life of quartz burners. During the start-up period, the mains voltage falls entirely on the spiral, however, as the mercury lamp burns up, the voltage on it increases, and the voltage on the ballast spiral decreases to the operating value. The light output of mercury-tungsten lamps is 18 - 20 lm / W, since about 50% of the power is spent on heating the coil. Therefore, in terms of efficiency, these lamps cannot compete with DRL lamps and other high pressure lamps. Their use is limited to special fields, for example, irradiation technology.
Lamps of the DRVE type have an outer bulb made of special glass that transmits ultraviolet radiation. Such lamps are used for combined lighting and irradiation, for example, in greenhouses. The service life of such lamps is 3 - 5 thousand hours, it is determined by the service life of the tungsten filament.
Tubular mercury lamps
In addition to lamps operating on the basis of a high-pressure discharge in mercury vapor and intended for lighting purposes, several types of radiation sources are manufactured, the development of which is associated with the need to use not only visible, but also ultraviolet radiation. As you know, ultraviolet radiation has a chemical and biological effect. The actinicity of ultraviolet radiation is widely used, that is, the effect on light-sensitive materials used in the printing industry. Powerful streams of bactericidal radiation, greater than those of bactericidal, allow the use of high-pressure mercury lamps for the purpose of disinfecting water and other substances. The chemical activity of ultraviolet radiation and the ability to concentrate high radiation powers on small surfaces have led to the widespread use of high-pressure mercury lamps in the chemical, woodworking and other industries.
This type of lamp requires bulbs made of mechanically strong and refractory quartz glass. The applied quartz glass, which transmits ultraviolet radiation from a wavelength of 220 nm, that is, practically the entire spectrum of radiation of a mercury discharge, allows changing the radiation parameters only by changing the operating pressure. The opacity of silica glass for resonance radiation with a wavelength of 185 nm is of no practical importance, since ultraviolet radiation of this wavelength is almost completely absorbed by air.
This has led to the creation of high pressure mercury lamps, differing in design due to operating pressure and field of application. the main parameters of high pressure lamps are shown in table 2.
table 2
Main parameters of high pressure mercury tubular lamps in accordance with GOST 20401-75
| Lamp type | Power, W | Voltage, V | Current, A | Arc length, mm | Overall length, mm | Burner diameter, mm | Average service life, h |
| DRT230 DRT400 DRT1000 DRT2500 DRT2800 DRT5000 DRT4000 | 230 400 1000 2500 2800 5000 4000 | 70 135 145 850 1150 1800 1900 | 3,8 3,25 7,5 3,4 2,4 3,1 2,4 | 60 120 175 1000 610 1100 1000 | 190 265 350 1200 700 1290 1118 | 20 22 32 21 15 20 14 | 1500 2700 1500 3500 1000 1500 13000 |
The industry produces mercury lamps of the DRT type (arc mercury tubular) with a pressure of up to 2 × 10 5 Pa in the form of straight tubes with a diameter of 14 - 32 mm. Figure 4 shows the general view and overall dimensions of DRT lamps of various powers. Both ends of the tubes have extensions of a smaller diameter, into which a molybdenum foil is soldered to serve as inlets. On the inner side of the lamps, tungsten activated self-heating electrodes are welded to the bushings, the design of which is shown in Figure 5. For fixing the lamps in the armature, the lamps are equipped with metal clamps with holders. The nose in the middle of the bulb is the remainder of the stem, sealed off after the vacuum treatment of the lamp. To facilitate ignition, the lamps have a special strip to which an ignition pulse is supplied.
Figure 4. General view of DRT-type lamps (mercury vapor pressure up to 0.2 MPa) with power, W:
and - 230; b - 400; in - 1000
Figure 5. Electrodes (cathodes) of high pressure mercury lamps:
1
- active substance (oxide); 2
- tungsten core; 3
- spiral
Tubular xenon lamps
High-pressure tubular lamps also include lamps that use xenon radiation at pressures from hundreds to millions of pascals. A characteristic feature of a discharge in inert gases at high pressures and high current densities is a continuous spectrum of radiation, which provides good color rendering of illuminated objects. In the visible region, the spectrum of a xenon discharge is close to that of the sun with a color temperature of 6100 - 6300 K. An important feature of such a discharge is its increasing volt-ampere characteristics at high current densities, which makes it possible to stabilize the discharge with the help of low ballast resistances. Xenon tube lamps of considerable length can be connected to the network without any additional ballast at all. The advantage of xenon lamps is that there is no burn-in period. The parameters of xenon lamps practically do not depend on the ambient temperature down to temperatures of -50 ° C, which makes it possible to use them in outdoor lighting installations in any climatic zone. At the same time, xenon lamps have a high ignition voltage and require the use of special ignition devices. The low potential gradient led to the use of more massive bushings in lamps.
The luminous efficiency of lamps increases with an increase in the specific power and diameter of the discharge tube. At high current densities, the discharge in inert gases has a very high brightness. According to theoretical estimates, the limiting brightness of a discharge in xenon can reach 2 × 10³ Mcd / m². The main parameters of high pressure xenon lamps are shown in Table 3. Tubular xenon lamps work with both natural and water cooling. The use of water cooling made it possible to raise the luminous efficiency of lamps from 20 - 29 to 35 - 45 lm / W, but somewhat complicated the design. The water-cooled lamp burner is enclosed in a glass vessel, and distilled water circulates in the space between the burner and the outer cylinder vessel.
Table 3
Main Parameters of High Pressure Xenon Lamps
| Lamp type | Power, W | Voltage, V | Current, A | Luminous flux, 10³, lm | Tube inner diameter, mm | Full length, mm | Average service life, h | Connection diagram |
| DKsT2000 DKsT5000 DKsT10000 DKsT20000 DKsT50000 DKsTV3000 DKsTV5000 | 2000 5000 10000 20000 50000 3000 5000 | 40 110 220 380 380 90 150 | 49 44 46 56 132 30 30 | 35,7 97,6 250 694 2230 81,2 139 | 24 22 21 21 38 4 4 | 356 646 1260 1990 2700 285 315 | 300 300 800 800 500 100 100 | with ballast with ballast without ballast without ballast without ballast with ballast, DC also without ballast with rectifier without ballast without ballast |
High tube temperatures (about 1000 K) require the use of quartz glass and appropriate designs of molybdenum bushings, designed for high currents. The lamp electrodes are made of activated tungsten. One of the designs of a water-cooled xenon lamp is shown in Figure 6.
Figure 6. General view of a tubular xenon lamp with a power of 6 kW with water cooling
The parameters of ballastless xenon lamps are strongly influenced by the mains voltage. If the mains voltage deviates by ± 5% of the nominal, the lamp power changes by about 20%.
The designation of the lamps consists of the letters D - arc, Xenon X, T - tubular, B - water-cooled and numbers indicating the lamp power in watts and, through a hyphen, the development number.
First, we note that all mercury sources are divided into three groups - these are low (RLND), high (RLVD) and ultra-high pressure (RLVD) lamps. The first group is represented by the most common type in the household and professional sphere - fluorescent lamps... Among them:
1. ... They are U-shaped, ring-shaped and rectilinear (in the form of a conventional discharge tube). They are equipped with a pin base and have various standard sizes and a wide power range (from 15 W to 80 W). They are economical in energy consumption and are used everywhere - from apartments, offices and educational institutions to shops and industrial premises.
2. ... Equipped with pin and screw type base. The latter are intended for direct replacement of the classic incandescent lamp and are characterized by their energy efficiency. They are made in a spiral shape, in the form of a square, folded in two and four tubes, and also repeat the external design of the predecessor: "pear", "ball", "candle" and "candle in the wind". The power varies from 5 W to 30 W, which corresponds to 25 W and 100 W of a conventional Ilyich bulb.
Low pressure mercury lamps are used mainly for lighting residential premises and public buildings, they are mounted in street systems (light of the adjacent territory, entrances). Using energy efficiently, they create bright streams of light of different color temperatures - from yellow notes, reminiscent of incandescent light, to daylight and cold light.
On the contrary, high pressure mercury sources have found application exclusively in street and industrial lighting. They are used in places where economy is much more important than color rendition: light bulbs create good illumination, but without clear reproduction of colors and contours. In view of this "blur", it is not recommended to use lamps in a room with a constant presence of people, as this can provoke vision problems. Ideal premises for RLVD are industrial workshops, corridors, etc.
High and ultra high pressure mercury lamps:
1. Arc mercury lamp or DRL... The principle of operation and the appearance of bulbs is very similar to mercury-tungsten lamps, with which they are often confused in practice, so let's talk about the key difference between them. DRL functions only with ballast, which acts as a current limiter. DRV bulbs can easily do without a ballast, since there is no inductive ballast in the design, and the tungsten wire itself acts as a limiter.
This feature reduces the intensity of mercury-tungsten sources by 30%, allowing arc mercury to take the first place in the creation of street lighting (the color of the bulbs is improved by the phosphor that covers the bulb from the inside). With the help of DRL, they illuminate highways, streets, parks and squares, parking lots and gas stations, warehouses and industrial facilities.
2. Arc mercury lamp with emitting additives or DRI... The design of the light bulb repeats the previous version, but the constituent substances for filling the burner are different. The type of bulbs belongs to metal halide, therefore, along with mercury, metal halides (sodium, indium and other elements in strict proportions) are placed in the burner. The presence of halides allows you to increase the light output of the sources (on average 70-90 lm / W and above), as well as improve color rendering.
Improved versions of DRI are produced with a ceramic burner, as the most heat-resistant and practical option: unlike glass, the inner ceramic flask is several times less darkened, since it tolerates the reaction of chemicals very well. The devices are equipped with a soffit base (Rx7S and others), as well as the classic E27 and E40, which are ideal for replacing a conventional incandescent lamp.
Arc sources with additives are used in common systems street lighting and as a colored architectural lighting (the color of the glow depends on the burner fillers). And certain types of DRI with a color rendering index of 12 Ra, which forms a greenish glow, are used by fishing vessels to attract plankton.
3. Arc mercury lamp with mirror coating or DRIZrepresenting a metal halide light source. The composition of the burner repeats the DRI formula, but the bulb contains a reflective coating on the inside. The presence of a mirror layer allows you to create a directed stream of light, and a special additional base, which is equipped with a light bulb, makes it possible to adjust the direction of radiation.
4. Mercury-quartz spherical sources or DRSh... These are ultra-high pressure bulbs that generate a powerful stream of light. The burner is made in the shape of a ball and is placed in an outer flask with cylindrical "legs". The unusual design provides durability under high pressure conditions, partially removes heat from the burner and protects parts from oxidation.
The concentration of electrical discharges in such lamps falls on a narrow gap between the electrodes, so the brightness of the light is very high. The peculiarities of the work made the ball lamp a popular source of light in projectors and spotlights, it is often used in filming, creating film projections and other activities where it is extremely important to correctly convey the color of objects and the surrounding space.
5. Arc mercury tube lamp or DRT, made in a cylindrical quartz glass flask. The burner is filled with inert gas (argon) and metallic mercury, structurally repeating the format of the DRL. Require control gear connection to ensure full start of the light bulb. They have a very wide power range (from 100 W to 12000 W) and are designed for special applications: disinfection of air and surfaces, disinfection of food and water, drying varnishes, paints and other activities.
Subtypes of tubular lamps:
Quartz... They are made in the form of a conventional fluorescent tube, but differ in the absence of a phosphor. For the manufacture of flasks used, capable of transmitting ultraviolet light. Such devices are designed for the disinfection of surfaces, rooms and objects. The presence of people or animals during quartzing must be excluded, since ozone is concentrated in the air, and its large concentrations are harmful to health.
There are special ultraviolet lamps known as erythemal... Their bulb also consists of quartz glass, but here, unlike a conventional quartz lamp, the walls are covered from the inside with a phosphor of a certain composition, which transmits ultraviolet light in a strictly specified range. As a rule, these are near and medium waves, which. Reception of such a "sun bath" is limited to a few minutes, and in large quantities it can harm the body.
Bactericidal... For the manufacture of the flask, special uviol glass is used, which thoroughly filters out ozone during operation, preventing it from entering the air. Lamps are designed for the treatment of premises, surfaces or water, possess, but work in a mode that is sparing for living organisms. Ozone-free quartz lamps are used in apartments, childcare facilities, in food production and in any other areas where it is necessary to destroy the bacterial background without harm to health.
Mercury lamps of various designs are still used today, since they have occupied their niche: they are used in organizing lighting systems for large industrial facilities, streets. The general designation of the most common high-pressure design is DRL, which means an arc mercury fluorescent lamp. This type represents gas-discharge light sources and is characterized by 1 hazard class due to the fact that, among other things, mercury is included in the composition.
Features of the device
The design provides for several main elements:
- the base is a contact part, and lighting elements with a holder E40, E27 are easy to install in any modern lamp;
- quartz flask - contains inert gas and some mercury, connected to electrodes;
- outer flask - made of heat-resistant glass, resembles an incandescent analog in shape, inside there is a quartz flask (burner).
Gas-discharge light sources are coated with a phosphor from the inside. The arc lamp contains carbon dioxide, which fills the outer bulb. Most of these lighting elements function by means of a ballast (ballast), but there are also separate species - gas-discharge lamps of direct connection, which do not require the installation of ballasts, but are connected directly to the network.
DRL lamp design
Arc light sources operate on the basis of the phenomenon of luminescence. In this case, the glow occurs under the influence of ultraviolet radiation. It is also produced by mercury vapor, which is part of the gaseous filling of a quartz flask. These processes occur under the condition that an electric discharge passes through the quartz burner.
Overview of existing species
High-pressure gas-discharge light sources, which include arc bulbs DRL, are divided into two main groups: general and highly specialized. The first option is installed in a street lighting luminaire. The second group of high pressure light sources is used in medicine, certain industries, and agriculture.
In addition, gas-discharge lamps are divided into types in accordance with structural and functional differences. Power range: 80 to 1,000 watts. More powerful versions of 100 W, 250 W, 400 W, etc. are used more often. Moreover, there is a division by the number of electrodes: two-electrode (power from 80 to 1000 W); four-electrode (250-1000 W).
Arc metal halide light sources (DRI)
The peculiarity of such lamps is in emitting additives, hence the designation: DRI (arc mercury lighting elements with emitting additives). Outwardly, this light source is similar to the DRL analog.
DRI mercury lamps
The difference between them is that the composition of DRI also includes specialized components that are strictly dosed: sodium, indium halide and some others. This contributes to a significant increase in radiation efficiency.
The bulb can be in the form of an ellipsoid or a cylinder. Mercury lamps of this type today increasingly contain a ceramic burner instead of a quartz analogue. Also, gas-discharge light sources of this group have a more perfect design, in particular, the shape of the inner bulb can be spherical. DRI mercury lamps require inclusion of a choke in the circuit.
Gas-discharge lighting elements of this type are used in the organization of outdoor lighting: parks, streets, squares, they are used as illumination of buildings, shopping and exhibition halls, as well as large areas (sports, football fields).
Metal halide with a mirror layer (DRIZ)
Mercury lamps of this type have a similar composition with analogs of DRI: the main filling + emitting additives. But in addition to this, the design provides for a mirror layer. Thanks to this feature, DRIZ high-pressure bulbs provide a directed beam of light.
Metal halide light sources with a mirror layer (DRIZ)
They are used in conditions of poor visibility, since a high level of power, along with design features, contributes to the organization of effective illumination of a site of an object due to directional glow.
Mercury-quartz ball light sources (DSH)
Such high pressure bulbs stand out from a number of analogues. This is facilitated by the following factors: the spherical shape of the bulb, radiation of increased intensity. In addition to that, the mercury quartz lamp is characterized by ultra-high pressure.
High pressure bulbs DRSH
Scope - highly specialized areas, in particular, projection systems, laboratory equipment.
Mercury-quartz (PRK, DRT)
This type of bulbs has a different bulb shape than the analogs discussed above. For example, PRK stands for direct mercury-quartz lighting element. This is the original designation of the DRT lamp (arc tube mercury).
The transition to another marking took place in the 80s. last century. The mercury quartz lamp in this version is characterized by the shape of a bulb in the form of a cylinder, while the electrodes are located on the end sections of the bulb.
Radiation color
Mercury-containing lamps, due to the presence of a phosphor in the output, give a color as close to white as possible. A neutral shade is obtained by mixing the emissions of the gaseous constituents of the flask and the phosphor. In particular, mercury vapor produces a glow different colors: blue, green, purple, orange. And besides that, they emit ultraviolet light (soft, hard).
The combined luminescence of the phosphor and the gaseous filling of the flask located inside the high-pressure DRI lamp makes it possible to obtain different glow colors: green, violet, etc. This is achieved by changing the composition and ratio of the emitting additives.
Ballast devices
Fluorescent mercury lamps are connected to the network in most cases through a choke (ballast). Essentially, this assembly is a current limiter that smoothly brings the high pressure light source into service. In the absence of a ballast, the DRL lamp will burn out due to the passage of high current through the electrodes.
However, there are also analogues of direct inclusion. For their normal operation, a choke is not required; you can install a high pressure lamp in the luminaire. Such light sources are designated DRV (mercury arc tungsten arc). They are similar in characteristics to the DRL variant. The choice of the control gear is made based on the data on the power of the light bulb.
General specifications
Determination of the most suitable type of lamp is carried out taking into account the main parameters of the light source:
- supply voltage - usually indicated for direct-on lighting elements installed without a choke (DRV);
- power - varies from 80 to 1,000 W;
- the luminous flux directly depends on the level of the generated load: varies from 1,900 to 59,000 lm;
- burning time: from 1,500 to 20,000 hours, with the shortest operating life observed for direct-on tungsten lamps;
- base type: E27, E40;
- product dimensions - vary depending on the lamp version.
Features and characteristics of various light sources
For DRL light sources and other analogs connected with a choke, the voltage on the lamp can be indicated.
Storage and disposal
Considering that mercury (hazard class 1) is included in the composition of lighting elements such as DRL and other similar designs, it is prohibited to store products with damaged flasks in rooms that are not prepared for this. Especially when it comes to the amount of hazardous waste on an industrial scale. Organizations that have the appropriate license (UNEP) should be engaged in storage, transportation and further disposal.
