In 1964, the American company General Electric first used a new type of lamp - metal halide (MHL) - to illuminate the pavilions of the Expo 64 World Exhibition in New York. Since 1969, the production of such lamps was mastered by Philips and Osram, and in the 70s, the Saransk Electric Lamp Plant in the USSR.
In design, MGLs are similar to high-pressure mercury lamps, but their outer bulb is not coated with phosphor, but is made of transparent or (much less commonly) frosted glass. The primary source of radiation, as in DRL lamps, is a burner made of quartz or polycrystalline aluminum oxide filled with an inert gas and mercury. But if in DRL lamps a phosphor is used to correct color and increase luminous efficiency, then in metal halide lamps For the same purpose, special light-emitting additives are used: halogen compounds of various metals (most often sodium and scandium, as well as gallium, indium, thallium and rare earth elements - dysprosium, holmium, thulium, etc.).
In order for the vapor pressure of light-emitting additives in metal halide lamps to be sufficiently high, the burner must be heated to higher temperatures than in DRL lamps, and the pressure of the “starting” inert gas in it must be higher. Such a simple solution for igniting a discharge, as in DRL (installation of igniting electrodes near the main ones), is no longer enough: if in DRL a discharge occurs at a voltage below the mains voltage, then in MGL this requires a voltage of 3 to 5 kilovolts.
By changing the composition of light-emitting additives, it is possible to change the color of the radiation over a wide range - from warm white with 7Tsv = 3000 K to daylight with 7Tsv = 6500 K, as well as create colored lamps.
Today, more than 250 types of metal halide lamps with power from 20 to 3500 W are produced in the world.
Metal halide lamps have greater light output than DRL and better color rendering (Ra up to 90). Due to the fact that the light source in the MGL is a small-sized burner, and not an external bulb, their luminous flux is much more easily redistributed in space using reflectors or lenses. This property made it possible to create deep-emitting lamps and spotlights with a very narrow light beam, which is impossible when using DRL due to the large dimensions of the luminous body.
Parameters of metal halide lamps just like DRL, they depend little on the ambient temperature, but much more on fluctuations in the mains voltage. In this case, an interesting phenomenon is often observed - a change in voltage even within relatively small limits (± 5%) causes a noticeable change in the color of the radiation. A change in color also occurs spontaneously during the operation of the lamps, and in different instances of the lamps in different ways (the so-called “color divergence”). This is especially noticeable in multi-lamp lighting installations, when, when the installation is put into operation, all lamps shine equally, and after some time the lighting becomes “multi-colored”. According to the standards of different countries, the color temperature of the radiation of metal halide lamps during their service life can change by 500 K, that is, a lamp with Hz = 3500 K (“white”) can become “warm white” with Hz = 3000 K or “bright white” with Hz = 4000 K. This occurs because light-emitting additives interact differently with quartz and tungsten, and due to this, the composition of the filling gradually changes during lamp operation.
It should be noted that the color of the radiation of some types of metal halide lamps also depends on the operating position of the lamps, therefore the lamps should be operated only in the position regulated by the documentation for each specific type.
Metal halide lamps are very labor-intensive to manufacture and require extremely high production standards. Particular difficulties in the manufacture of lamps are associated with hermetic welding of burners, since the existing technology for pressing in the bushings does not provide sufficient accuracy in maintaining the dimensions of the burners.
To increase the stability of the parameters of metal halide lamps, since 1998, Philips and Osram began making burners not from quartz, but from polycrystalline aluminum oxide AI2O3. In terms of chemical composition, polycrystalline aluminum oxide is completely identical to precious sapphire and ruby, as well as ordinary clay. Technologists from different countries, primarily the USA and the USSR, as part of their space programs have long ago learned how to make this material of very high quality and make tubes of a given diameter from it with good accuracy. From the blanks you can make tube sections of strictly maintained length. In terms of chemical and thermal resistance, polycrystalline aluminum oxide is superior to quartz, so it is quite suitable for creating burners for high-pressure discharge lamps, in which, unlike quartz, all geometric dimensions will be maintained with very high accuracy. The problem of creating such burners was to ensure the tightness of current inputs capable of operating at high temperatures in an environment of fairly aggressive halogen luminous additives. But by 1998, this problem was successfully resolved. Now MGLs with burners made of polycrystalline aluminum oxide or, as they are more often called, with ceramic burners are produced in large quantities by leading electric lamp companies.
The precise dimensions of the burners and the high chemical resistance of the ceramics significantly increased the stability of the light parameters of the MGL. The change in color temperature at the end of the service life of lamps with ceramic burners does not exceed ± 200 K, the decline in luminous flux over 4000 hours is no more than 20%. So far, such lamps are produced only at low power (20-150 W).
The main area of application of metal halide lamps is lighting for color television reports, filming and lighting of large sports arenas. The creation of low-power lamps, especially with ceramic burners, opened up a wide way for the introduction of MGL in interior lighting - for sales areas, shop windows, exhibition pavilions, some administrative premises, etc.
The service life of certain types of modern metal halide lamps reaches 15,000 hours. Lamps are produced with different radiation colors and with different color rendering qualities.
Since a voltage of several kilovolts is required to ignite a discharge in a metal halide lamp, the lamps are turned on only with special ignition devices. In Fig. Figure 1 shows a typical connection diagram for metal halide lamps. Like all gas discharge lamps, metal halide lamps can only be operated in conjunction with a ballast choke, which creates a phase shift between current and voltage. Therefore, power factor compensation is required, that is, the inclusion of a compensating capacitor.
Rice. 1.
In recent years, a number of companies have begun to produce electronic devices for switching low-power metal halide lamps. High-frequency power supply of high-pressure lamps does not provide such advantages as we have seen with fluorescent lamps, and, in addition, leads to discharge instability (the so-called “acoustic resonance”). Therefore, unlike fluorescent lamps, metal halide lamps through such devices are powered not by high-frequency current, but by a rectangular voltage with a frequency of 100 - 150 Hz. Electronic devices for switching on metal halide lamps are significantly (3-4 times) lighter than chokes and, in addition, combine the functions of a ballast and an ignition device, and sometimes a compensating capacitor. Lamps with ceramic burners are generally recommended for use with electronic devices.
Disadvantages of metal halide lamps are: high cost (several times more expensive than DRL, especially lamps with ceramic burners); long burn-up time (up to 10 minutes); large depth of light flux pulsations (for lamps with rare earth elements, which have the best color rendition, up to 100%); the impossibility of re-starting a hot lamp after it goes out for at least a split second; the need to use ignition devices.
Since high-wattage metal halide lamps are used to illuminate large sporting events with large crowds, lamp failure can cause panic among spectators, not to mention disruption of the sporting event. To eliminate such phenomena, in floodlights for illuminating sports arenas, in addition to conventional ignition devices, instant lamp re-ignition units are used - complex, heavy and very expensive devices that automatically send pulses to the lamp when it goes out with a voltage of up to 50 kV, capable of igniting even a hot lamp. Lamps designed to work with such units have a special design - one of the electrodes is output through the base, the other through the side of the outer bulb opposite the base.
A metal halide lamp (MHL) is a high-pressure gas-discharge light source. During operation of the lamp, an arc discharge occurs in mercury vapor in an inert argon environment, while the spectrum is determined by special emitting additives - halides of certain metals.
Halides, such as scandium and sodium iodides, help the discharge to exist and do not react with the quartz glass of the flask. While the lamp is cold, the halides are condensed in the form of a thin film on the walls of the discharge tube (burner), but as the temperature rises, the halides evaporate, mix with mercury vapor in the discharge area, and decompose into ions. As a result, excited ionized atoms.
The burner is made of quartz glass or ceramics, and the outer protective flask is made of borosilicate glass (in addition to the protective mechanical function, the flask cuts off ultraviolet light from the spectrum).
In a number of industrial types of MGL there is no external flask; in this case, ozone-free quartz glass is used to make the base. It prevents increased ozone formation and reduces the risk of mercury resonance (185 nm) in the lamp.
The principle of operation of a metal halide lamp was described and proposed by the American electrical engineer Charles Steinmetz in 1911. The lamp is started, which first ensures the ignition of the arc, and then maintains the operation of the lamp.
The starting device can be a direct inductor or an auxiliary high-voltage transformer. Then, when the discharge is ignited, the electrodes are maintained at rated voltage and the lamp emits visible light.
Today, MGL type lamps are produced in a wide range of wattages. For outdoor lighting, lamps of 70, 150, 250, 400, 1000, 2000 watts, single or double base, with pin or soffit bases are used. They are designated as SE or DE - single-ended (single-ended) and double-ended (double-ended).
Since the arc plasma is affected by gravity, the operating position of the lamp must be strictly defined. Thus, metal halide lamps come in horizontal orientation, vertical orientation and universal. Markings accordingly: BH, BUD, U – base horizontal, base up/down, and universal. If the lamp is not used in the correct operating position, its life will be shortened and performance will be poor.
According to the American National Standards Institute, ANSI, metal halide lamps are labeled starting with the letter "M", followed by a number code indicating the electrical characteristics of the lamp and the type of ballast. After the numbers there are two letters indicating the size and shape of the flask and its coating. Further, each manufacturer in its own way indicates the power of the lamp and the color of its glow. European markings differ slightly from ANSI.
The bulb of a metal halide lamp is designated by letters indicating its shape and numbers indicating the maximum diameter of the bulb. Letters BT (Bulbous Tubular) - bulbous-tubular, E or ED (Ellipsoidal) - ellipsoidal, ET (Ellipsoidal Tubular) - ellipsoidal-tubular, PAR (Parabolic) - parabolic, R (Reflector) - reflective, T (Tubular) - tubular .
For example, the Lisma DRI 250-7 lamp is marked relative to the E90 bulb - ellipsoidal in shape, diameter about 90 mm. Base type E40, power 250 watts. As you can see, the designation here is different. In general, the range of metal halide lamps is very wide.
Characteristics of metal halide lamps
The emission color of a metal halide lamp and the color temperature are mainly related to the type of halogen used. Sodium compounds give a yellow tint, thallium - green, indium - blue. Initially, metal halide lamps were used where light close to natural was required, white, without an admixture of blue.
It is possible to obtain pure daylight with a color rendering index above 90 from metal halide lamps. In principle, any color temperature in the range from 2500 to 20000 K is achievable.
Special types of MGL are used in greenhouses and greenhouses for plants, in aquariums for animals, where a special spectrum is required. At the same time, when choosing a lamp, it is important to remember that the color characteristics in reality will initially differ from those indicated in the specification, since the specified characteristics relate to a lamp that has already worked for 100 hours, that is, at first they will be slightly different.
The greatest discrepancy in characteristics is observed in metal halide lamps with preheating; in them, the difference in color temperature reaches 300 K. In lamps with pulse start, the discrepancy is smaller - from 100 to 200 K.
A long-term deviation of the supply voltage from the nominal one can lead to a change in the color of the light and luminous flux. Sudden fluctuations in the mains voltage above +/-10% may cause the lamps to turn off.
If the power supply fluctuates, the color temperature will also fluctuate - if the voltage is less than the nominal voltage, then the light will be colder, since the additives responsible for color are not ionized in sufficient quantities.
If the voltage is higher than the nominal value, the color will be warmer, but prolonged excess of voltage threatens to cause the bulb to explode due to the increased pressure in it. It is best to provide stabilization of the supply voltage.
Advantages of metal halide lamps
The spectral and electrical characteristics of metal halide lamps can vary widely; the market range is huge. The quality of light and high luminous efficiency explain the widespread use of MGL today in various lighting installations and lighting devices.
The lamps are compact, powerful, effective as a light source, and are today a promising replacement for traditional mercury arc fluorescent lamps (MAFLs) and high-pressure sodium lamps (HPS), thanks to a softer and safer spectrum for humans.
The luminous flux of MGL lamps is up to 4 times higher than that of incandescent lamps, and the light output averages 80-100 Lm/W. Color temperatures: 6400 K (cold light), 4200 K (natural light) or 2700 K (warm light) - easily achievable with a color rendering of about 90-95% - this is very good color rendering for a lamp whose efficiency is 8 times higher than that of incandescent lamps.
The power can vary from 20 W to 3500 W from one source, and uninterrupted operation does not depend on the ambient temperature and its changes if the lamp has already been lit. The service life of an MGL lamp is calculated on average at 10,000 hours of continuous operation.
MGL lamps are used very widely today. Film lighting, outdoor lighting in architecture, decorative lighting, stage and studio lighting, etc. Metal halide lamps are extremely popular in industrial lighting in workshops, in floodlights in open spaces of railway stations, in quarries, on construction sites, at sports facilities, etc. d.
Lighting of public and industrial buildings, special lighting for plants and animals, as a source of near ultraviolet light. Finally, street lighting, illumination of landscapes and shop windows, to create lighting effects in design and advertising, in shopping centers... - metal halide lamps have taken their rightful place everywhere.
One of the latest developments of modern technologists is the invention of metal halide lamps (MHLs). This is a type of gas discharge lamps, which, despite their compact shape, are one of their most powerful light sources. They are widely used in a variety of fields, from architectural and stage lighting to lighting of greenhouses and aquariums.
Operating principle of MGL
MGL has similar features to some types of discharge lamps, where the principle of a luminous body lies in the operation of the plasma of a high-pressure electric arc discharge. The MGL burner is filled with inert gas, mercury and a number of halides (halide salts). The operating principle of a metal halide lamp is as follows: the emission of light in the MGL flask occurs under high pressure due to the reaction of an inert gas and mercury with a certain number of halide salts. During the initial supply of voltage to the MGL, the heat, which is focused in the flask after ignition of the argon arc, with increasing temperature and pressure, begins to convert the mercury and salt mixture into vapor, which leads to the emission of light.
Like many gas-discharge lamps, MGLs require auxiliary devices (additionally igniting electrodes, pulse-igniting units) to initiate the discharge and operate at the proper level of operating voltage.
In order for the parameters of the power supply and the lamp to correspond to each other, a ballast (ballast) is used, known to everyone as a ballast.
MGL design features
Considering the configuration, the MGL device has its own distinctive characteristics:
- the presence of an internal shell, MGL with a unidirectional base, or its absence, MGL with a bidirectional base;
- metal base;
- The outer flask is made of borosilicate glass, which serves to preserve the internal elements of the MGL, acts as a light filter and temperature regulator, and is a source of protection against oxidation of the elements of the inner shell. MGLs without an outer flask are made of ozone-free quartz glass in order to reduce the release of mercury;
- additional (ignition) and tungsten electrodes;
- special phosphorus coating of the inner shell of the outer glass bulb to improve the quality of color rendering;
- wires supporting the electric arc inner bulb (torch), which is made of fused silica, or the aluminum inner bulb, made of polycrystalline aluminum oxide.
Types of metal halide lamps
Types of MGL
The specific shape of the arc in the inner bulb affects the fixed position of the lamp, which determines its type:
- single-base / one-sided MGLs with the symbol SE (single-ended) are inserted into the cartridge using a thread on the base;
- double-ended / double-ended MGLs have the symbol DE (double-ended) and are inserted into sockets that are located on both sides of the lamp;
- universal MGLs marked “universal”, which can operate in a horizontal or vertical position.
Double-ended MGL
Technical characteristics of MGL
Efficiency is determined by a whole range of highly technical characteristics of metal halide lamps.
Power. The spectrum of the nominal energy of the MGL is unusually huge. The range starts from a small number of tens of watts (70, 100, 150, 175, 250, 400 and 1000 W) and can go up to 10 - 20 kW.
Life time. The duration of a few types of MGL can be 15,000 hours. To determine the average service life of MGLs, it is recommended to take into account the duration of operation and their technical design (chokes or electronic ballasts). The average switching frequency and switching rhythm are another important feature that affects the service life of the MGL. The service life of such lamps depends on maintaining a constant rated power and avoiding turning off the MGL during startup.
It is not recommended to use MGL whose service life exceeds at least 25% of the specified service life due to the possibility of cracking. At the end of their service life, such lamps may reduce the quality of the luminous flux.
Color rendering quality. When choosing lamps for illuminating various objects and structures, you need to take into account its ability to convey true color and take into account the possible effects of light shades. This is determined by the color rendering index parameter, which read about. Initially, MGLs were used to create light as close as possible to natural light, since they were capable of emitting white daylight with a transmission index of 80.
Modern MGLs already have a color rendering index of over 90. For example, a color rendering index of over 80 or 90 plays a dominant role in giving natural color to products. The unnatural shade that is created when illuminated by lamps with a low color rendering index leads to the fact that the buyer does not pay attention to the product or, moreover, avoids purchasing it.
However, it is not always possible to determine 100% MGL color coefficients due to factory deviations or without exceeding the 100-hour combustion threshold. The power supply of the electrical network also affects the color rendition of the lamp. Insufficient power supply changes the physical temperature, so that the light of such a lamp acquires a bluish tint. The quality of color rendering often changes during use, reflected in the light of the lamp.
Colorful temperature. The characteristics of color temperature and the spectral composition of radiation, measured in units of Kelvin (K.), are very important for creating warm or cool shades when lighting objects and creating the correct visual image. Thus, the ability of MGL to create a combustion temperature with a spectrum from 2500 Kelvin units (becomes yellow) to 20,000 Kelvin units (becomes blue) may be due to the need for various applications, for example, for plants or animals.
Some MGLs have a “pre-heating” function (approximately 300 Kelvin units), which affects color rendition, but new generation MGLs have improved readings from 100 to 200 Kelvin units.
Base. The most commonly used MGLs are lamps with a one-sided screw base, which is screwed into the lamp socket. Double-ended MGLs are popular due to their ability to reduce light energy loss.
The scope of application directly depends on the MGL, among which there are single-ended MGL with a ceramic / quartz burner, double-ended MGL with a ceramic / quartz burner, and single-ended MGL with a quartz burner.
Light flow. The luminous flux of metal halide lamps is very important in determining the luminous intensity of the lamp. This technical characteristic of a lamp can reveal the capabilities of a certain light source when lighting a room.
The luminous value of the MGL is 75 - 100 lm/W and exceeds that of other light sources. Thus, a tungsten incandescent lamp has only a light output of 10 - 22 lm / W.
MGL connection diagram
The switching circuit for a metal halide lamp is similar to that of all gas-discharge lamps. The only slight difference is that together with electromagnetic or electronic ballasts, which you read about, you need a special ignition device that provides ignition of several kW.
Connecting metal halide lamps comes with a ballast, which creates a shift between current and voltage, and a capacitor, which serves to compensate for the power factor. MGLs absorb low-frequency current, and electronic switching devices are sometimes much lighter (3-4 times), since they function as a ballast, ignition device and compensating capacitor.
Metal halide spotlight for architectural lighting
MGL is an energy-efficient type of lamp that has increased light output and color rendering. The long service life and good quality of lighting make it possible to use these lamps in various fields, and their compactness and small size are suitable for installation in hard-to-reach places.
In contact with
Due to its compactness, power and efficiency, they are considered a widespread light source in various lighting devices. metal halide lamps (MGL) . They are classified as gas discharge lamps (GRL) .
Specificity of MGL
The principle of glow of a metal halide lamp is the same as in other GRL is an electric arc discharge occurring between the electrodes in a flask filled with mercury vapor. The main distinguishing feature of metal halide lamps is the presence of radiating additives (certain metal halides) in the filler composition (mercury vapor).
Metal iodides are required to correct the spectral characteristics of the arc discharge; thanks to them, the quality of light radiation is much improved. They also prevent volatilized tungsten from settling on the inner walls of the flask. During operation of metal halide lamps, a reaction occurs between tungsten vapor and metal halides. As a result of this reaction, tungsten iodide (a gaseous mixture) is formed, which evaporates from the electrodes. After the lighting device is turned off, tungsten settles back onto the electrodes.
Installation of metal halide lamps
Metal halide lamps mainly consist of the following components:
- Discharge tube (torch) – which is the basis of the IGL. The burner is often made of quartz glass; there are also options made of special ceramics. Ceramic burners have higher heat resistance. The burner with electrodes is placed in the outer flask.
- Outer flask– performing the functions of a light filter. It is made from borosilicate glass. Borosilicate flasks have high thermal and mechanical resistance. The flask reduces heat loss from the burner, providing it with normal thermal conditions.
- Base.
It is impossible to launch an MGL without ballast; electromagnetic or electronic ones are used as it. The use of electronic ballasts ensures even light when lighting bulbs, significantly reducing currents (operating and starting), as well as increasing the service life of the lighting device.
Principle of operation
The luminous body of the MGL is the arc discharge plasma flowing in the torch between the electrodes.
The discharge tube is filled with inert gases and halogen compounds, which, when cold, condense on its walls in the form of a thin film. As the temperature of the arc discharge increases, the halides begin to evaporate and decompose into ions. After which the already ionized atoms are irritated and they create optical radiation.
The inert gas performs a buffer function, due to which the flow of electric current through the burner is possible even at its low temperature. As the burner warms up, mercury and emitting additives evaporate, thereby changing the emission spectrum, luminous flux and electrical resistance of the MGL.
To ionize the discharge, metal halide lamps require the use of special devices. Eg, And pulse ignition devices (IZU) ignition electrodes, such as in arc mercury phosphor lamps (MAL). And ignition occurs using ballasts. As such a device, you can use a choke or a transformer that has increased magnetic dissipation.
Classification and designations
Metal halide lamps are usually classified according to:
The base has a thread with which the light bulbs are screwed into the socket. These models are designated single-ended, with the letters SE;
- double-ended. Double-ended metal halides are called soffit; the outer bulb is usually made of quartz and has a small diameter. They operate in a horizontal position and are often used in floodlights for architectural and artistic lighting.
These lamps are inserted into sockets located on opposite sides of the lamp. They are designated double-ended, with the letters DE.
- Base type. Typically, single-base MGLs are produced with an E40 base, lamps with a ceramic burner come with an E27 base, and in low-power versions special bases G8.5, G12, etc. are installed.
Orientation of the position in which they work:
— horizontal. When operating these lamps, it is recommended to point the bulb nipple upward. Designation: BH;
- vertical. The lamps are designated by the letters BUD;
- universal. Lamps can work in different positions. But when they are used in a vertical position, they have a longer service life, as well as radiation intensity. Denoted by the letter U.Availability and shape of the flask:
- cylindrical(tubular Tubular = T);
- ellipsoidal. To reduce the glare effect, these lamps are made frosted (Ellipsoidal = “E”);
— ellipsoidal-tubular (Ellipsoidal Tubular = "ET");
— bulbous-tubular (bulbous tubular = BT);
- reflex(reflector = "R");
- parabolic(parabolic = "P");
- without flask. Bulbs without an outer bulb are manufactured to effectively utilize their ultraviolet radiation. These MGLs are prepared for use in technological processes.
Some MGLs are manufactured to replace DRL lamps. In such models, the inner walls of the outer flask are covered with a layer of phosphor.
Marking of MGL lamps
Domestic metal halides are marked with the letters DRI and DRISH, the letters are deciphered as follows:
- D – arc.
- R - mercury.
- AND - iodide
- Ш – spherical shape of the discharge tube.
After the letter value, the power of the light bulb is indicated, as well as the design. For example, DRI400 - 1 - arc mercury iodide lamps with a power of 400W, intended for filming.
Lamps with ceramic burners are marked with three letters CDM with numbers indicating the power; such light bulbs are produced only abroad. Various foreign manufacturers label lamps at their own discretion and do not adhere to uniformity.
Advantages and disadvantages
Advantages of MGL:
- High light output.
- Low power consumption.
- The service life is longer than that of incandescent lamps.
- Compactness.
- Reliable operation at low temperatures.
- Good color rendition.
Flaws:
- Lack of ability to regulate light output.
- Long time to warm up (working level is reached about 10 minutes after switching on).
- The need to use IZU.
- It is impossible to re-ignite the lamp immediately after turning it off until it has completely cooled down.
- They react to voltage surges (voltage changes of about 5% contribute to a change in the color of the light flux).
Despite the disadvantages, metal halide lamps are widely used in various lamps and lighting devices, this is due to their wide range of advantages.
Areas of use
- Film, studio and stage lighting.
- Architectural.
- Decorative.
- Utilitarian.
- Street lighting, namely for railway stations, quarries, sports facilities, etc.
Metal halide lamps are also used as light sources for car headlights and lighting installations in industrial buildings.
Metal halide lamps (MHLs) are one of the types of high-pressure gas-discharge lamps (GRLs). The light bulb differs from other GRLs in that emitting additives (EAs) - metal halides - are dosed into the MGL burner to correct the spectral characteristics of the arc discharge in mercury vapor. Among light sources they are the most compact and powerful.
Metal halide lamps: what is important to know before buying?
Photo 1 - HPS lamp 70W/2000K 5800Lm E27 10t.h. (156x39) HPSL-70-E27-T IEC Use MGL:
- in construction;
- in architectural design;
- for illumination of greenhouses.
Types of metal halide lamps:
- single-base;
- double-ended;
- universal.
Photo 2 - Osram G12 70W In single-base cartridges, the cartridge is located on one side; double-base - double-sided, which allows it to be installed only in a horizontal position; The universal design can be installed both horizontally and vertically.
Most often, single-ended screw-type lamps are used, but double-ended lamps are considered more economical - their energy consumption is minimal.
Lamps are distinguished by burner type:
- quartz;
- ceramic.
IMPORTANT! Pay attention to the BLV MGL for the lines HITLITE, HIT-ULTRALITE, C-HILITE, TOPSPOT G12, TOPSPOT SHROUD, TOPSPOT G8.5, C-TOPSPOT, TOPLITE, TOPLITE SHROUD, TOPFLOOD.
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Lamps according to GOST must be designed so that their characteristics are reliable when used correctly.
Operating principle of MGL
Photo 3 - TDM DRI 70 6000 K Rx7s SQ0325-0012 The operating principle is based on the passage of an electric arc discharge in a gaseous environment, similar to that used in mercury lamps. The gas used in MGL is mercury and inert argon. The sodium and scandium iodides present in the gas ensure the passage of the arc discharge.
These substances do not react with the lamp bulb material (quartz glass). In the absence of a discharge, halides cover the walls of the product with a film. When the contact is closed, the temperature rises and an arc discharge is observed, which promotes the evaporation of halides and their decomposition into iodine and metal ions.
The glow of the lamp, visible to the eye, causes the presence of ions in the gas. In this case, the movement of ions from the hot zone of the lamp to the colder walls is observed - the connections are restored and condensation occurs on the walls in the form of a film. The lamp operates on a closed cycle principle.
Connecting light bulbs
Connecting the lamp to the network is carried out according to the rules, due to the design features and operating principle of the MGL. The peculiarity is that they depend on voltage, so the lamps require the inclusion of a current-limiting element (ballast) in a sequential order.
Most MGLs operate with serial ballasts designed for gas-discharge lamps (mercury or sodium arc lamps). There are ballasts with a built-in IZU with the functions of igniting the light source and limiting the current.
Photo 4 - MASTER CDM-T 70W/942 G12 PHILIPS 871150019927015 As the lamp warms up, the voltage and current in it fluctuate, so special requirements are placed on the design and quality of the current-limiting element. Poor quality causes low voltage and when turned on the lamp will begin to go out.
How to check?
Photo 4 - HQI-TS 150W/NDL EXCELLENCE RX7s-24 OSRAM 4008321678386 You can check the performance of the MGL in the usual way - turn on the lamp: if it lights intermittently, the lamp is faulty. You should check that the connection is correct, perhaps this is the reason.
If the lamps show unstable operation - they light up, go out, cannot flare up to the full expected power - you need to measure the voltage in the network. Metal halide lamps operate unstable at a voltage of 190 V.
Please pay attention to the correct connection in the power cable connector: the connection is correct if the voltage is normal and the phases correspond to the designations.
You also need to check:
- serviceability of the power cable (it may be broken);
- whether the power supply was inserted into the track correctly;
- correct connection to the panel.
If more than 20 lamps are mounted on a lighting structure consisting of several busbars, you should check whether they have enough power from the line supplying the structure. If the power is insufficient, unstable operation of metal halide lamps and ballasts (ballast control) is possible.
- Base G9
Suitable for small metal halide lamps and equipped with two pins spaced 9mm apart. The socket is a socket with holes at the same distance, so installing a light bulb in a lamp looks like a regular plug-socket connection.
IMPORTANT! The service life of some types of modern MGLs reaches 15,000 hours. They are produced with different radiation colors and color rendering quality.
Photo 5 - HQI-T 400W/N E40 OSRAM 4008321526786 To turn on the lamp, special ignition devices are required, since a voltage of several kilovolts is required to ignite the discharge. MGL, like all gas-discharge lamps, can only operate with a ballast choke, which creates a phase shift between current and voltage, therefore power factor compensation will be required, that is, the inclusion of a compensating capacitor.
The power supply current for 12 V lamps is quite large.
The radiation spectrum is of great importance, especially in greenhouses for growing seedlings and plants. The ability to correct the spectrum from warm white to yellow distinguishes them favorably from the xenon discharge with its cool white color.
Shelf life of MGL
Photo 6 - TDM DRI 250 6000 K E40 SQ0325-0016 Depends on:
- quality of quartz burners;
- processing quality;
- manufacturing company;
- storage conditions.
For example, Lisma lamps have a shorter shelf life under equal conditions than Osram or GE. As a rule, if storage conditions are met, MGLs are stored for decades, the main thing is that they do not leak.
Application of MGL
MGL, like sodium, is used in industry for lighting or landscape design. Gas-discharge MGL is often used on streets, squares and parks in night lighting devices, to illuminate monuments or buildings.
Photo 7 - It is an invariable attribute of stadium lighting, lighting design of circuses and arenas, office buildings and retail, advertising and other structures. Floodlight systems are the upper limit of power.
MGLs are not only plant-friendly, but also suitable for aquariums. A lamp with MGL provides high luminous flux and excellent color rendering throughout the entire operating period of the lamps.
MGLs are powerful lamps operating at high pressure and temperature. They are used with ballasts in special-purpose lamps. Typically, the MGL kit with built-in electronic ballasts includes a ballast starting device (required for arc lamps). Usually this is a large throttle and ignition device.
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150 W 4000K E27 |
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GU6.5 20-35W |
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Optimal conditions for metal halide lamps
When igniting the MGL, the conditions are very important, which directly affect the type of ballast used with a specific type of lamp. MGL require to adjust the value:
- ballast resistance current;
- supplying the correct voltage to the arc-creating electrodes.
For ballast-lamp systems, ANSI standards contain values for all required parameters for all components. A starter operating from an alternating current network is also important for the ignition device. It differs in straightening parameter and size. Ballast for electromagnetic type starters.
An ignition unit is required in any arc discharge lamp. There are two types for MGL:
- electronic ballasts (electronic);
- EmPRA (electromagnetic).
