In a living room or office there is enough light bulb, the power of which varies from 60 to 150 watts. But they will be too dim for studio, decorative or street lighting. For this, there are special metal halide lamps. Their features and characteristics differ significantly from other products, which is important to consider when choosing.
What it is?
Metal halide lamps (MGL) are gas-discharge light sources, which means that light is emitted due to an electric discharge in metal vapors. The key feature of such products is the use of special additives in the form of mercury vapor and halides of several chemical componentsthat are in the gas environment.
When the bulb is not functioning, all additives settle on the surface of the burner. When heated, this "precipitate" begins to evaporate, accompanied by decomposition into ions. Ionized metal atoms in a state of excitation form light emission.
The emission spectrum of metal halide lamps is quite wide - from warm to cold light, so they can be comfortable for lighting. In addition, such models are very economical, as they consume little electricity. Their service life is also an advantage - they work up to 15 thousand hours.
However, the disadvantages of these lamps should also be taken into account. Given light sources harmful to the human body due to the content of mercury and other chemical elements. And due to significant heat dissipation, their height is limited.
Types and characteristics
Metal halide lamps have different capacities, so there is always the opportunity to choose the most optimal option for work and other matters.
There are several types of such bulbs, the classification of which occurs depending on the following indicators:
- Power. To connect to an electric network, the voltage of which is 220 volts, products with a capacity of 20 W and above, but not more than 2000 W, are used. Such lamps are used where the voltage reaches 380 volts.
- Radiated shades. This type of attribute can emit a colored light flux: blue, magenta, green, etc.
- Working position. There are bulbs that operate in only one position: horizontal or vertical. However, there are universal models - they work in any position.
- Type of construction:
- Baseless. This type does not have a cap, and its power is from 2 thousand to 3.5 thousand watts. Connection is due to flexible down conductors.
- Single-ended. Among their great variety there are models that work only in horizontal or vertical position, as well as those that work normally in both positions.
- Two-basement. Another name is spotlight. Their flask is made of quartz, has a small size. They give light exclusively in a horizontal position.
The main characteristics of metal halide lamps are conventionally indicated by the letters DRI: arc, mercury, iodide lamp. Some types have the letter “W” at the end (DRISH), which means the ball shape of the discharge tube. The following is the power designation: 400, 700, 1000, etc. It turns out the following: DRI700.
Principle of operation
The heart of MGL is a quartz flask, which manufacturers began to replace more often with a ceramic one because of the resistance of the material to temperature extremes. This flask acts as a burner, surrounded by another flask - external.
The burner is filled with inert gases and impurities of metal halides necessary for the full spectrum of radiation (because mercury does not give all colors). When the metal halide lamp is turned off, the chemical components settle in a thin layer on the surface of the burner. When it turns on, it takes some time to warm up all the components. Evaporating, mercury and other chemical elements emit light. Here, the outer bulb plays a very important role - it holds high temperature, preventing the structure from cooling, and thereby extends the life of the burner itself.
Metal halide lamps are connected according to the rules, since the principle of operation and the design of the attribute has its own characteristics (it depends on voltage). In particular, these products need to include a current limiting element (PRA).
Application options
The different power and wide color range of metal halide lamps make it possible to use them in the following areas:
- movie studios,
- architectural structures
- car lights,
- installations for lighting public buildings,
- scenes
- railway stations
- sports facilities, etc.
Lighting devices of this type can have high power, so they find their application in industry and landscape design. Often, such attributes are used as street lighting at night in parks, squares, to illuminate buildings, monuments, etc.
At the stadium, metal halide lamps are indispensable devices. Circuses, shopping centers, advertising structures, arenas, office buildings - those structures that require powerful lighting.
Fixtures with MGL are favorable for plants, so they can be used in greenhouses and greenhouses. They are also great for aquariums.
Comparison with LED models
In the modern world, metal-halide and LED light sources are gradually replacing incandescent lamps from everyday life. These attributes save energy and provide excellent lighting, but there are significant differences between them. To clearly distinguish between them, you should consider the advantages of each of the lighting fixtures.
Advantages of MGL:
- high energy efficiency
- high light output
- excellent power
- uninterrupted operation of the product regardless of the temperature indoors or outdoors,
- color reproduction is as close to sunlight as possible, therefore comfortable for visual perception,
- small dimensions of products allow you to control its luminous flux.
LED attributes have their own advantages:
- low power consumption
- lack of ultraviolet radiation,
- long term of operation,
- these are environmentally friendly models,
- resistant to shock,
- instant warm-up.
It is noticeable that the advantages of both light bulbs are many. Therefore, the decisive role is played by the disadvantages:
- MGL:
- high price,
- change in voltage affects color reproduction,
- long time to warm up,
- harmful due to mercury.
- LEDs:
- an unpleasant spectrum of illumination for reading literature and small work, however, in this case, models should be selected correctly,
- high price.
The main preference is given to LED attributes because of their safety and greater energy savings. In addition, they are more suitable for residential premises. Metal halide lamps are indispensable for scenes, industrial and public buildings, sports facilities and other similar structures.
How to check serviceability?
The operability of these lighting devices is checked simply: the lamp with this lamp turns on and its functioning is observed. If interruptions are noticed, then the product is defective. The reason may be a wrong connection or the light bulb itself.
You should also check the voltage of the mains: if it does not reach 220 Volts, the MGL is unstable, which means it can ignite and go out, not warm up at full power.
If these attributes give poor lighting, you need to check the following:
- serviceability of the cable (it may be broken),
- the correct installation of power in the track,
- correct connection to the shield.
Since MGL cannot be started without ballast, which are used ballasts, ballasts, it is also checked for proper operation. After all, the evenness of lighting depends on it.
If problems with MGL are detected, you can replace them with LED ones. If metal-halide devices have high power, then instead of one such lamp two LED ones are used.
Shelf life
The life of metal halide lighting attributes depends on several criteria:
- quality of quartz burners,
- storage conditions for products
- quality finishes
- manufacturer.
Lamps of some companies can be stored for decades, other companies - much less, so the brand should also be paid attention to. The main thing is that the products themselves do not leak.
Another important point - creating the right conditions for the storage of MGL. If observed, the attributes will last longer.
Examples and options
In a residential building, metal halide lamps are rarely used or not used at all in connection with the content of mercury in them. However, they are an excellent lighting fixture in greenhouses and greenhouses. This is because plants need a special spectrum of color rendering: red is needed during flowering and fruit setting, and blue is needed for vegetative growth. True, recently, scientists have "insisted" that such artificial lighting in one tone serves as stress for plants, and they need a different spectrum of light flux. This is how greenhouses and greenhouses are illuminated using MGL.
Aquarium is another place for the successful location of metal halide lighting fixtures. These attributes cannot be replaced by others because of their undeniable advantages specifically for aquariums:
- the necessary level of illumination, while saving electricity,
- due to the point nature of the source, the light rays reach the bottom,
- change in the appearance of the aquarium: the picture is embossed and contrasting.
Such lamps in aquariums look as follows.
In sports facilities and on the stages of the MGL it looks a bit different.
Buildings are highlighted no less skillfully.
See how to connect a metal halide lamp in the next video.
MGL principle of operation
MGL has similar features with some types of discharge lamps, where the principle of a luminous body is enclosed in the plasma of a high-pressure electric arc discharge. The MGL burner is filled with an inert gas, mercury and a number of halogens (halide salts). The principle of operation of a metal halide lamp is as follows: light is emitted in a MGL flask 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 that focuses in the flask after ignition of the argon arc, with increasing temperature and pressure, begins to turn mercury and salt mixture into steam, which leads to the emission of light.
Like many MGL gas-discharge lamps, auxiliary devices (additionally igniting electrodes, pulse-igniting units) are needed to initiate a discharge and to 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 ballasts (ballasts) are used, commonly known as ballasts.
Design features MGL
Given the configuration, the MGL device has its own distinctive characteristics:
- the presence of an inner shell, MGL with a unidirectional cap, or its absence, MGL with a bi-directional cap,
- metal base
- the outer bulb made of borosilicate glass, which serves to preserve the internal elements of MGL, acts as a light filter and a temperature regulator, is a source of protection against oxidation of the elements of the inner shell. MGL without an outer bulb, made of ozone-free quartz glass in order to weaken the release of mercury,
- additional (ignition) and tungsten electrodes,
- special phosphorus coating of the inner shell of the outer glass flask to improve color rendering,
- wires supporting the inner bulb of the electric arc (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
A certain shape of the arc in the inner bulb affects the fixed position of the lamp, which determines its type:
- single-ended / single-sided MGLs with the symbol SE (single-ended) are inserted into the cartridge using threads on the base,
- double-ended / double-sided MGLs are labeled DE (double-ended) and are inserted into the cartridges that are on both sides of the lamp,
- universal MGL with marking "universal" which can work in horizontal or vertical position.
Technical specifications MGL
Efficiency is determined by a whole set of high-tech characteristics of metal halide lamps.
Power. The range of nominal MGL energy is unusually huge. The range starts from a small number of tens of watts (70, 100, 150, 175, 250, 400 and 1000 watts) and can reach up to 10 - 20 kW.
Life time. The validity of few types of MGF can be 15,000 hours. To determine the average service life of MGL, it is recommended to take into account the duration of operation and their technical device (throttle or electronic ballasts). The average turn-on frequency and turn-off rhythm is another important sign that affects the life of the MGL. The service life of such lamps depends on a constant rated power and avoiding the shutdown of the MGL during startup.
It is not recommended to use MGL, the service life of which exceeds at least 25% of the specified service life due to the possibility of cracking. After the end of their service life, such lamps may decrease the level of luminous flux quality.
Modern MGLs already have a color rendering index of over 90. For example, a color rendering index of more than 80 or 90 plays a dominant role in giving natural color to products. The unnatural shade that is created when lighting lamps with a low color rendering index leads to the fact that the buyer does not pay attention to the product or, moreover, avoids its purchase.
However, it is not always possible to determine the MGL color coefficients of 100% due to factory deviations or without overcoming the combustion threshold of 100 hours. The power supply of the electric network also affects the color rendering of the lamp. Insufficient power supply changes the physical temperature, so that the light of such a lamp becomes a bluish tint. Color rendering quality often changes as you use it, reflected in the light of the lamp.
Colour temperature. Characteristics of color temperature and the spectral composition of radiation, measured in Kelvin (K.) units, are very important for creating warm or cold shades when illuminating objects and creating the correct visual image. So, the ability of MGL to create a combustion temperature with a spectrum from 2500 Kelvin units (acquires a yellow tint) to 20 000 Kelvin units (turns blue) can be caused by the need for various applications, for example, for plants or animals.
Some MGLs have a “preheat” function (approximately 300 Kelvin units), which affects color reproduction, but the new generation MGLs have improved readings from 100 to 200 Kelvin units.
Basement The most common MGL are considered lamps with a single-sided screw base, which is screwed into the lamp holder. Double-ended MGLs are popular for their ability to reduce the loss of light energy.
The scope directly depends on the types of MGL socles, among which there are single-ended MGLs with a ceramic / quartz burner, double-ended MGLs with a ceramic / quartz burner, baseless MGLs with a quartz burner.
Light flow. The luminous flux of metal halide lamps is very important in determining the luminous intensity of a lamp. This technical characteristic of the lamp is able to reveal the possibility of a particular light source when lighting a room.
The luminous magnitude of the MGL is 75 - 100 lm / W and exceeds the performance of other light sources. So, a tungsten incandescent lamp has only a light output of 10 - 22 lm / W.
MGL inclusion circuit
Metal halide lamps are connected with ballast, which creates a shift between current and voltage, and a capacitor that serves to compensate for the power factor. MGL absorb a low-frequency current, and electronic switching devices are sometimes much lighter (3-4 times), since they function as a ballast, an ignition device and a compensating capacitor.
Connection scheme for metal halide lamps
The use of MGL
MGL have a wide range of applications not only in industrial fields, but also in specific areas:
- lighting in greenhouses, conservatories, aquariums,
- street lighting in your city,
- external lighting or illumination of architectural structures,
- indoor or outdoor lighting of large objects, sports arenas,
- lighting of industrial buildings, gas stations,
- interior lighting of circus arenas, shopping centers, shops, advertising screeds, store windows,
- exterior lighting of various career developments,
- while filming television reports and movies.
Metal halide floodlight for architectural lighting
MGL is an energy-efficient type of lamp that has enhanced light output and color rendering. The high lifetime and good lighting quality makes it possible to use these lamps in different fields, and their compact size and small size are suitable for installation in hard-to-reach places.
What it is
These bulbs belong to gas-discharge lamps, therefore, their work is due to electric discharge in metal vapors.
The main feature of MGL is the use of additional substances, such as mercury vapor and halides, which in turn are in the gas environment.
When the lamp does not work, the vapor settles on the walls of the burner. When cracked, this “precipitate” forms fumes, and at the same time decomposes into ions. Thus, the MGL glow is obtained.
Unfortunately, such products are very harmful to health due to the content of hazardous substances inside.
Below you can find out the technical specifications of metal halide lamps.
Specifications
The luminous flux of a metal halide lamp of 250 volts is mainly associated with the type of halogen used. Additives of sodium give an orange color, thallium - light green, india - blue. In ancient times, metal halide products were used where light similar to natural daylight was needed.
Sometimes from MGL products you can get 100% daylight with a color rendering index of more than 90. You can get any color temperature in the range from 2500 to 20,000 K.
Some types of metal halide lamps are used for better growth of flowers or vegetables, for fish or animals where a special spectrum is needed.
Note! When buying a lamp, you need to pay attention to the fact that the color indicators may initially differ from those specified in the specification, because these indicators relate to the product that has already worked for more than 70 hours, that is, at first they may vary slightly.
A large difference in parameters can be seen in metal halide products with preheating, in which the difference in color temperature reaches 350 K.
A long deviation from the medium voltage can change the color of the bulbs. If the voltage changes sharply, then the MGL lamps may simply burn out or turn off.
The brightness of the glow depends on the voltage, for example, if the voltage is low, the light will be cold, and if it is very high, a warm shade will appear. Therefore, it is better to have a voltage regulator at home, so as not to spoil not only the lamps, but also the electrical appliances.
Advantages and disadvantages
The electrical parameters of metal halide products can vary quite a lot, the choice on the market is large. The quality of light bulbs and increased light output make MGL products very popular.
The bulbs are small, powerful, suitable for a light source, and will be by far the best replacement for classic arc luminescent products, because of the safe spectrum for people.
The brightness of the MGL is 3 times higher than that of the LN, and the light output will mainly be 70-90 Lm / watt.
Color temperature can be:
- 6500 K (cold shade),
- 4500 K (daylight) or 2500 K (warm shade).
They can be obtained with a color rendering of about 90-95%, the efficiency will exceed 6 times the incandescent bulb.
The power range from 15 W to 3500 W for one lamp, also the temperature in the room and beyond does not affect the operation of the light bulb. MGL serve for a long time, on average 10,000 hours of uninterrupted operation.
But there are also a number of disadvantages of MGL:
- the price is considered above average on the market,
- if the voltage jumps, the color of the lighting changes dramatically,
- a long time before turning on the lamp, as well as the inability to quickly start after a short turn off,
- metal halide products must be installed in closed fixtures, otherwise they may burst due to power surges.
Electricians recommend buying only well-known brands of halogen, as in Chinese fakes there are a large number of hazardous chemicals and substances, and the service life is very low, and there is a high risk of bulb rupture.
Metal halide lamp design
Metal halide products have a heavy internal structure. In appearance it is a transparent vessel with a cap, although many species are similar in appearance to pear-shaped LN.
Inside the lamp is another working shell made of glass, as well as conductive parts and a resistor.
The first shell is filled mainly with nitrogen, and the second with an inert gas (argon) under high pressure, a small volume of mercury and additives of halides of substances. This structure explains the name of the bulb.
Mostly sodium iodine or scandium are used as halides of substances. They are necessary for editing the light flux and affect the area of use of MGL products. In an inoperative state, mercury and substances are in a solid state in the form of a film on the walls of the flask.
Flask
The flask is very important to give the necessary temperature, reduces energy loss and prevents the release of ultraviolet radiation. This part of the bulb is made of borosilicate glass, it is very durable and can withstand high temperatures. You need to know that industrial types are not equipped with an external flask, there is used a ozoneless quartz coating.
Sealant
Metal halide lamps have a housing inside which there is a ballast system, at the ends of which there are sealant cartridges for these lamps, while the ballast system is equipped with an additional sealed chamber on which the cable bends are installed.
Marking
There are no common international labeling patterns for metal halide products, but in many cases the letter M says that the product is “metal halide” and H indicates the content of mercury vapor inside.
Russian factories can apply their abbreviation: D - arc, I - iodide, P - mercury. After the type designation, the type and size of the base are usually determined.
P - mercury
The marking P indicates that the composition of the lamps contains additives from mercury vapor. Such lamps are considered more dangerous to human health, so it is advisable to handle them carefully. During the ignition of the light, the mercury is heated for 5 minutes and then a slight evaporation begins.
And - iodide
Iodide metals eliminate the deposition of tungsten vapor on the inner surface of the bulb. During the operation of MGL products, the chemical interaction of the vapor of tungsten and metal halides begins. The result of this interaction is tungsten iodide, which escapes from the electrodes. After turning off the light, tungsten returns to the electrodes.
Area of use
The use of metal halide products at home is not only not economically viable, but also not safe due to the content of mercury. The lamp may explode during a power surge and the house will be filled with harmful fumes.
Therefore, because of this danger, they are used in such rooms:
- movie platforms
- transport lighting
- illumination of monuments and shop windows
- shopping centers,
- factories and workshops
- construction sites
- street lighting
- sports grounds and gyms,
- park places
- greenhouses
- street lighting verandas.
Note! Many people do not face the purchase of metal halide lamps, because they are quite difficult to find in stores. They are mainly bought by production facilities and businessmen from professional enterprises.
How to connect
Many people appreciate metal halide lamps, and they are quite common: they are loved for their long life and uniform lighting. MGL products are used where powerful, similar to daylight, lighting is needed, for example, in shops, at cosmetologists, in concert halls. Devices in which, in addition to adding mercury and argon, metal halides are added, are used to illuminate aquariums, and they also give a strong light blue tint to xenon headlights.
Like many discharge lamps, metal halide devices are not inserted into the network sequentially. For work, you need a professional ballast (PRA), it is also called a choke.
In order for the bulbs to shine for a long time and work uninterruptedly, you need to accurately select the inductor with the current and voltage indicators appropriate for the product: any errors from these indicators will lead to a weakening of the light beam.
There are electromagnetic ballasts and electronic ballasts. The latter will be best, because they help increase the service life of MGL devices by 40%, reduce energy costs and give an even bright light, balancing the voltage in the network. But, unfortunately, the electromagnetic ballasts are quite noisy and large.
In addition to the throttle, to install metal halide devices you need:
- ignition starter,
- phase compensating capacitor.
The IZU starts to work during startup, making a series of pulses with a voltage of 5 kilovolts. High-voltage discharge gives arc ignition and light bulb. Subsequently, the inductor will stabilize the intermittent voltage inside the network. The capacitor compensates for the phase in the network, so that the lamp will be energy-saving. In Figure 11, you can see the correct MGL connection diagram.
It is also advisable to adhere to the main rules when buying MGL:
- clearly read the instructions on the box, which may indicate a restriction on the use of light bulbs in certain conditions,
- the indicated operating position of the bulb must correspond to the position of the lamp for which it is purchased. The worst resource for vertically placed products,
- the size of the cap must be under the size of the cartridge,
- ballast housing must be made of metal with a large number of ventilation holes. Because depending on the type, the ballast consumes 15-20% of the MGL power,
- The ballast is suitable for the same voltage, so when replacing the lamp, it also needs to be changed,
- Instant ignition of a metal halide lamp is sometimes very important, so you need to read about this rule and the ignition time on the package.
If the MGL device is bought to replace a burned out one, then you need to show the seller a sample of the lamp.
The price of these products is high, therefore, all bona fide manufacturers issue a guarantee, checks must be kept, so that in case of a problem immediately contact the store.
After using MGL, it must be disposed of in a special container for hazardous waste. In no case do not leave home and do not break it. Store new lamps in a cardboard box, away from children and animals.
Note! Never use in places with high voltage or permanent blackout in order to avoid explosive situations.
In conclusion, it should be noted that although metallogenic bulbs have many advantages, at present they are used by less and less people, like incandescent lamps. This is due not only to the high price, but also to the danger of use, especially there are small children in the house. When connecting such light bulbs, it is desirable that the person has basic knowledge in the field of electrics. Since the scheme is not simple. If this causes difficulties, it is best to seek the help of specialists.
Terminology
Until the mid-1970s in domestic lighting technology, the term “metal halide lamp” was used, which was due to the name of the chemical elements of group VII of the periodic system - “halogens”. The use of this term was recognized as incorrect in the chemical nomenclature, since “halogen” literally translated from Greek is “salt-like”, and the word “halogen” - literally “salt-maker”, which indicates the high chemical activity of these substances and the formation in reactions, has become widespread. with them metal salts. Therefore, the Russian term “metal halide lamp” is currently used, which is included in the Russian edition of the International Lighting Technical Dictionary of the ICE. The use of verbal cribs from the English term “metal halide lamp” (“metal halide”, “metal halide”) is unacceptable.
Schemes of inclusion in the electric network
The sharp dependence of the MGL current on the voltage on it requires the inclusion of a current-limiting element (PRA) in series with the lamp. Most MGLs are designed to work with serial ballasts of DRL lamps of appropriate power (if there are no special ignition devices in the lamp bulb in such circuits, an IZU installation is required). There are MGLs for working with ballasts of both DRL and DNaT. There are also ballasts of special designs with step-up autotransformers or transformers with increased magnetic scattering or with built-in IZU, combining the functions of current limiting and starting ignition of the lamp.
The process of heating and putting the MGL into operation is accompanied by significant changes in the lamp current and voltage on it, and special requirements are made to the design of ballasts and IZUs, which differ significantly [ source not specified 3355 days ] from ballast requirements for DRL and high pressure sodium lamps. The evaporation of the ID during the heating of the MGL makes the extinction of the lamp likely due to the insufficiently high voltage on it.
Extremely dangerous for MGL is acoustic resonance (AR), which occurs when the lamp is powered by alternating current of a certain frequency (in the acoustic range). The reason for the occurrence of AR is that when the direction of the current flow changes, the arc goes out and, when the voltage rises, it lights up again. In this case, due to a sharp change in pressure in the discharge region, an acoustic wave arises, which is reflected from the walls of the burner. At a certain value of the frequency, a resonance phenomenon occurs. The frequency of the AR depends on the geometric dimensions of the lamp burner and the speed of sound in it (that is, on the pressure at the moment). The consequences of acoustic resonance are the instability of the lamp burning, spontaneous extinction and, in the worst case, the physical destruction of the burner. This phenomenon makes it difficult to design high-frequency electronic ballasts for MGL. As one of the methods to combat AR, frequency modulation with a random signal is used.For low power lamps, rectified (ripple) current power is successfully applied.
Short-term power outages cause the extinction of MGL. Strong vibration can lead to the same outcome, especially dangerous for lamps with a long arc operating in a horizontal position. For re-ignition, the MGL must cool down so that the vapor pressure in it, and, accordingly, the breakdown voltage of the RT, decrease. To illuminate especially critical facilities where interruptions are unacceptable, ballasts for fast re-ignition are used. In them, the ignition of hot MGL is achieved by supplying more powerful ignition pulses with an amplitude of up to 30-60 kV. This mode significantly accelerates the destruction of the lamp electrodes, moreover, it requires the use of more powerful insulation of live parts, and therefore it is rarely used.
Color temperature
Initially, MGLs were used instead of mercury lamps in those places where it was necessary to create light, which in its characteristics was close to natural, due to the fact that these lamps emit white light (mercury lamps emit light with a large admixture of blue light). However, at present, the difference between the spectra of these types of lamps is not so significant. Some metal halide lamps can emit very pure white daylight with a color rendering index of more than 90.
MGLs are capable of emitting light with a color temperature in the range from 2500 K (yellow light) to 20 000 K (blue light). Some types of special lamps were created to emit the spectrum necessary for plants (used in greenhouses, greenhouses, etc.) or animals (used in lighting aquariums). However, one should take into account the fact that due to the presence of tolerances and standard deviations in the factory production of lamps, the color characteristics of the lamps cannot be indicated with 100% accuracy. Moreover, according to ANSI standards, the color characteristics of metal halide lamps are measured after 100 hours of burning (so-called shutter speed). Therefore, the color characteristics of these lamps will not correspond to those stated in the specification until the lamp is subjected to this exposure.
The most significant discrepancies with the declared specifications are for lamps with the “preheating” start-up technology (± 300 K). The lamps produced using the latest “pulse start” technology have improved compliance with the declared characteristics, as a result of which the difference is from 100 to 200 K. The color temperature of the lamps can also be affected by the electrical characteristics of the mains, as well as due to deviations in the lamps themselves. In the event that the power supplied to the lamp has insufficient power, it will have a lower physical temperature and its light will be “cold” (with a greater admixture of blue light, which will make them very similar to mercury lamps). This phenomenon occurs due to the fact that an arc with a temperature that is not high enough cannot completely evaporate and ionize the IDs, which give the lamp light a warm shade (yellow and red colors), because of which the spectrum of lighter ionizing mercury will dominate the lamp spectrum. The same phenomenon is also observed during lamp heating, when the lamp bulb has not yet reached the operating temperature and the IDs are not completely ionized.
For lamps powered by excessively high voltage, the opposite is true, but this situation is more dangerous, due to the possibility of an explosion of the inner bulb due to its overheating and the occurrence of excessive pressure in it. In addition, when using metal halide lamps, their color characteristics often change over time. In large lighting installations using metal halide lamps, often all lamps differ significantly in color characteristics.
Types and their designations
The MGL power range starts from tens of watts and reaches 10 - 20 kW. The most popular are lamps used in outdoor lighting opamps (single-ended 70, 150, 250, 400, 1000, 2000 W and spotlights 70 and 150 W).
Single-ended lamps are denoted by the abbreviation SE (single-ended), and two-sided, respectively, by the abbreviation DE (double-ended). Lamps with a one-sided base, as a rule, are screwed into the cartridge using the thread available on the base (they have the so-called Edison base). Lamps with a double-sided socket must be inserted into the cartridges located on both sides of the lamp used.
Convection flows of metal halides in the plasma of the MGL arc depend on the direction of gravity and significantly affect the distribution of the energy flow exiting the MGL burner. Therefore, metal halide lamps are sensitive to the position in which they are installed. Lamps are designed only for work in a certain orientation. However, lamps marked with the “universal” marking can work in any position, although when they are not in an upright position, the lifespan and intensity of the emitted light will decrease. To obtain the best performance when using the lamp, if its orientation is known in advance, it is necessary to choose a lamp that is not universal but that matches this position.
Various codes are used to indicate the recommended lamp orientation in which it should operate (e.g., U = universal (universal), BH = base horizontal (horizontal), BUD = Base up / down (vertical), etc.). When using the lamps in a horizontal position, it is best to point the spigot nozzle of the inner bulb (the so-called nipple) upward.
In the ANSI system, the MGL designation begins with the letter “M”, followed by a digital coding indicating the electrical characteristics of the lamp, as well as the corresponding ballast type (the letter “H” is used to indicate mercury discharge lamps, and the letter “S” to indicate sodium lamps "). After digital coding, two letters follow, indicating the size of the lamp, its shape, as well as the type of coating, etc., with the exception of color. After this designation, the manufacturer can optionally add any digital or letter codes to display information not displayed by the ANSI notation system, such as lamp power and color. For the choice of ballast, only the letter “M” and the next digital coding are important. For example, the coding M59-PJ-400 in the ANSI system designates a lamp that works only with ballasts of the M59 type. Lamps from European manufacturers are manufactured using European standards, which in some cases are slightly different from ANSI standards.
Another designation often found when choosing MGL is the abbreviation HQI. This abbreviation is a trademark of OSRAM and refers to a special type of lamp manufactured by this company. But over time, they began to call this abbreviation MGL of any manufacturer, including a two-sided base. European MGLs do not exactly comply with ANSI standards and operate at different current and voltage values. In most cases, the direct European analogue of the lamp for the ANSI standard cannot work with the American ballast, so to work with this type of lamp it is necessary to select the corresponding ballast marked with the HQI marking. For example, ballasts M80 and M81 also have the designation HQI, and are used with lamps with a power of 150 and 250 W, respectively.
Flasks
The designation of the flasks consists of a letter (s) indicating their shape and a digital code indicating in eighths of an inch the maximum possible diameter of the flask. For example, the marking E17 indicates that the lamp is ellipsoidal in shape with a maximum diameter of 17 /8 or 2 1 /8 inches.
Bulb letter designations: BT (Bulbous Tubular) - bulb-like tubular, E or ED (Ellipsoidal) - ellipsoidal, ET (Ellipsoidal Tubular) - ellipsoidal, PAR (Parabolic) - parabolic, R (Reflector) - reflex, T (Tubular ) - tubular.
