Discharge lamps: types and principle of operation + features of work

Do you want to buy gas discharge lamps to create a special atmosphere indoors? Or look for bulbs to stimulate plant growth in a greenhouse? Equipping with economical light sources will not only make the interior more advantageous and help in crop production, but will also allow you to save electricity. Right?

We will help you to deal with the range of lighting devices of gas-discharge type. The article discusses their features, characteristics and scope of high and low pressure lamps. Selected illustrations and videos that will help find the best option for energy-saving lamps.

Device and characteristics of discharge lamps

All the main parts of the lamp are enclosed in a glass flask. Here is the discharge of electrical particles. Inside can be either sodium vapor or mercury vapor, or any of the inert gases.

Such options as argon, xenon, neon, and krypton are used as gas filling. More popular products filled with vaporous mercury.

The capacitor is responsible for operating without blinking. The transistor has a positive temperature coefficient, which provides instant start GRL without flicker. The work of the internal structure begins after the generation of the electric field takes place in the discharge tube.

In the process, free electrons appear in the gas. Colliding with metal atoms, they ionize it. In the transition of some of them, there is excess energy, generating sources of illumination - photons. The electrode, which is the source of the glow, is located in the center of the GRL. The entire system combines the base.

The lamp can emit different light shades that people can see - from ultraviolet to infrared. To make this possible, the inside of the flask is covered with a fluorescent solution.

GRL application areas

Discharge lamps are in demand in various areas. Most often they can be found on city streets, in production shops, shops, offices, train stations, large shopping centers. They are used for highlighting billboards with advertising, facades of buildings.

GRL used in the headlights of cars. Most often it is a lamp characterized by high light output - neon models. Some car headlights are filled with metal halide salts, xenon.

The first gas-discharge lighting devices for vehicles had the designation D1R, D1S. The following - D2R and D2Swhere S points to a spotlight optical circuit, and R - reflex. Apply GH bulbs and when taking pictures.

In the process of photographing these lamps allow you to keep the luminous flux under control. They are compact, bright and economical. The negative point is the inability to visually control the light and shadows that form the light source itself.

In the agricultural field GRL is used to irradiate animals, plants, to sterilize and disinfect products. For this purpose, the lamps must have a wavelength of the appropriate range.

The concentration of radiation power in this case is also of great importance. For this reason, the most suitable products are powerful.

Types of gas discharge lamps

GRL is divided into types according to the type of luminescence, such a parameter as pressure, with reference to the purpose of use. All of them form a specific luminous flux. Based on this feature, they are divided into:

• fluorescent devices;
• gas light species;
• induction options.

In the first of these, the source of light is atoms, molecules, or combinations thereof, excited by a discharge in a gaseous medium.

Secondly - phosphors, the gas discharge activates the photoluminescent layer covering the flask, as a result, the lighting device begins to emit light. Lamps of the third type function due to the glow of the electrodes, heated by a gas discharge.

Depending on the content arc-discharge devices divided into mercury, sodium, xenon, metal halide lamps other. Based on the pressure inside the flask, they are further separated.

Starting from a pressure value of 3x10⁴ and up to 10⁶ Pa they belong to the high-pressure lamps. In the category of low devices fall when the value of the parameter from 0.15 to 10⁴ Pa. More than 10⁶ Pa - super high.

View # 1 - high pressure lamps

RLVD differ in that the contents of the flask are subject to high pressure. They are characterized by the presence of significant luminous flux in combination with low power consumption. These are usually mercury samples, so they are most often used for street lighting.

Such discharge lamps have a solid light output and efficient operation in bad weather conditions, but they tolerate low temperatures poorly.

There are several basic categories of high pressure lamps: DRT and DRL (mercury arc), DRI - the same as DRL, but with iodides and a number of modifications created on their basis. This series also includes arc sodium (DNAT) and DKST - xenon arc.

The first development is the DRT model. In marking D designates arc, the symbol P - mercury, that this model is tubular, indicates the letter T in the marking. Visually, this is a straight tube made of quartz glass. On its two sides - tungsten electrodes. It is used in irradiation plants. Inside - a little mercury and argon.

The lamp is connected to the network in series with choke using a resonant circuit. The luminous flux of the DRT lamp consists of 18% of ultraviolet radiation and 15% of infrared. The same percentage is visible light. The rest is a loss (52%). The main application - as a reliable source of ultraviolet radiation.

To illuminate the places where the quality of color rendering is not very important, they use lighting devices DRL (arc mercury). There is practically no ultraviolet radiation. Infrared is 14%, visible - 17%. Heat loss accounts for 69%.

The design features of DRL lamps make it possible to ignite them from 220 V without the use of a high-voltage pulse igniting device. Due to the fact that the circuit has a choke and a capacitor, the fluctuations of the luminous flux decrease, the power factor increases.

When the lamp is connected in series with the choke, there is a glowing discharge between the additional electrodes and the main neighbors. The discharge gap is ionized as a result a discharge appears between the main tungsten electrodes. The operation of the firing electrodes is terminated.

DRL burners basically have four electrodes - two workers, two igniting ones. Their interior is filled with inert gases with a certain amount of mercury added to their mixture.

Metal halogen lamps DRI also belong to the category of high-pressure devices. Their color efficiency and color quality is higher than the previous ones. The appearance of the emission spectrum is affected by the composition of the additives. The shape of the bulb, the absence of additional electrodes and the phosphor coating are the main differences between DID lamps and DRL lamps.

The scheme, which includes DRL in the network, contains IZU - pulse ignition device. In the tubes of the lamps there are components that are included in the halogen group. They improve the quality of the spectrum of visible radiation.

As it warms up, both mercury and additives evaporate, thereby changing the resistance of the lamp, the luminous flux, the radiating spectrum. On the basis of devices of this type created DRIZ and DRISH. The first of the lamps used in dusty wet areas, as well as in dry. The second - cover color television filming.

The most effective are the lamp DNaT sodium. This is due to the length of the emitted waves - 589 - 589.5 nm. High-pressure sodium devices operate at a value of this parameter of about 10 kPa.

For discharge tubes of such lamps a special material is used - light-transmitting ceramics. Silicate glass is unsuitable for this purpose. sodium fumes are very dangerous for him. The working vapor of sodium introduced into the flask has a pressure of from 4 to 14 kPa. They are characterized by small ionization and excitation potentials.

To compensate for the loss of sodium, inevitably arising in the combustion process, it requires some of its excess. This generates a proportional dependence of the indicators of pressure of mercury, sodium and temperature of the cold point. In the latter, excess amalgam condensation occurs.

When the lamp is lit, evaporation products settle at its ends, which leads to darkening of the ends of the flask. The process is accompanied by a change in the direction of increasing the temperature of the cathode, increasing the pressure of sodium and mercury. As a result, the potential and voltage of the lamp increases. When installing lamps sodium ballasts from DRL and DID are unsuitable.

View # 2 - low pressure lamps

In the internal cavity of such devices there is a gas under pressure lower than the external one. Separate them on LL and CFLs and are used not only to illuminate retail outlets, but also for home furnishing. Fluorescent lamps in this series are the most popular.

The conversion of electricity energy into light occurs in two stages. The current between the electrodes provokes radiation in mercury vapor. The main component of the radiant energy appearing in this case is short-wave UV radiation. Visible light is close to 2%. Further, the arc radiation in the phosphor is transformed into light.

Marking fluorescent lamps contains both letters and numbers. The first symbol is a characteristic of the emission spectrum and design features, the second is power in watts.

Decoding of letters:

• LD - fluorescent daylight;
• Lb - white light;
• LHB - also white, but cold;
• Ltbs - warm white.

In some lighting devices, the spectral composition of the radiation has been improved in order to obtain more perfect light transmission. In their labeling there is a symbol "C». Fluorescent lamps provide rooms with a uniform, soft light.

The radiation surface of an LL is rather large, so it is difficult to control the spatial dispersion of light. In non-standard conditions, in particular, when it is very dusty, reflex lamps are used. In this case, the internal area of ​​the bulb does not completely cover the diffuse reflecting layer, but only two thirds of it.

The phosphor is coated with 100% of the inner surface. The part of the bulb, which does not have a reflector coating, transmits a luminous flux that is much larger than a tube of a conventional lamp of the same volume — about 75%. It is possible to recognize such lamps by marking - the letter “P” is included in it.

In some cases, the main characteristic of LL is Colour temperature TC Equate it to the temperature of the black body, issuing the same color. Outlines LL are linear, U-shaped, in the form of the symbol W, ring. The designation of such lamps includes the corresponding letter.

The most popular devices with a power of 15 - 80 watts. With a light output of 45 - 80 lm / W, the LL burning lasts at least 10,000 hours. The quality of the work of LL is greatly influenced by the environment. The outdoor temperature from 18 to 25⁰ is considered working for them.

With deviations, both the luminous flux and the efficiency of light output and the ignition voltage decrease. At low temperatures, the chance of ignition approaches zero.

To lamps of low pressure also fluorescent compact belong - CFL.

Their device is similar to the usual LL:

1. High voltage between the electrodes.
2. Mercury vapor is ignited.
3. There is an ultraviolet glow.

The phosphor inside the tube makes UV rays invisible to human vision. Only visible light becomes available. The compact design of the device became possible after changing the composition of the phosphor. CFLs, like ordinary LNs, have different powers, but the first indicators are much lower.

The color temperature is measured in kelvins. A value of 2700 - 3300 K indicates a warm yellow color. 4200 - 5400 - white normal, 6000 - 6500 - white cold with blue, 25000 - lilac. Color adjustment is carried out by changing the components of the phosphor.

The color rendition index gives a characteristic of such a parameter as the naturalness of the color with the standard approximated to the maximum by the sun. Absolutely black - 0 Ra, the highest value - 100 Ra. CFL lighting fixtures range from 60 to 98 Ra.

Sodium lamps, belonging to the low pressure group, have a high temperature of the coldest point - 470 K. The lower will not be able to help maintain the desired level of sodium vapor concentration.

The resonance radiation of sodium approaches its peak at a temperature of 540-560 K. This value is commensurate with the pressure of sodium vapor 0.5-1.2 Pa. The light output of this category of lamps is the highest compared to other lighting fixtures of general use.

Positive and negative sides of GRL

There are GRL both in professional equipment and in devices intended for scientific research.

As the main advantages of the lighting devices of this type are usually called their characteristics:

• Light output high. This indicator does not reduce even thick glass.
• Practicalityexpressed in durability, which allows them to be used for street lighting.
• Resistance in difficult climatic conditions. Before the first drop in temperature, they are used with ordinary lampshades, and in the winter - with special lamps and headlights.
• Affordable cost.

The cons of these lamps are not very many. An unpleasant feature is the rather high level of pulsation of the light flux. The second major drawback is the complexity of inclusion. For steady burning and normal operation, they simply need a ballast that limits the voltage for the limits required by the instruments.

The third minus is the dependence of the combustion parameters on the temperature reached, which indirectly affects the pressure of the working steam in the flask.

Therefore, most gas-discharge devices gaining standard burning characteristics after a certain time period after switching on. Their emitting spectrum is limited, therefore the color rendition like that of high-voltage and low-voltage lamps is not ideal.

Operation of devices is possible only in the conditions of alternating current. Activate them with a ballast choke. It takes some time to warm up. Due to the mercury vapor content, they are not completely safe.

Conclusions and useful video on the topic

Video # 1. Information on GL. What it is, the principle of operation, the pros and cons in the following video:

Video # 2. Popular fluorescent lamps:

Despite the emergence of more sophisticated lighting fixtures, gas discharge lamps do not lose their relevance. In some areas they are simply irreplaceable. Over time, GRL will definitely find new applications.

Tell us about how you chose a discharge lamp for installation in a country street or home lamp. Share what has become a decisive factor for you personally. Please leave comments in the box below, ask questions and post a photo on the subject of the article.