Detailed information about fluorescent lamps. We analyze the technical characteristics of different types of fluorescent lamps Modern fluorescent lamps

S.I. Palamarenko, Kyiv

Classification of fluorescent lamps, characteristics of conventional fluorescent lamps, dependence of lamp parameters on network voltage, dependence of characteristics on ambient temperature and cooling conditions, changes in the characteristics of fluorescent lamps during combustion, energy-efficient fluorescent lamps, foreign fluorescent lamps, compact fluorescent lamps, electrodeless fluorescent lamps.

Classification of fluorescent lamps

Fluorescent lamps (FL) are divided into general-purpose and special-purpose lighting. General purpose LLs include lamps with a power from 15 to 80 W with color and spectral characteristics that imitate natural light of various shades. To classify special-purpose LLs, various parameters are used. Based on power, they are divided into low-power (up to 15 W) and high-power (over 80 W); by type of discharge into arc, glow discharge and glow; by radiation from natural light lamps, colored lamps, lamps with special radiation spectra, ultraviolet lamps; according to the shape of the flask: tubular and curly; according to light distribution with non-directional light emission and directional (reflective, slot, panel, etc.).

The marking usually consists of 2-3 letters. The first letter L means luminescent. The following letters indicate the color of the radiation: D - daylight; ХБ - cold white; B - white; TB - warm white; E - natural white; K, F, 3, G, S - red, yellow, green, blue, blue, respectively; UV - ultraviolet. For lamps with improved color rendering quality, the letters denoting color are followed by the letter C, and for particularly high-quality color rendering, the letters CC are used. At the end there are letters characterizing the design features: P - reflex, U - U-shaped, K - ring, A - amalgam, B - quick start. The numbers indicate power in watts. The marking of glow lamps begins with the letters TL.

Characteristics of conventional LLs

IN table 1 The characteristics of the most common daylight luminaires are given. Designations: P - power; U is the voltage across the lamp; I - lamp current; R - luminous flux; S - luminous efficiency.

Dependence of lamp parameters on mains voltage

When the mains voltage changes within + 10%, the change in lamp parameters can be determined from the ratio dX/X = Nx dUc/Uc, where X is the corresponding lamp parameter; dX - its change; Nx - coefficient for the corresponding parameter. For a circuit with a choke, the coefficients have the following values: for luminous intensity Ni = 2.2; for power Np = 2.0; for luminous flux Nф = 1.5. In a circuit with a capacitive-inductive ballast, the Nx values ​​are somewhat smaller.

When the network voltage drops below the permissible level, re-ignition conditions worsen. Increasing the voltage above the permissible level causes overheating of the cathodes and overheating of the ballasts. In both cases, there is a significant reduction in lamp life.

Table 1
						Dimensions, mm (Fig. 1) L1 L2 D
						1199,4 1214,4 38
						1199,4 1214,4 38
						1199,4 1214,4 38
						1199,4 1214,4 38
						1199,4 1214,4 38

Dependence of characteristics on ambient temperature and cooling conditions

A change in the tube temperature compared to the optimal temperature, either upward or downward, causes a decrease in luminous flux, deterioration of ignition conditions and a reduction in service life. The ignition reliability of standard lamps when working with starters begins to drop especially noticeably at temperatures below -5°C and when the mains voltage drops. For example, at -10°C and a network voltage of 180 V instead of 220 V, the number of lamps that do not light up can reach 60-80%. Such a strong dependence makes the use of LL in rooms with low temperatures ineffective.

An increase in temperature relative to the optimal one can occur with an increase in ambient temperature and when the lamps are operated in a closed fitting. Overheating of LLs, in addition to a decrease in luminous flux, is accompanied by some change in their color. On Fig.2 The dependence of LL parameters on ambient temperature is shown.

Changes in LL characteristics during combustion

In the first hours of combustion, there is some change in the electrical characteristics of the lamps, associated with the additional activation of the cathodes, the release and absorption of various impurities. These processes usually end within the first hundred hours. During the rest of the service life, the electrical characteristics change very little. There is a gradual decrease in the brightness of the phosphor and the luminous flux of the lamp (Fig. 3: curve 1 for LL 40 W, curve 2 for LL 15 and 30 W). In some lamps, after several hundred hours of burning, dark deposits and spots begin to appear at the ends of the tube, associated with sputtering of the cathodes. They indicate poor quality lamps.

Energy-efficient fluorescent lamps (FLLs)

ELLs are designed for general lighting and are completely interchangeable with standard LLs with a power of 20, 40 and 65 W in existing lighting installations without replacing lamps and ballasts. They have a standard length, standard values ​​of operating currents and voltages on the lamps and the same or similar luminous flux values ​​as standard lamps of the corresponding color with a power reduced by 10% (18, 36 and 58 W). Externally, ELLs differ from standard lamps only in their smaller diameter (26 mm instead of 38 mm). By reducing the diameter, the consumption of basic materials (glass, phosphor, gases, mercury, etc.) is reduced.

To ensure the same voltage drop across the lamps when reducing their diameter, it was necessary to use a mixture of argon and krypton for filling and reduce the pressure to 200-330 Pa (instead of the usual 400 Pa in standard lamps). In the ELL, the tube temperature increases to 50°C, but special conditions for cooling are not required. The phosphor layer in ELLs is subject to more severe operating conditions, so rare-earth phosphors are most suitable for these lamps. However, such phosphors are approximately 40 times more expensive than standard calcium halophosphate (HPA), therefore lamps with such phosphors are several times more expensive than conventional ones. To reduce the cost of lamps, a two-layer coating is used. First, GFC is applied to the glass, and on top of it is a rare-earth phosphor of small thickness.

The industry produces ELLs with a power of 18, 36 and 58 W in the colors LB, LDC and LEC with light parameters that coincide with the parameters of conventional LLs of the same colors with a power of 20, 40 and 65 W. Under the LBCT brand, ELLs with a three-component mixture of rare-earth phosphors with a service life of 15,000 hours are produced.

Foreign ELLs

Foreign companies produce ELLs in three or four standardized color tones and with a two- or three-component mixture of rare earth phosphors. IN table 2 The parameters of some types of ELLs in flasks with a diameter of 26 mm from OSRAM (Germany) are given.

Compact fluorescent lamps (CFLs)

In the early 80s, numerous types of compact FLs with power from 5 to 25 W with luminous efficacy from 30 to 60 lm/W and service life from 5 to 10,000 hours began to appear. Some types of CFLs are designed to directly replace incandescent lamps. They have built-in ballasts and are equipped with a standard E27 threaded base.

The development of CFLs became possible only as a result of the creation of highly stable narrow-band phosphors activated by rare earth elements, which can operate at higher surface irradiation densities than standard LLs. Due to this, it was possible to significantly reduce the diameter of the discharge tube. As for reducing the dimensions of the lamps in length, this problem was solved by dividing the tubes into several shorter sections, located in parallel and connected to each other either by curved sections of the tube or by welded glass pipes.

Lamp brand	Lamp type		Luminous flux, lm,
			lamp power, W
	Lumilux
	Daytime color
	White
	Warm white
	"Interna"
	Lumilux deluxe
	White
	Warm white
	Standard
	Universal white
	Bright white
	Warm white

Table 3

Lamp type	Power, W	Voltage, V		Luminous flux, lm	Dimensions.mm
First group KL7/TBC KL9/TBC KL11/TBC					27x13x135 27x13x167 27x13x235	Special G23
Second group KLS9/TBC KLS13/TBC KLS18/TBC KLS25/TBC			0,093 0,125 0,18 0,27	425 600 900 1200	Zh85x150 Zh85x160 Zh85x170 Zh85x180	Threaded E27
Third group CIRCOLUX CIRCOLUX CIRCOLUX					Zh165x100 Zh165xY0 Zh216xY0	Threaded E27

The entire variety of CFLs currently produced can be divided into four main groups.

1. Without an outer shell, with an H- or U-shaped discharge tube, a special base, remote control gear (ballast) and a built-in starter (Fig. 4, a), where 1-bit tube; 2 - special base G23 with a starter and capacitor mounted inside it).

2. With prismatic or opal outer shell, complex curved discharge tube, standard threaded (or pin) base and built-in starter and ballast (Fig. 4, b), where 1 is the discharge tube; 3 - throttle; 4 - outer flask; 5 - the hollow part of the body, inside which a choke, starter, capacitor, and thermal switch are mounted).

3. Ring, without an outer shell, with a standard threaded (or pin) base and a built-in starter and ballast (Fig. 4, c).

4. With a glass outer shell, a complexly curved discharge tube, a special base, a remote starter and ballasts.

The first group includes CFLs, which are most widespread. The lamps have a discharge tube with a diameter of 12.5 mm and are equipped with a special two-pin G23 base. They are produced by the domestic industry (under the KL/TBC brand) and a number of foreign companies. The lamps are filled with argon at a pressure of 400 Pa, which ensures normal operation of the cathodes and discharge conditions. The lamps light easily even at temperatures down to -20°C, the ignition time does not exceed 10 s. The main parameters of such lamps are given in Table 3.

The high-power CFL series consists of three lamps with a power of 18, 24 and 35 W, lengths of 251, 362 and 443 mm, with a nominal luminous flux of 1250, 2000 and 2500 lm, respectively, and a service life of 5000 hours. The lamps are manufactured in tubes with a diameter increased to 15 mm and mounted on a special 4-pin base.

To the second group includes CFLs that are quite common abroad with a glass or plastic outer shell and a standard E27 threaded base (see Fig. 4b). A ballast, a starter and a double-U-shaped discharge tube are mounted inside the shell. The main parameters of CFLs of this type (domestic CFLs.../TBTs and those produced abroad (SL) are given in table 3(RE2/2001) (second group).

Due to the fact that the discharge tubes in this type of lamp operate in a closed outer shell at temperatures significantly higher than optimal, and there is no possibility of artificially creating a cold zone, the discharge tubes are filled with mercury amalgam.

The lamps are designed to directly replace incandescent lamps and provide great energy savings. Their disadvantages include relatively large

dimensions and especially weight compared to incandescent lamps, inseparable design, due to which, after the discharge tube fails, the entire lamp, including the inductor, has to be replaced. In this regard, some foreign companies produce such lamps in a collapsible design.

To the third group includes a family of ring CFLs with a threaded base and built-in ballast mounted in a plastic housing located along the diameter of the ring-shaped discharge tube (see RE2/2001, Fig. 4, c). The luminous efficiency of ring CFLs, even with semiconductor ballasts, is inferior to the luminous efficiency of H-shaped CFLs of corresponding powers. The convenience of ring CFLs is that they can directly replace incandescent lamps in a lighting fixture. To the fourth group included

lamps having a cylindrical or pear-shaped outer shell, a special 4-pin base, remote control gear and a starter. These lamps have lower light output compared to H- and U-shaped CFLs. Therefore, data on these lamps is not provided.

The main economic advantages of CFLs are significant energy savings and a reduction in the number of lamps required to produce the same number of lumen-hours compared to incandescent lamps.

Modern CFLs are difficult to manufacture. Therefore, theoretical and experimental research is being conducted aimed at improving such lamps.

Electrodeless CFLs.

In these lamps, to excite the glow of phosphors, a discharge in low-pressure mercury vapor mixed with

inert gases (argon, krypton). The charge is maintained due to the energy of the electromagnetic field, which is created in the immediate vicinity of the discharge volume. The creation of electrodeless CFLs became possible thanks to modern microelectronics, which made it possible to create small-sized and relatively cheap sources of high-frequency energy with high efficiency.

All possible types of electrodeless lamps consist of three main components: a small-sized source of RF energy, a device for effectively transferring RF energy into the discharge, called an inductor, and a discharge volume. Differences in the design and design of units are determined by the high frequency chosen to excite the discharge. Currently, there are three main types of electrodeless CFLs with approximately the same energy parameters: with a toroidal inductor on a ferromagnetic core (frequencies from 25 to 1000 kHz), with a solenoidal inductor (frequencies from 3 to 300 MHz) and microwaves (with frequencies over 100 MHz) .

The analysis showed that at present it is most advisable to use a design with a solenoidal inductor and an external location of the discharge volume relative to it. The design of such a lamp is shown in Fig.5, where 1 - base E-27; 2 - autogenerator block; 3 - filling, mercury and inert gas, 4 - solenoidal inductor; 5 - phosphor layer; 6 - cylindrical cavity in the flask; 7 - glass flask. Experimental samples of electrodeless CFLs with a solenoidal inductor (at a frequency of 18 MHz) with a power of 30 W at a mains voltage of 220 V 50 Hz with an outer bulb diameter of 75-85 mm have a luminous efficiency of 30-40 lm/W. In this case, the ferrite core heats up to 300°C.

Currently, there is no industrial production of electrodeless CFLs in any country and only experimental samples are produced.

A fluorescent lamp represents a group of gas-discharge light sources, but is used much more often in comparison with its simpler analogues. Their popularity is due to a number of advantages. Therefore, even the relatively high cost is not an obstacle to purchasing a light source of this type.

In what areas are they used?

Previously, the main purpose of such lighting devices was to organize lighting systems for administrative and public buildings (hospitals, shops, schools, office premises), which was associated with a rather massive structure. Today, fluorescent lamps are characterized by a more advanced design (compact dimensions, electronic ballast as a replacement for the outdated magnetic version).

In addition to this, the standard base also simplifies operation, which allows you to install such light sources instead of an analogue with an incandescent filament.

Modern fluorescent lamps are widely used in everyday life (lighting of private houses, apartments), and advertising (signs, billboards). Another direction is façade lighting. More than other types of light sources, fluorescent lamps are also suitable for illuminating large areas and large-scale objects.

Structure and principle of operation

The main structural elements: a tube or flask (depending on the design), one or two bases, which is also determined by the product model, electrodes are installed inside. A fluorescent lamp is coated on the inside with a phosphor, without which it would be impossible to convert the expended energy into light radiation. Inside the flask/tube there is an inert gas, mercury vapor.

When electricity is applied, a glow discharge is formed between the electrodes. Ideal conditions for this phenomenon: a low level of pressure in the flask along with a low current value. As a result of the passage of electric current through a gaseous medium, ultraviolet radiation is generated.

In order for a fluorescent lamp to provide light visible to the eye, the phenomenon of luminescence is used. Just for this purpose, the inner walls of the tube or bulb of the light source are coated with phosphor.

The principle of operation of this type of lamp is not fully described, since for full operation it is also necessary to ensure normal operating conditions. We are talking about additional equipment that reduces the current value to the required level so that the lighting device does not fail. Previously, electromagnetic ballast elements (also called ballast) were used for this purpose; today electronic analogs are more popular.

If you use the second of the above-mentioned ballast options, as a result you can achieve a significant reduction in the noise effect (hum) during operation, and light sources in such conditions stop flickering.

What are the types of lamps?

There are several versions that differ in the emission spectrum. There are only three types:

• standard;
• special;
• fluorescent lamps with improved light transmission.

The radiation of the first option is characterized by various shades of white. This is due to the fact that the design provides for a single-layer phosphor coating. As a result, the scope of application of such light sources is somewhat narrowed. They are usually used in organizing lighting systems for industrial, administrative and public facilities (offices, shops, etc.).

Various execution forms

Special type versions are characterized by a different emission spectrum. Their main task is to provide the most natural conditions for staying in various rooms. For example, there are also design options designed for installation in aquariums specifically for plants or animals.

There are also versions that are used in premises where birds are bred. In addition, there are light sources for decorative purposes. Their main difference from other options is the multi-colored glow.

Lamps with improved light transmission have one main advantage over other types; the name of such light sources speaks volumes about it - better color reproduction. This is achieved by applying a multilayer coating (3-5 layers of phosphor) to the inner surface of the bulb/tube.

Classification by type of base

The classification of this type of lighting device is also carried out on the basis of differences in designs:

1. Linear executions.
2. Compact fluorescent lamps.

The first option is also called tubular. And, in addition, this variety comes in straight and U-shaped designs. Linear light sources are also divided into groups based on differences in size (length and diameter). Moreover, there is a direct relationship between the dimensions of the product and its power: the longer the lamp, the higher the value of this parameter. The diameter of the flask is also different: T4, T5, T8, T10, T12. From the designation you can find out the size of the product in inches. The base type for such light sources is G13.

Divided into versions according to the design of the flask

Compact fluorescent lamps are divided into versions according to the design of the bulb (it can be curved in different ways) and base: E14, E27, E40, as well as 2D, G23, G27, G24, G53 and several subtypes (G24Q1, G24Q2, G24Q3). The first three of the above structural elements make it possible to install a lighting device instead of versions with an incandescent filament.

Review of pros and cons

If we study in more detail the characteristics of the main options for light sources (halogen, incandescent, fluorescent and LED analogues), we can highlight their strengths and weaknesses. For example, in terms of heating intensity, of all existing designs, only LED versions are superior, while fluorescent lamps still heat up, albeit to a slightly lesser extent than light sources with incandescent filaments.

In terms of fragility, gas-discharge devices are inferior to the diode-based option. But the power level of fluorescent versions and LED light sources is almost at the same level. For example, both versions provide approximately the same lighting intensity (700-800 lm) with a power difference of only 5 W. Incandescent lamps consume the most energy.

Another parameter for comparison is the service life. Of course, LED versions are in the lead (on average up to 50,000 hours of operation). However, from all other analogues, fluorescent lamps have a fairly long service life (from 4,000 to 20,000 hours), which is influenced by operating conditions.

Which manufacturers should you prefer?

Some of the most famous brands today: Philips, Osram, General Electric. The range of lighting equipment is very wide and sometimes it is quite difficult to figure out which manufacturer is more reliable and responsible in its approach to work. After all, the cost of fluorescent light sources is quite high, so it is important to immediately make the right choice and buy a high-quality lamp.

Symbols from manufacturers

The products of the first two of the above-mentioned brands deserve special trust, since they produce various types of light sources, including lamps with fluorescent lamps, and in each direction the high quality of the products is noted. In addition, all three manufacturing plants have been on the market for quite some time.

Exploitation

Significant voltage drops in the network have a negative impact on such light sources. Overload to a large extent (above 240 V) is especially undesirable. It is also recommended to turn on the lamp only after it has completely cooled down. The permissible ambient temperature values ​​for operating the light source are within the range: from -15 to +40 degrees.

Labeling of Russian products

It is prohibited to use fluorescent lamps along with standard dimmers.

Low-pressure fluorescent lamps were the first gas-discharge lamps, which, due to their high luminous efficiency, good spectral composition and long service life, found application for general lighting purposes, despite some difficulty in connecting them to the electrical network. The high luminous efficiency of fluorescent lamps is achieved due to the combination of an arc discharge in low-pressure mercury vapor, characterized by the high efficiency of the transition of electrical energy into ultraviolet radiation, with the conversion of the latter into visible radiation in the phosphor layer.

Fluorescent lamps are long glass tubes, into the ends of which legs carrying electrodes are soldered (Figure 1). The electrodes are a tungsten bi-helix or tri-helix with a layer of active substance deposited on it, which has a low work function at a heating temperature of about 1200 K (oxide cathodes), or a cold oxide cathode with an increased surface, preventing its temperature from exceeding while the lamp is burning.

Figure 1. Diagram of a fluorescent lamp:
1 - leg; 2 - electrode; 3 - cathode; 4 - phosphor layer; 5 - flask tube; 6 - base; 7 - mercury vapor

The oxide cathode is covered with a layer of emitting substance consisting of oxides of alkaline earth metals obtained by heating and decomposition of carbonides (BaCO 3, CaCO 3, SrCO 3). The coating is activated by small impurities of alkaline earth elements. As a result, the outer surface of the cathode turns into a semiconductor layer with a low work function. Oxide cathodes operate at 1250 - 1300 K, providing long service life and low cathode voltage drops.

A small amount of mercury is introduced into the tube of a fluorescent lamp, creating a saturating vapor pressure at 30 - 40 ° C, and an inert gas with a partial pressure of several hundred pascals. The mercury vapor pressure determines the decrease in the discharge ignition voltage, as well as the output of ultraviolet radiation from the mercury resonance lines of 253, 65 and 184.95 nm. Argon is mainly used as an inert gas in a fluorescent lamp at a pressure of 330 Pa. Recently, a mixture consisting of 80 - 90% Ar and 20 - 10% Ne at a pressure of 200 - 400 Pa has been used to fill general-purpose lamps. The addition of an inert gas to mercury vapor facilitates the ignition of the discharge, reduces the sputtering of the oxide coating of the cathode, increases the gradient of the electric potential of the discharge column and increases the radiation output of the resonance lines of mercury. In fluorescent lamps, 55% of the power comes from the 253.65 nm line, 5.7% from the 184.95 nm line, 1.5 - 2% from the 463.546 and 577 nm lines, and 1.8% from the light emission of other lines. The rest of the power is spent on heating the bulb and electrodes. A thin layer of phosphor is applied to the inner surface of the tube evenly along its entire length. Thanks to this, the luminous efficiency of a mercury discharge, equal to 5 - 7 lm/W, increases to 70 - 80 lm/W in modern 40 W fluorescent lamps. When using phosphors based on rare earth elements, the luminous efficiency of a fluorescent lamp with a diameter of 26 mm increases to 90 - 100 lm/W.

The low mercury vapor pressure used in fluorescent lamps, resulting at a bulb temperature that differs little from the ambient temperature, makes its parameters dependent on external conditions. The operating parameters of the lamps are determined by the parameters of the ballasts.

Due to the variety and complexity of the above dependencies, we will consider each of them separately. At the same time, we will keep in mind that in real operating conditions of lamps they are interconnected.

Basic properties of low pressure mercury discharge

The main part of the radiation power of a low-pressure mercury discharge used in a fluorescent lamp is concentrated in the resonance lines of mercury with wavelengths of 253.65 and 184.95 nm. This radiation occurs in the discharge column at a mercury vapor pressure of 1 Pa and a current density of about 10 A/mm². The pressure of saturated mercury vapor is determined, as is known, by the temperature of the coldest part of the lamp bulb containing mercury in the liquid phase.

The emission of resonance lines depends on the pressure of mercury vapor, the type and pressure of the inert gas used in the lamps. This dependence for pure mercury and mercury with argon is shown in Figure 2. An increase in the radiation flux in lamps filled with mercury vapor (curve 2 in Figure 2) at pressures up to 5 Pa, almost proportional to the pressure of mercury, at high pressures saturation occurs. The latter is due to the fact that with increasing pressure, the concentration of mercury atoms increases, leading to an increase in the number of collisions of mercury atoms with electrons, an increase in the number of excited atoms and, as a consequence, an increase in the number of emitted photons.

Introduction of an inert gas additive (curve 1 in Figure 2) increases the yield of resonant radiation of mercury atoms, since the presence of an inert gas, even in small concentrations, leads to an increase in pressure in the lamp. In a mercury discharge there is also a significant concentration of unstable atoms, which usually settle on the walls of the tube, increasing its temperature. As the pressure in a lamp filled with an inert gas increases, the probability of metastable atoms reaching the walls without colliding with other gas atoms or electrons decreases sharply. As a result, most of the mercury atoms go into an excited state with subsequent energy emission, which increases the luminous output.

Figure 3 shows the dependence of the resonance radiation output for the 253.65 nm mercury line on the current density J. Since the main source of resonant radiation is the discharge column, which occupies only part of the space between the electrodes, it is obvious that the luminous efficiency of the resonant radiation will depend on the length of the lamp, with an increase in which the influence of the cathode region, which is not involved in the creation of resonant radiation, will decrease. Figure 4 shows the dependence of the luminous efficiency of a fluorescent lamp on its length l.

The voltage drop across the lamp decreases with increasing current density. This means that the potential gradient per unit length of the discharge column also decreases with increasing current density. The value of the voltage drop per unit length of the column depending on the current is necessary for calculations related to determining the parameters of the lamp. Figure 5 shows the dependence of the potential gradient E per unit column length versus current for lamps of different diameters, and Figure 6 shows the dependence of the voltage drop in the cathode region of the discharge U to the pressure and type of filling gas.
For a fluorescent lamp with self-heating oxide cathodes, the cathode voltage drop, obtained by extrapolating the dependence of the voltage across the lamp on the length of the discharge column, is from 12 to 20 V. Therefore, for most types of fluorescent lamps, it is believed that the cathode voltage drop accounts for 10 - 15 V, and anode 3 - 6 V.

Figure 5. Dependence of the potential gradient per unit length of the positive column on the current for lamps of different diameters, mm: 1 - 19; 2 - 25; 3 - 38; 4 - 54	Figure 6. Dependence of the voltage drop in the cathode region of the discharge on the pressure and type of inert gas (mercury vapor pressure about 1 Pa)

In modern fluorescent lamps, as a rule, oxide cathodes are used, operating in a self-heating mode with a cathode spot and increased thermionic emission from the entire surface. Oxide cathode designs are shown in Figure 7.

Figure 7. Designs of fluorescent lamp cathodes:
A- cold cathode of glow discharge; b- self-heating oxide cathode; 1 - cathode; 2 - anode; 3 - electrodes

The amount of activating substance contained in the oxide layer determines the actual service life of the lamps, since it is this substance that is consumed during the combustion process.

The ends of the tungsten wire, which forms the basis of the self-heating oxide cathode, are brought out of the lamp, which allows current to be passed through it both for processing and activating the cathode, and for preheating it in order to reduce the ignition voltage under operating conditions. During the formation of the oxide layer, an intermediate layer appears at the interface between the tungsten wire and the oxide paste due to the diffusion of alkaline earth metal ions into the surface layer of tungsten. This promotes the transfer of electrons from tungsten to the oxide. Their exit into the gas-discharge gap is ensured due to the low work function of heated barium. After the arc discharge is formed, the electron output is concentrated at the cathode spot located at the new lamp near the end of the electrode that is directly connected to the power source. As the barium evaporates into the lamp becomes depleted, the cathode spot moves along the electrode spiral to the opposite end, which leads to a gradual slight increase in the voltage across the lamp. At the end of the lamp's life, when barium has been consumed along the entire oxide cathode, the lamp's firing voltage increases significantly; a lamp switched on with conventional ballasts stops lighting.

Currently, there is no complete method for calculating cathodes. Therefore, their development is carried out on the basis of experimental data and represents one of the most labor-intensive processes for creating luminescent paws.

The optimal yield of resonant radiation depends on the pressure of saturated mercury vapor, which is determined by the temperature of the coldest part of the flask. The temperature of the ends of the bulb, in which the cathodes are located, is quite high, since the temperature of thermionic emission of the oxide cathode exceeds 1200 K. Thus, in the absence of any special devices in conventional fluorescent lamps, the area of ​​the discharge column in the middle of the bulb will be the coldest. Dependence of flask temperature t to from power P 1st, released in the discharge column, per unit external surface and depending on the outer diameter of the flask tube, can be obtained from the relation

P 1st = π × d 2× c × ( t To - t V),

Where c- coefficient weakly dependent on tube diameter d 2 ; t c - ambient (air) temperature.

Due to the fact that it is difficult to measure the diameter of tubes on production lines, a certain range of diameters was selected for the manufacture of lamps of different power - 16, 25, 38 and 54 mm. The dependence of the temperature of the outer surface of the lamp tube on current and diameter is shown in Figure 8. The figure shows that with increasing current, that is, lamp power, in order to obtain a practically acceptable length and ensure the wall temperature, it is necessary to increase the diameter of the bulb tube. Lamps of the same power can, in principle, be created in flasks of different diameters, but they will have different lengths. To unify the lamps and the possibility of their use in various lamps, the lengths of fluorescent lamps are standardized and are 440, 544, 900, 1505 and 1200 mm.

Color and composition of lamp radiation

The radiation of fluorescent lamps is created mainly due to the phosphor, which transforms the ultraviolet radiation of the discharge into mercury dust. The efficiency of converting ultraviolet radiation into visible radiation depends not only on the parameters of the original phosphor, but also on the properties of its layer. In fluorescent lamps, a layer of phosphor covers the almost completely closed surface of the tube, and the glow is excited from the inside and used from the outside. In addition to the luminescence flux, the total luminous flux of fluorescent lamps contains visible radiation from mercury discharge lines, which shines through the phosphor layer. The luminous flux of fluorescent lamps thus depends on both the absorption coefficient of the phosphor and the reflection coefficient. The color of the fluorescent lamp does not exactly match the color of the phosphor used. The radiation flux of a mercury discharge seems to shift the color of the lamp to the blue region of the spectrum. This offset is negligible, so the color correction is within the lamp color tolerance.

For fluorescent lamps used in general lighting installations, from the numerous shades that can be obtained using calcium halophosphate phosphor, four were selected that define the types of fluorescent lamps: LD - daylight, color temperature 6500 K; LCB - cold white light with a color temperature of 4800 K; LB - white light with a color temperature of 4200 K; LTB - warm white light with a color temperature of 2800 K. Among the lamps of the indicated colors, there are also lamps with an improved spectral composition of radiation, providing good color rendition. To the designation of such lamps, after the letters characterizing the color of the radiation, the letter C is added (for example, LDC, LHBC, LBC, LTBC). To produce lamps with improved color rendering, other phosphors are added to calcium halophosphate, emitting mainly in the red region of the spectrum. Monitoring the compliance of lamps with emission of a given color is carried out by checking the color of the radiation using colorimeters.

In fluorescent lamps, radiation covers almost the entire visible range with a maximum in the yellow, green or blue part. It is not possible to estimate the color of such complex radiation only by wavelength. In these cases, color is determined by chromaticity coordinates x And y, each pair of values ​​of which corresponds to a specific color (a point on the color graph).

Correct perception of the color of surrounding objects depends on the spectral composition of the light source. In this case, it is customary to talk about the color rendering of the light source and evaluate it by the value of the parameter R a, called the general color rendering index. Meaning R a is an indicator of the perception of a colored object when illuminated by a given artificial light source in comparison with the reference one. The higher the value R a(maximum value 100), the higher the color rendering quality of the lamp. For fluorescent lamps type LDC R a= 90, LHE - 93, LEC - 85. The overall color rendering index is an averaged parameter of the light source. In a number of special cases, in addition to R a use color rendering indices, denoted R i, which characterize the perception of color, for example, with its strong saturation, the need for correct perception of the color of human skin, and the like.

Processes in gas, phosphor and at the cathode of lamps during the combustion process

Let us trace the processes that occur over time in gas or metal vapor when an electric current passes through them, as well as some specific processes characteristic of fluorescent lamps, in particular their phosphor layer.

In the first hours of combustion, some change in electrical parameters occurs, associated with the completion of activation of the cathode and with the absorption and release of some impurities from the materials of the internal parts of the lamps under conditions of increased chemical activity characteristic of plasma. During the rest of the service life, the electrical parameters remain unchanged until the supply of the activating substance in the oxide cathode is used up, which leads to a significant increase in the ignition voltage, that is, to the practical impossibility of further operation of the lamps.

A reduction in the service life of fluorescent lamps can also occur as a result of a decrease in the mercury content, which determines its saturated vapor pressure. When the lamp is cooled, the mercury partially settles on the phosphor, which, with the appropriate layer structure, can bind it so that it no longer participates in the further evaporation process.

Irreversible processes occur during the service life in the phosphor layer, which leads to a gradual decrease in the luminous flux of fluorescent lamps. As can be seen from the curves of changes in the luminous flux of fluorescent lamps during their service life shown in Figure 9, this decrease occurs especially intensely during the first 100 hours of combustion, then slows down, becoming after 1500 - 2000 hours approximately proportional to the duration of combustion. This nature of the change in the luminous flux of fluorescent lamps during their service life is explained as follows. Within 100 hours, changes in the phosphor composition associated with chemical reactions with impurities in the filling gas predominate; During the entire combustion process, there is a slow destruction of the phosphor under the influence of high-energy quanta, corresponding to the resonant radiation of mercury. Added to the latter process is the formation of a layer of adsorbed mercury on the surface of the phosphor, which is opaque to exciting ultraviolet radiation. In addition to these processes, as well as changes as a result of interaction with glass, decay products of the cathodes are deposited on the phosphor layer, forming characteristic dark, sometimes greenish annular zones near the ends of the lamp.

Experiments have established that the durability of the phosphor layer depends on the specific electrical load. For fluorescent lamps with increased electrical load, phosphors that are more resistant than calcium halophosphate are used.

Basic parameters of lamps

Fluorescent lamps are characterized by the following main parameters.

Light parameters: 1) color and spectral composition of radiation; 2) luminous flux; 3) brightness; 4) pulsation of the light flux.

Electrical parameters: 1) power; 2) operating voltage; 3) type of supply current; 4) type of discharge and used luminous area.

Operational parameters: 1) light output; 2) service life; 3) dependence of light and electrical parameters on supply voltage and environmental conditions; 4) dimensions and shape of lamps.

The main feature that distinguishes lamps for mass use for lighting from the entire variety of fluorescent lamps is their combustion voltage, which is associated with the type of discharge used. Based on this feature, lamps are divided into three main types.

1. Arc discharge fluorescent lamps with a combustion voltage of up to 220 V. These lamps are most widespread in our country and European countries. Such lamps have a self-heating oxide cathode and ignite when it is preheated, which determines the main features of their design.

2. Arc discharge fluorescent lamps with a combustion voltage of up to 750 V. Such lamps (Slim line type) have become widespread in the USA, they operate without preheating the cathodes, and have a power of more than 60 W.

3. Glow discharge fluorescent lamps with cold cathodes. This type of lamp is used for advertising and signal lighting. They operate at low currents (from 20 to 200 mA) in high voltage installations (up to several kilovolts). Due to the small diameter of the tubes used, they can easily be molded into any shape.

A special group includes high-intensity lamps of increased power, having the dimensions of lamps of the first group. In such lamps it turned out to be necessary to use special methods of maintaining the pressure of saturated mercury vapor.

Let's consider the main parameters of fluorescent lamps of the first group. Of the parameters listed above that characterize fluorescent lamps, we have already considered the color and spectral composition of the radiation, luminous flux, power, type of discharge and the luminous area used. The values ​​of other parameters of fluorescent lamps are given in Table 1. The average service life of lamps of all types with a power from 15 to 80 W currently exceeds 12,000 hours with a minimum burning time of each lamp of 4,800 - 6,000 hours. During the average service life, the standard allows for a decline in luminous flux of no more than 40% of the initial one, and for a time equal to 70% of the average service life - no more than 30%.

Table 1

Characteristics of general purpose fluorescent lamps according to GOST 6825-74

Types of lamps	Power, W	Current, A	Operating voltage, V	Dimensions, mm		Luminous flux, lm		Service life, h
				Length with pins	Diameter	average	after minimum burning time	average	minimum
LB15 LTB15 LHB15 LD15 LDC15	15	0,33	54	451,6	27	820 820 800 700 600	600 540 525 450 410	15000	6000
LB20 LTB20 LHB20 LD20 LDC20	20	0,37	57	604	40	1200 1100 1020 1000 850	940 760 735 730 630	12000	4800
LB30 LTB30 LHB30 LD30 LDC30	30	0,36	104	908,8	27	2180 2020 1940 1800 1500	1680 1455 1395 1180 1080	15000	6000
LB40 LTB40 LHB40 LD40 LDC40	40	0,43	103	1213,6	40	3200 3100 3000 2500 2200	2490 2250 2250 1900 1630	12000	4800
LB65 LTB65 LHB65 LD65 LDC65	65	0,67	110	1514,2	40	4800 4650 4400 4000 3160	3720 3310 3165 2705 2500	13000	5200
LB80 LTB80 LHB80 LD80 LDC80	80	0,865	102	1514,2	40	5400 5200 5040 4300 4800	4170 3745 3650 3100 2890	12000	4800

The brightness of fluorescent lamps of various colors and power ranges from 4 × 10³ to 8 × 10³ cd/m². The brightness of a lamp is related to its luminous flux F l and geometric dimensions by the ratio

Where L 0 - average diameter brightness of the middle part of the lamp in the direction perpendicular to the axis, cd/m2; F l - luminous flux, lm; k- coefficient taking into account the decrease in brightness towards the ends of the tube, k= 0.92 for all lamps, with the exception of 15 W lamps, for which k = 0,87; d- internal diameter of the tube, m; l sv - length of the luminous part of the tube, m.

The unevenness of brightness along the diameter of the tube is associated with a change in the reflectance of the glass, which increases with increasing angle of incidence. It should be noted that all the indicated electrical and light parameters of fluorescent lamps are determined when the lamp is turned on with an exemplary measuring choke (DOI) at a rated stabilized voltage.

Luminous intensity of fluorescent lamps I v in the direction perpendicular to their axis, is related to the luminous flux by the relation

I v= 0.108 × F l.

The spatial distribution of luminous intensity of fluorescent lamps in the longitudinal plane is close to diffuse.

When fluorescent lamps are switched on to an alternating current network, in each half-cycle the discharge in the lamp goes out and re-ignites, which leads to a pulsation of the light flux. Due to the afterglow of the phosphor, the pulsation of the lamp's light flux is weakened compared to the pulsation of the discharge. The stroboscopic effect created by the pulsating light flux of fluorescent lamps is reduced by appropriately connecting groups of simultaneously switched fluorescent lamps to the power supply network, for example, on two or three opposite phases of the supply network.

The electrical and light parameters of fluorescent lamps are determined by the parameters of the switching circuit and the network voltage. When the network voltage changes, the electrical parameters of the lamps and those of the light and operational parameters that are directly related to the electrical parameters also change. For any switching scheme, the parameters of fluorescent lamps depend much less on the supply voltage than.

The dependence of the parameters of fluorescent lamps on the pressure of saturated mercury vapor determines their sensitivity to changes in ambient temperature and cooling conditions. Figure 10 shows the dependence of the luminous flux on the ambient temperature. As is known, air, depending on the speed of its movement, significantly changes its cooling effect. Therefore, the dependence of the luminous efficiency of lamps, as can be seen from Figure 10, is determined not only by temperature, but also by the speed of air movement.

Lamps with self-heating oxide cathodes

The bulk of fluorescent lamps with self-heating oxide cathodes are manufactured in the form of straight tubes, differing in diameter and length, that is, in power. The length of the lamps is strictly regulated by the standard. This makes it possible to install lamps in luminaires.

For direct fluorescent lamps, several base designs are used. The design established by GOST 1710-79 with nominal dimensions is shown in Figure 11. The base is connected to the lamp using pinning mastic in the same way as incandescent lamps.

The long length of straight fluorescent lamps limits their use in some cases, especially in everyday life. Therefore, fluorescent lamps of various shapes have been developed and produced: U And W-shaped, ring and, in the last few years, compact fluorescent lamps whose design is close to the incandescent lamp for general lighting, including the base, which ensures their successful use. Curly U And W-shaped lamps provide the possibility of one-sided fastening and connection to the power supply. Shaped lamps are made by bending welded but not yet evacuated straight lamps of the required power. The luminous output of curved lamps is less than that of straight lamps due to the mutual shielding of the bulb parts. Ring fluorescent lamps are bent into an almost continuous ring. The distance between the ends of the bent lamp is determined by the possibility of connecting the bent lamp to a vacuum installation for pumping and vacuum processing. This small gap is filled in the finished lamp with a special base with four pins. The parameters of some fluorescent lamps are given in Table 2.

table 2

Parameters of special-purpose fluorescent lamps

Lamp type	Power of fluorescent lamps, W	Current, A	Operating voltage, V	Dimensions, mm		Luminous flux, lm		Service life, h
				Length without pins	Diameter	nominal	After 40% of average burning time	average	Each lamp
Small-sized
LB4-1 LB6-2 LB8-3 LB13-1	4 6 8 13	0,15 0,15 0,17 0,175	30 46 61 95	135,8 211,0 288,2 516,8	16 16 16 16	110 250 385 780	85 187 290 585	6000 6000 6000 6000	- - - -
Curly (U-, W-shaped, ring)
LBU30-U4 LB30-U4 LBK22 LBK32 LBK40	30 30 22 32 40	0,36 0,35 0,38 0,41 0,44	104 108 66 82 110	465 231 - - -	86 230 216 311 412	1920 1800 1050 1900 2600	1280 1280 790 1420 1950	15000 15000 7500 7500 7500	6000 6000 3000 3000 3000
Reflex
LBR40 LBR80 LHBR40 LHBR80	40 80 40 80	0,43 0,865 0,43 0,865	103 102 103 102	1213,6 1514,2 1213,6 1514,2	40 40 40 40	2500 4350 2080 3460	390 * 600 * 300 * 500 *	10000 10000 10000 10000	4000 4000 4000 4000
Amalgam
LBA15-1 LBA30-1 LBA40	15 30 40	0,33 0,36 0,43	54 104 103	451,6 908,8 1213,6	27 27 40	780 2040 3040	550 1450 2260	12000 12000 12000	4800 4800 4800
Colored
LK40BP LV40BP LR40BP LZ40BP LG40BP	40 40 40 40 40	0,43 0,43 0,43 0,43 0,43	103 103 103 103 103	1213,6 1213,6 1213,6 1213,6 1213,6	40 40 40 40 40	330 1450 560 2100 1000	230 1020 390 1500 700	7500 7500 7500 7500 7500	4000 4000 4000 4000 4000

* Luminous intensity in candelas

In order to take advantage of the color advantages of fluorescent lamps and their low temperature in local lighting installations, a series of small-sized lamps in a bulb with a diameter of 16 mm has been developed. Lamps of this series, the parameters of which are given in Table 2, differ from the lamps of the main series in lower luminous efficiency and service life. To connect to the power supply, they are equipped with cylindrical pin sockets of type G-5 in accordance with GOST 17100-79 (Figure 11).

To operate at high ambient temperatures, for example in closed lamps, special amalgam fluorescent lamps are produced in which mercury is replaced by amalgam (Table 2). Amalgam is an alloy of metal and mercury. Depending on the ratio of mercury and metal, amalgams at room temperature can be in a liquid, semi-liquid or solid state. At high temperatures, the amalgam decomposes with the release of mercury, which, when evaporated, participates in the processes of creating a gas discharge, as in a conventional fluorescent lamp. The introduction of amalgam increases the temperature at which the optimal mercury vapor pressure is achieved (up to 60 - 90 °C), which made it possible to create lamps with high specific power per unit length, operating at ambient temperatures elevated to 70 - 95 °C. However, the introduction of mercury in the form of an amalgam makes it difficult to light lamps. In addition, the gradual evaporation of mercury leads to a gradual increase in the luminous flux of the lamps - their combustion over a certain time. The burning time of amalgam lamps at the above ambient temperatures is 10 - 15 minutes. As an amalgam in domestic lamps, a composition consisting of 20% mercury, 75% lead and 5% beryllium in the solid state is used.

A further increase in the power of fluorescent lamps in dimensions acceptable for their practical use required the development of techniques and methods for maintaining the pressure of saturated mercury vapor within the required limits under conditions of increasing temperature in the middle part of the bulb. Maintaining the mercury vapor pressure at high specific loads is achieved by creating a colder place on the lamp bulb than its middle part. The main methods of this kind are: welding a cylindrical extension in the middle of the flask, as if extending part of the outer surface of the flask to a greater distance from the discharge axis (Figure 12, A); increasing the length of the cascade region with shielding of the end of the tube from heating by cathode radiation (Figure 12, b). The disadvantage of these methods is that when the lamp cools, all the mercury accumulates in a cold place, as a result of which the lamp flare slows down. An increase in the length of the cascade region leads to a decrease in the length of the discharge column. Therefore, the luminous efficiency of such amalgam lamps is lower than lamps with a conventional cathode design. Their areas of application are determined by environmental parameters. Among the additional disadvantages of lamps with a branch, we point out the difficulty of their packaging and transportation.

Figure 12. Methods for obtaining cold zones on a flask:
A- a branch on the flask; b- elongated and screened cascade area; V- grooved flask

The best results are obtained by using grooved tubes (Figure 12, V). This shape of the flask leads to an elongation of the discharge channel, the axis of which seems to bend following the alternating grooves, while a number of sections of the tube surface move away from the discharge axis. However, increasing the length of the discharge gap in such designs does not lead to a noticeable increase in the ignition voltage. A longer discharge gap allows the same power to be obtained at the expense of a slightly lower current. The development of such fluorescent lamps has recently stalled due to the successes achieved in the production of high-pressure lamps, primarily sodium lamps with improved color rendering and high luminous efficiency.

Of the special fluorescent lamps, mention should also be made of the so-called irradiation lamps, the radiation of which lies outside the visible region. Such lamps include, in particular, bactericidal lamps that do not have a phosphor. Germicidal lamps have a significant radiation flux in the ultraviolet region of the spectrum (dominant wavelength 253.65 nm), characterized by a bactericidal effect, that is, the ability to neutralize bacteria. For the bulbs of such lamps, special uviol glass is used, which transmits more than 50% of the radiation flux with a wavelength of 253.65 nm.

Germicidal lamps of the DB type with a power of 8, 15, 30 and 60 W are produced in flasks of the same sizes as fluorescent lamps of the same power. The radiation of bactericidal lamps is assessed in special units of bactericidal flux - bacts (1bq - radiation flux with a power of 1 W with a wavelength of 253.65 nm). Lamps of type DBR8 (reflector) have a radiation flux of 3 bq, DB15 - 2.5 bq, DB30-1 - 6.6 bq, DB60 - 8 bq.
Fluorescent lamps with bulbs made of uviol glass, but with worse transmission of radiation with a wavelength of 253.65 nm due to the application of a phosphor based on calcium phosphate on the inner wall, create an erythemal radiation flux used in a number of tanning and therapeutic installations. The radiation of erythema lamps is estimated in units of erythema flux - eras (1 er - radiation flux with a power of 1 W with a wavelength of 297 nm). Erythema lamps are produced in the LE, LER and LUFSh types with a power from 4 to 40 W with an erythema flux at a distance of 1 m from 40 to 140 mayor/m².

In addition to those discussed, irradiation fluorescent lamps of special design, advertising, signal and decorative ones are produced. Thus, a series of decorative lamps includes lamps of different colors, which is indicated in their markings (R - red, F - yellow, P - pink, Z - green, G - blue).

In addition to the considered fluorescent lamps with oxide self-heating cathodes used in starter circuits, there are lamps designed to operate in starterless circuits and instant ignition circuits. Lamps for operation in starterless circuits - quick-ignition lamps do not differ in design from starter lamps, but have normalized cathode resistance values ​​and a conductive strip on the bulb, which facilitates ignition.

A special group of fluorescent lamps consists of reflector lamps with directional light distribution. A layer of metal powder with diffuse reflection is applied to the inner surface of the tube (up to 2/3 of its circumference), and then a layer of phosphor. The reflective layer concentrates the radiation flux. Such lamps have lower luminous efficiency due to absorption in the reflective layer, but provide greater luminaire efficiency. Lamps with such a coating are called slit lamps. Slit lamps have a high radiation concentration, which allows them to be used in electrical devices (LShch47 type lamps) and for irradiating plants in greenhouses (LFR150 type).

In connection with the development of highly stable narrow-band phosphors based on rare earth elements, it became possible to produce highly economical fluorescent lamps in a bulb with a diameter of 26 mm instead of 38 mm. Such lamps have a reduced power - 18 instead of 20 W, 36 instead of 40 W, 58 instead of 65 W and high luminous efficiency (up to 100 lm/W), due to which their luminous flux is higher than that of standard lamps of higher power.

The production of fluorescent lamps involves the use of toxic mercury. Therefore, the development of mercury-free lamps has long attracted attention. It was possible to create low-pressure lamps in flasks with a diameter of 38 and a length of 1200 mm, filled with neon, with a phosphor based on yttrium oxide, with a luminous efficiency of 23 - 25 lm/W. Due to the greater potential gradient of the discharge column in neon (about 2 times higher than in mercury fluorescent lamps), it is possible to create economical lamps for certain purposes. Due to their easier ignition conditions at low temperatures, mercury-free fluorescent lamps are used, for example, in lighting installations for underwater fishing.

The most common are high and low pressure discharge lamps.

• high pressure lamps used mainly in street lighting and high-power lighting installations;
• low pressure lamps used for lighting residential and industrial premises.

Low-pressure gas-discharge mercury lamp (GRLND) - is a glass tube with a layer of phosphor applied to the inner surface, filled with argon under a pressure of 400 Pa and (or amalgam).

Advantages and disadvantages

The popularity of fluorescent lamps is due to their advantages (over incandescent lamps):

The disadvantages include:

• the presence of an additional device for starting the lamp - a ballast (a bulky, noisy choke with an unreliable starter or electronic ballast);
• flickering of the lamp at the frequency of the mains supply (evened out by the use of electronic ballasts);
• a failed starter causes a false start of the lamp (several flashes are visually detected before stable ignition), reducing the service life of the filaments;
• very low power factor of lamps - such lamps are an unsuccessful load for the electrical network;

There are also smaller disadvantages.

Story

The first ancestor of the fluorescent lamp was gas discharge lamps. For the first time, the glow of gases under the influence of electric current was observed by Mikhail Lomonosov, passing the current through a glass ball filled with hydrogen. It is believed that the first gas-discharge lamp was invented in 1856. Heinrich Geissler obtained a blue glow from a gas-filled tube that was excited by a solenoid. On June 23, 1891, Nikola Tesla patented a system of electric lighting with gas-discharge lamps (patent No. 454,622), which consisted of a high-voltage high-frequency source and gas-discharge argon lamps he had previously patented (patent No. 335,787 dated February 9, 1886, issued by the United States Patent Office). Argon lamps are still used today. In 1893, at the World's Fair in Chicago, Illinois, Thomas Edison demonstrated luminescence. In 1894, M. F. Moore created a lamp that used nitrogen and carbon dioxide to produce a pink-white light. This lamp was a moderate success. In 1901, Peter Cooper Hewitt demonstrated a mercury vapor lamp that emitted blue-green light and was thus unusable for practical purposes. However, its design was very close to modern ones, and had much higher efficiency than Geissler and Edison lamps. In 1926, Edmund Germer and his associates proposed increasing the operating pressure within the flask and coating the flasks with a fluorescent powder that converted the ultraviolet light emitted by the excited plasma into a more uniform white-colored light. E. Germer is currently recognized as the inventor of the fluorescent lamp. General Electric later bought Germer's patent, and under the leadership of George E. Inman, brought fluorescent lamps into widespread commercial use by 1938. In the USSR, the first fluorescent lamps were developed under the leadership of Academician S.I. Vavilov by V.A. Fabrikant, F.A. Butaeva and others.

Principle of operation

When a fluorescent lamp operates, a glow discharge occurs between two electrodes located at opposite ends of the lamp. The lamp is filled with inert gas and mercury vapor, the passing current leads to the appearance of UV radiation. This radiation is invisible to the human eye, so it is converted into visible light using the phenomenon of luminescence. The inner walls of the lamp are coated with a special substance - phosphor, which absorbs UV radiation and emits visible light. By changing the composition of the phosphor, you can change the shade of the lamp. Calcium halophosphates and calcium-zinc orthophosphates are mainly used as phosphors.

Marking

The three-digit code on the lamp packaging usually contains information regarding the quality of light (color rendering index and color temperature).

The first number is the color rendering index of 1x10 Ra (compact fluorescent lamps have 60-98 Ra, so the higher the index, the more reliable the color rendering)

The second and third numbers indicate the color temperature of the lamp.

Thus, the marking “827” indicates a color rendering index of 80 Ra, and a color temperature of 2700 (which corresponds to the color temperature of an incandescent lamp)

In addition, the color rendering index can be designated in accordance with DIN 5035, where the color rendering range of 20-100 Ra is divided into 6 parts - from 4 to 1A. (German)

Peculiarities of perception

Human color perception varies greatly depending on brightness. At low brightness, we see blue better and red worse. Therefore, the color temperature of daylight (5000-6500K) will appear excessively blue in low light conditions. The average illumination in residential areas is 75 lux, while in offices and other work areas it is 400 lux. At low brightness (50-75 lux), light with a temperature of 3000K looks most natural. At a brightness of 400 lux, such light already appears yellow, and light with a temperature of 4000-6000K seems most natural.

International markings for color rendering and color temperature

Code	Definition	Peculiarities	Application
530	Basic warmweiß/warm white	Light of warm tones with poor color rendering. Objects appear brownish and have low contrast. Mediocre light output.	Garages, kitchens. Lately it has become less and less common.
640/740	Basic neutral white / cool white	“Cool” light with mediocre color rendering and light output	Very common, should be replaced by 840
765	Basic Tageslicht/daylight	Bluish “daylight” light with mediocre color rendering and light output	Found in office spaces and for illuminating advertising structures (city lights)
827	Lumilux interna	Similar to incandescent light with good color rendering and luminous efficiency	Housing
830	Lumilux warmweiß / warm white	Similar to the light of a halogen lamp with good color rendering and luminous efficiency	Housing
840	Lumilux neutral white / cool white	White light for work surfaces with very good color rendering and luminous efficiency	Public areas, offices, bathrooms, kitchens. External lighting
865	Lumilux Tagslicht / daylight	“Daylight” light with good color rendering and mediocre light output	Public places, offices. External lighting
880	Lumilux skywhite	Daylight with good color rendering	External lighting
930	Lumilux Deluxe warmweiß/warm white	“Warm” light with excellent color rendering and poor light output	Housing
940	Lumilux Deluxe neutralweiß / cool white	“Cold” light with excellent color rendering and mediocre light output.	Museums, exhibition halls
954, 965	Lumilux Deluxe Tageslicht / daylight	“Daylight” light with a continuous spectrum of color rendering and mediocre light output	Exhibition halls, aquarium lighting

Color rendering marking according to GOST 6825-91*

Fluorescent lamp manufactured in the USSR with a power of 20 W (“LD-20”). The foreign analogue of this lamp is TLD 20W

In accordance with GOST 6825-91* (IEC 81-84) “Tubular fluorescent lamps for general lighting”, current, general purpose linear fluorescent lamps are marked as:

• LB (white light)
• LD (daylight)
• LE (natural light)
• LCB (cold light)
• LTB (warm light)

Adding the letter C at the end means the use of a “de-luxe” phosphor with improved color rendering, and TsTs means the use of a “super deluxe” phosphor with high-quality color rendering.

Special purpose lamps are marked as:

The color rendering parameters of lamps produced in the USSR are given in the table:

Abbreviation	Decoding	Hue	Color t-ra, K	Purpose	Color rendition	Approximate equivalent according to international marking
Fluorescent lamps
LDC, LDTS	Fluorescent lamps with improved color rendering; LDC - de-luxe, LDTS - super-de-luxe	White with a slight bluish tint and relatively low light output	6500	For museums, exhibitions, photography, industrial and administrative premises with increased requirements for color rendering, educational institutions, residential premises	Good (LDTS), excellent (LDTS)	865 (LDC), 965 (LDCC)
LD	Fluorescent lamps	White with a slight bluish tint and high luminous efficiency	6500	In production and administrative premises without high requirements for color rendering	Acceptable	765
Natural light lamps
LETZ, LETZ	Natural light lamps with improved color rendering; LETS - deluxe, LETS - super deluxe	Sunny white with relatively low light output	4000	For museums, exhibitions, photography, educational institutions, residential premises	Acceptable (LETS), good (LETS)	754 (LEC), 854 (LEZZ)
LE	Natural light lamps	White without tint and high luminous efficiency	4000		Unsatisfactory	640
Other lighting lamps
LB	White light lamps	White with a purple tint, poor color rendering and high luminous efficiency	3500	In rooms where bright light is needed and color rendering is not required: production and administrative premises, in the subway	Unsatisfactory	635
LHB	Cool white lamps	White with a noticeable blue tint	4850		Unsatisfactory	685
LTB	Warm white lamps	White with a “warm” pink tint, for illuminating rooms rich in white and pink tones	2700	In grocery stores, catering establishments	Relatively acceptable for warm tones, unsatisfactory for cold tones	530, 630
LTBC	Warm white lamps with improved color rendering	White with a “warm” pink tint	2700	The same as for LTB, as well as for residential premises.	Acceptable for warm tones, less satisfactory for cool tones	730
Special purpose lamps
LG, LC, LZ, LV, LR, LGR	Lamps with colored phosphor	LG - blue, LK - red, LZ - green, LV - yellow, LR - pink, LGR - lilac	-	For lighting design, artistic lighting of buildings, signs, shop windows	-	LG: 67, 18, BLUE LC: 60, 15, RED LZ: 66, 17, GREEN LV: 62, 16, YELLOW
LSR	Blue reflector lamps	Bright blue lamps	-	In electrophotographic duplicating machines	-	-
LUF	Ultraviolet lamps	Lamps of dark blue light with a pronounced ultraviolet component	-	For night illumination and disinfection in medical institutions, barracks, etc., as well as “black light” for lighting design in nightclubs, discos, etc.	-	08

Connection features

Cheap electronic connection option

A fluorescent lamp, unlike an incandescent lamp, cannot be connected directly to the electrical network. There are two reasons for this:

• To strike an arc in a fluorescent lamp, a high voltage pulse is required.
• A fluorescent lamp has a negative differential resistance; after the lamp is ignited, the current in it increases many times. If it is not limited, the lamp will fail.

To solve these problems, special devices are used - ballasts. The most common schemes today are: electromagnetic ballast with a neon starter and various types of electronic ballasts.

Electromagnetic ballast

Electromagnetic ballast “1UBI20” series 110, VATRA plant, USSR.

Modern Electromagnetic ballast “L36A-T” from Helvar plant, Finland.

Electromagnetic ballast is an electromagnetic choke connected in series with the lamp. A starter is connected in series with the lamp filaments, which is a neon lamp with bimetallic electrodes and a capacitor. The choke generates a triggering pulse due to self-induction and also limits the current through the lamp. Currently, the advantages of electromagnetic ballast are simplicity of design, reliability and low cost. There are quite a lot of disadvantages of this scheme:

• Long startup (1-3 seconds depending on the degree of lamp wear);
• Higher energy consumption than that of an electronic circuit - at a voltage of 220 Volts, lamp 2 of 58 Watts = 116 Watts consumes 130 Watts;
• Small cos φ =0.5 (without compensating capacitors);
• Low-frequency hum (100Hz) emanating from the throttle, increasing as the throttle ages;
• Flickering of a lamp with double the mains frequency, which can damage vision and is sometimes dangerous (due to the stroboscopic effect, objects rotating synchronously with the mains frequency may appear motionless. Therefore, fluorescent lamps with electromagnetic ballast are not recommended for lighting moving parts of machines and mechanisms);
• Large dimensions and weight;
• At temperatures below 10 °C, the brightness of the lamp decreases significantly due to a decrease in gas pressure in the lamp;
• At negative temperatures, lamps according to the classical scheme may not light up at all; under these conditions, autotransformers are used.

Electronic ballast

Electronic ballast supplies voltage to the electrodes of the lamp not at the mains frequency, but at a high frequency (25-133 kHz), as a result of which the blinking of the lamps, noticeable to the eye, is eliminated. However, high-frequency oscillations, passing through a lamp like an antenna, create electromagnetic interference in a wide spectrum, so the DV radio range - long waves, starting at 150 kHz, became unsuitable for use, but they argued that it was unprofitable to build large antennas and switched to VHF range, the waves of which propagate only within the line of sight and repeaters are needed.

One of two options for starting lamps can be used:

• Cold start- in this case, the lamp lights up immediately after switching on. This circuit is best used if the lamp turns on and off rarely, since the cold start mode is more harmful to the lamp electrodes.
• Hot start- with preliminary heating of the electrodes. The lamp does not light up immediately, but after 0.5-1 seconds, but the service life increases, especially with frequent switching on and off.

Electricity consumption of fluorescent lamps when using electronic ballast is usually 20-25% lower. Material costs (copper, iron) for production and disposal are several times less. The use of centralized lighting systems with automatic adjustment allows you to save up to 85% of energy. There are electronic ballasts with the ability to dim (adjust brightness) by changing the duty cycle of the lamp supply current.

Lamp starting mechanism with electromagnetic ballast

In the classic switching circuit with an electromagnetic ballast, a starter (starter), which is a miniature gas-discharge lamp, usually neon, is used to automatically regulate the lamp ignition process. One starter electrode is stationary and rigid, the other is bimetallic, bending when heated. There are also starters with two flexible electrodes (symmetrical). In the initial state, the starter electrodes are open. The starter is connected in parallel to the lamp so that when its electrodes are short-circuited, current passes through the coils of the lamp.

At the moment of switching on, the full mains voltage is applied to the electrodes of the lamp and starter, since there is no current through the lamp and the voltage drop across the inductor is zero. The lamp electrodes are cold, there is no discharge, and the mains voltage is not enough to ignite it. But in the starter, a glow discharge occurs from the applied voltage, and the current passes through the electrodes of the lamp and starter. The discharge current is small to heat the lamp electrodes, but is sufficient to heat the starter electrodes, causing the bimetallic plate to bend and close with the hard electrode. Current flows through the electrodes of the lamp and heats them up. When the starter electrodes cool down, the circuit opens and, due to self-induction, the voltage surge across the throttle occurs, which is necessary to ignite the discharge. A miniature capacitor of small capacity is connected in parallel to the starter, which serves to ensure the condition for the occurrence of current resonance together with the inductance of the inductor and, as a result, ignition of the lamp. In the absence of a capacitor, this pulse will be too short and the amplitude too large, and the energy accumulated in the inductor will be spent on the discharge in the starter. By the time the starter opens, the electrodes of the lamp are already sufficiently warmed up, but not all the mercury in the lamp has evaporated and the discharge takes place in an argon atmosphere, which is why the discharge in the lamp is unstable and the starting process can be repeated several times. As soon as all the mercury in the lamp bulb evaporates in sufficient quantities, the lamp enters operating mode.

The operating voltage of the lamp is lower than the mains voltage due to the voltage drop across the inductor, so the starter does not operate again. During the process of igniting the lamp, the starter sometimes fires several times in a row if it opens at a moment when the instantaneous value of the throttle current is zero, or the electrodes of the lamp are not yet warmed up enough. As wear occurs, the operating voltage increases, the number of starter cycles increases, and eventually the lamp can no longer reach operating mode. This causes the characteristic blinking of the failed lamp. When the lamp goes out, you can see the glow of the cathodes, heated by the current flowing through the starter.

Lamp starting mechanism with electronic ballast

Unlike an electromagnetic ballast, an electronic ballast usually does not require a separate special starter to operate, since such a ballast is generally capable of generating the necessary voltage sequences itself. There are different ways to start fluorescent lamps. Most often, electronic ballast heats the cathodes of the lamps and applies a voltage to the cathodes sufficient to ignite the lamp, usually alternating and of a higher frequency than the mains voltage (which at the same time eliminates the flickering of the lamp, characteristic of electromagnetic ballasts). Depending on the design of the ballast and the timing of the lamp startup sequence, such ballasts can provide, for example, a smooth start of the lamp with a gradual increase in brightness to full brightness in a few seconds, or instantaneous switching on of the lamp. Often there are combined starting methods, when the lamp is started not only due to the fact that the cathodes of the lamp are heated, but also due to the fact that the circuit in which the lamp is connected is an oscillatory circuit. The parameters of the oscillatory circuit are selected so that in the absence of a discharge in the lamp, the phenomenon of electrical resonance occurs in the circuit, leading to a significant increase in the voltage between the cathodes of the lamp. As a rule, this also leads to an increase in the heating current of the cathodes, since with such a starting scheme, the filament coils of the cathodes are often connected in series through a capacitor, being part of an oscillatory circuit. As a result, due to the heating of the cathodes and the relatively high voltage between the cathodes, the lamp ignites easily. After the lamp is ignited, the parameters of the oscillatory circuit change, the quality factor decreases and the current in the circuit drops significantly, reducing the heating of the cathodes. There are variations of this technology. For example, in an extreme case, the ballast may not heat the cathodes at all, instead applying a sufficiently high voltage to the cathodes, which will inevitably cause the lamp to ignite almost instantly due to breakdown of the gas between the cathodes. This method is essentially similar to the technologies used to drive cold cathode tubes (CCFLs). This method is quite popular among radio amateurs, since it allows you to start even lamps with burnt-out cathode filaments, which cannot be started by conventional methods due to the impossibility of heating the cathodes. In particular, this method is often used by radio amateurs to repair compact energy-saving lamps, which are ordinary fluorescent lamps with a built-in electronic ballast in a compact housing. After a small modification of the ballast, such a lamp can serve for a long time despite the burnout of the heating coils, and its service life will be limited only by the time until the electrodes are completely atomized.

Reasons for failure

Checking the electrodes on one side for integrity. A resistance of 9.9Ω indicates that the electrode thread on this side is intact.

Checking the electrodes on one side for integrity. An infinitely high resistance indicates that the electrode thread is broken. The second sign is darkening near the electrode.

The electrodes of a fluorescent lamp are tungsten filaments coated with a paste (active mass) of alkaline earth metals. This paste ensures a stable discharge and protects the tungsten filaments from overheating. During operation, it gradually falls off the electrodes, burns out and evaporates. It crumbles especially intensively during startup, when for some time the discharge occurs not over the entire area of ​​the electrode, but on a small area of ​​its surface, which leads to local temperature changes. Therefore, fluorescent lamps still have a finite service life (it depends mainly on the quality of the electrodes and the ignition speed), although it is longer than that of conventional incandescent lamps, in which the spiral evaporates at a constant rate. Hence the darkening at the ends of the lamp, which intensifies closer to the end of its service life. When the paste burns out completely, the lamp current begins to drop and the voltage, accordingly, increases.

Failure of lamps with electromagnetic ballast

An increase in voltage on the lamp during its aging leads to the fact that the starter begins to constantly work - hence the well-known blinking of failed lamps. In this case, the lamp electrodes constantly heat up, and eventually (after about 2 - 3 days of blinking) one of the filaments burns out. Then the lamp burns for a minute or two without flickering, the discharge comes from the remains of a burnt-out electrode, on which there is no longer any paste made of alkaline earth metals, only tungsten remains. These remnants of the tungsten filament heat up very strongly, due to which they partially evaporate or crumble, after which the discharge passes to the traverse (the wire to which the tungsten filament with the active mass is attached), it partially melts and the lamp begins to flicker again. If you turn it off, it won't light up again. At the same time, due to long-term operation in continuous mode, the starter often fails, so when replacing the lamp you have to change it too. If the starter fails due to poor quality (short circuit of bimetallic contacts or breakdown of the capacitor), the lamp electrodes heat up and burn out after a few days. When the throttle fails, the lamp burns out instantly.

Failure of lamps with electronic ballast

As the lamp ages, the active mass of the electrodes gradually burns out, after which the filaments heat up and burn out. High-quality ballasts are equipped with an automatic shutdown circuit for a burnt-out lamp. In low-quality electronic ballasts there is no such protection, and after increasing the voltage the lamp will go out, and resonance will occur in the circuit, leading to a significant increase in current and burnout of the ballast transistors.

It is also common for low-quality ballasts (usually compact fluorescent lamps with a built-in ballast) to have a capacitor installed at the output, designed for a voltage close to the operating voltage of the new lamp. As the lamp ages, the voltage rises and a breakdown occurs in the capacitor, which also damages the ballast transistors.

When a lamp with an electronic ballast fails, there is no flickering, as is the case with an electromagnetic ballast, and the lamp goes out immediately. You can determine the cause of failure by checking the integrity of the lamp filaments with any ohmmeter, multimeter or specialized device for testing lamps. If the lamp filaments have a low resistance (about 10 Ohms, that is, they did not burn out), then the reason for the failure is the low quality of the ballast; if one or both of the filaments have a high (infinite) resistance, then the lamp burned out from old age or from overvoltage. In the latter case, it makes sense to try to replace the lamp itself, however, if the new lamp also does not light up and there is power to the ballast circuit, then this also indicates low quality of the ballast (and there is a risk of ruining the new lamp).

Phosphors and spectrum of emitted light

Typical spectrum of a fluorescent lamp.

Many people find the light emitted by fluorescent lamps to be harsh and unpleasant. The color of objects illuminated by such lamps may be slightly distorted. This is partly due to the blue and green lines in the emission spectrum of a gas discharge in mercury vapor, partly due to the type of phosphor used, partly due to an incorrectly selected lamp intended for warehouses and non-residential premises.

Many cheap lamps use halophosphate phosphor, which emits mainly yellow and blue light, while less red and green are emitted. This mixture of colors appears white to the eye, but when reflected from objects, the light may contain an incomplete spectrum, which is perceived as a color distortion. However, such lamps usually have a very high luminous efficiency.

If we consider that there are three types of color receptors in the human eye, and the perception of a continuous spectrum is only the result of the work of the brain, then there is no need to strive to recreate the continuous solar spectrum; it is enough to recreate the same effect on these three receptors. This principle has long been used in color television and color photography. Therefore, more expensive lamps use “three-band” and “five-band” phosphors. This allows for a more uniform distribution of radiation across the visible spectrum, resulting in a more natural reproduction of light. However, such lamps usually have lower luminous efficiency.

The bulbs of special lamps are made of uviol glass, which transmits rays in the ultraviolet wavelength range.

At home, you can evaluate the spectrum of a lamp using a CD. To do this, you need to look at the reflection of the lamp light from the working surface of the disk - the spectral lines of the phosphor will be visible in the diffraction pattern. If the lamp is located close, it is better to place a screen with a small hole between the lamp and the disk.

Special fluorescent lamps

There are also special fluorescent lamps with different spectral characteristics:

• Fluorescent lamps that meet the highest requirements for color rendering of natural colors in daylight 5400K serve to eliminate the effect of color mimicry. It is indispensable in cases where an atmosphere of living daylight is needed, for example, in printing houses, art galleries, museums, dental offices, and laboratories, when viewing transparencies and in specialized textile stores.

• Fluorescent lamps that emit light that is similar in spectral characteristics to sunlight. These lamps are recommended for rooms with insufficient daylight, such as offices, banks and shops. Thanks to its very good color rendering and high color temperature (6500K), it is ideal for comparing paints and medical light therapy.

• Fluorescent lamps for plants and aquariums with enhanced radiation in the spectral range of blue and red light. Ideally affects photobiological processes. These lamps with the designations emit light with a minimum content of ultraviolet component type A (with the absolute absence of ultraviolet components type B and C). Usually combined with fluorescent lamps (5400K - 6700K) to give natural background lighting.

• Lamps for marine life of aquariums with radiation in the blue and ultraviolet range. Serve to impart natural color to corals and coral reef inhabitants. Also, these lamps allow some types of corals to fluoresce, which in turn “revitalizes” the composition. Usually combined with fluorescent lamps (5400K - 6700K) to give natural background lighting.

• Decorative lamps in red, yellow, green, blue and crimson colors. Colored fluorescent lamps are especially suitable for decorative lighting and creating special lighting effects. The color of the lamp is obtained by using a special phosphor or by painting the bulb. Among other things, a yellow fluorescent lamp does not contain an ultraviolet component in its spectrum. Therefore, this lamp is recommended for sterile production, for example, for microcircuit manufacturing workshops (in such production photoresists are used - substances that react with UV), as well as for general lighting without UV radiation.

• Fluorescent lamps designed to illuminate rooms in which birds are kept. The spectrum of these lamps contains near ultraviolet, which makes it possible to create lighting that is more comfortable for them, bringing it closer to natural, since birds, unlike people, have four-component vision.

Lamps made from black light lamps

• Lamps with special color characteristics:
  • varnishes, paints to a depth of no more than 1 mm; treatment of hyperbilirubinemia.
  • for polymerization of plastics, adhesives, varnishes, paints to a depth of more than 1 mm; psoriasis treatment; attracting insects to insect traps; to recognize counterfeits.

Execution options

Fluorescent lamps - low-pressure gas-discharge lamps - are divided into linear and compact.

Linear lamps

Linear fluorescent lamp- a low-pressure mercury lamp of a straight, ring or U-shape, in which most of the light is emitted by a luminescent coating excited by the ultraviolet radiation of the discharge. Often such lamps are completely incorrectly called - bulb-shaped or tubular; this definition is outdated, although it does not contradict GOST 6825-91, in which the designation “tubular” is adopted.

A double-ended straight fluorescent lamp is a glass tube, at the ends of which glass legs with electrodes (spiral heating filaments) attached to them are welded. A thin layer of crystalline powder - phosphor - is applied to the inner surface of the tube. The tube is filled with an inert gas or a mixture of inert gases (Ar, Ne, Kr) and hermetically sealed. A dosed amount of mercury is introduced inside, which turns into a vapor state when the lamp is operating. At the ends of the lamp there are sockets with contact pins for connecting the lamp to the circuit.

Linear lamps differ in:

• Tube length(usually the length of the tube is proportional to the power consumption):

• Tube diameter and have the following designations:

Designation	Diameter in inches	Diameter in mm
T4	4/8	12,7
T5	5/8	15,9
T8	8/8	25,4
T10	10/8	31,7
T12	12/8	38,0

• Base type G13 - distance between pins 13 mm.

Lamps of this type can often be seen in production facilities, offices, shops, transport, etc.

In the practice of manufacturers of LED lamps and lamps, the designation of lamps such as “T8” or “T10”, as well as the base “G13”, is also often found. LED lamps can be installed in a standard lamp (after minor modification) for fluorescent lamps. But the principle of operation is different and, apart from external similarity, they have nothing in common with fluorescent lamps.

Compact lamps

Compact fluorescent lamps

They are lamps with a curved tube. They differ according to the type of base:

• G24
  • G24Q1
  • G24Q2
  • G24Q3

Lamps are also produced for standard sockets E27, E14 and E40, which allows them to be used in many lamps instead of incandescent lamps.

Safety and disposal

All fluorescent lamps contain (in doses from 1 to 70 mg) a toxic substance of the 1st hazard class. This dose can cause harm to health if the lamp breaks, and if you are constantly exposed to the harmful effects of mercury vapor, it will accumulate in the human body, causing harm to health. At the end of its service life, the lamp is usually thrown away anywhere. Individual consumers do not pay attention to the problems of recycling these products in Russia, and manufacturers strive to distance themselves from the problem.

Fluorescent lamps begin their history with gas-discharge devices invented in the 19th century. In terms of light output and efficiency, they are significantly superior to incandescent lamps. They are used for lighting residential premises, institutions, hospitals, sports facilities, and workshops of manufacturing enterprises.

Operating principle and main properties

For a discharge to occur, electrodes are connected to the flask on opposite sides. Gas-discharge lamps cannot be connected directly to the network. Be sure to use ballasts.

If the number of starts does not exceed 5 times a day, then the luminescent source is guaranteed to last 5 years. This is almost 20 times more than for incandescent lamps.

Among the disadvantages of fluorescent lamps are:

• Unstable operation at low temperatures.
• Need for proper disposal due to mercury vapor.
• The presence of flicker, to combat which it is necessary to complicate the circuit.
• Relatively large sizes .

However, fluorescent lamps are extremely economical because they consume little energy, produce more light and last longer. Not surprisingly, they have replaced conventional light bulbs in almost all institutions and businesses.

Types of fluorescent lamps

Lamps come in low and high pressure. Low pressure pipes are installed in rooms, high pressure pipes are installed on streets and in powerful lighting fixtures.

The range of fluorescent lighting devices is quite wide. They differ in the size and shape of the tube, type of base, power, color temperature, light output and other characteristics.

Depending on the shape of the tube, fluorescent lamps are:

• Tubular (straight), designated by the letter T or t, have a straight shape.
• U-shaped.
• Ring.
• Compact, used for lamps.

Straight, U-shaped and ring types will be combined into one type of linear lamps. The most common lighting fixtures are in the form of tubes. After the letter T or t there is a number. It indicates the diameter of the tube, expressed in eighths of an inch. T8 means the diameter is 1 inch or 25.4 mm, T4 means 0.5 inch or 12.7 mm, T12 means 1.5 inch or 38.1 mm.

To make the lamp more compact, its bulb is bent. To start such lamps, a built-in electronic choke is used. The base is made either for standard lamps or for special lamps.

The fluorescent lamp base can be type G (pin with two contacts) or type E (screw). The latter type is used in compact models. The numbers after the letter G indicate the distance between the contacts, and after the letter E the diameter in millimeters.

Marking

Domestic and international labeling is different. Russian originates from the times of the Soviet Union and uses Cyrillic letters. The meanings of the letters are as follows:

• L lamp;
• D daylight;
• B white;
• T warm;
• E natural;
• X is cold.

For compact models, the letter K is placed in front. If there is a C at the end of the marking, then a phosphor with improved color rendering is used. Two letters C mean that the color reproduction is of the highest quality.

If the lamp produces colored light of a narrow spectrum, then after L there is a corresponding letter. For example, LC means a source of red light, LV means yellow, and so on.

According to the international marking, the lamp is marked with power and a three-digit number separated by a slash, which determines the color rendering index and color temperature.

The first digit of the number indicates color rendition multiplied by 10. The higher the number, the more accurate the color rendition. The next two numbers indicate the color temperature, expressed in Kelvin and divided by 100. For daylight, the color temperature is 5-6.5 thousand K, so a lamp marked 865 will mean daylight with high color rendering.

For housing, lamps with codes 827, 830, 930 are used, for external lighting with code 880, for museums with code 940. More information about the meaning of the marking can be found in special tables.

Power is traditionally designated by the letter W. In general purpose light sources, the power scale varies from 15 to 80 W. For special-purpose lamps, the power can be less than 15 W (low-power) and more than 80 W (high-power).

Application

Fluorescent lamps with various shades of white are used for lighting indoors and outdoors. With their help, plants in greenhouses and greenhouses, aquariums, and museum exhibits are illuminated.

The most common T8 tubes with a G13 base with a power of 18 and 36 W. They are used in institutions and in production. They easily replace Soviet lamps of the LB/LD-20 and LB/LD-40 types.

Since fluorescent sources heat up slightly, they can be used in all types of lamps. By choosing the appropriate base, power and size, they are installed in sconces, pendant chandeliers, and night lights. Used in kitchens, baths, garages, and offices.

They produce fluorescent lamps that emit ultraviolet light. They are installed in laboratories, research centers, medical institutions - wherever this type of radiation is required.

The phosphor can produce colored light (yellow, blue, green, red, and so on). Such sources are used for design purposes for the decoration of shop windows, illumination of signs, and building facades.

In order for a luminescent device to last as long as possible, it is necessary to provide it with a stable voltage and infrequent switching on/off. Because the bulb of a fluorescent light source contains mercury, it should not be thrown away with other household waste. Fluorescent lamps must be handed over to special collection points. These could be rescue services, stores that sell electrical goods, or hazardous waste disposal companies.