Fluorescent lamps and their characteristics. Reference data. Part 1

Encyclopedia of radio electronics and electrical engineering / Reference materials

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

Classification of fluorescent lamps

Fluorescent lamps (LL) are divided into lighting general purpose and special. General-purpose LLs include lamps with a power of 15 to 80 W with color and spectral characteristics that imitate natural light of various shades. For the classification of LL for special purposes, various parameters are used. By power, they are divided into low-power (up to 15 W) and powerful (over 80 W); by type of discharge into arc, glow discharge and glow glow; by radiation to natural light lamps, colored lamps, lamps with special emission spectra, ultraviolet radiation lamps; according to the shape of the flask into tubular and figured; according to light distribution with non-directional light emission and with directional (reflex, slot, panel, etc.).

Marking usually consists of 2-3 letters. The first letter L means luminescent. The following letters indicate the color of radiation: D - daylight; HB - cold white; B - white; TB - warm white; E - natural white; K, F, 3, G, C - red, yellow, green, blue, blue, respectively; UV - ultraviolet. Lamps with improved color rendering quality have the letter C after the letters denoting the color, and with the color rendering of especially high quality, the letters CZ. At the end, they put letters characterizing the design features: R - reflex, U - U-shaped, K - ring, A - amalgam, B - quick start. The numbers indicate power in watts. The marking of smoldering discharge lamps begins with the letters TL.

Characteristics of conventional LL

В table 1 the characteristics of the most common fluorescent lamps are given. Designations: P - power; U is the voltage on the lamp; I - lamp current; R - luminous flux; S - light output.

Dependence of lamp parameters on mains voltage

When the mains voltage changes within + 10%, the change in the 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 the luminous flux Nf = 1,5. In a circuit with a capacitive-inductive ballast, the values ​​of Nx are somewhat smaller.

When the mains voltage drops below the permissible level, the conditions for re-ignition worsen. Increasing the voltage above the allowable one causes the cathodes to overheat and the ballasts to overheat. In both cases, there is a significant reduction in lamp life.

Table 1

Dependence of performance on ambient temperature and cooling conditions

A change in the temperature of the tube in comparison with the optimal one, both upward and downward, causes a decrease in the 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 with a decrease in mains voltage. For example, at -10°C and a mains voltage of 180 V instead of 220 V, the number of non-igniting lamps can reach up to 60-80%. Such a strong dependence makes the use of LL in rooms with low temperatures ineffective.

An increase in temperature relative to the optimum can occur when the ambient temperature rises and when lamps operate in closed fittings. Overheating of LLs, in addition to reducing the luminous flux, is accompanied by some change in their color. On fig. 2 shows the dependence of the LL parameters on the ambient temperature.

Change in the characteristics of LL during combustion

In the first hours of burning, there is a certain 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 in 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 glow 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, already after several hundred hours of burning, dark coatings and spots begin to appear at the ends of the tube, associated with cathode sputtering. They indicate the poor quality of the lamps.

Energy efficient fluorescent lamps (ELL)

ELLs are designed for general lighting and are fully interchangeable with standard 20, 40 and 65 W LLs in existing lighting installations without replacing lamps and ballasts. They have a standard length, standard lamp operating currents and voltages, and the same or similar luminous fluxes as standard lamps of the corresponding color at 10% reduced power (18, 36 and 58 W). Externally, ELLs differ from standard lamps only in a 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 with a decrease in 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 ELL, the temperature of the tube rises to 50°C, but it is not required to create special conditions for cooling. The phosphor layer in ELLs is under more severe operating conditions, so rare earth phosphors are the most suitable for these lamps. However, such phosphors are about 40 times more expensive than standard calcium halophosphate (HPA), so 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, HFC is applied to the glass, and a rare-earth phosphor of small thickness is applied on top of it.

The industry produces ELL with a power of 18, 36 and 58 W of colors LB, LDC and LEC with light parameters coinciding with the parameters of conventional LL of the same colors with a power of 20, 40 and 65 W. Under the LBCT brand, ELLs are produced with a three-component mixture of rare-earth phosphors with a service life of 15000 hours.

Foreign ELLs

Foreign firms produce ELL with 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 ELL 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 LLs with power from 5 to 25 W with light outputs from 30 to 60 lm / W and service life from 5 to 10000 hours began to appear. Some types of CFLs are intended for direct replacement of incandescent lamps. They have built-in ballasts and are equipped with a standard E27 screw 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 in standard LLs. Due to this, it was possible to significantly reduce the diameter of the discharge tube. With regard to reducing the dimensions of the lamps in length, this problem was solved by dividing the tubes into several shorter sections arranged in parallel and interconnected either by curved sections of the tube or by welded glass pipes.

Table 2

Table 3

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 (PRA) and a built-in starter (Fig. 4, a), where 1 is a discharge tube; 2 - a special G23 base with a starter and a capacitor mounted inside it).

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

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

4. With glass outer shell, intricately curved discharge tube, special base, remote starter and gear.

The first group includes CFLs, which have received the greatest distribution. The lamps have a discharge tube with a diameter of 12,5 mm and are equipped with a special G23 two-pin base. They are produced by the domestic industry (under the brand name KL / TBC) and a number of foreign firms. The lamps are filled with argon at a pressure of 400 Pa, which ensures the normal operation of the cathodes and discharge conditions. Lamps are easily ignited 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, 251, 362 and 443 mm long, 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. 4, b). A ballast, a starter, and a double U-shaped discharge tube are mounted inside the shell. The main parameters of this type of CFLs (domestic CLS.../TBTS and manufactured abroad (SL) are given in Table 3 (RE2/2001) (second group).

In view of the fact that the discharge tubes in this type of lamp operate in a closed outer shell at temperatures that are noticeably higher than the optimum, 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, non-separable design, due to which, after the failure of the discharge tube, it is necessary to replace the entire lamp, including the inductor. In this regard, some foreign companies produce such lamps in a collapsible version.

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

to the fourth group includes lamps with a cylindrical or pear-shaped outer shell, a special 4-pin base, remote control gear and a starter. These lamps have lower luminous efficacy compared to H- and U-shaped CFLs. Therefore, data on these lamps are not given.

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 studies aimed at improving such lamps are being carried out.

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 efficient transfer of RF energy into a discharge, called an inductor, and a discharge volume. Differences in the arrangement and design of the nodes are determined by the high frequency chosen for excitation of 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 microwave (with a frequency of more than 100 MHz) .

The analysis showed that at present it is most expedient to use a design with a solenoidal inductor and an external location of the discharge volume with respect to it. The design of such a lamp is shown in Fig. 5, where 1 - base E-27; 2 - oscillator 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 for a mains voltage of 220 V 50 Hz with an outer bulb diameter of 75–85 mm have a light output of 30–40 lm/W. In this case, the ferrite core is heated up to 300°C.

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

Author: S.I. Palamarenko, Kyiv; Publication: electrik.org

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