Fluorescent lamp voltage. Luminous flux of fluorescent lamps

Fluorescent lamps

Fluorescent Lamp- gas-discharge light source, the luminous flux of which is determined mainly by the glow of phosphors under the influence of ultraviolet radiation of the discharge; the visible glow of the discharge does not exceed a few percent. Fluorescent lamps are widely used for general lighting, while their light output several times more than incandescent lamps for the same purpose. The service life of fluorescent lamps can be up to 20 times longer than the service life of incandescent lamps, provided that sufficient quality of power supply, ballast and compliance with the restrictions on the number of switching operations are ensured, otherwise they quickly fail. The most common type of such source is a mercury fluorescent lamp. It is a glass tube filled with vapors, coated with inner surface a layer of phosphor.

Application area

Corridor lit by fluorescent lamps

Fluorescent lamps are the most common and economical light source for diffused lighting in rooms. public buildings: offices, schools, educational and design institutes, hospitals, shops, banks, businesses. With the advent of modern compact fluorescent lamps designed for installation in conventional E27 or E14 sockets instead of incandescent lamps, they began to gain popularity in everyday life. The use of electronic ballasts (ballasts) instead of traditional electromagnetic ones can improve the characteristics of fluorescent lamps - get rid of flickering and hum, further increase efficiency, and increase compactness.

The main advantages of fluorescent lamps in comparison with incandescent lamps are high luminous efficiency (a 23 W fluorescent lamp gives illumination as 100 W incandescent lamp) and a longer service life (2000-20,000 hours versus 1000 hours). In some cases, this allows fluorescent lamps to save significant costs, despite the higher initial price.

The use of fluorescent lamps is especially advisable in cases where the lighting is on for a long time, since switching on for them is the most difficult mode and frequent switching on and off greatly reduces the service life.

History

The first ancestor of the lamp daylight was the lamp of Heinrich Geissler, who in 1856 received a blue glow from a gas-filled tube that was energized by a solenoid. At the 1893 World's Fair in Chicago, Illinois, Thomas Edison showed a luminescent glow. In 1894, M.F. Moore created a lamp that used nitrogen and carbon dioxide to emit a pink-white light. This lamp has had moderate success. In 1901, Peter Cooper Hewitt demonstrated a mercury lamp that gave off light blue-green, and thus was unusable for practical purposes. It was, however, very close to modern design, and had much more high efficiency than the Geissler and Edison lamps. In 1926, Edmund Germer and his co-workers proposed increasing the operating pressure within the flask and coating the flasks with fluorescent powder, which converts the ultraviolet light emitted by the excited plasma into a more uniformly white-colored light. E. Jermer is currently recognized as the inventor of the fluorescent lamp. General Electric later bought Jermer's patent and, under the leadership of George E. Inman, brought fluorescent lamps to widespread commercial use by 1938.

Principle of operation

When a fluorescent lamp is operating, a glowing electric discharge occurs between two electrodes located at opposite ends of the lamp. The lamp is filled with mercury vapor and the passing current produces UV radiation. This radiation is invisible to the human eye, therefore 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 glow.

Connection features

From the point of view of electrical engineering, a fluorescent lamp is a device with a negative differential resistance (the more current passes through it, the lower its resistance, and the lower the voltage drop across it). Therefore, when directly connected to electrical network the lamp will fail very quickly due to the huge current passing through it. To prevent this, the lamps are connected through special device(ballast).

In the simplest case, it can be an ordinary resistor, but a significant amount of energy is lost in such a ballast. To avoid these losses, when the lamps are powered from the AC mains, a reactance (capacitor or inductor) must be used as ballast.

Currently most widespread received two types of ballasts - electromagnetic and electronic.

Electromagnetic ballast

An electromagnetic ballast is an inductive reactance (choke) connected in series with the lamp. A starter is also required to start a lamp with this type of ballast. The advantages of this type of ballast are its simplicity and low cost. Disadvantages - flickering lamps with a doubled frequency of the mains voltage (mains voltage frequency in Russia = 50 Hz), which increases fatigue and can negatively affect vision, relatively long start-up (usually 1-3 seconds, the time increases as the lamp wears out), higher consumption energy versus electronic ballast. The throttle can also emit a low-frequency hum.

In addition to the above disadvantages, one more can be noted. When observing an object rotating or vibrating with a frequency equal to or multiple of the flickering frequency of fluorescent lamps with electromagnetic ballast, such objects will appear stationary due to the strobing effect. For example, this effect can affect the spindle of a lathe or drilling machine, circular saw, a stirrer of a kitchen mixer, a block of knives of a vibrating electric shaver.

In order to avoid injury at work, it is forbidden to use fluorescent lamps with electromagnetic ballast to illuminate moving parts of machines and mechanisms without additional illumination with incandescent lamps.

Electronic ballast

electronic ballast

Electronic ballast is electronic circuit converting the mains voltage into high-frequency (20-60 kHz) alternating current, which powers the lamp. The advantages of such a ballast are the absence of flickering and hum, more compact size and less weight compared to an electromagnetic ballast. When using electronic ballast, it is possible to achieve an instant start of the lamp (cold start), however, this mode adversely affects the life of the lamp, therefore, a circuit with preliminary heating of the electrodes for 0.5-1 sec (hot start) is also used. The lamp will light up with a delay, but this mode allows you to increase the lamp life.

Lamp triggering mechanism with electromagnetic ballast

V classic pattern switching on with electromagnetic ballast for automatic regulation During the lamp ignition process, a starter (starter) is used, which is a miniature gas-discharge lamp with neon filling and two metal electrodes. One electrode of the starter is fixed rigid, the other is bimetallic, bending when heated. In the initial state, the starter electrodes are open. The starter turns on in parallel with the lamp.

At the moment of switching on, the full mains voltage is applied to the electrodes of the lamp and the starter, since there is no current through the lamp and the voltage drop across the choke is zero. The lamp electrodes are cold and the mains voltage is insufficient to ignite it. But in the starter, a discharge arises from the applied voltage, as a result of which the current passes through the electrodes of the lamp and the starter. The discharge current is small for heating the lamp electrodes, but sufficient for the starter electrodes, which is why the bimetallic plate, when heated, bends and closes with a rigid electrode. The current in the common circuit increases and heats up the lamp electrodes. V next moment the starter electrodes cool down and open. An instantaneous break in the current circuit causes an instantaneous peak in the voltage across the inductor, which causes the lamp to ignite, this phenomenon is based on self-induction. A miniature capacitor of small capacity is connected in parallel to the starter, which serves to reduce the generated radio interference. In addition, it influences the nature of the transients in the starter so that it helps to ignite the lamp. The capacitor, together with the choke, forms an oscillatory circuit that controls the peak voltage and duration of the ignition pulse (in the absence of a capacitor during the opening of the starter electrodes, a very short pulse of large amplitude occurs, generating a short-term discharge in the starter, the maintenance of which consumes most of the energy accumulated in the inductance of the circuit ). By the time the starter opens, the lamp electrodes are already warm enough. The discharge in the lamp occurs first in an argon atmosphere, and then, after the evaporation of mercury, takes the form of mercury. During combustion, the voltage on the lamp and the starter is about half of the mains voltage due to the voltage drop across the choke, which eliminates the repeated operation of the starter. During lamp ignition, the starter sometimes fires several times in a row due to deviations in the interconnected characteristics of the starter and the lamp. In some cases, when the characteristics of the starter and / or the lamp change, a situation may arise when the starter starts to operate cyclically. This causes a characteristic effect when the lamp periodically flashes and goes out, when the lamp goes out, you can see the glow of the cathodes heated by the current flowing through the activated starter.

Electronic ballast lamp trigger

Unlike an electromagnetic ballast, an electronic ballast often does not require a separate special starter. such ballast is generally capable of forming necessary sequences stress itself. Exists different technologies launching fluorescent lamps with electronic ballasts. In the most typical case, the electronic ballast heats the cathodes of the lamps and applies to the cathodes a voltage sufficient to ignite the lamp, most often - alternating and high-frequency (which at the same time eliminates the lamp flickering characteristic of electromagnetic ballasts). Depending on the design of the ballast and the timing parameters of the lamp start-up sequence, such ballasts can provide, for example, a smooth start of the lamp with a gradual increase in brightness to full in a few seconds, or instantaneous switching on of the lamp. Combined starting methods are often found 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 arises 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 scheme for starting the heating coil, 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 can be easily ignited. After ignition of the lamp, the parameters of the oscillatory circuit change, the resonance stops and the voltage in the circuit drops significantly, reducing the filament current of the cathodes. There are variations of this technology. For example, in the extreme case, the ballast may not heat the cathodes at all, instead applying enough high voltage to the cathodes, which will inevitably lead to an almost instantaneous ignition of the lamp due to gas breakdown between the cathodes. In essence, this method is similar to the technologies used for starting cold cathode lamps (CCFL). This method is quite popular with radio amateurs because it allows you to start even lamps with burned-out filaments of the cathodes, 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 a conventional fluorescent lamp with built-in electronic ballast in a compact housing. After a small alteration of the ballast, such a lamp can serve for a long time in spite of the burnout of the heating coils and its service life will be limited only by the time until the electrodes are completely sprayed.

Ballast from a burnt out energy-saving lamp is connected to a T5 lamp

Reasons for failure

The electrodes of the fluorescent lamp are tungsten filaments coated with a paste (active mass) of alkaline earth metals. This paste provides a stable glow discharge; if it were not there, the tungsten filaments would very soon overheat and burn out. During operation, it gradually crumbles from the electrodes, burns out, evaporates, especially with frequent starts, when for some time the discharge occurs not over the entire area of the electrode, but on small area its surface, which leads to overheating of the electrode. Hence darkening at the ends of the lamp, often seen near the end of its life. When the paste burns out completely, the lamp current begins to drop, and the voltage, accordingly, increases. This leads to the fact that the starter starts to work constantly - hence the well-known blinking of failed lamps. The lamp electrodes are constantly warming up and eventually one of the filaments burns out, this happens after about 2 to 3 days, depending on the lamp manufacturer. After that, for a minute or two, the lamp burns without any flickering, but these are the last minutes in her life. At this time, the discharge occurs through the remnants of a burned-out electrode, on which there is no longer a paste of alkaline earth metals, only tungsten remains. These remnants of the tungsten filament are very hot, due to which they partially evaporate or crumble, after which the discharge begins to occur due to the traverse (this is the wire to which the tungsten filament with the active mass is attached), it is partially melted. After that, the lamp starts flickering again. If you turn it off, re-ignition will be impossible. This is where it all ends. The above is true when using electromagnetic ballasts (ballasts). If electronic ballast is used, things will happen a little differently. The active mass of the electrodes will gradually burn out, after which their more and more heating will occur, sooner or later one of the filaments will burn out. Immediately after that, the lamp will go out without blinking or flickering due to the electronic ballast design providing for automatic shutdown of the faulty lamp.

Phosphors and emitted light spectrum

Typical spectrum of a fluorescent lamp.

Many people find the light emitted from fluorescent lamps harsh and unpleasant. The color of objects illuminated by such lamps may be somewhat distorted. This is partly due to blue and green lines in the emission spectrum. gas discharge in mercury vapor, partly due to the type of phosphor used.

Many cheap lamps use a halophosphate phosphor, which emits mostly yellow and blue light, while less red and green. Such a mixture of colors appears white to the eye, however, when reflected from objects, light may contain an incomplete spectrum, which is perceived as color distortion. However, these lamps usually have a very high luminous efficacy.

More expensive lamps use "three-band" and "five-band" phosphors. This allows for a more even distribution of radiation across the visible spectrum, resulting in a more natural reproduction of light. However, these lamps generally have lower luminous efficacy.

There are also fluorescent lamps designed to illuminate rooms where birds are kept. The spectrum of these lamps contains near ultraviolet light, which makes it possible to create more comfortable lighting for them, bringing it closer to natural, since birds, unlike humans, have four-component vision.

Lamps are produced for lighting meat counters in supermarkets. The light of these lamps has pink tint, as a result of such lighting, the meat acquires a more appetizing appearance, which attracts buyers.

Execution options

According to the standards, fluorescent lamps are divided into bulb and compact.

Bulb lamps

Soviet 20 W fluorescent lamp ("LD-20"). The modern European analogue of this lamp is T8 18W

They are lamps in the form of a glass tube. They differ in diameter and type of base, they have the following designations:

T5 (diameter 5/8 inches = 1.59 cm),
T8 (diameter 8/8 inches = 2.54 cm),
T10 (diameter 10/8 inches = 3.17 cm) and
T12 (diameter 12/8 inches = 3.80 cm).

Application

Lamps of this type can often be seen in industrial premises, offices, transport shops, etc.

Compact lamps

Universal lamp Osram for all types of G24 base / plinths

They are lamps with a bent tube. They differ in the type of base on:

G24
- G24Q1
- G24Q2
- G24Q3

Lamps are also available for standard E27 and E14 sockets, which allows them to be used in conventional luminaires instead of incandescent lamps. The advantages of compact lamps are resistance to mechanical damage and small size. The sockets for such lamps are very easy to install in conventional luminaires, the service life of such lamps is from 6,000 to 15,000 hours.

G23

The G23 lamp has a starter inside the base; to start the lamp, only a choke is additionally required. Their power usually does not exceed 14 watts. Main application - desk lamp, often found in shower and bathroom fixtures. The sockets of such lamps have special holes for mounting in conventional wall lamps.

G24

Lamps G24Q1, G24Q2 and G24Q3 also have a built-in starter, their power is usually from 11 to 36 watts. They are used in both industrial and household lighting fixtures. Standard plinth The G24 can be mounted with screws or on a dome ( modern models lamps).

Disposal

All fluorescent lamps contain (in doses from 40 to 70 mg) a poisonous substance. This dose can be harmful to health if the lamp breaks, and if you are constantly exposed to the harmful effects of mercury vapors, they will accumulate in the human body, causing harm to health. At the end of its service life, the lamp is usually thrown away. Individual consumers do not pay attention to the problems of disposal of these products in Russia, and manufacturers are trying to get away from the problem. There are several lamp recycling companies, and large industrial enterprises are obliged to hand over lamps for recycling.

The service life of fluorescent lamps is 10,000 hours, but by the end of their life the luminous flux of the lamp is reduced to 60% of the original.

The service life of fluorescent lamps with proper quality of their manufacture is several times longer than the service life of incandescent lamps. Thus, application in installations street lighting fluorescent lamps has all the prerequisites for the broadest development.

The service life of fluorescent lamps is longer than that of incandescent lamps; it reaches 2000 - 3000 hours.

The service life of fluorescent lamps is 5000 hours, after which their luminous flux is reduced to 60% of its initial value.

The service life of fluorescent lamps is reduced by 20 - 30%, and incandescent lamps and DKst - 2 times. This necessitates rigid stabilization of the voltage at the terminals of the light sources. Voltage stabilization can dramatically increase the efficiency of using lighting installations at industrial enterprises.

The service life of fluorescent lamps established by the standards is 5 times longer, and of mercury lamps is 3 times longer than the service life of incandescent lamps. Hence, gas discharge lamps efficient and economical for lighting the vast majority industrial premises railway transport enterprises.

Compared to incandescent lamps, fluorescent lamps have the following advantages: a) they are much more economical: at the same power, the luminous flux of a fluorescent lamp is several times greater than that of an incandescent lamp; b) fluorescent lamps give light that is close in spectrum to daylight, which in some cases is extremely necessary (for example, in the printing, textile industry, in rooms without natural light, etc.); c) the temperature of the bulb does not exceed - f - 50 C, this makes the lamp relatively fireproof; d) the service life of a fluorescent lamp is 2 - 2 5 times longer than that of an incandescent lamp.

Below are described the main methods of lighting the room with fluorescent lamps, since when using them, it is possible to dramatically increase the level of illumination due to the high luminous efficiency. In addition, the service life of fluorescent lamps is many times that of incandescent lamps.

The efficiency of fluorescent lamps, excluding losses in the ballast choke, ranges from 30 to 50 lm / W, and their luminous efficiency is 2 to 5 times higher than that of incandescent lamps. The choke is necessary, firstly, to stabilize the discharge and, secondly, because the lamp burning voltage is much lower than the mains voltage. The service life of fluorescent lamps is 2500 - 3000 hours versus about 1000 hours for incandescent lamps. Fluorescent lamp damage is usually caused by sputtering of the cathode.

The disadvantages of controlling illumination by turning off individual groups of light sources include the complication of networks (the need to lay additional lighting lines), the use of software control devices with the allocation of the sequence of switching off and turning on of individual groups of light sources negatively affects their service life. From multiple switching on of light sources (with three-shift work, part of the light sources is turned off between shifts 3 times a day or about 1000 times a year), so-called wear-out occurs, which significantly reduces the service life of some types of lamps. The service life of incandescent lamps with the number of switchings of about 2500 practically does not decrease. The reduction in the service life of fluorescent lamps for each activation is approximately 2 hours; with three-shift operation per year, the service life is reduced by 2000 hours, which is 17% of the nominal service life.

Content:

Artificial lighting has long and firmly entered daily life modern people... Lighting devices are constantly being improved and modernized. So, instead of conventional incandescent lamps, fluorescent or energy-saving lamps with a higher efficiency. They belong to the category of discharge lamps low pressure... Ultraviolet radiation is generated by a gas discharge and becomes visible light through a special phosphor coating. Thus, a luminous flux of fluorescent lamps is created, the intensity of which depends on the power of a particular light source.

The main types of fluorescent lamps

All lamps of this type fall into two main categories. The first type is presented lighting fixtures general purpose, the power of which is in the range of 15-80 watts. The color and spectral characteristics of these lamps allow you to simulate the various shades of natural light as much as possible.

The second type refers to light bulbs special purpose... To classify them, use various parameters... According to the power, they are divided into lamps low power- up to 15 W and high power - more than 80 W. These lamps different type discharge, therefore they are arc, as well as with a glow discharge and glow. According to the emitted light, special lamps can be natural light, colored, with ultraviolet radiation and with separate emission spectra. The distribution of light is carried out in different ways, that is, in the form of directional and non-directional light emission. The first option is represented by reflex, panel, slit and other light sources.

Fluorescent lamp marking

All fluorescent bulbs are labeled with letters. The letter L corresponds to the main name. Other letters are applied according to the color of the radiation:

D - daytime color;
HB - cold white;
TB - warm white;
B - regular white;
E is naturally white.
Other letters, for example, К, Ж, З, Г, С - correspond to certain colors- red, yellow, green, blue and blue.
UV symbols stand for ultraviolet light.
Lamps that have improved color rendering are indicated by the letter C after the first color letters.
The CC symbol indicates a particularly high quality.

Design features are indicated by letters affixed at the very end of the marking:

A - amalgam,
B - with quick start,
K - annular,
R - reflex and others.

The numbers following the letters indicate the wattage of the fluorescent lamp in watts.

Lamp parameters and mains voltage

There are tables in which the characteristics of the most common fluorescent lamps are reflected in comparative form. For example, in the event of a voltage drop in the electrical network below the permissible limits, the restart process is significantly impaired. Conversely, if the voltage rises significantly, this can lead to overheating of the cathodes and overheating of the ballasts. In all cases, when the conditions of normal functioning are violated, the service life of fluorescent lamps is significantly reduced.

Power P (W)	Lamp voltageU(V)	Lamp currentI(A)	Light flowR(lm)	Luminous efficiencyS(lm / W)

The characteristics of all other types of fluorescent lamps are displayed in the same way. It should be remembered that for luminaires with the same marking, the parameters may differ significantly due to the difference in their overall dimensions.

Influence of external temperature and lamp cooling conditions

During operation, the temperature of the tube may change and deviate from optimal value... That is, it increases or decreases, leading to a decrease in the luminous flux. At the same time, starting conditions deteriorate, and the service life of products is noticeably reduced.

The drop in the reliability of starting conventional bulbs becomes especially noticeable when the temperature reaches - 5 0 С and below, especially if such a decrease is accompanied. For example, with a mains voltage of 180 V instead of the prescribed 220 V and a temperature of -10 degrees, the number of failures in the launch of fluorescent lamps can be from 60 to 80% of their total number. This dependence makes the use of these light sources ineffective under conditions low temperatures and power surges.

The reasons for the rise in temperature can be environment and closed fittings. In both cases, overheating occurs. In these cases, the luminous flux is also reduced, and a color change is also possible.

The electrical characteristics of lamps can change during their operation, that is, during combustion. The reason is the additional activation of the cathodes, as well as the release and absorption of various impurities. These unpleasant manifestations usually end within the first hundred hours. In the future, changes in characteristics will be very minor and almost imperceptible. During operation, the brightness of the glow gradually decreases, the luminous flux of fluorescent lamps decreases. Sometimes, after 300-400 hours of burning, the appearance of dark spots and deposits on the ends of the tube becomes noticeable on the bulbs. This indicates a possible sputtering of the cathodes and poor quality the lamps themselves.

Other types of fluorescent lamps

Nowadays, it is being practiced more and more wide application energy efficient fluorescent lamps (ELL). They are used in general lighting and can be completely interchangeable with conventional products, with a capacity of 20, 40 and 65 watts. ELL are suitable for all existing lighting installations. Thus, all luminaires and control gear remain in place. All the main characteristics of ELLs remain the same as those of standard lamps when the power is reduced to 10%. Appearance also different since the tubes are 26 mm in diameter instead of the standard 38 mm. This reduces the consumption of glass, phosphor, mercury, gases and other materials.

Along with the standard products, there was a large number of all kinds of compact fluorescent lamps (CFLs). Their power is on average 5-25 W, the luminous efficiency is 30-60 lm / W, and the service life reaches 10 thousand hours. Certain types of CFLs can directly replace incandescent bulbs in a conventional socket. Their design includes built-in ballasts and standard threaded ones.

The emergence of compact light bulbs became possible when narrow-band phosphors with high stability appeared. To activate them, rare earth elements are used with the ability to operate at a surface irradiation density exceeding this value for conventional bulbs. This made it possible to significantly reduce the diameter of the discharge tube. The total length was reduced by dividing the tubes into separate short sections located in parallel and connected to each other. Others use curved tubing or welded fittings.

It should be noted electrodeless compact lamps, in which the glow of phosphors is excited by a discharge in a mixture of mercury vapor with inert gases... The required charge is maintained by the energy of the electromagnetic field created directly near the discharge mixture. Such lamps were created due to microelectronics, on the basis of which inexpensive and small-sized energy sources were created. high frequency with good efficiency.