Small-sized household lamps with fluorescent lamps. Features of operation and repair. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Lighting

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General information about household luminaires with fluorescent lamps and their components

In the early 80s, various compact fluorescent lamps (CFL, in the English version CFL - Compact Fluorescent Lamps) appeared with a power of 5 to 25 W with a luminous efficacy of 30 to 60 Lm / W and a service life of 3 to 10 thousand hours. For these characteristics, they are called "energy-saving lamps", or ESL. According to manufacturers, energy savings when using ESL can reach 80%. This is partly due to the fact that ESLs emit significantly less heat than incandescent lamps, in which most of the energy is spent on constantly heating the coil. This property of ESL makes it possible to increase the reliability and fire safety of the luminaires in which they are used. Currently, they are widely used for lighting office and residential areas.

Some well-known companies, such as Philips, General Electric, Osram and others, produce special lamps with increased durability and light output, capable of operating in a wide temperature range, including at negative temperatures, and comply with European safety and radio interference standards.

The main disadvantage of ESL is the high cost compared to traditional incandescent lamps. However, the expectations of the average consumer are not always justified. Most often this is due to the fact that the market presents products of different quality, which do not always correspond to advertising and even to the characteristics indicated on the packaging. In particular, these are table and wall lamps produced in the countries of Southeast Asia. Therefore, information about the real experience of using ESL is of interest, which will allow you to make the right choice when buying them, avoiding unnecessary costs and avoiding mistakes, which are often the result of ignorance of the features and factors that affect their service life.

It is important to know that CFLs are vacuum devices that contain substances inside the flask that are harmful to the environment and human health, in particular, mercury vapor, which requires careful handling, especially during installation, attempts to repair and disposal. Readers who do not have experience in operating ESLs may be interested in issues related to the choice of high-quality products, and experienced craftsmen will be interested in the issues of reuse of failed ESLs, that is, the features of their repair. Let us dwell on the malfunctions of the ballast, which is often called electronic ballast (EB). Detailed information about the device, principle of operation and varieties of CFL and ESL is given in [1-7].

On the basis of CFLs, ESLs were created with an EB built into the base, which allows them to be powered from a standard AC mains (these standards differ in different countries of the world). Such ESLs are widely used due to the fact that they can be installed in fixtures of any configuration that have standard cartridges, replacing conventional incandescent lamps with them. For this, ESLs of various capacities are produced with several standard types of threaded base (E27, E14). Another type of ESL is table and wall lamps, in which the EB is located in the body of the lamp itself. It is advisable to repair just such lamps. They use CFLs with pin contacts. CFLs are produced operating at various nominal AC voltages with a frequency of 30 to 80 kHz. The diet recommended by manufacturers, according to them, is the most favorable and economical, increases light output and efficiency. It is important to know that these recommendations indicate different optimal modes that must be maintained at the time of starting and operating the lamp.

Compliance with these requirements increases the efficiency and service life of the ESL as a whole. It is these conditions that the electronic ballast should provide. It must have high durability and meet the following requirements: reduce overloads that occur during start-up and shutdown, stabilize the lamp operation mode when non-standard processes occur in the power grid, reduce the level of radio interference that can penetrate into the power grid from the side of the EB generator during start-up and operation. The durability of the ESL is determined not only by the quality of the assembly as a whole, but also by external factors - climatic and energy operating conditions, excessive mechanical loads, shock and vibration.

The durability of the ESL is affected by the intensity of switching on and off, as well as sudden surges in the supply voltage in the mains, although some ESLs can also work when the voltage in the mains drops to 180 V. At the same time, a properly designed EB completely eliminates the flickering of the light flux. Practice has shown that in most cases ESL fail during transients, sudden voltage and current surges that occur mainly when the ESL is turned on and off, as well as in the power grid itself during non-standard processes.

Currently, switches for lamps with smooth brightness control have appeared on the market and in everyday life. Most often these are conventional thyristor power controllers. The use of ESL with these devices is highly undesirable. This partly applies to illuminated switches. Ordinary ESLs cannot be used in outdoor luminaires and fully enclosed luminaires with a high degree of IP protection, as well as in rooms with high humidity and dustiness, although ESLs have already been developed and are being produced that can operate even at low temperatures.

The EB of modern ESL is an electronic device based on active and passive electronic components. EB can be produced in the form of an assembly filled with a compound. In this case, they cannot be repaired. Another EB option is on a printed circuit board with components installed on it. Special microcircuits, developed and produced by well-known manufacturers, not only reduce the number of external elements, but also improve the parameters and quality of the ESL as a whole. At the same time, their durability increases and among faulty ESL they are less common. For example, MICRO LINEAR has developed a series of special microcircuits ML4830-ML4835, and INTERNATIONAL RECTIFIER - microcircuits IR51HD420, IR53YD420, IR2157, IR2520D and others.

Using modern special microcircuits together with high-voltage field-effect transistors (FETs), it is possible to create reliable EBs without any transformers, which simplifies their design and, accordingly, mass production. More than 10 years ago, domestic special microcircuits 1182GG1, GG2, GG3 were developed, on which it is possible to build an EB with a current transformer, but without additional transistors. Despite this, at present, there are practically no products of domestic manufacturers. The market is filled with fixtures and lamps made in China and Southeast Asia.

It should be noted that the opinion widely spread among poorly informed consumers that all these products are of poor quality is erroneous. The production of high-quality ESL at the end of the last century was established by well-known companies GENERAL ELECTRIC, PHILIPS, OSRAM, SYLVANIA and others, which currently have their branches around the world, including in Asia. The quality of these products is much higher than those produced in the same countries without any trademark by little-known firms and one-day firms.

In addition, the products of some Asian manufacturers, and among them there are many Chinese firms, have also proven themselves well in various countries, including Russia. They received both international and Russian quality certificates, which should be the first thing to pay attention to when choosing. ESL production has been established by Bulgaria, Poland, Hungary, Ukraine and other European countries. Good quality products are made in Europe with the participation of such well-known companies as TESLA and TUNGSRAM. But it is rarely found on the Russian market.

Schematics of electronic ballasts

Let's consider the design and operation of an EB made on an "open" printed circuit board (Fig. 1). The basis of the EB is a voltage converter - a generator operating at frequencies of 30 ... 80 kHz that are optimal for powering the lamp. The blocking oscillator circuit with transformer positive feedback, operating in a self-oscillating mode, has become most widespread. Its main active elements, as a rule, are two bipolar high-voltage transistors VT1, VT2, which act as keys connected in series to one of the arms of the so-called half-bridge. The other arm is formed by series-connected oxide capacitors C3 and C4. Load EL1 through the starting circuit is included in the diagonal of the half-bridge between the specified capacitors and transistors. There are other types of EB circuits in which the load is connected asymmetrically. In these cases, the role of a smoothing filter can be performed by one oxide capacitor installed in parallel or instead of C2, with a capacity of at least 4,7 μF and an operating voltage of at least 350 V, and half-bridge capacitors C3, C4 may be non-oxide capacitors with a capacity of less than 1 μF and an operating voltage at least 250 V.

In the event of failure of any of these capacitors, it is better to use capacitors with the same or larger capacity, but designed for a higher operating voltage, as it is possible that non-standard short-term processes occur in your electrical network, which caused such a malfunction. For replacement, an appropriate capacitor should be selected with an operating temperature of 105 °C. When starting in the diagonal of the bridge, an alternating voltage is created on the load with a frequency determined by the elements of the generator. An important element of the circuit is the current transformer T1. It is with its help that positive feedback is created. To do this, its base windings must be connected in antiphase, as shown in fig. 1, which must be taken into account when repairing the electronic unit. Modern special microcircuits (controllers) allow you to create generators that operate without a current transformer. To create a high voltage in the start mode of the lamp EL1, a starting circuit is used - the starting inductor L2, capacitor C5 and posistor RT1.

In some EBs, a posistor may be absent. In some cases, this is due to the improvement of the EB circuit by introducing additional circuits into it that perform the same functions as the posistor. In particular, these are EBs in which controller microcircuits are used. In other cases, on the contrary, this is caused by the desire of manufacturers to reduce their costs in any way, even to the detriment of product quality. In this case, the so-called "hard start" occurs, which reduces the life of the ESL. The fact is that for forced heating of the filaments of the EL1 lamp, a start delay of 2-3 seconds is necessary. During this period of time, a heating current flows through its filaments. The starting circuit enters into resonance with the frequency of the generator, and a cold posistor prevents this. Its temperature begins to rise, increasing its resistance until it no longer shunts the circuit.

When the filaments are warm enough and the starting circuit enters resonance, a voltage jump occurs, creating a discharge in the bulb of the EL1 lamp, which ensures its start. The maximum heated filaments reach a resistance much higher than the resistance of the ionized gas in the bulb, and the current begins to flow through it. shunting the starting circuit, which goes out of resonance. The EB goes into operating mode, while the voltage on the lamp decreases to the nominal voltage necessary to maintain the discharge, usually for most CFLs it does not exceed 350 V. In addition, in EBs assembled according to circuits similar to those shown in Fig. 1, the RF generator is started using a starting device (PU). It can be performed on dinistors, transistors operating in an avalanche mode, or, in the simplest case, using a triggering oxide capacitor. It should be noted that the PU on the dinistor increases the reliability of the EB, and the PU with an oxide capacitor is the least reliable, which is found in unfinished and outdated circuits, since the electrolyte service life is limited by the number of charge / discharge cycles.

Currently, modern high-voltage FETs are increasingly being used in EB. The parameters of the transistors depend on the power of the ESL and, accordingly, the generator. Of the bipolar transistors, it is recommended to use transistors of the 1 (TO-9) series for 13001 ... 92 W ESL, for 11 W - the 13002 (TO-92) series, for 15.20 W - the 13003 (TO-126) series, for 25.40 W - series 13005 (TO-220), for 40.65 W - series 13007 (TO-200). Of the PTs, high-voltage ones from the IRF series are suitable, for example, IRF840 and others similar to them in terms of characteristics, including modern domestic-made PTs. When repairing an EB, in the event of a transistor failure, it is better to choose more powerful ones for replacement, which will increase the reliability of the EB and the service life of the ESL as a whole. It should be noted that transistors with similar parameters under the same brands are produced by different manufacturers, and may differ not only in the location of the pins, but also in the internal structure, for example, the absence of built-in protective diodes in them.

In the diagram, Fig. 1, this function is performed by diodes VD5, VD6. There are EBs in which there is no place on the board for installing these diodes at all. When repairing for replacement, transistors with built-in diodes should be used in them, or additional diodes should be installed. The generator requires a low ripple DC voltage. It comes from a full-wave rectifier made on a VD1-VD4 diode assembly. Since the EB converter generator is designed for the corresponding lamp power and operates in a certain frequency range, which are classified as both ultrasonic and ultra-long radio waves, it can create radio interference, as well as sound vibrations that are often unpleasant for hearing, reminiscent of a mosquito squeak.

To reduce the level of radio interference in the EB, in addition to the smoothing filters, simple LC filters are installed, consisting of an RF inductor L1 and a non-polar capacitor C1 with a capacity of up to 0,5 μF. Resistor R1 serves to protect the ESL from overloads at the time of start-up and shutdown, as well as during non-standard processes in the network. Resistors R3, R4 in the base or emitter circuits of transistors VT1, VT2 protect them from current overloads and make the generator's operation mode softer, and the shape of its oscillations more symmetrical. It is they who, in the event of a malfunction of the EB, most often completely or partially fail. Moreover, in some cases in such a way that it is impossible to determine their initial face value by marking. Usually it does not exceed several tens of ohms.

Rice. 1. Typical scheme of electronic ballast on bipolar transistors

Fuse FU1, usually with a rating of about 1 A, increases the electrical and fire safety of the entire device. Unpleasant sound vibrations, the sources of which are often some inductive elements of the EB, can be eliminated during the repair process by treating the transformer or chokes with some kind of varnish or, in extreme cases, with synthetic glue.

As an example, in fig. 2 and 3 show schematic diagrams of ESL produced in the countries of Southeast Asia. Such schemes are most often found among failed ESL. Comparing these schemes even with the simplified typical one shown in Fig. 1, it is easy to understand that there are many flaws in these options. In particular, in the one shown in Fig. 2 "Studying table lamp" made in China uses a CFL with pin terminals, and the EB and switch are at the base of the lamp. The EB is assembled on an "open" board and it would seem that such a device is maintainable. In practice, its repair caused big problems. It is easy to see that there are no protective diodes in this lamp. In all likelihood, they were built into failed transistors. When they tried to replace these transistors with analogues without protective diodes, they quickly failed. The circuit also lacks elements that ensure the normal mode of warming up and starting the lamp, and the filter capacitors C1 and C2 are installed with the lowest possible capacitance, which also reduces the quality of the product as a whole.

In the diagram in fig. 2. there is no fuse and resistor R1 (see Fig. 1), which reduces overloads, as well as any filter that reduces high-frequency interference (C1, L1 in Fig. 1). Since the appearance of the luminaire design and the quality of its execution were satisfactory, and several unsuccessful attempts to repair the EB, as before, ended in its rapid failure, it was decided to manufacture another EB, designed according to a more advanced scheme. On fig. 3 shows a schematic diagram of the ESL on the IR2520D chip, recommended by its manufacturers. A detailed description of such an EB and a microcircuit can be found in the literature. Another, more advanced EB scheme is shown in Fig. 4. It also has flaws and some of the important elements mentioned above are missing from it. Although the advantage of this EB over the previous one is that it has a soft start circuit with a symmetrical VD9 dinistor. EBs assembled according to this and similar schemes are also often found among those that failed not only in table and wall lamps, but also in ESL, in which the EB is built into the base.

Rice. 2. Scheme of the EB table lamp STUDYING TABLE Lamp (China)

Rice. 3. Electric circuit of the EB with the IR2520D chip

Rice. 4. EB circuit with a dinistor starter

Conclusions on the feasibility of repairing ESL and the problems of their disposal

Studying the experience of some specialists and amateurs of electronics, described in [1-7], and other sources of information, we can come to the following conclusions. Despite claims that repairing ESL is in principle inexpedient for economic reasons, exceptions can be made. For example, if it is known for sure that the failed ESL was purchased recently, and its main element, the CFL, is in good condition (for example, there are no signs of strong mechanical stress, scratches visible on the bulb, dark spots near the filaments, etc.), but rather faulty everything, EB. Especially if it is not possible to replace the lamp through the distribution network. This applies to table and wall lamps, in which the EB is made on an open circuit board and is located at the base of the lamp. This allows you to quickly draw the right conclusion about its quality and, knowing the circuitry of the EB, understand how it meets modern requirements. If the EB is assembled according to an outdated scheme, repair is advisable only with the completion of the EB or its replacement with a more advanced one.

If it is necessary to completely replace the EB by its own production, then it is unprofitable for professional specialists to perform such work. Only home craftsmen and electronics enthusiasts with the necessary experience can do this.

In Russia, as, indeed, in many other countries, the issues of ESL disposal have not been resolved. Given the rapid mass distribution of CFLs, this may pose a serious problem in the near future. It should also be taken into account that already at the present time trading enterprises have accumulated a certain amount of defective and low-quality products of this type, with which they need to do something. Part of it refused to work at the first check before the sale. Even more often, failures occur in the very first days of operation, when buyers still have purchase documents, and they, outraged by this fact, return it, protecting their rights. Naturally, its number will grow rapidly in the future. In order for society to change its attitude towards the problem of recycling, additional measures are likely to be required.

Considering the relatively high cost of ESL, initially it could be, for example, the organization of collection points for their disposal, which would give the consumer confirmation that he has returned a faulty ESL and can receive a discount when buying a new one. Of course, this is not the only proposal, but representatives of large ESL manufacturers, suppliers, trade and authorities should develop a unified policy on this issue, which will save money that would otherwise have to be spent on improving the environment. It will be useful if repairmen also participate in solving these problems.

Literature

1. Shirokov V. Compact electronic fluorescent lamps: choose, apply, repair. "Radiohobby", No. 3, 2001, p. 48-52.
2. Dyakonov V., Remnev A., Smerdov V. Electronic ballasts. "Repair and Service", No. 9, 2001, p. 29-38.
3. Samelyuk V. Power supply for low-power fluorescent lamps. "Electrician", No. 5, 2002, p. 9-10.
4. Kavyev A. Power sources for fluorescent lamps. "Radio", No. 4, 2007, p. 41-45.
5. Kashkarov A. Energy-saving lamps: repair tricks. "Radiomir", No. 10, 2009, p. 45.
6. Kashkarov A. The energy-saving lamp is flashing! "Radiomir", No. 3, 2010, p.34.
7. Andreev S. Return of the incandescent lamp. "Radioconstructor", No. 12, 2010, p. 26.

Author: V. Efremov

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