Diagram of a fluorescent lamp with electronic ballast. About power supply systems for fluorescent lamps. Using an electromagnetic throttle and starter

Fluorescent lamps at one time made a real revolution in lighting, since their light output is several times greater than that of conventional incandescent lamps. For example, one fluorescent lamp (this is another name for fluorescent lamps) with a power of 20 W produces a luminous flux that is only available to a 100 W incandescent lamp. If an incandescent lamp can simply be connected to a network using only a switch socket and wires, then a fluorescent lamp, like a “capricious lady,” must be created with special “comfortable conditions.” It must first be prepared for launch, then launched, and after it lights up, constantly monitor its “well-being.” This is done by ballasts (ballasts). The most modern and efficient ballast is electronic ballast (EPG), which is commonly called electronic ballast.

The word “ballast” in the name of this device may cause a certain dissonance in some readers, since one of its meanings is a useless load that has to be carried. However, ballast is not always useless, and sometimes even necessary. For example, without ballast, any ship would not have the necessary landing and stability, and airships and balloons cannot adjust their flight altitude. By the way, linguists attribute the origin of the word “ballast” to the Dutch, a nation of seafarers and shipbuilders. Therefore, we propose to perceive the concept of electronic ballast in a purely positive way, as something that is really necessary.

Conditions required for starting and burning a fluorescent lamp

Let us briefly consider the structure of the lamp and find out what processes occur in it.

Fluorescent lamps can be of various shapes, but the most common are linear, which have the form of an elongated sealed cylinder made of thin glass. The air from inside is pumped out, but inert gases and mercury vapor are pumped in. The mixture of gases in the lamp is under reduced pressure (approximately 400 Pa).

At one and the other end of the lamp there is an electrode (cathode) of a complex design. Each cathode has two pin connectors on the outside, and a tungsten spiral with a special emissive coating is placed between them inside. If a voltage of 220 V is applied to the opposite cathodes, then nothing will happen in the lamp, since the rarefied gas simply does not conduct electric current. It is known that for electric current to flow, two conditions are necessary:

• The presence of free charged particles (electrons and ions).
• Presence of an electric field.

When we apply an alternating voltage of 220 V to the cathodes, then everything will be fine with the electric field in the flask, since it exists in any environment, even in a vacuum. But the main “difficulty” is the presence of free charged particles. The gas in the flask is neutral and does not react in any way to changes in the field. There are two ways to obtain a glow gas discharge:

• The first method is that a very high voltage is immediately applied to the cathodes of the lamp, which forcibly “pulls out” electrons from the cathodes and “breaks through” the gas in the lamp, which causes its ionization and the appearance of a discharge. This type of start is called “cold”, it allows the lamps to start very quickly. Moreover, this method can make those lamps glow that no longer work in standard lamps due to burnt-out cathode spirals (one or even two).
• The second method involves smoothly heating the coils, which causes electron emission (the appearance of free charges), and then raising the voltage at the cathodes to a threshold until a discharge occurs in the lamp. Free electrons are accelerated and ionize the gas inside the lamp bulb.

The second method of lighting lamps is preferable, since this increases their service life significantly. The quick cold start method is very popular among radio amateurs who make, in their words, “devices that revive dead lamps.” This, of course, is a very interesting experimental field for those who like to sit with a soldering iron, but from the point of view of economic feasibility, such an activity may seem very strange to an ordinary person when the price of a new lamp is a maximum of 100 rubles and a service life of 12,000 hours. Isn’t it better to ensure a smooth start and long service life for a new lamp, instead of “resurrecting” those that require disposal? If a cold start is applied to new lamps, then their cathodes from the “shock” effect of increased voltage will very quickly become unsuitable for operation in normal lamps.

After a glow discharge occurs in the lamp, its resistance will drop sharply, and if this issue is left uncontrolled, the current will increase so much that a real high-temperature plasma electric arc will ignite in the lamp, which will lead to rapid failure of the lamp, which can be and with unpleasant consequences. Therefore, after lighting the lamp, the ballasts must also limit the flowing current, keeping it such that a glow discharge occurs.

There is an article on our portal that describes in detail all the processes occurring in a fluorescent lamp both during start and during combustion. The article also describes how to properly connect lamps using electromagnetic ballast (EMB). We read: "".

Based on the foregoing, it can be noted what functions the ballast should perform:

• Smooth heating of the filaments of the lamp cathodes, initiating thermionic emission.
• Initiating the appearance of a glow discharge by increasing the voltage at the cathodes.
• After the discharge appears, the filament is turned off, the lamp current is limited and the combustion process is maintained even with an unstable mains voltage.

In principle, electromagnetic ballasts perform the same functions, but they are very sensitive to mains voltage and ambient temperature.

Electronic ballast device for fluorescent lamps

An electronic ballast (EPG) is a complex electronic device, the operation of which not everyone can understand in principle. Therefore, we will first show the block diagram, explain the purpose of all the elements, and then briefly consider the principle one.

The electronic ballast must be present at the input EMI filter whose task is to suppress electromagnetic interference that is generated in the electronic ballast. If there is no filter, the interference may disrupt the operation of nearby electronic devices. In addition, high-frequency interference can “leak” into the power grid from electronic ballasts. Some manufacturers from the country with the largest population do not solder elements related to the filter on the printed circuit board, although places are provided for them. Such “scam” is difficult to notice, since the electronic ballast will work. Only an “opening” and inspection by a specialist will help you find out whether there is a filter in the electronic ballast or not? Therefore, it is worth choosing electronic ballasts only from well-known manufacturers.

After the noise filter comes rectifier , assembled using a conventional diode bridge circuit. To power the lamp, a mains frequency of 50 Hz does not suit us, as it causes the lamp to flicker and the noise of the chokes to be clearly audible. To prevent these unpleasant things from happening, a high frequency voltage of 35-40 kHz is generated in the electronic ballasts. But in order to be able to obtain it, it is necessary to have “raw materials” in the form of constant voltage. It makes it easier to make various transformations.

Power factor correction circuit needed in order to reduce the influence of reactive power. Electronic ballasts have an inductive load, therefore, the current lags behind the voltage by a certain angle φ. Power factor is nothing more than cosφ. If there is no phase lag, then the load is active, the current and voltage are completely in phase and therefore φ = 0°. This means cosφ=1. Power is calculated by the formula P=I*U* cosφ (I is the current in Amperes, and U is the voltage in Volts). The greater the current phase lag, the lower the power factor cosφ will be and the less useful active power will be and the more reactive power, which is useless, will be. In order to correct the current lag, the correction circuit uses capacitors whose capacitance is precisely calculated. As a result, cosφ can reach a value of 0.95 in good electronic ballasts. That's quite a lot!

One of the best explanations of reactive power (Q is exactly that)

DC filter designed to smooth out ripples that are invariably present after rectification with a diode bridge. The result is a constant voltage of 260-270 V, which is not entirely ideal, since small ripples are still present, but absolutely sufficient for further conversion. A DC filter is most often a large-capacity electrolytic capacitor that is connected in parallel. Graphs of voltage versus time are shown in the figure.

Next, constant voltage is supplied to the most complex part of the electronic ballast - inverter . It is here that the direct voltage is converted into high-frequency alternating voltage. Most electronic ballasts are assembled using a half-bridge circuit, a generalized view of which is shown in the following figure.

Between the input terminals from the rectifier and the filter, a constant voltage of approximately 300 V is supplied to the inverter. The diagram shows the lower terminal of 300 V. One of the main elements are the keys K1 and K2, which are controlled from the logical control unit CU. When one key is closed, the other is open; they cannot be in the same state. For example, the control unit sent a command to close K1 and open K2. Then the current will flow along the following path: the upper input terminal, Key K1, inductor, filament of one lamp cathode, capacitor (parallel to the lamp), protection unit, capacitor C2 and negative lower terminal. Then key K2 closes, and K1 opens and the current flows along the following path (from plus to minus): upper terminal, capacitor C1, protection unit, spiral of one cathode of the lamp, capacitor (parallel to the lamp), spiral of the other cathode of the lamp, inductor, key K2 and bottom terminal. Key switching occurs at a frequency of approximately 40 kHz, that is, 40,000 times per second.

Electric current flowing along such trajectories causes heating of the lamp coils and thermionic emission at the cathodes. The capacitance of the capacitor connected in parallel with the lamp is selected such that the frequency of the oscillatory circuit formed together with the inductor coincides with the switching frequency of the keys. This causes resonance and an increased voltage appears at the cathodes of the lamp - about 600 V, which at this frequency is quite enough for the lamp to light up. After this has happened, the resistance of the lamp decreases sharply and current no longer flows through the capacitor and cathode spirals. The lamp bypasses the capacitor. The keys continue to work, but a lower voltage is already supplied to the lamp, since there is no resonance. The choke limits the current in the lamp, and the protection unit monitors all parameters. If there is no lamp in the lamp or it turns out to be faulty, the protection unit will stop the generation of alternating voltage by switches K1 and K2, since the inverters fail without load.

Feedback And brightness control not found in all electronic ballasts, but only in the best ones. The purpose of feedback is to monitor the state of the load and respond to it. For example, an attempt was made to start the electronic ballast without a lamp. This causes switching power supplies to fail, but if there is feedback, the inverter simply will not receive a start command. Feedback also allows you to change the generation frequency of the inverter. When the lamp starts, it can be 50 kHz, and after that it drops to 38-40 kHz.

All electronic ballasts operate approximately according to this algorithm. High-voltage bipolar transistors are used as switches. The best inverters use field-effect transistors, also called MOSFETs. They have better characteristics, but their price is significantly higher. Let's imagine a typical circuit diagram of a simple electronic ballast.

We will not analyze in detail the operation of this scheme, realizing that most readers will not understand. Let's just draw an analogy with the previous diagram. The role of switches K1 and K2 is performed by transistors T1 and T2. The switching frequency is determined by symmetrical dinistor DB3, capacitor C2 and resistor R1. When a voltage of 220 V is applied to the input of the device, after rectification it begins to charge capacitor C2. The charging rate is determined by resistor R1; the greater its resistance, the longer it will take to charge the capacitor. As soon as the voltage on the capacitor exceeds the opening threshold of the dinistor (approximately 30 V), it opens and supplies a pulse to the base of transistor T2. It opens and current begins to flow through it. As soon as capacitor C2 is discharged and the voltage across it drops below 30 V, the dinistor will close, and so will transistor T2, but transistor T1 will open, since its base is connected to the transformer TU38Q2, which coordinates the synchronous operation of the switches and the load. If one transistor is open, the other will be closed. As soon as the transistor closes, the self-inductive emf that appears in the winding of another transistor opens it. This is how self-generation of alternating voltage occurs in the inverter.

In addition to MOSFET transistors, the best modern models of electronic ballasts also use integrated circuits (ICs), which are specifically designed to control lamps. Their use reduces the dimensions of the device and greatly increases its functionality. Let's give an example of an electronic ballast circuit with an IC.

The main part of this electronic ballast is the UBA2021 integrated circuit, which is “responsible” for absolutely all processes occurring in the lamp and electronic ballast. Lamps that will work with such electronic ballasts with such an IC will last a very long time.

Video: Electronic ballast

Advantages and disadvantages of electronic ballast

Currently, the production volume of electronic ballasts has already exceeded the production of electromagnetic ballasts. And the further trend is clearly indicated - electronic devices will replace electromagnetic ones. It is already almost impossible to find luminaires with classic chokes and starters on sale, and during repairs they often give preference to electronic ballasts. Let's figure out what their advantages are?

• The lamp with electronic ballasts is started according to a correct and gentle algorithm, but nevertheless very quickly - no more than 1 second.
• The frequency generated by electronic ballasts is 38-50 kHz, so fluorescent lamps do not have flicker, which tires the eyes, and there is also no stroboscopic effect characteristic of electromagnetic ballasts.
• The service life of lamps operating with electronic ballasts is doubled.
• When a fluorescent lamp burns out, a high-quality electronic ballast immediately stops generating alternating voltage, which affects economy and safety.
• The use of electronic ballasts eliminates the cold start of fluorescent lamps, and this prevents erosion of the cathodes.
• Electronic ballasts operate absolutely silently, so only electronic ballasts should be used in residential areas, hospitals and school classrooms.
• It is very easy to connect electronic ballasts, since they always have a very clear diagram that even those who have never done anything electrical in their life can understand.
• Electronic ballasts do not heat up as much during operation as electromagnetic ballasts. This saves energy. Savings are approximately 30%.
• The power factor (cosφ) of good electronic ballasts can reach 0.98. For this type of load, this is a very good indicator.
• High-quality electronic ballasts can operate at reduced or increased network voltage (160-260 V).
• Electronic ballasts have higher efficiency than electromagnetic ones. It can reach 95%.
• Electronic ballasts do not require starters or capacitors to operate; everything necessary for starting and operating the lamps is already provided in the circuit.
• Compared to electronic ballasts, electronic ballasts have comparable dimensions, but much less weight.

With such an impressive list of advantages, we can only talk about two disadvantages. This is a higher price and a greater probability of failure than with electric ballasts due to power surges in the network. True, the last drawback applies only to those electronic ballasts that are low in both quality and price.

How to choose a quality electronic ballast

Electronic ballasts are used to being perceived as separate blocks - rectangular boxes on which there are terminals or connectors for connecting lamps and mains voltage. but do not forget that there are electronic ballasts in every compact fluorescent lamp (CFL) or, as they like to call them, energy-saving lamps. Lamp designers manage to place the entire electronic ballast circuit on a round circuit board, which is somehow “stuffed” into the housing between the luminous part and the base. Of course, in such cramped conditions these ballasts have a hard time. The problem of heat removal from the electronic ballast board is very serious, which each manufacturer solves differently. More precisely, we can say that while some decide, others do not decide at all.

Naturally, no one will be able to check what is in the lamp body before purchasing, but the type of board itself and the presence of certain elements on it can tell a specialist a lot. Some manufacturers, taking advantage of the secrecy of electronic ballasts in CFLs, want to save on some elements, which affects the operation of the lamp and its service life. It turns out that buying a CFL is essentially identical to buying a “pig in a poke”? Unfortunately, this is true in most cases. Well-known world brands, of course, “sin” less with this, but there are many fakes, so it’s worth finding a seller who receives official supplies from the manufacturer.

There is a way to judge the quality of electronic ballasts in CFLs. It is not objective, but subjective; nevertheless, it has been used for a long time and has already proven its worth. What is it?

In good CFLs, the lamp starts up smoothly; an increased voltage is supplied to the cathodes to ignite the glow discharge only after warming up. These processes take some time, so when you turn on a good lamp, there is always a pause between turning it on and igniting it. It's small, but noticeable. If the lamp lights up cold, then high voltage is applied immediately and this causes instant breakdown and ignition. If the pause after switching on is not felt, then with a high degree of probability we can say that the electronic ballast is “simplified” and it is better not to purchase such a lamp. Some manufacturers “improve” the electronic ballast circuit, “throwing out” from their point of view “extra” parts.

When purchasing an electronic ballast in the form of a separate unit, first of all you need to find out which lamps it is intended for. All linear fluorescent lamps are available with different tube diameters: T4 - 12.7 mm, T5 - 15.9 mm and T8 - 25.4 mm. T4 and T5 lamps have a G5 base (5mm pin spacing) and T8 lamps have a G13 base (13mm pin spacing). Its power depends on the size of the fluorescent lamp: the longer it is, the greater the power:

• A lamp with a length of 450 mm corresponds to a power of 15 W;
• A lamp 600 mm long, which is widely used in Armstrong-type suspended ceilings, corresponds to a power of 18-20 W;
• Lamp 900 mm long – 30 W
• Lamp 1200 mm long – 36 W;
• And a lamp with a length of 1500 mm corresponds to a power of 58 W or 70 W.

It is very easy to find out whether an electronic ballast corresponds to a luminaire intended for a certain type of lamp, since all the necessary information is already included in the electronic ballast labeling. Let's look at a specific example and find out what these or those numbers and symbols mean. In general, the marking of an electronic ballast sample looks like this.

Let’s “decipher” the general information about the device, which is located on the left side of the electronic ballast.

This electronic ballast model is manufactured by the Vossloh-Schwabe Group, whose headquarters are in Germany. However, the Vossloh-Schwabe Group is part of the Japanese Panasonic Electric Works group. The products of this manufacturer are distinguished by their impeccable quality and reliability. And also from the markings it is clear that this electronic ballast is designed to work with T8 lamps, produced in Serbia, where the Vossloh-Schwabe Group has a branch. Let's also consider what is important in labeling.

The mains voltage input 220 V 50 Hz is indicated on the housing so you can understand where the terminals are located. The polarity is not indicated, which means that phase and zero can be connected to this electronic ballast arbitrarily. The ground wire must be connected to the housing; for this there must be a special screw on it. We move closer to the center of the electronic ballast and look at the symbols.

It’s nice that on the body of this electronic ballast there is information about the wire that can be used for switching, its cross-sectional area and how long to remove the insulation so that it fits well in the terminals.

The EEI energy efficiency index is an assessment of how much input power is used to receive light from the lamp. The efficiency index is calculated, which is determined by the ratio of the lamp power to the input power Pl/Pin, and then according to Table 6.3, located on page 61 in the document, the link to which is below, the compliance of the electronic ballast with the energy efficiency index is determined.

In Europe, there is a certain set of rules and regulations that all devices and materials used must comply with. Just as in Russia there are SNiPs, PUEs, and SanPin, so “over the hill” our neighbors have rules that are designated by the letters EN and a digital code. It is not without reason that this list is included in the labeling, since when any facility is put into operation, documentary evidence of the justification for the use of a particular device is required.

The main characteristics of this electronic ballast are printed directly on the body in the form of a table:

All information presented in the table is as accurate and concise as possible, requiring no explanation except the position of the tc point, where the maximum temperature in this electronic ballast should not exceed 60°C. This point is marked on the ballast body (to the right of the top of the table); it is located exactly at the location of the transistor switches - the hottest parts of the electronic ballast.

If you don’t have an electronic ballast at your disposal, but have a lamp with a known type of lamp used in it, then you can select electronic ballasts from manufacturers’ catalogs, which are easy to find on the Internet. Here is an excerpt from the catalog of electromagnetic chokes from the Helvar company from Finland, whose products are high-quality and reliable. For example, let's take electronic ballasts for T8 lamps from the EL-ngn series. These electronic ballasts are characterized by: energy efficiency, “warm” start of fluorescent lamps, no flicker, good electromagnetic compatibility, low interference, minimal losses and stable operating modes.

Electronic ballasts for T8 fluorescent lamps Helvar EL-ngn
Pl*Number of lamps	Ballast model	EEI	Dimensions, L*W*H, mm	Weight, g	Power Circuits, W	Circuit current, A	P per lamp, W	Price, rub
14*1	EL1x15ngn	A2	190*30*21	120	15	0,09-0,07	13	415
15*1	EL1x15ngn	A2	190*30*21	120	15.5	0,09-0,07	13.5	415
18*1	EL1x18ngn	A2	280*30*28	190	19	0,09-0,08	16	594
18*2	EL2x18ngn	A2 BAT	280*30*28	200	37	0,16-0,15	16	626
18*4	EL4x18ngn	A2 BAT	280*30*28	200	72	0,33-0,30	16	680
30*1	EL2x30ngn	A2 BAT	190*30*21	120	26.5	0,14-0,11	24	626
36*1	EL1*36ngn	A2	280*30*28	191	36	0,16-0,15	32	594
36*2	EL2x36ngn	A2 BAT	280*30*28	205	71	0,32-0,29	32	626
58*1	EL1x58ngn	A2	280*30*28	193	55	0,26-0,23	50	594
58*2	EL2x58ngn	A2 BAT	280*30*28	218	108	0,50-0,45	50	626

In addition to what is shown in the table, electronic ballasts of the Helvar EL-ngn series still have characteristics common to all. We list them in the following table.

Characteristic	Index
Maximum temperature of the “tc” point, °С	75
Maximum ambient temperature, °C	-20…+50
Storage temperature, °C	-40…+80
Maximum permissible humidity	No condensation
Minimum number of lamp starts	>50 000
AC voltage, V	198-264
Constant voltage (for start >190 V)	176-280
Maximum overvoltage, V	320 V, 1 hour
Power factor (λ, cosφ)	0,98
Ground leakage current, mA
Maximum output voltage, V	350
Lifetime (up to 10% failure rate)	50,000 hour at tc
Maximum length of wires to the lamp	1.5v
Lamp warm-up time, sec

In addition to these ballasts, the characteristics of which we have shown in the table, Helvar’s assortment includes many more models of electronic ballasts that are designed for other types of lamps. Linear ones are T5 and T5-eco, and compact ones are: TC-L, TC-F, TC-DD, TC-SE, PL-R, TC-TE. We have made a brief overview of classic electronic ballasts for T8 lamps, but Helvar also has 1-10 V electronic ballasts controlled by an analog signal, which can change their brightness and are controlled with just one button to turn on and off, as well as to change the brightness of fluorescent lamps.

And also this manufacturer has fully digital iDIM ballasts, which can have external bus control (DALI) and manual control from just one button (Switch-Control). You can view the entire range of electronic ballasts in the Helvar catalog, which can be opened at the following link. The catalog is in English, prices are not indicated.

All good manufacturers have similar albums with all the technical information about electronic ballasts on their official websites. Readers may have a question - which electronic ballasts can be considered good? We would recommend first of all paying attention to the following brands: Helvar, Vossloh-Schwabe, Tridonic, Osram, Philips, Sylvania.

Procedure for replacing the electromagnetic throttle and starter with electronic ballast

All new lamps with fluorescent lamps are equipped with electronic ballasts by default, and if they fail, replacement is very simple: one unit is “thrown out” and another is put in its place. If there were “classics” - electromagnetic ballast and starters, then it is better to change them to electronic ballast. In this case, the lamp must undergo some simple modernization. Let's consider this process in detail.

The tools you will need are a set of screwdrivers, a knife, wire cutters, an insulation stripper (optional) and a multimeter. You may also need a PV-1 mounting wire with a cross-sectional area from 0.5 to 1.5 mm², of which there are 4 types in this range: 0.5 mm², 0.75 mm², 1 mm² and 1.5 mm². If an aluminum wire was used in the lamp, then it is better to immediately change it to copper.

It happens that they are used in lamps, but with copper plating. When stripping, the illusion of a copper wire appears, and when cut, the wire is white. It is better to get rid of such “hybrids” immediately.

Image	Process description
	The lamp will be upgraded to 4 T8 18 W lamps. It contains 2 electromagnetic chokes, 2 capacitors and 4 starters.
	Instead, OSRAM QTZ8 4X18/220-240 VS20 electronic ballasts will be installed, which does not require either starters or capacitors.
	The lamp is turned off, then the indicator screwdriver is used to check the lack of phase on the input terminal and on the housing, the input wires are disconnected, the lamp is dismantled and placed on the table for ease of working with it.
	The front panel is removed from the lamp and all fluorescent lamps are removed.
	The input screw terminal is removed from its seat and all wires are removed from it.
	Electromagnetic chokes and capacitors are dismantled.
	The starter socket is removed. This is done very simply, as it is attached to the lamp body with plastic latches.
	The wires going to the starter are cut off near it. The same operations are performed with all starters.
	The location of the electronic ballast is selected. It is better if it is on the edge of the lamp, so that all the wires leading to the ballast can be routed near the sides, so they will be less noticeable. Then, according to the connection diagram shown on the electronic ballast housing, the position of each lamp is “assigned”. Those on the left in the diagram in the lamp will be in the center, and those on the right will be on the edges.
	Each fluorescent lamp socket has terminals with two pairs of spring contacts. Each pair is connected to one of the T8 lamp pin sockets with a G13 base. This is very convenient, since in order to make a branch you do not need to solder or twist anything. The wire stripped to 9 mm is simply inserted into the terminal until it stops, where it is clamped by a spring contact.
	The wiring is carried out according to the circuit diagram shown on the electronic ballast. Tags made from pieces of masking tape are glued to those ends of the wires that will be connected to the ballast and the terminal number is written on them. This will avoid confusion.
	After the wiring is completed, the electronic ballast is placed close to that location. Where it will be installed and all numbered wires are connected to the corresponding terminals. To do this, press the contact mechanism with a screwdriver, and then the wire stripped to 9 mm is inserted into the terminal hole until it stops. The contact mechanism is released and the reliability of the wire connection is checked.
	Input terminals L, N, PE (phase, neutral, ground) are connected by wires to the input screw terminal of the lamp.
	Once all the wires are connected to the electronic ballast, it is installed in place and secured with screws to the housing, which has special holes. If necessary, a hole can be drilled.
	The wires laid in the lamp are grouped and placed as close to the edge as possible. The lamp body may have stamped antennae. If necessary, you can use plastic ties to organize the wires.
	After checking all connections, the lamp is given a test run on the table and, if successful, it is mounted in its regular place.

Readers have probably noticed that installing electronic ballast is a simple undertaking that does not require the participation of a highly qualified electrician. We can say that anyone can handle this. In order not to make mistakes when connecting, we suggest drawing a diagram by hand, and then after connecting some contacts in the lamp, mark this in your drawing. Tested - it helps.

All modern lamps are equipped in such a way that they do not require a soldering iron for installation, and there is no need to make twists. All connections must be made at terminals only. If the wire left over from the old connection diagram is not enough, then under no circumstances should you twist or solder it. It is better to replace this section with a solid wire. 1 meter of excellent installation wire PV-1 with a 1 mm² core costs 7 rubles. Connecting to the terminal takes a few seconds, but soldering already takes tens of minutes.

Video: Replacing two electromagnetic ballasts with one electronic one

Repair of faulty electronic ballast

Electronic ballast is a wonderful device that treats the fluorescent lamp very carefully, but, unfortunately, sometimes cannot protect itself. In this regard, electromagnetic ballast is much more reliable; you have to try very hard to “burn” it. Diagnosing a faulty electronic ballast is quite difficult for a person unfamiliar with electronics, but nevertheless we will give some advice.

If nothing happens when you turn on a lamp with an electronic ballast, then you should try changing the lamp, maybe that’s the problem. To do this, you need to have a known working lamp, which you need to insert into the lamp sockets and try to start it. If nothing happens again, then you need to switch your attention to the electronic ballasts, since besides it and the lamps there is nothing in the lamp. If you don’t have a working lamp at hand, you can check the integrity of the spirals in the dialing mode. If they are intact and the lamp bulb is intact, then most likely it is in good condition, unless there is a strong blackening of the phosphor layer near the cathodes.

Electronics is the science of contacts. That's what the experts say. And before “climbing” into the complex ballast device, you need to ring all the electrical connections in the lamp, which, of course, must be disconnected from the network. It is also useful to ring the connections with the lamp inserted. To make sure that the pins of its base come into contact with the socket. If these actions did not reveal anything “criminal,” then it’s time to look at the “inner world” of the electronic ballast.

The electronic ballast must be removed from the housing by first disconnecting the connectors or removing the wires from the terminals. If the wires are not marked, then before disconnecting them, they must be marked in some way. The easiest way is to stick strips of masking tape with the terminal number on the wire. After this, the ballast can be removed from the luminaire body.

An external inspection of electronic ballasts can also tell a lot. If there was a strong thermal effect, it will definitely leave marks. You can note exactly where there was strong heating, so that later you can see what elements of the circuit could provoke it.

After opening the ballast housing, you need to carefully inspect the board. It happens that you don’t even need to inspect anything, since most of the elements are black, with obvious signs of overheating. Repairing such electronic ballasts will not be economically feasible, so after desoldering the entire elements (if any), the board can be thrown away.

The weak point of any electronic device is electrolytic capacitors, which are easily recognized by their “barrel-shaped” appearance. If their ratings are not observed, if their quality is poor, if the voltage is exceeded, or if they overheat, they may swell and even rupture, which occurs due to boiling of the electrolyte. Such signs clearly indicate a malfunction, so the capacitor is soldered off and all adjacent elements are checked. A new capacitor should be chosen with a higher operating voltage, for example, it was 250 V, but a new one should be installed at 400 V. Very often, dishonest manufacturers solder elements with a lower operating voltage into the electronic ballast board, which eventually leads to breakdown.

After the capacitors, you need to carefully examine all other elements, which can also show their malfunction by their appearance. Usually burnt resistors “speak” about themselves very clearly - they darken, become black as coal, and sometimes they simply break. Naturally, such parts also need to be changed, but it is better to choose a level of power dissipation that is a step or even two more than the rated one.

Resistors can be dialed directly in the circuit without desoldering them, since their main malfunction is burnout, which is equivalent to a break. Before checking, it is better to remove other elements - capacitors, diodes and transistors - from the circuit, and then use a special universal device for testing.

Burnt or “broken” diodes can also very often be easily seen by their characteristic darkening if they are in a plastic case. Diodes in a glass case often break into two parts or the bulb cracks. It is very easy to ring diodes. After desoldering from the printed circuit board (only one “leg” is possible), take a multimeter and set it to measure resistance or to a special mode indicated by a diode (if there is one). In the forward direction, the diode must conduct electric current well. To check this, the red probe of the multimeter is connected to the anode, and the black probe to the cathode (on diodes in a plastic case there is a strip near the cathode). If the multimeter shows some resistance values, then current is flowing. By swapping the probes, you need to make sure that the diode does not pass electric current in the opposite direction, its resistance is infinite. If so, then the diode is good. In all other cases it is faulty.

One of the most “problematic” parts in electronic ballasts are transistors. They work in the most difficult conditions - they need to switch high currents on and off at 40 thousand per second, which makes the transistors very hot. When they overheat, the properties of semiconductors change and “breakdown” can occur, which will render the transistor useless. As a result, uncontrollably large currents begin to “walk” through the circuit, which simultaneously burn out other nearby elements that have the least resistance. That is, the transistor never burns out in “splendid isolation”; it “pulls” the other transistor and other elements with it. To prevent the transistor from overheating, it is installed on a radiator that dissipates heat. And in good electronic ballasts they do this.

If there are no radiators on the transistors, then you can install them yourself by purchasing them at a radio store and screwing them with a screw through the hole in the case. In this case, between the transistor and the radiator there must be thermal paste of the KPT 8 type, which is used for computer processor coolers.

Externally, the transistor may not show any signs of its malfunction and appear to be absolutely “healthy”. This may be true, but transistors in electronic ballasts should always be checked. They are one of the weak points. Although some sources on the Internet claim that the transistor can be checked without removing it from the board, this is actually not the case. Let's consider another version of the electronic ballast circuit.

It can be seen that the transistors are literally “hung” with various elements that conduct well. This means that the continuity of the transistors directly in the circuit will simply be incorrect. Therefore, our advice is that the transistors must be completely removed from the board, since in 80% of cases they will still be faulty if the electronic ballast is not working. Testing a transistor with a multimeter is as easy as shelling pears; you need to imagine it as two diodes, and then check each of them.

If you find at least one burnt-out transistor, you still need to change both, in any case. After one of the transistors fails, large currents begin to flow uncontrollably through the circuit, including through the second transistor, which can cause some changes in the semiconductor crystal. And they will most likely appear in the future.

Chokes and transformers very rarely fail, but nevertheless it is worth checking them simply by testing the windings with a multimeter. A high-voltage capacitor connected in parallel to the cathodes of the lamp requires special attention. It happens that manufacturers install a capacitor with an operating voltage not of 1200 V, but with a lower one. Considering that this capacitor is involved in starting the lamp, the voltage on it can reach 700-800 V, which can cause its breakdown. Therefore, it is necessary to check it and, in case of replacement, select a nominal operating voltage of at least 1.2 kV, and preferably 2 kV.

When checking and diagnosing faults in the electronic ballast, it is still better to check absolutely all elements. The only “hard” nut to crack that cannot be checked with a multimeter is the dinistor. It is tested only at a special stand. Its breakdown is usually visible, since the bulb of this element is glass. But it happens that in the absence of external signs of failure, it is he who is to blame for the “silence” of the electronic ballast. Therefore, it is better to have a new dinistor on hand, especially since the price for them is cheap.
Diagnostics and repair of electronic ballasts with integrated circuits can no longer be carried out. This requires special laboratory equipment and specialist services.

Video: Repairing the electronic ballast of a lamp

Video: Electronic ballast repair

Conclusion

The massive introduction of electronic ballasts into the control circuits of fluorescent lamps has made it possible to improve the comfort of this type of lighting, increase the service life of the lamps, and achieve significant energy savings. With electronic ballasts, fluorescent lighting literally received a “rebirth” because, in addition to simply turning it on and off, “smart” electronics also made it possible to adjust the brightness in a very decent range.

The increased interest in electronic ballasts has unfortunately increased the activity of illegal and dishonest manufacturers who are flooding the market with low quality products. This greatly spoils the reputation of electronic ballasts in general, but smart people understood before, and understand now, that it is better to purchase one good electronic ballast for 10 years, even if they pay twice as much for it, than to change a cheaper one every year or two. Therefore, you should trust only those manufacturers who have earned their good reputation for many decades.

Despite the widespread use of LED chandeliers and lamps, fluorescent lamps are not losing ground. But such a lamp cannot simply be connected to a 220V network. To operate, it requires an additional device - a ballast, or a ballast - ballast.

Why do you need a ballast in a lamp?

A fluorescent lamp is a sealed glass tube. Inside it are inert gas and a small amount of mercury vapor. At the ends of the tube there are filaments made of tungsten spirals. Their heating causes the emission of electrons and facilitates the appearance of a glow discharge inside the tube.

The light that appears in this case is pale blue, with a lot of ultraviolet, so the inner walls of the tube are covered with a layer of phosphor that re-emit ultraviolet into visible light.

Interesting. Bulbs without phosphor are used in hospitals for quartzing wards and for tanning.

Turning on fluorescent lamps

There are three main types of LDS starting devices.

Using starter and throttle

With this switching circuit, the filaments are connected in series with the starter and ballast. Another name for an electromagnetic ballast is a choke. This is an inductor that limits the current through the lamp.

When the lamp is turned on, the starter connects the tungsten spirals in series with the choke. When they are heated, electrons are emitted, which facilitates the appearance of a discharge between the electrodes. Periodically, the starter breaks the circuit and if the light bulb starts up at this time, the voltage between the electrodes drops and it no longer turns on. If the discharge does not occur, the starter closes the circuit again and the ignition process is repeated.

Disadvantages of this scheme:

• long startup time, especially in winter in unheated rooms;
• the throttle hums during operation;
• the light flickers at a frequency of 100Hz, which is invisible to the eye, but can cause headaches.

Interesting. To reduce flicker in luminaires consisting of two lamps, one of them is switched on through a capacitor. At the same time, the light fluctuations in them do not coincide, which has a beneficial effect on the illumination in the room.

To operate such lamps, homemade voltage multipliers were previously used. The role of a current-limiting ballast in this circuit is played by capacitors C3 and C4, and C1 and C2 create the high voltage necessary for the discharge to appear inside the discharge tube.

A high-voltage discharge ignites the LDS immediately, but the flickering of such a lamp is stronger than in a circuit with a starter and choke.

Interesting. The voltage multiplier allows the use of flasks with burnt-out tungsten coils.

Electronic ballast (EPG)

An electronic ballast for fluorescent lamps is a voltage converter that ignites and powers the lamp during operation. There are many options for implementing such devices, but they are assembled according to one block diagram. Some designs add brightness control.

Lamps with electronic ballasts are launched in two ways:

• Before turning on, the filaments heat up, which is why the start is delayed by 1-2 seconds. The brightness of the light can increase gradually or immediately turn on at full power;
• The lamp is ignited using an oscillating circuit that resonates with the bulb. In this case, there is a gradual increase in voltage and heating of the filaments.

Such devices have a number of advantages:

• The lamp is powered by high frequency voltage, which eliminates flickering of light;
• compactness, which allows reducing the dimensions of the lamp;
• fast but smooth switching on, extending the life of the lamp;
• absence of noise and heating during operation;
• high efficiency – up to 95%;
• built-in short circuit protection.

Electronic ballasts are manufactured for 1, 2 or 4 lamps.

Design of electromagnetic ballasts

The circuits of electronic ballasts from different manufacturers differ from each other, but are built on the same principle.

The board consists of the following elements:

• a filter that protects the circuit from interference created by other equipment;
• a rectifier that converts alternating mains voltage into direct voltage, necessary for the operation of the circuit;
• a filter that smoothes out voltage ripples after the rectifier;
• an inverter that powers the board elements;
• the electronic ballast itself.

The board has three pairs of pins or terminals: one for connecting 220V and two for filaments.

Operating principle of electronic ballast

Conventionally, the process of ignition and operation of a fluorescent lamp is divided into three stages:

1. Warming up the filaments. This is necessary for the emission of free electrons to occur, facilitating the appearance of a discharge inside the flask;
2. Appearance of a discharge between the electrodes. This is done using a high voltage pulse;
3. Stabilization of the glow discharge and further operation of the lamp.

This sequence provides a smooth start, increasing lamp life and stable operation at low temperatures.

Schematic diagram of electronic ballast

The following figure shows one of the common circuit diagrams of electronic ballasts.

The order of its operation is as follows:

1. The diode bridge converts 220V AC network voltage into pulsating DC voltage. Capacitor C2 smoothes out ripples;
2. DC voltage is supplied to a push-pull half-bridge inverter. It is assembled on two n-p-n transistors, which are high-frequency generators;
3. The RF control signal is supplied in antiphase to the windings W1 and W2 of the transformer. This is a three-winding transformer L1, wound on a ferrite magnetic core;
4. Winding W3 supplies a high resonant voltage to the filament. It creates a current sufficient to heat the coils and cause electron emission;
5. Capacitor C4 is connected in parallel to the flask. When the voltage resonates, a high voltage appears across it, sufficient to cause a discharge to appear inside the tube;
6. The resulting arc short-circuits the capacitance and stops the voltage resonance. Further operation is ensured by current-limiting elements L2 and C3.

Repair and replacement of electronic ballasts

There are two types of lamp malfunctions: a burnt-out lamp and a faulty unit. The light bulb must be replaced, and a faulty electronic ballast can be repaired or replaced with a new one.

Electronic ballast repair

In order to repair fluorescent lamps and troubleshoot electronic ballasts, you need basic skills in repairing electronic equipment:

1. Check and replace the fuse. Some models use a 1-5 Ohm resistor for this. Instead, a piece of thin wire is soldered;
2. A visual inspection and testing of board elements with a tester are carried out;
3. Estimate the cost of faulty parts. Provided that it is lower than the price of a new electronic ballast, repair the electronic ballast.

Replacing electronic ballasts

The faulty electronic throttle is replaced with a new one. This could be a finished circuit board or a circuit made from a burnt-out energy-saving light bulb. Using such a board, you can repair lamps with fluorescent lamps or make a fluorescent lamp yourself.

The operating principle and startup of a compact fluorescent lamp is similar to conventional tubular LDS. The board that is inside it controls a regular fluorescent lamp without any problems.

Important! The power of an energy-saving lamp must be equal to or greater than the power of a fluorescent lamp.

How to check the CFL board:

1. Disassemble the plastic housing. It consists of two halves connected by latches. A knife is inserted into the gap and drawn in a circle;
2. On the board there are four pins with wound wires, arranged in pairs. These are filaments. They are called by the tester;
3. If the threads are intact, then there is a breakdown in the board. The wires are unwound and the bulb is disconnected for use with a board from another CFL;
4. If one of the filaments is broken, the board is disconnected and connected instead of the burnt-out electronic ballast into a fluorescent lamp. When installing, it must be isolated from the metal body and secured with a glue gun or silicone sealant.

Important! Repair of fluorescent lamps is carried out with the voltage turned off.

The use of electronic ballasts in fluorescent lamps increases their service life and makes the lighting more pleasant. This is an alternative to replacing such lamps with CFLs.

Video

I have already said more than once that many things that surround us could have been realized much earlier, but for some reason they entered our everyday life quite recently. We have all encountered fluorescent lamps - those white tubes with two pins at the ends. Remember how they used to turn on? You press a key, the lamp begins to blink and finally enters its normal mode. This was really annoying, so they didn’t install such things at home. They were installed in public places, in production, in offices, in factory workshops - they are really economical compared to conventional incandescent lamps. But they blinked at a frequency of 100 times per second, and many people noticed this blinking, which was even more annoying. Well, to start each lamp there was a ballast choke, like a piece of iron weighing about a kilogram. If it was not assembled well enough, it would buzz rather disgustingly, also at a frequency of 100 hertz. What if there are dozens of such lamps in the room where you work? Or hundreds? And all these dozens turn on and off in phase 100 times per second and the throttles hum, although not all of them. Did it really have no effect?

But, in our time, we can say that the era of buzzing chokes and blinking lamps (both at start and during operation) is over. Now they turn on immediately and to the human eye their operation looks completely static. The reason is that instead of heavy chokes and periodically sticking starters, electronic ballasts (electronic ballasts) came into use. Small and light. However, just looking at their electrical diagram, the question arises: what prevented their mass production back in the late 70s and early 80s? After all, the entire element base was already there then. Actually, in addition to two high-voltage transistors, it uses the simplest parts, literally of a pittance cost, which were available in the 40s. Well, okay, the USSR, here production responded poorly to technological progress (for example, tube TVs were discontinued only in the late 80s), but in the West?

So, in order...

The standard circuit for switching on a fluorescent lamp was, like almost everything in the twentieth century, invented by the Americans on the eve of the Second World War and included, in addition to the lamp, the choke and starter we have already mentioned. Yes, a capacitor was also hung parallel to the network to compensate for the phase shift introduced by the inductor or, in even simpler terms, to correct the power factor.

Chokes and starters

The principle of operation of the entire system is quite tricky. At the moment the power button is closed, a weak current begins to flow through the circuit network-button-throttle-first spiral-starter-second spiral-mains - approximately 40-50 mA. Weak because at the initial moment the resistance of the gap between the starter contacts is quite large. However, this weak current causes ionization of the gas between the contacts and begins to increase sharply. This causes the starter electrodes to heat up, and since one of them is bimetallic, that is, it consists of two metals with different dependences of changes in geometric parameters on temperature (different coefficients of thermal expansion - CTE), when heated, the bimetal plate bends towards the metal with a lower CTE and closes with another electrode. The current in the circuit increases sharply (up to 500-600 mA), but still its growth rate and final value are limited by the inductance of the inductor; inductance itself is the property of preventing the instantaneous inductance of current. Therefore, the choke in this circuit is officially called a “ballast control device”. This high current heats up the coils of the lamp, which begin to emit electrons and heat the gas mixture inside the cylinder. The lamp itself is filled with argon and mercury vapor - this is an important condition for the occurrence of a stable discharge. It goes without saying that when the contacts in the starter close, the discharge in it stops. The entire process described actually takes a fraction of a second.

Now the fun begins. The cooled contacts of the starter open. But the inductor has already stored energy equal to half the product of its inductance and the square of the current. It cannot instantly disappear (see above about inductance), and therefore causes the appearance of a self-induction EMF in the inductor (in other words, a voltage pulse of approximately 800-1000 volts for a 36-watt lamp 120 cm long). Added to the amplitude mains voltage (310 V), it creates a voltage on the electrodes of the lamp sufficient for breakdown - that is, for a discharge to occur. The discharge in the lamp creates an ultraviolet glow of mercury vapor, which in turn affects the phosphor and makes it glow in the visible spectrum. At the same time, let us remind you once again that the choke, having an inductive reactance, prevents an unlimited increase in the current in the lamp, which would lead to its destruction or tripping of the circuit breaker in your home or other place where similar lamps are used. Note that the lamp does not always light up the first time; sometimes it takes several attempts for it to enter a stable glow mode, that is, the processes that we described are repeated 4-5-6 times. Which is really quite unpleasant. After the lamp has entered the glow mode, its resistance becomes significantly less than the resistance of the starter, so it can be pulled out, the lamp will continue to glow. Well, also, if you disassemble the starter, you will see that a capacitor is connected in parallel to its terminals. It is needed to reduce radio interference generated by contact.

So, very briefly and without delving into the theory, let’s say that a fluorescent lamp is turned on with a high voltage, and is kept in a luminous state by much less (for example, it turns on at 900 volts, glows at 150). That is, any device for switching on a fluorescent lamp is a device that creates a high switch-on voltage at its ends, and after lighting the lamp, reduces it to a certain operating value.

This American switching scheme was actually the only one, and only 10 years ago its monopoly began to rapidly collapse - Electronic ballasts (EPG) entered the market en masse. They made it possible not only to replace heavy buzzing chokes, to ensure instantaneous switching on of the lamp, but also to introduce a lot of other useful things such as:

- soft start of the llama - pre-heating of the coils, which dramatically increases the life of the lamp

— overcoming flicker (lamp power frequency is significantly higher than 50 Hz)

— Wide input voltage range 100…250 V;

— reduction in energy consumption (up to 30%) with a constant luminous flux;

— increase in the average service life of lamps (by 50%);

— protection against power surges;

— ensure the absence of electromagnetic interference;

- O no switching current surges (important when many lamps turn on simultaneously)

— automatic shutdown of defective lamps (this is important, devices are often afraid of idling)

— Efficiency of high-quality electronic ballasts — up to 97%

— lamp brightness control

But! All these goodies are sold only in expensive electronic ballasts. And in general, not everything is so rosy. More precisely, maybe everything would be cloudless if the EPR circuits were made truly reliable. After all, it seems obvious that electronic ballast (EPG) should in any case be no less reliable than a choke, especially if it costs 2-3 times more. In the “former” circuit consisting of a choke, a starter and the lamp itself, it was the choke (starter control element) that was the most reliable and, in general, with high-quality assembly could work almost forever. Soviet chokes from the 60s still work, they are large and wound with a fairly thick wire. Imported chokes with similar parameters, even from well-known companies such as Philips, do not work as reliably. Why? The very thin wire with which they are wound raises suspicion. Well, the core itself is much smaller in volume than the first Soviet chokes, which is why these chokes get very hot, which probably also affects reliability.

Yes, so, as it seems to me, electronic ballasts, at least cheap ones - that is, costing up to 5-7 dollars apiece (which is higher than that of a throttle), are made deliberately unreliable. No, they can work for years and may even work forever, but it’s like in a lottery - the probability of losing is much higher than winning. Expensive electronic ballasts are made to be conditionally reliable. We will tell you why “conditionally” a little later. Let's start our little review with the cheap ones. As for me, they make up 95% of purchased ballasts. Or maybe almost 100%.

Let's consider several such schemes. By the way, all “cheap” circuits are almost identical in design, although there are nuances.

Cheap electronic ballasts (EPG). 95% of sales.

These types of ballasts cost 3-5-7 dollars and simply turn on the lamp. This is their only function. They don't have any other useful bells and whistles. I drew a couple of diagrams to explain how this newfangled miracle works, although as we said above, the principle of operation is the same as in the “classic” throttle version - we ignite with a high voltage, keep it low. It's just implemented differently.

All the circuits of electronic ballasts (EPG) that I held in my hands - both cheap and expensive - were half-bridges - only the control options and the “piping” differed. So, an alternating voltage of 220 volts is rectified by the diode bridge VD4-VD7 and smoothed out by capacitor C1. In the input filters of cheap electronic ballasts, due to saving price and space, small capacitors are used, on which the magnitude of voltage ripple with a frequency of 100 Hz depends, despite the fact that the calculation is approximately as follows: 1 watt of lamp - 1 µF of filter capacitance. In this circuit there are 5.6 uF per 18 watts, that is, clearly less than necessary. This is why (although not only this), by the way, the lamp glows visually dimmer than from an expensive ballast of the same power.

Then, through the high-resistance resistor R1 (1.6 MOhm), capacitor C4 begins to charge. When the voltage on it exceeds the operating threshold of the bidirectional dinistor CD1 (approximately 30 volts), it breaks through and a voltage pulse appears at the base of transistor T2. Opening the transistor starts the operation of a half-bridge self-oscillator formed by transistors T1 and T2 and transformer TR1 with control windings connected in antiphase. Typically these windings contain 2 turns, and the output winding contains 8-10 turns of wire.

Diodes VD2-VD3 dampen negative emissions occurring on the windings of the control transformer.

So, the generator starts at a frequency close to the resonant frequency of the series circuit formed by capacitors C2, C3 and inductor C1. This frequency may be equal to 45-50 kHz, in any case, I was unable to measure it more accurately; I did not have a storage oscilloscope at hand. Please note that the capacitance of capacitor C3 connected between the electrodes of the lamp is approximately 8 times less than the capacitance of capacitor C2, therefore, the voltage surge across it is the same times higher (since the capacitance is 8 times greater - the higher the frequency, the greater the capacitance on a smaller capacity). That is why the voltage of such a capacitor is always chosen to be at least 1000 volts. At the same time, a current flows through the same circuit, heating the electrodes. When the voltage on capacitor C3 reaches a certain value, breakdown occurs and the lamp lights up. After ignition, its resistance becomes significantly less than the resistance of capacitor C3 and it does not have any effect on further operation. The generator frequency also decreases. Choke L1, as in the case of the “classic” choke, now performs the function of limiting the current, but since the lamp operates at a high frequency (25-30 kHz), its dimensions are many times smaller.

Appearance of ballast. It can be seen that some elements are not soldered into the board. For example, where I soldered a current-limiting resistor after the repair, there is a wire jumper.

One more product. Unknown manufacturer. Here they did not sacrifice 2 diodes to make an “artificial zero”.

"Sevastopol scheme"

There is an opinion that no one will do it cheaper than the Chinese. I was sure of it too. I am sure until I got my hands on electronic ballasts from a certain “Sevastopol plant” - at least the person who sold them said so. They were designed for a 58 W lamp, that is, 150 cm in length. No, I won’t say that they didn’t work or worked worse than the Chinese ones. They worked. The lamps glowed from them. But…

Even the cheapest Chinese ballasts (electronic ballasts) consist of a plastic case, a board with holes, a mask on the board on the printed circuit side, and a designation indicating which part is which on the mounting side. The “Sevastopol version” was devoid of all these redundancies. There, the board was also the cover of the case, there were no holes in the board (for this reason), there were no masks, no markings, the parts were placed on the side of the printed conductors and everything that could be made of SMD elements, which I never I haven’t seen it even in the cheapest Chinese devices. Well, the scheme itself! I've watched a lot of them, but I've never seen anything like it. No, everything seems to be like the Chinese: an ordinary half-bridge. It’s just that the purpose of elements D2-D7 and the strange connection of the base winding of the lower transistor is completely unclear to me. And further! The creators of this miracle device combined a half-bridge generator transformer with a choke! They simply wound the windings on an W-shaped core. No one has thought of this, not even the Chinese. In general, this scheme was designed either by geniuses or alternatively gifted people. On the other hand, if they are so ingenious, why not sacrifice a couple of cents to introduce a current-limiting resistor to prevent current surge through the filter capacitor? Yes, and for a varistor for smooth heating of the electrodes (also cents) - they could go broke.

IN THE USSR

The above “American circuit” (choke + starter + fluorescent lamp) operates from an alternating current network with a frequency of 50 hertz. What if the current is constant? Well, for example, the lamp must be powered from batteries. Here you won’t be able to get by with the electromechanical option. You need to “make a diagram.” Electronic. And there were such schemes, for example, on trains. We all traveled in Soviet carriages of varying degrees of comfort and saw these fluorescent tubes there. But they were powered by a direct current of 80 volts, the voltage produced by the carriage battery. For power supply, “that same” circuit was developed - a half-bridge generator with a series resonant circuit, and to prevent current surges through the spirals of the lamps, a direct heating thermistor TRP-27 with a positive temperature coefficient of resistance was introduced. The circuit, it must be said, was exceptionally reliable, and in order to convert it into ballast for an AC network and use it in everyday life, it was necessary to essentially add a diode bridge, a smoothing capacitor and slightly recalculate the parameters of some parts and the transformer. The only "but". Such a thing would be quite expensive. I think its cost would be no less than 60-70 Soviet rubles, with the cost of the throttle being 3 rubles. Mainly due to the high cost of powerful high-voltage transistors in the USSR. And this circuit also produced a rather unpleasant high-frequency squeak, not always, but sometimes it could be heard; perhaps, over time, the parameters of the elements changed (the capacitors dried out) and the frequency of the generator decreased.

Power supply diagram for fluorescent lamps in trains in good resolution

Expensive electronic ballasts (EPG)

An example of a simple “expensive” ballast is a product from TOUVE. It worked in the aquarium lighting system; in other words, it powered two green llamas of 36 watts each. The owner of the ballast told me that this thing is something special, specially designed for lighting aquariums and terrariums. "Eco-friendly". I still don’t understand what is environmentally friendly; another thing is that this “ecological ballast” did not work. Opening and analyzing the circuit showed that, compared to cheap ones, it is significantly more complicated, although the principle - half-bridge + triggering through the same DB3 dinistor + series resonant circuit - is retained in full. Since there are two lamps, we see two resonant circuits T4C22C2 and T3C23C5. The cold coils of the lamps are protected from surge current by thermistors PTS1, PTS2.

Rule! If you buy an economical lamp or an electronic ballast, check how this same lamp turns on. If it’s instant, the ballast is cheap, no matter what they tell you about it. In more or less normal conditions, the lamp should turn on after pressing the button in about 0.5 seconds.

Further. The RV input varistor protects the power filter capacitors from surge current. The circuit is equipped with a power filter (circled in red) - it prevents high-frequency interference from entering the network. The Power Factor Correction is outlined in green, but in this circuit it is assembled using passive elements, which distinguishes it from the most expensive and sophisticated ones, where the correction is controlled by a special microcircuit. We will talk about this important problem (power factor correction) in one of the following articles. Well, a protection unit has also been added in abnormal modes - in this case, generation is stopped by shorting the SCR base Q1 to ground with the SCR thyristor.

For example, deactivation of the electrodes or a violation of the tightness of the tube leads to the appearance of an “open circuit” (the lamp does not light up), which is accompanied by a significant increase in the voltage across the starting capacitor and an increase in the ballast current at the resonance frequency, limited only by the quality factor of the circuit. Long-term operation in this mode leads to damage to the ballast due to overheating of the transistors. In this case, the protection should work - the SCR thyristor closes the Q1 base to ground, stopping generation.

It can be seen that this device is much larger in size than cheap ballasts, but after repair (one of the transistors flew out) and restoration, it turned out that these same transistors heat up, as it seemed to me, more than necessary, up to about 70 degrees. Why not install small radiators? I am not saying that the transistor failed due to overheating, but perhaps operation at elevated temperatures (in a closed case) was a provoking factor. In general, I installed small radiators, since there was room.

Content:

Lighting in large rooms is increasingly carried out using tubular fluorescent lamps. They can significantly save energy and illuminate the space with diffused light. However, their service life largely depends on the normal operation of all components. Among them, the ballast circuit of fluorescent lamps, which ensures ignition and maintains normal operating mode, is of great importance.

Ballast for fluorescent lamps

Most traditional 50 Hz designs use magnetic ballasts for power supply. High voltage is generated through the reactor when the bimetallic key opens. A current flows through it, providing heating of the electrodes when the contacts are closed.

These starting devices have a number of serious disadvantages that do not allow fluorescent lamps to fully use their resource when lighting rooms. It creates flickering light, increased noise levels, and unstable light during voltage surges.

All these shortcomings are eliminated by using electronic ballasts (), called electronic ballast. Using a ballast allows you to light the lamp almost instantly without noise or flickering. The high frequency range makes the lighting more comfortable and stable. The negative impact of network voltage fluctuations is completely neutralized. All flashing and flashing faulty lamps are switched off using the monitoring system.

All electronic ballasts have a relatively high cost. However, in the future, there is a visible compensation of initial costs. With the same quality of light flux, energy consumption is reduced by an average of 20%. The light output of a fluorescent lamp is increased due to the higher frequency and increased efficiency of electronic ballasts compared to electromagnetic devices. A gentle start-up and operation mode using ballast allows you to increase the life of the lamps by 50%.

Operating costs are significantly reduced as starters do not need to be replaced and the number of starters is also reduced. By using a lighting control system, additional energy savings of up to 80% can be achieved.

Typical ballast circuit

The electronic ballast design uses an active power factor correction, ensuring compatibility with the electrical network. The basis of the corrector is a powerful boost pulse converter controlled by a special integrated circuit. This provides rated operation with a power factor close to 0.98. The high value of this coefficient is maintained in any operating mode. Voltage changes are allowed in the range of 220 volts + 15%. The corrector ensures stable illumination even with significant changes in network voltage. To stabilize it, an intermediate is used.

An important role is played by the mains filter, which smoothes out high-frequency ripples of the supply current. Together with the corrector, this device strictly regulates all components of the consumed current. The line filter input is equipped with a protective unit with a varistor and a fuse. This allows you to effectively eliminate network overvoltages. A thermistor having a negative temperature coefficient of resistance is connected in series with the fuse, which ensures that the input current surge is limited when the electronic ballast is connected from the inverter to the network.

In addition to the main elements, the ballast circuit for fluorescent lamps requires the presence of a special protection unit. With its help, the status of the lamps is monitored, as well as their shutdown in case of malfunction or absence. This device monitors the current consumed by the inverter and the voltage supplied to each lamp. If during a certain period of time the specified voltage or current level exceeds the set value, then the protection is triggered. The same thing happens during a load circuit break.

The executive element of the protective unit is a thyristor. Its open state is maintained by current passing through a resistor installed in the ballast. The value of the ballast resistance allows the thyristor current to maintain the on state until the supply voltage is removed from the electronic ballast.

The electronic ballast control unit is powered through a mains rectifier when current passes through the ballast resistor. Reducing the power of the electronic ballast and improving its efficiency allows the use of smoothing circuit current. This circuit connects to the point where the inverter transistors connect. Thus, the control system is powered. The construction of the circuit ensures that the control system is launched at the initial stage, after which the power circuit is started with a slight delay.

Although incandescent lamps are cheap, they consume a lot of electricity, so many countries refuse to produce them (USA, Western European countries). They are replaced by compact fluorescent fluorescent lamps (energy-saving), they are screwed into the same E27 sockets as incandescent lamps. However, they cost 15-30 times more, but they last 6-8 times longer and consume 4 times less electricity, which determines their fate. The market is overflowing with a variety of such lamps, mostly made in China. One of these lamps, from DELUX, is shown in the photo.

Its power is 26 W -220 V, and the power supply, also called electronic ballast, is located on a board measuring 48x48 mm ( Fig.1) and is located in the base of this lamp.

Its radioelements are mounted on a circuit board, without the use of chip elements. The schematic diagram was drawn by the author from an inspection of the circuit board and is shown in Fig.2.

Note on the diagram: there is no point on the diagram indicating the connection of the dinistor, diode D7 and the base of the EN13003A transistor

First, it is appropriate to recall the principle of igniting fluorescent lamps, including when using electronic ballasts. To ignite a fluorescent lamp, it is necessary to heat its filaments and apply a voltage of 500...1000 V, i.e. significantly higher than the mains voltage. The magnitude of the ignition voltage is directly proportional to the length of the glass bulb of the fluorescent lamp. Naturally, for short compact lamps it is less, and for long tubular lamps it is more. After ignition, the lamp sharply reduces its resistance, which means that a current limiter must be used to prevent short circuits in the circuit. The electronic ballast circuit for a compact fluorescent lamp is a push-pull half-bridge voltage converter. First, the mains voltage is rectified using a 2-half-wave bridge to a constant voltage of 300...310 V. The converter is started by a symmetrical dinistor, indicated in the diagram Z; it opens when, when the power supply is turned on, the voltage at its connection points exceeds the operating threshold. When opened, a pulse passes through the dinistor to the base of the lower transistor in the circuit, and the converter starts. Next, a push-pull half-bridge converter, the active elements of which are two n-p-n transistors, converts a direct voltage of 300...310 V into a high-frequency voltage, which makes it possible to significantly reduce the size of the power supply. The load of the converter and at the same time its control element is a toroidal transformer (indicated in the diagram L1) with its three windings, of which two control windings (each with two turns) and one working winding (9 turns). Transistor switches open out of phase from positive pulses from the control windings. To do this, the control windings are connected to the bases of the transistors in antiphase (in Fig. 2, the beginning of the windings is indicated by dots). Negative voltage surges from these windings are suppressed by diodes D5, D7. Opening each key causes impulses to be generated in two opposite windings, including the working winding. Alternating voltage from the working winding is supplied to the fluorescent lamp through a series circuit consisting of: L3 - lamp filament - C5 (3.3 nF 1200 V) - lamp filament - C7 (47 nF / 400 V). The values ​​of the inductances and capacitances of this circuit are selected so that voltage resonance occurs in it at a constant frequency of the converter. When the voltages in a series circuit resonate, the inductive and capacitive reactances are equal, the current in the circuit is maximum, and the voltage on the reactive elements L and C can significantly exceed the applied voltage. The voltage drop across C5, in this series resonant circuit, is 14 times greater than across C7, since the capacitance of C5 is 14 times less and its capacitance is 14 times greater. Consequently, before igniting the fluorescent lamp, the maximum current in the resonant circuit heats up both filaments, and the high resonant voltage on capacitor C5 (3.3 nF/1200 V), connected in parallel with the lamp, lights the lamp. Pay attention to the maximum permissible voltages on capacitors C5 = 1200 V and C7 = 400 V. Such values ​​were not chosen by chance. At resonance, the voltage on C5 reaches about 1 kV and it must withstand it. A lit lamp sharply reduces its resistance and blocks (short-circuits) capacitor C5. Capacitance C5 is removed from the resonant circuit, and the voltage resonance in the circuit stops, but the already lit lamp continues to glow, and inductor L2 limits the current in the lit lamp with its inductance. In this case, the converter continues to operate in automatic mode, without changing its frequency from the moment it was started. The entire ignition process lasts less than 1 second. It should be noted that the fluorescent lamp is constantly supplied with alternating voltage. This is better than constant, as it ensures uniform wear of the emissive abilities of the filament and thereby increases its service life. When lamps are powered by direct current, their service life is reduced by 50%, so direct voltage is not supplied to gas-discharge lamps.

Purpose of converter elements.
The types of radioelements are indicated in the circuit diagram (Fig. 2).
1. EN13003A - transistor switches (for some reason the manufacturers did not indicate them on the wiring diagram). These are bipolar high-voltage transistors of medium power, n-p-n conductivity, TO-126 package, their analogues MJE13003 or KT8170A1 (400 V; 1.5 A; 3 A per pulse), or KT872A (1500 V; 8 A; T26a package), but They are larger in size. In any case, it is necessary to correctly determine the outputs of the BKE, since different manufacturers may have different sequences, even for the same analogue.
2. A toroidal ferrite transformer, designated L1 by the manufacturer, ring dimensions 11x6x4.5, probable magnetic permeability 2000, has 3 windings, two of them are 2 turns each and one is 9 turns.
3. All diodes D1-D7 are the same type 1N4007 (1000 V, 1 A), of which diodes D1-D4 are a rectifier bridge, D5, D7 suppress negative emissions of the control pulse, and D6 separates the power supplies.
4. Chain R1СЗ provides a delay in starting the converter for the purpose of a “soft start” and preventing the inrush current.
5. Symmetrical dinistor Z type DB3 Uзс.max=32 V; Uoc=5 V; Unotp.i.max=5 V) ensures the initial start-up of the converter.
6. R3, R4, R5, R6 - limiting resistors.
7. C2, R2 - damper elements designed to dampen emissions of the transistor switch at the moment of its closing.
8. Choke L1 consists of two W-shaped ferrite halves glued together. Initially, the inductor participates in voltage resonance (together with C5 and C7) to ignite the lamp, and after ignition, its inductance extinguishes the current in the fluorescent lamp circuit, since the lit lamp sharply reduces its resistance.
9. C5 (3.3 nF/1200 V), C7 (47 nF/400 V) - capacitors in the circuit of a fluorescent lamp, participating in its ignition (through voltage resonance), and after ignition, C7 maintains the glow.
10. C1 - smoothing electrolytic capacitor.
11. A choke with a ferrite core L4 and a capacitor C6 form a barrier filter that does not allow impulse noise from the converter to enter the power supply network.
12. F1 - 1 A mini-fuse in a glass case, located outside the circuit board.

Repair.
Before repairing the electronic ballast, you need to “get” to its circuit board; to do this, just use a knife to separate the two components of the base. When repairing a board under voltage, be careful, as its radioelements are under phase voltage!

Burnout (break) of the filament coils of a fluorescent lamp, while the electronic ballast remains operational. This is a typical malfunction. It is impossible to restore the spiral, and glass fluorescent bulbs for such lamps are not sold separately. What is the way out? Or adapt a working ballast to a 20-watt lamp with a direct glass lamp instead of its “original” choke (the lamp will work more reliably and without hum) or use board elements as spare parts. Hence the recommendation: buy compact fluorescent lamps of the same type - it will be easier to repair.

Cracks in circuit board solder. The reason for their appearance is periodic heating and subsequent, after switching off, cooling of the soldering area. The soldering area heats up from elements that heat up (spirals of a fluorescent lamp, transistor switches). Such cracks may appear after several years of operation, i.e. after repeated heating and cooling of the soldering area. The malfunction is eliminated by re-soldering the crack.

Damage to individual radio elements. Individual radioelements can be damaged both from cracks in soldering and from voltage surges in the power supply network. Although there is a fuse in the circuit, it will not protect radio elements from voltage surges, as a varistor could. The fuse will burn out due to breakdown of radio elements. Of course, the weakest point of all the radio elements of this device is the transistors.

Radioamator No. 1, 2009

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
	Bipolar transistor	MJE13003A	2	N13003A, KT8170A1, KT872A		To notepad
D1-D7	Rectifier diode	1N4007	7			To notepad
Z	Dinistor		1			To notepad
C1	Electrolytic capacitor	100 µF 400 V	1			To notepad
C2, C3	Capacitor	27 nF 100 V	2			To notepad
C5	Capacitor	3.3 nF 1200 V	1			To notepad
C6	Capacitor	0.1 µF 400 V	1			To notepad
C7	Capacitor	47 nF 400 V	1			To notepad
R1, R2	Resistor	1.0 Ohm	2