How does a welding transformer work?

Welding transformer device

Electric arc welding using alternating current is carried out using welding transformers. These devices are widely used in manufacturing, construction and other industries. In order to properly operate the equipment and get maximum effect, you need to know the general structure of the welding transformer. First of all, this is due to adjustments that are made during operation.

How does a welding transformer work?

The design of a welding transformer includes several basic elements. One of the main parts is the magnetic circuit, which is a steel core made of plates with two insulated windings. The primary winding is connected to a network with a voltage of 220 or 380 volts. One end of the secondary winding is connected to the electrode holder, and the other end is connected to the part to be welded.

The secondary winding is divided into two parts, located on different coils. The moving coil plays the role of a choke that controls the welding current. The choke winding moves along the magnetic core using a special control screw.

The welding current parameters are determined by the air gap between the moving element of the secondary winding and the primary winding. If the current changes, the air gap also changes. As the gap increases, the value of the welding current increases. Adjustments can be made in the range of 60-400 amperes. All devices are equipped with protection against possible short circuits.

Types of welding transformers

A distinctive feature of the transformer is the shape of the core. It is divided into rod and armor types. In the first case, welding transformers have a higher efficiency, and the current density in the windings has a higher value. Therefore, most of the equipment is of the rod type.

The design of the windings assumes cylindrical and disk options. In a cylindrical design, one winding is wound on top of the other. In this case, the magnetic flux of the primary winding is coupled to the secondary winding. These devices are not suitable for manual welding and require additional elements that complicate the overall design.

The design of a welding transformer with disk windings involves separating the primary and secondary windings from each other. In this case, the magnetic flux does not connect these windings to each other. Typically, the welding current is adjusted by changing the distance between the primary and secondary windings. In this regard, fixed welding current values ​​are provided in transformers in advance.

Source: https://electric-220.ru/news/ustrojstvo_svarochnogo_transformatora/2014-10-24-726

Instructions for assembling a welding machine with your own hands

A welding machine is highly specialized equipment, but almost every man has had to look for a similar unit more than once in his life to repair home appliances or a car. It is quite easy to make a welding machine with your own hands, but you should understand that the equipment is suitable for working on small structures. This will be electric arc welding from an AC or DC source.

Argon and gas welding require special knowledge and equipment. You can make a gas generator at home, but if the master does not have a specialized education, there is a high risk of making a mistake. It is easier to rent an argon-arc welding machine; it costs tens of times less than making the equipment yourself.

Block diagram of the welding machine

A welding machine for home use is a simplified design with the simplest components and a simple assembly diagram. The main part is a welding transformer, which you can make yourself or use a component from a household appliance (for example, a microwave oven).

The inverter welding unit is designed according to the following diagram:

• power supply;
• rectifier;
• inverter

You can make a transformer yourself using waste wire cables and copper tape of the required length.

If the transformer uses round copper wire, the operation of the device is limited to 2-3 welding rods. Transformer oil is used for cooling.

The seam on the parts being connected is formed due to heat, the source of which is an electric arc that occurs between two electrodes. One of the electrodes is the material being welded.

A short circuit, which is required to heat up the electrode (cathode), will lead to a stable discharge with a temperature of up to 6000°C. Under its influence, the metal will begin to melt.

This is a rough description of the welding process for non-specialists who, in everyday life, simply need to quickly fix the required profile or part.

Product contents

Welding inverters are rarely made independently. This electronic device requires repeated testing, specific knowledge and experience. It is easier to make a homemade product based on a transformer, and since it must work from a household network (usually 220 V), this device will be quite sufficient for minor home repairs.

A welding inverter for a 220 V network is assembled according to a circuit that is used for devices operating from an industrial three-phase network. You need to know that these devices will have an efficiency 60% higher than equipment adapted for a single-phase network.

The transformer welder is manufactured without additional components, the package includes:

• transformer (you can make it yourself);
• insulating material;
• welding rod holder;
• PRG cable.

More complex inverter products are equipped with:

• transformer;
• inverter;
• ventilation system;
• ampere regulator.

After assembly, the voltage of the secondary winding is measured: the values ​​should not exceed the parameters of 60-65 V.

Power supply for a simple welder

Homemade welding transformers are simple equipment for rare repairs. The stator can serve as a magnetic core. The primary winding will be connected to the network, the secondary winding is designed to receive an electric arc and perform work. The transformer winding consists of copper wire or tape (up to 30 meters).

When welding, it is recommended to use an electrode with a diameter of 3-4 mm. The transformer core is made in the shape of a horseshoe, its cross-sectional area is about 50 sq. cm. These parameters are sufficient for maximum power.

The primary winding is made of copper strip with cotton insulation. You can use a “bare” magnetic core and insulate it separately. The wire is wrapped in strips of cotton fabric and impregnated with any varnish for electrical work. The secondary winding is wound after insulating the primary. The cross-section of the primary winding is 5-7 square meters. mm, secondary section - 25-30 sq. mm. After insulation, the parameters are tested: a larger number of turns may be required.

An inverter-type welding machine has a more complex device, can operate on direct or alternating current and provides better weld quality.

But if in everyday life you only need to carry out spot welding (for example, when repairing household appliances), then making an inverter welder is not practical.

 If you are using a transformer from a vacuum cleaner or microwave oven, it is important not to damage the primary winding. In 80% of cases, the secondary winding must be removed and redone so that the unit does not overheat.

Rectifier block

The rectifier unit converts the AC signal voltage into a DC signal and consists of a small number of small parts:

• diode bridges;
• capacitors;
• throttle;
• Voltage boost.

The rectifier is assembled on the principle of a bridge circuit, where alternating current is supplied at the input, and direct current comes out from the output terminals. Both devices - a transformer and a rectifier for a welder - are equipped with a forced cooling unit. You can use a cooler from the computer power supply.

Inverter block

The inverter unit converts direct current from the rectifier into alternating current and produces a voltage of up to 40 V and a current of up to 150 A.

The inverter operates according to the following scheme:

1. From the outlet, alternating current (frequency 50-60 Hz) is supplied to the rectifier, where the frequency is equalized. The current is supplied to transistors, where the constant signal is converted into alternating current with an increase in the oscillation frequency to 50 kHz.
2. Reducing the voltage of the high-frequency flow on the step-down transformer from 220 to 60 V. At the same time, the current increases. Due to the increase in frequency, only the minimum permissible number of turns is used in the inverter coil.
3. At the output rectifier, the final conversion of the electric current into a constant one with high power and low voltage occurs, which is optimal for high-quality welding.

In addition to the main stages, the welding device adjusts the current strength and ensures optimal ventilation. You can make an inverter yourself, guided by a detailed diagram.

Required Tool

To assemble the welding machine and manufacture you will need the following tools and devices:

• hacksaw;
• fasteners;
• soldering iron;
• knife, chisel, tweezers and screwdrivers;
• sheet metal for the frame;
• electrodes;
• assembly elements for a transformer, asynchronous stator.

The parts of the device are assembled on a textolite base; sheets of aluminum or industrial steel are used for the body.

Manufacturing

All parts in the scheme for manufacturing a transformer welder at home will be arranged in the following order:

• rectifier;
• network filter;
• converter;
• transformer;
• power rectifier.

Source: https://InfoKuzov.ru/material-instrument/svarochnij-apparat-svoimi-rukami

How does a DC welding machine work? Design and main parameters of a welding transformer

The use of direct current allows you to obtain a better quality seam due to the fact that the electric arc is stable. There are no zero crossings like an AC unit, so no splashing.

The ability to use direct and reverse polarity allows you to weld stainless steel and non-ferrous metals, that is, direct current electric arc welding has a wider range of applications, all other things being equal. When using inverters, the welding machine is significantly smaller in size and weight.

The disadvantages are the relatively high cost (compared to AC devices) and sensitivity to dust. You have to clean the indoor units often.

Simple design of DC welding machine

Based on the installation principle, the following parts can be distinguished:

• homemade transformer for welding;
• its power supply circuit is from network 220;
• output welding hoses;
• power unit of a thyristor current regulator with an electronic control circuit from a pulse winding.

Pulse winding III is located in power zone II and is connected through capacitor C. The amplitude and duration of the pulses depend on the ratio of the number of turns in the capacitor.

Calculation of a welding transformer

Different types of welding require transformers of different power. The main calculation is made based on the difference in winding turns between the primary and secondary coils. For step-down devices, the rule is that if the outgoing voltage needs to be reduced by 10 or 100 times, then the number of turns on the secondary coil should be 10 or 100 less. This value has an error of 3%. The same rule applies in the opposite direction.

Each device of this type has its own transformation ratio. This value (n) shows the current scaling from primary (i1) to secondary (i2). The calculation is: n = i1/i2. Based on this, you can create a device suitable for specific types of welding.

Reliable welding current control circuit

The work involves three blocks:

1. stabilized voltage;
2. formation of high-frequency pulses;
3. separation of pulses into circuits of thyristor control electrodes.

Voltage stabilization

An additional transformer with an output voltage of about 30 V is connected from the power winding of the 220 volt transformer. It is rectified by a diode bridge based on D226D and stabilized by two zener diodes D814V.

In principle, any power supply with similar electrical characteristics of current and output voltage can work here.

Pulse block

The stabilized voltage is smoothed by capacitor C1 and supplied to the pulse transformer through two bipolar transistors of direct and reverse polarity KT315 and KT203A.

Transistors generate pulses to the primary winding Tr2. This is a toroidal type pulse transformer. It is made of permalloy, although a ferrite ring can also be used.

Winding of three windings was carried out simultaneously with three pieces of wire with a diameter of 0.2 mm. Made 50 turns. The polarity of their inclusion matters. It is shown by dots in the diagram. The voltage on each output circuit is about 4 volts.

Windings II and III are included in the control circuit for power thyristors VS1, VS2. Their current is limited by resistors R7 and R8, and part of the harmonic is cut off by diodes VD7, VD8. We checked the appearance of the pulses with an oscilloscope.

In this chain, the resistors must be selected for the voltage of the pulse generator so that its current reliably controls the operation of each thyristor.

The unlocking current is 200 mA, and the unlocking voltage is 3.5 volts.

Welding current regulation

Variable resistor R2, with its resistance, determines the position of each pulse passed through the control electrode of the thyristor. The shape of the pulsating current at the output of the power circuit of the welding machine depends on it.

Half-sine ripples can pass through completely when the welding current is set to maximum or be cut off to almost zero.

Classification of welding transformers

The division into types of welding transformers is based on the type of welding and phase control. The first feature distinguishes devices for manual arc welding and automatic ones using flux. The second received a more impressive classification, which looks like this:

1. Devices with standard magnetic leakage amplitude control (there is an air gap or saturation choke);
2. Devices with increased magnetic dissipation (contain movable, spaced apart windings, magnetized capacitors, pulse rectifiers);
3. Thyristor (contain pulsed rectifiers or make-up).

We have looked at the general classification of AC welding transformers, which is only superficial. For a more accurate understanding of existing device models, you should understand transformers that differ from each other primarily in phase control.

Devices operating on alternating current with sinusoidal control of the welding process do this by changing the resistance or switching the no-load current. In this case, it is possible to transmit without changes the sinusoidal shape of the input current of transformer welding.

The toroidal transformer is considered one of the most interesting in its design. Its peculiarity is that most of the devices are assembled according to a pattern similar to the letters Ш or П, but this one repeats the shape of a donut.

Thanks to this arrangement, it was possible to reduce the size of the device, while obtaining more power from the current volume of the mechanism. Only a three-phase transformer with a step-down system with three single-phase devices can compete with it.

This is the most compact and easy to use among the models currently on the market.

We recommend! What is a welding mark, how is it assigned and where is it applied?

All of the above applies to alternating current, but it is also worth mentioning direct current transformers, or rather devices that have an alternating current to direct current rectifier in their design. They are more convenient, produce a stable arc, but working with them requires a certain specialization.

Such mechanisms are rarely used due to the complex operating principle, which not only makes the device heavier, but also makes it prohibitively expensive.

Due to the availability of work with non-ferrous metal and stainless steel, DC transformers are most often used in small and large enterprises for processing rare metals. We should not forget that they require special electrodes, so their domestic use is practically excluded.

When comparing the two models for AC and DC, the first one should be chosen for personal needs, and the second option is better suited for demanding work in the field of welding services.

Types of construction

Welding transformers are also classified according to the design principle. There are three main groups:

1. Equipment with rated magnetic dissipation. It has a choke to regulate the output voltage.
2. Equipment with increased magnetic dispersion. It has a complex design. It includes several moving windings, a pulse stabilizer and a capacitor. Other components may also be present.
3. Thyristor types of welding transformers. They have a corresponding phase regulator device. Thyristor-type devices are characterized by relatively low weight.

The presented classification is for AC devices. There are DC models. They have larger dimensions and a more complex structure. They contain a rectifier.

Such models are more stable and easier to use. The purpose of the welding transformer, which operates at direct current, in this case is defined as industrial. The equipment allows the master to work with non-ferrous metals and stainless steel. The cost of such devices is quite high. Therefore, welding transformers of this type are used exclusively for professional purposes. AC devices are quite suitable for household needs.

Source: https://fermeram.info/instrumenty-i-materialy/kak-ustroen-apparat-dlya-svarki-postoyannym-tokom-ustrojstvo-i-osnovnye-parametry-svarochnogo-transformatora.html

Welding transformer – Welding transformer: calculation, device and diagram

Reading time: 7 minutes

A welding transformer is a classic type of welding machine that has been used for more than a hundred years. Transformers have proven themselves to be reliable and unpretentious devices that are capable of welding even the thickest metal due to the high strength of the welding current. Nowadays, transformers are used infrequently, since manufacturers offer inexpensive functional inverters. But for professionals and old-school welders, transformers still play a big role.

In this article we will explain in detail what a welding transformer is, how it works, what types of welding transformers exist, and what a welding transformer is used for. This material was created specifically for those who are just learning the basics of welding and choosing a welding machine for themselves.

articles

general information

A transformer-type welding machine is one of the classic representatives of welding equipment. The main function of a welding transformer is to convert 220V or 380V network voltage to low, as well as convert current from low to high values. Any transformer (be it modern or produced 30 years ago) is designed for manual arc welding using coated electrodes.

With the help of a transformer, both household and professional or industrial welding is possible. In the 20th century, welding transformers were widely used for professional welding work until they were replaced by new generation compact inverters. However, transformers are still used by many welders.

Advantages:

• Low cost of the device itself, as well as its spare parts and maintenance
• Unpretentiousness to storage and operation
• High maintainability
• Great power
• Possibility of welding thick metals

Flaws:

• Large weight and dimensions making transportation difficult
• Non-intuitive current adjustment (no knobs or buttons, adjustment is made by changing the value of inductive reactance or secondary open circuit voltage)
• Often unstable arc burning, difficult ignition

Design and principle of operation

The design and operating principle of a welding transformer is extremely simple. It is because of this feature that transformers are so repairable and inexpensive to maintain.

Welding transformer device

The transformer consists of a transformer and a regulator unit. A transformer unit is necessary to reduce the voltage coming from a 220V or 380V network. The regular knot allows you to set the current strength you need.

The composition of the transformer assembly may vary depending on the voltage required for stable operation of the device. There are single-phase, two-phase and three-phase devices. A single-phase transformer consists of a core and two windings. Two-phase - from two single-phase. Three-phase - from three single-phase ones, respectively.

Source: https://forvardplast.ru/raznoe-2/transformator-svarochnyj-svarochnyj-transformator-raschet-ustrojstvo-i-sxema.html

How does a welding machine work? DIY welding machine

Dear visitors!!!

A welding machine, or rather a welding transformer, in contrast to ordinary step-down or step-up voltage transformers, has a slight difference between them.

 If you take any diagram of a welding transformer, you can see from the diagram that the primary winding is connected to the electrical circuit in parallel, where it is short-circuited.

 A short circuit is eliminated by the largest number of turns compared to the secondary winding wound on the stationary part of the magnetic circuit made of transformer steel.

Operating principle of the welding machine

The secondary winding of the welding transformer is connected to the electrical circuit in series with the additional winding. The additional winding is a current regulator.

 The current regulator consists of a stationary part of a magnetic core made of transformer steel, the wiring itself is wound directly on the magnetic core \winding\ and a choke, which is a moving part of the current regulator, consisting of only one transformer steel - a magnetic core made without a winding. The moving part is called the throttle, the stationary part is called the armature.

 Due to the gap adjusted by the throttle in relation to the stationary part of the magnetic circuit, it is possible to regulate the electric arc during welding and create the welding current we need. One end of the secondary winding is fixed to any metal structure with which we need to do welding work, the second end of the secondary winding is attached to a holder with an electrode.

 Here we can observe the same example from electrical engineering, when the gap on the current regulator decreases, the resistance increases \ the lower the resistance, the greater the current\, and therefore the welding current decreases.

Welding machine design

Schematic diagram of a bridge rectifier for a welding machine, indicating polarity

when welding thin sheet metal

It can be added that one end of the winding, fixed to a metal structure for welding work, has a zero potential, and the holder with a fixed electrode has a positive potential. Contact of the electrode holder with ground creates a short circuit.

 A short circuit in this example does not occur due to the gap in the magnetic circuit between the moving and stationary parts of the current regulator.

 When carrying out welding work, it is necessary to observe your own safety measures, namely, not to come into contact with the ground \neutral wire\ and the holder \phase wire\ at the same time, given that the welding transformer has its idle voltage of just over 60 volts.

Welding machine current regulator

In the above example, the gap of the current regulator between the moving and stationary parts of the magnetic circuit was adjusted manually - with a screw. Welding transformers have become more widely used with the following circuit.

 There are three windings on the stationary part of the magnetic circuit, the first is connected to the power source, the secondary winding is connected in series with the winding of the current regulator. The gap between the moving and stationary parts of the magnetic circuit is independently adjustable.

 This welding transformer circuit, like the device itself as a whole, differs from the previous one in its compactness and low cost of production.

The photo shows the device of the TDM series welding transformer, represented by a schematic image:

• Pos. 1 – primary winding of the transformer made of insulated wire.
• Pos. 2 – the secondary winding is not insulated, with air channels for better cooling.
• Pos. 3 – moving component of the magnetic circuit.
• Pos. 4 – transformer suspension system in the unit housing.
• Pos. 5 – air gap control system.
• Pos.6 – air gap control lead screw.
• Pos. 7 – control screw drive handle.

Source: http://zapiski-elektrika.ru/elektrooborudovanie/kak-ustroen-svarochnyj-apparat.html

DIY welding machine from a transformer

Equipment for welding work does not have to be purchased in a store. It can be made in a home workshop. After all, in fact, the design of the simplest device is elementary and assembling a welding machine with your own hands is not difficult. To do this, you only need some components and a little knowledge of electrical engineering.

How to make simple and, at the same time, functional machines for welding work and what is required for this - more on this later in our article.

What is needed for welding assembly

To assemble a simple welding machine, you need to understand the principle of its operation.

All welding work is based on the conversion of electrical current from the network. For domestic use, we have access to electricity with a voltage of 220 volts and a current of 16-32 amperes.

As we know, this is not enough for welding.

A welding arc requires power, and it is provided by current, measured in amperes (in simple terms, this is the number of electrons supplied to the electrode). The more charge, the more productive the device will be.

To increase power, transformers are used that lower the voltage several times, but increase the flow of electrons, which allows the use of such current to form a welding arc.

A transformer is the main element that allows you to assemble a simple device that runs on alternating current.

The basis of the transformer is a magnetic core (core made of transformer steel), on which windings are wound: the primary, made of thinner wire and a large number of turns. and a secondary one, consisting of a thick cable with the least number of windings.

Magnetic cores for assembling welding machines can be used, for example, from old power transformers.

Power is provided from a household outlet and applied to the primary winding.

The windings should not be in contact with each other. Even if the transformer has windings one on top of the other, there must be a layer of insulation between them! Current from one winding to another is transmitted through the core by magnetic flux.

As welding cables, you can use factory-made products, or select a wire with a suitable cross-section. The main thing is that they must withstand the power of the device.

The holders are made from rods or reinforcement of small diameter. In shape they resemble a three-pronged fork, into the teeth of which the electrode is fixed.

How to assemble transformer welding

To do this, you need to find a working step-down transformer. You can take models S-B22, IV-10, or IV-8, the power of which should be 1-2 kW. Such elements are typically used to power various power tools and reduce the voltage from 220 to 36 volts.

Transformer welding is assembled according to the following algorithm.

• Initially, you need to remove the secondary winding from the transformer, but you must not damage the primary.
• The removed wire is wound onto the primary coil, which is located in the middle of the core. At the same time, for every 30 skeins, a layer is created (8-10 pieces are needed), which are numbered for convenience.
• The other two sides of the core are wrapped with a cable with several cores (at least three copper wires with a cross-section of 6-8mm). Each coil will require up to 12 meters of such wire. This will be the secondary winding of the device (VO).
• The terminals are made of a copper tube with a diameter of 10-12 mm, while the cable is inserted into one end and clamped, the other edge is flattened and a hole is drilled for fastening. The VO cables are attached to this clamp.
• On the transformer, the M6 ​​fastener must be replaced with a more powerful one (located on the top panel). The secondary winding cable is connected to this mount.
• For the primary winding you will need a piece of textolite board with ten holes, in each of which an M6 mount is mounted.
• To ensure operation, you need to connect the primary winding in series from the outer coils, and then from the middle coil. Taps from the secondary winding are inserted into the board holes numbered 1 to 10. The current will be regulated by the terminals.
• The electrode holder can be made from a 5 mm steel bar to which the cable is attached. It is made in the form of a three-pronged fork. A piece of rubber hose is put on the handle.
• You can attach a magnet holder to the mass cable, or you can make a steel hook that can be attached to workpieces.

In such a device, the current in the primary winding will be 25 Amperes, and in the secondary - 60-120 A. Power is provided through a household outlet. The power of the device will ensure excellent operation of electrodes with a diameter of 2 mm. For a triple consumable, the welding time will be limited (non-stop up to 10-15 electrodes, then you need to let the transformer cool).

If you have little experience in electrical engineering, then you need to study in more detail the materials on how to create such a device.

Microwave spot welding

Spot welding allows you to join very thin metal where traditional welding machines would simply burn the part.

The simplest homemade spot welding machine can be assembled with a minimum amount of materials, using an old working microwave, from which you will need to remove a transformer with a power of 1 kW or more. One such element will be enough to weld metal up to 1 mm thick in spots. To increase power, two transformers can be used.

In a microwave, most of the work is done by the magnetron, which requires about 4,000 volts of power. For this purpose, the transformer works not to lower, but to increase the voltage. At the output, such an element gives up to 2000 V.

Source: https://MyTooling.ru/instrumenty/svarochnyj-apparat-svoimi-rukami-iz-transformatora

How does a welding transformer work?

Currently, inverter-type welding machines have become very popular and affordable.

Despite their positive qualities, they, like any other electronic device, sometimes fail.

To repair a welding machine inverter, you need to at least superficially know its structure and main functional blocks.

The first two parts will talk about the design of the welding machine model TELWIN Tecnica 144-164 . The third part will consider an example of a real repair of a welding inverter model TELWIN Force 165 . The information will be useful to all those novice radio amateurs who would like to learn how to independently repair inverter-type welding machines.

There will be a lot of letters further - be patient.

The inverter welding machine itself is nothing more than a fairly powerful power supply. According to the principle of operation, it is very similar to switching power supplies, for example, AT and ATX computer power supplies. You ask: “How are they similar? These are completely different devices.” The similarity lies in the principle of energy conversion.

The main stages of energy conversion in an inverter welding machine:

1. Rectification of alternating voltage 220V;

2. Converting direct voltage to high frequency alternating voltage;

3. Reducing high frequency voltage;

4. Rectification of reduced high-frequency voltage.

This is brief, so to speak, on the fingers. The same transformations occur in switching power supplies for PCs.

The question arises, why do we need these dances with a tambourine (several stages of voltage and current conversion)? And here's the thing.

Previously, the main element of the welding machine was a powerful power transformer. It lowered the alternating voltage of the electrical network and made it possible to obtain huge currents (tens - hundreds of amperes) from the secondary winding, necessary for welding. As you know, if you lower the voltage on the secondary winding of a transformer, you can increase the current that the secondary winding can deliver to the load by the same amount. At the same time, the number of turns of the secondary winding decreases, but the diameter of the winding wire also increases.

Due to their high power, transformers that operate at a frequency of 50 Hz (this is the frequency of the alternating current mains) are very large in size and weight.

To eliminate this drawback, inverter welding machines were developed. By increasing the operating frequency to 60-80 kHz or more, it was possible to reduce the dimensions, and, consequently, the weight of the transformer. By increasing the operating frequency of the conversion by 4 times, it is possible to reduce the dimensions of the transformer by 2 times. And this leads to a reduction in the weight of the welding machine, as well as saving copper and other materials for the manufacture of the transformer.

But where can you get these same 60-80 kHz if the frequency of the alternating current mains is only 50 Hz? This is where the inverter circuit comes to the rescue, which consists of powerful key transistors that switch at a frequency of 60-80 kHz.

But for the transistors to work, it is necessary to apply a constant voltage to them. It is obtained from the rectifier. The mains voltage is rectified by a powerful diode bridge and smoothed by filter capacitors.

As a result, the output of the rectifier and filter produces a constant voltage of more than 220 volts. This is the first stage of transformation.

This voltage serves as the power source for the inverter circuit. Powerful transistors of the inverter are connected to a step-down transformer. As already mentioned, transistors switch with a huge frequency of 60-80 kHz, and, therefore, the transformer also operates at this frequency.

But, as already mentioned, to operate at high frequencies, less bulky transformers are required, because the frequency is no longer 50 Hz, but 65,000 Hz! As a result, the transformer is “shrinked” to a very small size, and its power is the same as that of its hefty brother, which operates at a frequency of 50 Hz.

I think the idea is clear.

All this parsley with the transformation has led to the fact that a bunch of all sorts of additional elements appear in the circuitry of the welding machine, which serve to ensure that the device works stably. But enough theory, let’s move on to the “meat”, or rather to the real hardware and how it works.

The design of an inverter-type welding machine. Part 1. Power block

It is advisable to understand the structure of a welding inverter using the circuit diagram of a specific device.

Unfortunately, I did not find a diagram for the TELWIN Force 165 , so we will brazenly borrow the diagram from the repair manual for another device - TELWIN Tecnica 144-164 .

Photos of the device and its contents will be from TELWIN Force 165, since it was this one that was at my disposal. Based on the analysis of the circuit design and element base, there are practically no special differences between these models, if you do not take into account the little things.

Appearance of the TELWIN Force 165 welding board indicating the location of some circuit elements.

The schematic diagram of an inverter-type welding machine TELWIN Tecnica 144-164 consists of two main parts: power and control .

First, let's look at the circuitry of the power section. Here's the diagram. The picture is clickable (click to enlarge - will open in a new window).

Mains rectifier

As already mentioned, first the 220V alternating current is rectified by a powerful diode bridge and filtered by electrolytic capacitors. This is necessary so that the alternating current of the electrical network with a frequency of 50 hertz becomes constant. Capacitors C21, C22 are needed to smooth out the ripples of the rectified voltage, which are always present after the diode rectifier. The rectifier is implemented according to the classic diode bridge circuit. It is made on a PD1 diode assembly.

You should know that the voltage on the filter capacitors will be 1.41 times than at the output of the diode bridge.

Thus, if after the diode bridge we get 220V pulsating voltage, then the capacitors will already have 310V DC voltage ( 220V * 1.41 = 310.2V ).

Typically, the operating voltage is limited to 250V (the voltage in the network may be too high). Then at the filter output we will get all 350V. That is why capacitors have an operating voltage of 400V, with a margin.

On the printed circuit board of the TELWIN Force 165 welding machine, the elements of the mains rectifier occupy a fairly large area (see photo above). The rectifying diode bridge is installed on the cooling radiator. Large currents flow through the diode assembly and the diodes naturally heat up. To protect the diode bridge, a thermal fuse is installed on the radiator, which opens when the radiator temperature exceeds 90C 0 . This is an element of protection.

Source: https://crast.ru/instrumenty/kak-ustroen-svarochnyj-transformator

Design of welding transformers: operating principle and characteristics, common faults - Machine

• Welding transformers are indispensable for manual arc and some types of industrial welding.
• These are devices designed to convert voltage from the citywide network to the optimal voltage for the welding machine.
• A welding transformer reduces the voltage to no-load voltage and ensures uninterrupted operation of such a device.

This process is based on the simplest principle of electromagnetic induction: the difference between the number of turns in the primary and secondary windings determines the conversion coefficient, and the ability to control the dissipation of the magnetic field by moving the moving parts of the device allows you to regulate the output voltage.

The current passing through the magnetic circuit creates an alternating voltage in each turn of the coil, which is summed up at the output into the optimal voltage.

To quickly carry out complex welding work, professionals use plasma welding technology. Plasma welding is a rather complex process that requires appropriate skills and abilities.

For high-quality welding work, it is important to choose the right consumables. Read here about how to choose stainless steel welding wire.

The design of a welding transformer is quite simple, so many amateurs prefer not to buy, but to make a welding machine for home:

1. The central part is a core (magnetic core), consisting of several steel plates isolated from each other. For homemade welding machines, it is recommended to assemble it from electrical steel plates taken from “donor” equipment.
2. One or more windings with insulated wire are placed on the core. The primary winding is always one, current is supplied to it from the network, the remaining windings are secondary.
3. Adjustment of the output voltage in different designs is achieved through the movement of the lead screw passing through the magnetic core and winding, and the movement of movable windings (in most designs the mains winding is stationary).
4. The housing protects the device from damage.
5. Additional elements (ventilation, handles, wheels for convenient movement of heavy models).

  Selecting a Welding Table

Homemade designs

On amateur devices, the winding terminals are simply made on copper terminals; factory versions are equipped with more reliable switches.

The detailed diagram of the welding transformer depends on the type of core (rod or toroidal) and the materials available to the master.

A more complex device has a transformer for a welding inverter, the difference is the presence of several converters in which alternating current is converted at the first stage into direct current, and then into alternating current, but of a given voltage. In addition, the design is complicated by the addition of electronics, allowing more precise control of the process.

The weight of an AC welding transformer depends on the model, the lightest ones weigh from 3 kg, but more often on the market you can find models weighing from 10 kg.

Types and characteristics of welding transformer

1. The power of a welding transformer of industrial models is sufficient to provide several jobs; these are multi-position devices with a complex structure.
2. Single-post models are used in everyday life.

Separation by phase regulation:

1. Single-phase models operate only at a voltage of 220V. The current output from such devices is sufficient for domestic needs.
2. Three-phase welding transformers operate at a network voltage of 380V; they provide a higher output current, which allows welding metal of greater thickness. There are models that are designed to operate at both 220V and 380V.

When welding soft metals, there is a danger of burning through them. Welding aluminum with an inverter must be carried out very carefully and using appropriate consumables.

Simple garage welding work can even be carried out independently. Find out how to use semi-automatic welding using this link.

And if you do not have the appropriate welding machine, you can use cold welding. For example, read here whether it is possible to cold weld a muffler.

According to the design of the device, they are distinguished:

1. Models with rated magnetic dissipation. They consist of two parts: a transformer and a choke for voltage regulation.
2. Products with increased magnetic dispersion have a more complex design consisting of several moving windings, a capacitor or pulse stabilizer and other elements.
3. Thyristor models are a relatively new type of such devices. They consist of a power transformer and a thyristor phase regulator. Thyristor models have less weight compared to other types.

  5 Features of Electric Arc Welding

Operating principle

A transformer for spot welding must produce an output current of 5-10 kA for low-power models and up to 500 kA for high-power models, so the secondary winding is made in one turn.

A transformer for contact welding must have a high conversion coefficient, and the interrupting devices must have reliability and a rather complex device, otherwise the quality of welding will suffer.

A transformer for welding wires, on the contrary, is a very compact and cheap device that replaces an expensive welding inverter. The performance requirements will not be the most stringent: the nominal voltage is about 9-40V. Even an amateur can assemble such a device.

When making and purchasing such a device, you should pay attention to the basic characteristics:

• Mains voltage – the number of phases in which the device operates depends on it.
• Rated welding current - for household models it is around 100A, professional products can give up to 1000A.
• Wide limits of welding current regulation allow the use of electrodes of different diameters. For household models, the typical values ​​are about 50-200A.
• Rated operating voltage is the voltage at the output of the device. For arc welding, 30-70V is sufficient.
• The rated operating mode determines how long the device can operate continuously.
• Open circuit voltage is an important characteristic for arc welding. According to safety rules, it cannot exceed 80V, but the closer the open circuit voltage is to this limit, the easier it is to cause an arc.
• Power consumption and output power allow you to calculate the efficiency of the device. The higher it is, the more efficiently the device works.

Are you looking for a universal welding machine to work with different types of metals? Use a semi-automatic welding machine. Learn how to work with a torch for a semi-automatic welding machine for high-quality welding.

For each type of welding work, different types of welding machines have been invented, more details in this publication.

When carrying out welding work, do not forget about protection. Read here about the benefits of using chameleon welder shields.

Possible malfunctions in the operation of the welding transformer

  2 types of welding technological devices

The most common cause of problems is a short circuit in the circuit between the elements of the device, which can cause the device to turn off.

To eliminate this malfunction of the welding transformer, you should disassemble the device and replace the faulty element if the cause of the short circuit is obvious (often the source of trouble is the terminal block and the winding near it).

Another common problem is excessive heat. It is caused by setting a current higher than the recommended value.

Constant excessive heating can lead to failure of a key element of the device - it may be necessary to rewind the welding transformer in whole or in part with a wire of the same cross-section.

A strong hum indicates that a bolt or nut has become loose inside the housing. To fix it, you just need to disassemble the product and tighten all connections.

1. After repair, you need to test the welding transformer; if the device is operating normally, you can continue to use it.
2. The design of the welding transformer is simple, and the device itself is reliable and affordable.
3. Welding transformers are widely used by amateurs for arc welding; they can be used to join thin sheets of metal and perform almost any repair of metal parts necessary for a non-professional.

• Thermal pencil for welding A welding pencil in appearance is a tube or rod that is tightly filled with a dry compressed flammable substance, a substance at []
• Welding rectifiers Since the current source for welding inverters is alternating current, to convert alternating current into direct or high-frequency []

Source: https://regionvtormet.ru/okrashivanie/konstruktsiya-svarochnyh-transformatorov-printsip-raboty-i-harakteristiki-rasprostranennye-neispravnosti.html