Why do you need a welding transformer - Metals and their processing

Welding transformer - device, principle of operation and types

Of all the different types of industrial equipment, the most common is the welding transformer. Such a device consists of several key components and is capable of creating a current, the arc of which melts the steel and connects the sides of the product into a single seam.

The equipment is divided into several types according to the complexity of the design, as well as the ability to produce the required voltage.

What is the principle of operation of a welding transformer and its design? What physical processes occur inside the device? How can some products differ from others? The article and video will fully cover these issues.

Welding transformer device

To melt metal with an electric arc, it is necessary to change the parameters of the current consumed from the network. In the device, it is upgraded so that the voltage decreases (V) and the current increases (A). Welding metal with this equipment is possible thanks to the simple components included in its design. Most models include:

magnetic circuit;
stationary primary winding made of insulated wire;
moving secondary winding, often without insulation, to improve heat transfer;
vertical screw with tape-shaped thread;
screw running nut and fastening to the winding;
handle for rotating the screw;
clamps for output and fastening of wires;
housing with louvers for cooling.

Some AC welding transformers contain additional equipment that improves their operation, which will be described below in the circuits section.

The design of the welding transformer includes a magnetic circuit. The core does not affect the current strength, but only contributes to the formation of a magnetic field. For this, a package of special steel plates is used. Their surface is covered with oxide insulation.

Some models are varnished. If the core were made of solid metal, then the eddy currents (Foucault currents) resulting from the action of the magnetic flux would reduce the field induction.

Due to the stacked components, the core does not form a continuous conductor, which reduces the influence of Foucault currents.

For quieter operation, it is important to tighten the core plates. A loose connection causes the components to vibrate due to the passage of alternating current at a frequency of 50 Hz. But even tight tightening does not eliminate all the noise, so any calculation of a welding transformer implies a hum, which can be heard in the video of its operation.

Operating principle of a welding transformer

The device, consisting of the above-described elements, works according to the following principle:

Voltage from the network is supplied to the primary winding, in which a magnetic flux is formed, which closes on the core of the device.
After this, the voltage is transferred to the secondary coil.
A magnetic core made of ferromagnetic materials, placing both windings on itself, creates a magnetic field. The inducing magnetic flux forms alternating electromotive forces (EMF) in the windings.
The difference in the number of turns of the coils allows you to change the current with the values V and A required for welding. Based on these indicators, the welding transformer is calculated.

There is a direct relationship between the number of turns of the secondary winding and the resulting voltage. If it is necessary to increase the outgoing current, the secondary coil is wound in larger quantities. The transformer for welding is of the step-down type, so the number of turns of the secondary winding is significantly less than that of the primary.

The design and principle of operation of the welding transformer is designed to regulate the strength of the outgoing current by changing the distance between the primary and secondary coils. This is precisely what the moving part of the structure is designed for.

In some videos it is clearly visible that rotating the handle and bringing the coils closer to each other leads to an increase in the welding current. Reverse rotation and separation of the windings helps to reduce the current strength.

This occurs due to a change in magnetic resistance, as a result of which quick voltage adjustment is possible, allowing you to select the welding current depending on the thickness of the steel and the position of the seam.

Idling

The welding transformer has two operating modes: under load and idle. While making a seam, the secondary winding is closed between the electrode and the product. Powerful welding current allows you to melt metal and form a reliable connection. But when the welding is finished, the secondary circuit opens. And the device goes into idle mode.

The electromotive forces in the primary coil have a dual origin. The former are formed due to the working magnetic flux, and the latter by scattering. These EMFs are created by branching off from the main flux in the magnetic circuit and closing between the turns of the coil through the air. It is they who form the value of the no-load current.

Idling must be safe for the life of the welder and limited to 48 V. Some models have an acceptable value of 60-70 V. If the EMF from the leakage flow exceeds these values, then an automatic limiter of this value is installed.

It should operate in less than a second after the circuit breaks and welding stops.

For additional protection of the welder, the body of the device is always grounded so that the voltage that arises on the casing, due to damage to the insulation of the primary winding, bypasses the human body and goes into the ground.

Welding transformer diagram and its modifications

In addition to standard devices for changing current, a welding transformer may contain some improving components. The diagrams of this equipment can be supplemented:

several secondary windings;
capacitors;
pulse stabilizers;
thyristor phase regulators.

Additionally, a resistance is added to the transformer circuit to continue adjusting the current where routing the windings does not give the desired result.

This is in demand when working with thin metal or very powerful equipment models.

The resistance can be in the form of a separate housing with a set of contactors that set a certain Ohm value through which the current from the secondary winding will pass, or an ordinary high-carbon steel spring attached to the ground cable.

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.

Differences and types of equipment

Types of welding transformers are divided according to their intended purpose. They differ in:

Weight and size. From compact ones with a shoulder strap to large ones moved on wheels or by a hoist
The output idle voltage is from 48 V to 70 V.
Current strength is from 50 to 400 A. At large manufacturing enterprises there are models with an indicator of 1000 A.
Current consumption and number of phases - 220-380V. Single and three phase versions.
Pulse current supply or continuous.
Possibility of working with different electrode diameters, from 2 to 6 mm.

Transformer welding is an easy way to get a strong connection. It is well suited for installing fences, welding pipes, creating shelving and gazebo frames. The noise emitted from the device and the crackling sound of the welding arc bring some discomfort from using the device.

Welding transformers are affordable in stores and easy to assemble at home. Their principle of operation is simple, and the operation of the device in the video helps to understand the basics of handling the unit. The quality of the seam is maintained at a high level, so they are widely used in everyday life and industrial applications.

Source: https://svarkalegko.com/oborudovanie/vse-o-svarochnom-transformatore.html

DIY welding machine from a transformer

If you need to perform some simple welding work for domestic needs, it is not at all necessary to purchase an expensive factory unit. After all, if you know some subtleties, you can easily assemble a welding machine with your own hands, which will be discussed below.

Welding machines: classification

Any welding machines can be electric or gas. It’s worth saying right away that homemade welding machines should not be gas. Since they include explosive gas cylinders, you should not keep such a unit at home.

Therefore, in the context of self-assembly of structures, we will talk exclusively about electrical options . Such units are also divided into varieties:

Generator units are equipped with their own current generator. A distinctive feature is its large weight and dimensions. This option is not suitable for home needs, and it will be difficult to assemble it yourself.
Transformers - such installations, especially the semi-automatic type, are very common among those who make welding equipment themselves. They are powered from a 220 or 380 V network.
Inverters - such installations are easy to use and ideal for home use; the design is compact and lightweight, but the electronic circuit is quite complex.
Rectifiers - these devices are easy to assemble and use for their intended purpose. With their help, even a beginner can make high-quality welds.

How to make an inverter-type welding machine

To assemble an inverter at home, you will need a circuit that will allow you to comply with the necessary parameters. It is recommended to take parts from old Soviet devices:

transistors;
diodes;
chokes;
finished transformers;
capacitors;
resistors;
thyristors.

The following parameters can be selected for the device:

It must work with electrodes whose diameter does not exceed 5 mm.
The maximum operating current is 250 A.

Source: https://moy-instrument.ru/instrumenty/svarochnyj-apparat-svoimi-rukami-iz-transformatora.html

Welding transformer: what it is, how it works and how it works, why it is used

A welding transformer is a classic type of equipment for welding metals. Its history goes back more than 100 years.

The welding transformer has proven to be an unpretentious but reliable technique, capable of welding very thick-walled parts. It has a fairly high level of welding current. In the 21st century, welding transformers have somewhat lost demand.

After all, companies began to produce inverters with suitable functionality and at a relatively low price. However, for the older generation of craftsmen it remains an important tool in their work.

A description of the transformer device for welding metals, its types and application can be found in this article. It will help you understand the basics of welding metals using this machine and select the appropriate model.

As well as mains voltage parameters, functionality, number of work stations and methods for changing current strength.

general information

Transformer type welding equipment is a classic among welding equipment.

Its main task is to convert the mains voltage from 220-380V to lower values, or to increase the missing voltage level to operating parameters.

Regardless of the year of manufacture, they are used for manual arc welding using coated electrodes.

The welding transformer is suitable for all types of work, domestic or industrial.

In the twentieth century, this type of welding equipment was used for professional welding, but by the end of the century they began to give way to more compact inverters - equipment of a new generation. But they are still used by many craftsmen.

The advantages of welding transformers include the low cost of the device itself and its parts. Combined with the simplicity of the device, this allows you to carry out repairs yourself in case of malfunctions.

Such devices are quite powerful, capable of welding thick-walled parts. At the same time, they are unpretentious in storage and easy to use.

However, the device also has disadvantages. Large size and weight reduce mobility. Difficulties in ignition and instability of the welded arc affect the speed and quality of the work of an inexperienced craftsman.

There are no switches to adjust the current strength - this occurs by changing the inductive reactance value. Or by adjusting the secondary type of open circuit voltage.

The structure of the transformer apparatus and the principles of its use

The transformer consists of 2 units: transformer and regulator. The first is designed to reduce the voltage level that comes from the 220-380V power supply. The second is responsible for setting the required current strength.

There are several types of transformer units. They depend on the voltage level that ensures stable operation of the device. There are three main types of transformers: single-phase, two-phase and three-phase.

The single-phase model is equipped with a core and two windings. A two-phase one consists of two single-phase elements, and a three-phase one contains three single-phase elements.

The control unit consists of a saturation choke. The current is adjusted by changing the gap of the choke magnetic circuit. To do this, you need to remove the case cover, which is not very convenient.

Therefore, craftsmen often modify the transformer on their own, equipping it with an external handle, which is used to regulate the current strength mechanically.

Transformer and control units are the basis of a welding transformer. However, besides them, it includes other devices.

They do not complicate the mechanism too much, so devices of this type rarely suffer from malfunctions. And in the event of a breakdown, you can carry out repairs yourself.

Operating principle of a transformer unit

The operating principle of welding devices works on converting current from direct to alternating. This is done in order to ignite the arc.

However, transformer units for welding metals are designed differently. They are devices that perform work using direct welding current. For it, it is enough to adapt the mains voltage to a level suitable for welding.

The transformer unit included in its package copes with this task. With its help, the voltage received from the electrical network is reduced to the operating value.

And the adjustment unit adjusts the strength of the welding current. The principle of operation is simple and clear. An additional element in the work will be grounding.

Types of transformers for welding metals

The classification of transformer equipment for welding works falls into several categories:

Mains voltage
Functional
Methods for adjusting welding current
Number of work posts.
Let's study the classification categories in more detail.

The transformer for arc welding is suitable for power supply from 220-380V mains. Compatibility with different mains voltages depends on the number of phases in the device.

There are 3 types of devices (single-phase, two-phase and three-phase). The first type is compatible with 220V voltage. Three-phase is suitable for working with a 380V outlet. Two-phase models are quite rare.

Combined transformer models work with any mains voltage.

Functionality

This criterion determines the purpose of the device model. There are 3 types of transformers based on functionality: household, professional and industrial. They have different characteristics and functions.

The residential type has limited 200A capabilities. While the professional one is capable of generating over 300A. This allows them to work with fairly thick metal parts.

For complex tasks, the industrial type of welded transformers is suitable. However, now in industry most of them have been replaced by more technologically advanced models.

THIS IS INTERESTING: What is checked when inspecting welding materials

Number of working posts

Transformer type welding equipment is used for a different number of work stations. Their number depends on how many welding cables can be connected to the machine.

Conventionally, transformers are divided into two types. Single-post and multi-post. The first type provides one workplace. That is, it is possible to connect only one cable to it for the operation of one master.

The second type is designed to connect 3-6 welding cables, allowing the same number of workers to work simultaneously.

Methods for regulating the strength of welding current

One of the main transformer parts is the adjustment unit, consisting of a saturation choke. It adjusts the strength of the welding current by changing the distance between the coils. But there are other ways to regulate this indicator.

Adjustment of the strength of the welding current is carried out not only using a saturation choke.

You can use a magnetic gap choke, a movable or magnetized shunt, a reactive or dissipative winding, or a movable type of capacitor coil. As well as thyristor regulators or pulse stabilizers.

Varieties of transformer models provide the opportunity to choose the one that suits you. When determining which model to take, it is worth proceeding from the work tasks for which it will be used.

For household work, a single-phase single-station welding unit with a current strength of up to 300A and adjustment by a saturation choke is suitable. These models are easy to use and store.

Conclusion

A welding transformer is a simple, understandable unit for welding metals on a domestic or industrial scale. They are being replaced by mobile and technologically advanced inverters.

However, even now they have capabilities that ensure their use in welding.

Using transformers for welding work, you can connect even thick-walled parts and carry out welding of any complexity. However, this requires experience and skill sufficient to create smooth, durable seams.

The ability to work with welding transformers ensures quick adaptation to easier-to-use models.

Source: https://prosvarku.info/apparaty/svarochnyj-transformator

Welding transformer - device and principle of operation, what it is used for, types

A welding transformer is equipment used for manual arc and other types of welding. Depending on the model and technical characteristics, there are household and industrial varieties. A welding rectifier or transformer converts the network electricity to the required value. The device consists of several main components. Their combined action forms an electric arc. It melts the metal, connecting the parts with a weld.

Design

The design of the welding transformer is quite simple. Many craftsmen manage to assemble the device themselves. A transformer with the simplest design for a welding machine works when connected to a single-phase network. It has three main elements:

magnetic drive (core);
primary stationary winding;
secondary moving winding.

The magnetic drive is an element made of ferromagnetic steel with a closed loop. The primary winding is connected to the network, and the secondary winding is connected to ground and the electrode holder. The circuit resistance decreases, their electromagnetic coupling increases.

More advanced designs include a throttle and other additional elements.

Principle of operation

The principle of operation of a welding transformer is to gradually lower the voltage to a level of 60-80V and simultaneously increase the current to 40-500 A. The device most often supports alternating current during operation. However, there are other varieties that produce a constant electrical current. They are called rectifiers.

The equipment operates according to the same principle. When voltage is connected, alternating current flows through the primary circuit. It creates magnetic flux. An electromotive force is induced in both windings. It can be correlated with the number of turns of the winding.

For example, the first winding has 100 turns, and the second - 5. The transformation ratio in this case is 100:5 = 20. If this equipment is connected to a household network, the output voltage will be 220:20 = 11V.

To change the load, welders change the gap of the magnetic drive. As it increases, the current decreases. And vice versa. To select the required voltage value for welding, the required number of turns of the secondary winding is determined.

Components

The design of the welding transformer allows you to lower the voltage and increase the current to carry out the metal melting process. These indicators are determined when creating and configuring the device. In order for the equipment to perform the established functions, welding transformers include a certain set of components. In addition to the magnetic drive and two windings, the design includes:

vertical screw with tape-type thread;
handle for its rotation;
screw running nut;
suspension system (protects against damage);
clamps for fastening and exiting wires;
housing with ventilation grille.

Some welding transformers with variable current may use additional elements to facilitate the work of the master.

Additional nodes

Welding three-phase and single-phase transformers and rectifiers may have several additional components. They allow you to improve the operation of the device. Such nodes can be:

capacitors;
additional secondary windings;
pulse stabilizers;
thyristor phase regulators.

The unit comes with a movable shunt. The distance between the windings does not change due to the movement of the secondary winding, but with the help of an additional part. The shunt will change the gap distance. Also, the presence of a special sectional winding, arranged according to a different principle, helps regulate the voltage.

An industrial or household welding transformer sometimes needs additional resistance. The master is given the opportunity to continue the adjustment. Additional possibilities appear without the process of winding separation. Using such a device, a master will be able to weld very thin or thick sheets of metal.

The resistance can be made in the form of a separate housing. It contains a set of contactors. These elements set the required resistance value.

Varieties

The design and operating principle of an industrial or household welding transformer determine its technical characteristics. There are different principles for classifying equipment. According to their intended purpose, single-post and multi-post devices are distinguished. In the first case, the device is intended for domestic use. It is installed in inverters with a power of 3-10 kW. The household network is not designed to use a device with a power of more than 10 kW.

Multi-post devices have a complex design. They are used in professional, industrial devices with a power of 10 kW and above. Such a device can serve several workplaces simultaneously.

Based on the phase characteristics, three-phase and single-phase welding transformers are distinguished. There are devices that can switch to different mains voltages. Single-phase units (220 V) are suitable for domestic use, while three-phase equipment (380 V) is required for industrial use. This sign determines the load at the output. A three-phase device can weld thick parts. Single-phase models cannot do this.

Types of construction

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

Equipment with rated magnetic dissipation. It has a choke to regulate the output voltage.
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.
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.

What to look for when choosing?

When choosing welding transformers, you should pay attention to the main technical characteristics. These include the following:

Mains voltage. The indicator must correspond to the value specified by the manufacturer (220 or 380 V).
Range of regulation. The wider the limits, the more options available to the welder. You can choose electrodes of different diameters. Household varieties are characterized by a regulation range from 50 to 200 A.
Rated current. Professional devices produce about 1000 A, and household ones - up to 100 A.
Operating voltage. The output from the arc welding device should be rated at 30-70V.
Welding duration. The indicator determines how long the unit can operate continuously. Household models perform continuous welding for about 15-20 minutes, and professional ones – for several hours.
No-load voltage. The indicator should not exceed 70 V.
Power consumption. The higher this indicator, the more efficiently the equipment operates. However, it is necessary to take into account the capabilities of the household network. Too much load may be unacceptable.

When choosing, you must consider the purpose for which the equipment is purchased. In this case, you will be able to buy a unit with optimal performance at an affordable price.

Possible faults

Welding transformers can fail for several reasons. In most cases, repairs can be done yourself. To do this, it is necessary to determine the cause of the failure.

Most often, the welding machine fails when there is a short circuit. It occurs between structural elements. A short circuit causes the device to shut down. To resume operation of the unit, it is necessary to disassemble it. The faulty element will need to be replaced. Most often, the cause of such a breakdown is the terminal block or the winding passing next to it.

The second reason for device failure is overheating. It occurs if the voltage value is set higher than that recommended by the manufacturer. If this problem occurs frequently, the rewind will need to be partially or completely replaced. To do this, purchase a wire with the same cross-sectional diameter.

If during operation there is strong noise or buzzing, you will need to disassemble the housing. The cause is a loose nut or bolt. All connections will need to be tightened.

After repairs, the operation of the equipment is tested. If everything is in order, you can start welding again. The design of the unit is simple and reliable. Therefore, breakdowns and malfunctions in its operation rarely occur.

Welding equipment is widely used by both amateurs and professionals. Using such a device, you can connect thin and thick workpieces, sheets of various materials using an electric arc. Depending on the purpose and conditions of use of the equipment, you should purchase a device with the required technical characteristics.

Source: https://derevyannie-doma.com/instruktsii/ustroystvo-i-princip-deystviya-svarochnogo-transformatora.html

Design and principle of operation of a welding transformer

Welding transformers are structures for manual, automatic, arc welding of parts. They can be roughly divided into household and professional devices depending on their technical characteristics. The resulting electricity is processed to the required value for the device. This is the principle of operation of a welding transformer. The device consists of several units, which together form an electric arc.

Device design

The device diagram is not complicated. Many users are able to independently assemble such a structure. The simplest welding scheme will work in one phase. But this is more than enough.

It consists of three components:

magnetic drive or core;
first layer of winding;
second layer of winding.

An element such as a magnetic drive or core is a part made of a ferromagnetic alloy with a closed loop. The first layer of the winding is connected to the network, and the second is directed to the ground and the electrode holder, which directly carries out welding. In this case, the circuit loses resistance, and the electromagnetic coupling increases.

But this is the design of the simplest model. More professional models also have additional elements, such as a throttle and others.

The complete design of an ordinary welding transformer consists of the following elements:

core;
box holder;
clip for connecting wires;
metal box;
cooling blinds;
lever;
bolt;
structure cover;
vertical screw;
screw nut;
primary and secondary windings of the transformer.

Operating principle of the device

The welding transformer operates according to the following algorithm: the voltage gradually decreases to 55-80 V, and at the same time the current increases to 50-450 amperes. In operation, such a design mainly functions thanks to the principle of alternating current. But there are alternative models that produce direct current. There are also names - rectifier welding machines.

The equipment works in a similar way. After connecting to the network, alternating current flows through the primary circuit, which creates a magnetic field. Electric force passes through both the first and second windings. It can be determined depending on the number of turns of the winding.

Source: https://pochini.guru/instrument/ustroystvo-svarochnogo-transformatora

What is a welding transformer?

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.

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.

Features of the application and design of welding transformers

With the advent of electricity, it became possible to connect metal elements using welding. For this purpose, special welding transformers are used, operating from three-phase and single-phase voltage. Single-phase models are designed for inclusion in a standard 220 Volt household network.

A three-phase welding machine is most often used for production purposes; it has great power, dimensions and long-term operation without interruption. However, there are also universal devices on the market for this equipment that can operate on both 220 V and 380 V.

Of course, different materials have their own individual welding process, so each welding unit is equipped with an adjustment and fine-tuning system.

Operating principle of a welding transformer

According to the principle of operation, it does not differ from another conventional step-down transformer, only the currents in the secondary winding are very high, since it operates in short circuit mode.

If you short-circuit the secondary winding of a conventional transformer, then it will not work in this mode for long, since it will quickly overheat and fail. The secondary winding of the welding machine is designed for high currents, and therefore is made of large-section copper wire.

The voltage U2 (at the terminals of the secondary winding) directly depends on the number of turns in it.

Of course, it’s not enough just to reduce the output voltage; you also need to change the current. To achieve this, transformers are equipped with a mechanism that moves the windings further apart, thereby reducing the magnetic flux, which, in turn, reduces the current in the secondary winding.

THIS IS INTERESTING: What can be made from a welding machine

Design and classification of transformers used in welding machines

Features of application and design of limit switches

Any transformer for welding various metal elements consists of:

Magnetic cores;
Insulated primary winding;
Secondary winding;
Fan for cooling.

Depending on the welding work, the welding process is controlled; all welding units are divided into AC and DC devices. Of course, the transformer itself cannot operate on direct current, so the rectification process itself is carried out after lowering the voltage. For this purpose:

controlled thyristors, which do not easily provide constant current for welding elements, but change the current strength during this process;
uncontrolled valves diodes, together with a choke.

Purpose of the welding transformer

Features of the application and selection of measuring current transformers

The welding step-down transformer is the key element that creates the arc during welding of metal parts. The voltage at the output of this step-down device operating in short circuit mode is allowed to be no more than 80 Volts.

The manual arc welding process requires electrodes. Household transformers for the home are made according to a single-phase circuit and have small currents when welding.

The main thing is that in domestic conditions it is also worth monitoring the presence of good contact in the socket, since the currents in the primary winding for apartments and houses are also very significant and not every socket will withstand them.

AC Welding Transformers

Methods for calculating various transformer configurations

This design is considered the least expensive, but at the same time has good characteristics for welding ferrous metals.

In order to regulate the current and, accordingly, the arc during this process, the welding unit is equipped with a sliding system that increases the distance between the coils, as well as the area of the core.

Because of their price category, they are very common in production, especially in workshops with outdated equipment. They are quite large in size and are often installed permanently.

And also as a current regulator for a welding machine, separately located chokes are used, which adds inductance to the circuit. The simplest way, but the most effective, to regulate voltage and current during welding is to output several contact points from the secondary winding. Of course, smooth changes in arc strength cannot be achieved in such a device.

DC welding transformers

Such devices are more effective for welding various materials, have smaller dimensions and smooth current control. Any transformer cannot operate on direct current, this is a fact.

The figure shows the simplest diagram of such a unit, which you can make with your own hands. It guarantees stable welding current and arc output characteristics, which is a key aspect of any welding.

Welders know that when working, a positive clamp generates more heat than a negative clamp. Therefore, for different thicknesses of metal it is worth developing your own methodology.

There are also new developments in this industry, so-called inverter-type welding machines. The transformer here operates at higher frequencies, which makes it possible to reduce the dimensions of the device, its weight, and the currents of the primary winding without consequences for creating a high-quality arc.

Welding transformer VDM

VDM devices are industrial welding multi-station rectifiers, often installed permanently and designed for welding stations of electric arc welding using a metal electrode.

Very often, VDMs are connected to a three-phase 380 Volt network. In an explosive environment saturated with dust of various fractions, or containing caustic gas vapors that destroy steel and insulation, operation is strictly prohibited.

Structurally, the VDM has the ability to regulate the current value using a rheostat and a choke.

How to calculate a welding transformer

The manufacture of a transformer for welding work, which should be close in its characteristics to an industrial design, must be carried out using standard calculation methods. This technique is more suitable for a household device; it contains optimal winding values and minimum overall dimensions of the core.

There are two types of core:

armored;
core;
toroidal (round).

At the same time, rod ones have slightly higher efficiency readings (efficiency coefficient) than armored ones.

Before proceeding directly to the calculation of the welding step-down transformer, it is necessary to determine its power, which depends on the amount of current needed for its operation. The most common options are from 70 to 150 A. It would be reasonable to take the maximum permissible secondary winding currents slightly higher, about 180–200 A.

The power of the AC welding transformer, and the machine as a whole, will be equal to:

P = U2 × I2 × cos (φ) / η

where, U2 is the open circuit voltage of the welding transformer, recommended from 30 to 60 Volts, I2 is the welding current, cos (φ) is the phase shift angle between current and voltage. In the case of calculating power consumption, cos (φ) can be taken equal to 0.8; η - efficiency, for this device can be taken approximately equal to 0.7.

It is also worth taking into account the duration of operation of the transformer, since, most likely, it will have to work for more than one hour.

Pdl = U2 × I2 × (PR/100)1/2 × 0.001

OL is the coefficient of work duration per shift, about 20-30% is recommended;

Winding a welding transformer

Winding is often done using existing iron, and here are the formulas for the approximate number of turns

With windings on one arm (figure below, a):

N1 = 7440 × U1/(Sout × I2)

With windings spaced apart (figure below, b):

N1 = 4960 × U1/(Sout × I2)

Source: https://amperof.ru/elektropribory/osobennosti-primeneniya-i-ustrojstva-svarochnyh-transformatorov.html

What is a welding transformer used for: device and principle of operation

29.10.2019

A welding transformer is still used for the installation of metal structures in industry and for self-repairs. Depending on the conditions for which the device is intended, models for household and industrial use are produced. Regardless of the type, the welding transformer remains operational even in adverse weather conditions.

How does a welding transformer work?

The classic design includes the following elements:

magnetic circuit (core);
a rigidly fixed primary coil wound with insulated wire;
movable secondary winding, sometimes uninsulated for better cooling;
vertically located screw with tape thread;
a screw nut secured to the secondary winding;
a handle attached to the upper end of the screw;
terminals for connecting cables.

Welding transformer device

The elements are mounted inside a rectangular housing with longitudinal cutouts on the walls for the passage of air to remove heat.

In the design of a welding transformer, the core does not affect the current parameters, but is intended to transmit magnetic flux between the windings.

The magnetic core is assembled from a package of electrical steel plates, the surface of which is coated with oxide insulation or varnish. In this way, losses due to eddy currents, which are formed when the magnetic flux interacts with a solid conductor, are reduced.

When alternating current passes through the windings during operation, the plates vibrate, producing a rattling sound. To reduce noise, the bag is pulled as tightly as possible.

To improve performance and safety, additional components are installed in the transformer for welding:

fans;
capacitors;
automatic switches for protection against overheating and overload;
several secondary windings;
current regulators on thyristors;
Surge Protectors.

To expand the current control range, when welding thin-walled metal, resistance is added in a separate housing. The required value is set by contactors. You can also use a steel spring as additional resistance by connecting it in series with the ground cable.

Advantages and disadvantages of a transformer over an inverter

When comparing a transformer-type welding machine with an inverter, the advantages include:

the price is 2 - 3 times less;
the design is simpler, since there are no electronic components;
repairs are cheaper;
easy to assemble with your own hands.

Flaws:

weight and dimensions, with equal characteristics, are greater;
higher power consumption when working with the same electrodes;
arc instability due to mains voltage fluctuations;
lack of additional functions that even budget inverters have.

Despite the shortcomings of transformers, we must not forget that the quality of the seams does not depend on the complexity of the apparatus, but on the skill of the welder.

Classification of welding transformers

According to their intended purpose, the devices are classified as single-station for household needs and multi-station. The power of the former usually does not exceed 10 kW, since the home electrical wiring cannot withstand the heavy load. An industrial multi-station welding transformer with a power of 500 kW supports a current of up to 1000 A. This is enough for the simultaneous work of several welders.

Depending on the connection diagram of the welding transformer, one or three-phase voltage is supplied to the primary winding. There are models with a 220/380 V switch. For domestic needs, single-phase 220 V equipment is produced. Three-phase welding transformers for industrial use are designed for connection to a 380 V network.

Classification by design contains the following types of devices:

With amplitude control at rated magnetic dissipation. The output voltage is changed by a choke, which is located on the core.
With amplitude control, but increased magnetic dissipation. Moving or spaced windings, shunts, capacitor or pulse stabilizers are added to the design.
With phase regulator based on thyristors.

The first two categories include varieties with current regulation by changing the magnetic resistance of the core or voltage without changing the shape. Phase controllers convert a sine wave into a sequence of rectangular pulses of different polarities.

DC devices are also produced with a rectifier installed at the output. Due to their large dimensions and price, they are classified as industrial equipment. This welding transformer allows you to work with workpieces made of non-ferrous metal and stainless steel.

What parameters to consider when choosing

When going for a transformer welding machine, you need to know about the operating conditions and the type of work performed. The choice is made according to the following parameters:

Mains voltage (220 or 380 V) at the workplace.
The voltage at idle is no more than 70 V. But at a low value it will be more difficult to ignite the arc.
Input and output power. The smaller the difference between them, the greater the efficiency of the transformer welding machine.
Rated welding current. For domestic models, the value does not exceed 200 A, semi-professional ones are designed for 300 A, and industrial ones are designed for up to 1000 A.
Adjustment range. Household models are capable of changing the current within the range of 50 - 200 A.
Duration of continuous operation. With household machines you can weld without a smoke break for 15 - 20 minutes, and with industrial machines for up to several hours.

Despite its simple design, the welding transformer provides high quality seams. Therefore, they are still widely used for domestic and industrial welding. Due to its low price, a single-phase device will quickly pay for itself even when carrying out occasional work.

What is a welding transformer used for: device and principle of operation Link to main publication

Source: https://svarkaprosto.ru/oborudovanie/svarochnyj-transformator

Welding transformer device

A welding transformer for performing manual arc welding, as well as some types of industrial welding, is considered an indispensable tool. Such devices convert the voltage they need from the citywide power grid.

Such equipment is capable of reducing the voltage to the no-load voltage of the welding transformer, thereby ensuring its uninterrupted operation.

Types of transformer welding

Today there are different types of welding transformers, which differ in design and operating principle. The most popular on the market among them, which you can make yourself, is considered to be a welding transformer for arc and resistance welding.

Arc Welding Transformer

Transformers for arc welding are widely used among home craftsmen. There are several reasons for this:

reliable and fairly simple design of the tool;
mobility;
quite wide operating range;
Ease of Management;
good performance.

Of course, in addition to numerous advantages, DC manual arc welding also has a number of disadvantages:

low efficiency rate;
The quality of the weld depends entirely on the level of professionalism of the welder himself.

A transformer for manual welding is usually used in the process of carrying out various construction or repair work, producing metal structures, joining individual metal samples, as well as connecting pipeline communications. Using manual arc welding, you can cut metal and weld it, with different thicknesses.

These types of instruments have a fairly simple design. The welding unit includes:

the transformer itself;
electrode holder;
current regulator;
mass clamp.

It is necessary to highlight the main element of the device - the transformer, which can have a different design. The most popular today are homemade instruments equipped with a magnetic core of a U-shaped, toroidal configuration.

Two windings of aluminum or copper wire are placed around the magnetic core. The thickness of the wire on the windings depends on the operating characteristics of the unit and the number of turns made.

Spot Welding Transformer

This type of welding is also called resistance welding. The TS transformer has characteristic differences from a tool designed for arc welding. The key one is the technology of welding metal samples.

For example, melting by arc welding is carried out by an electric arc, which is formed between the electrode and the product being welded, while in the case of resistance welding, the welded area is spot heated with electricity (for which two sharpened copper electrodes are used), the parts are connected under the influence of high pressure (such Thus, the metal of the welded samples melts at the connection point, after which it merges into one whole).

Spot welding is widely used in the automotive industry, the construction industry, for joining thin aluminum sheets, copper samples, stainless steel, for welding strands, creating reinforced concrete frames from reinforcement, and other metals for which special conditions must be created for joining.

Transformer circuit

When making a transformer (spotter) yourself, you must make a calculation. What parts does the welding transformer circuit include? Any tool of this type includes a copper wire wound on a core. The number of copper wires for the main apparatus does not matter; it can even be made from a microwave oven.

The overall transformer circuit must include a diode bridge. When the unit is intended for spot welding, the diagram is a little more complicated. Here, in addition to the copper wire and diode bridge, the presence of capacitors, thyristors, and diodes is required. These additional elements will allow you to adjust the current as accurately as possible, plus the quality of the seam will be much better.

The transformer for spot welding has a complex circuit and design. Of course, everyone decides for themselves which welding tool is more suitable at home. The main thing is to know exactly its functional responsibilities.

In order to correctly perform the required calculations, the first thing you need to do is decide on the indicators: winding voltage, welding current.

Transformer calculation

How is a welding transformer calculated?

As mentioned earlier, AC welding transformers include two windings, a core, which are responsible for the key technical characteristics of the tool. Assuming in advance the winding voltage, current strength, and other additional parameters, calculations are made of the core, windings, and copper wire cross-section.

When making calculations, the basis is the following parameters:

U1 is the voltage of the primary winding, which is the mains voltage, from which the welding will work (220V/380V).
U2 – voltage of the secondary winding (no more than 80V). The voltage of electricity created after a step down. It is necessary to excite the welding arc;
I – current strength of the secondary winding (calculated depending on the electrodes intended for the work and the thickness of the metal being welded).
Sc – cross-sectional area of the core (taken in the range of 45-55 cm²). This parameter affects the quality and reliability of the tool.
So – core window area (taken in the range of 80-110 cm²). The parameter is taken from the calculation of excess heat removal, high-quality magnetic dissipation, and the convenience of winding copper wire.
RT – winding current density (2.5-3A/mm2 – for homemade transformers). a rather significant parameter that is responsible for electrical losses on the windings of the tool.

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DIY welding tool

What is the difference between a homemade transformer?

On a homemade household welding unit, the winding is output as standard - to copper terminals; factory-produced options, of course, have more reliable switches. The detailed diagram of DC welding intended for manual welding depends on the type of core (toroidal, rod), and the availability of available parts to the home craftsman.

Transformers for inverters are difficult to assemble. In this case, several converters are used to convert the current first into alternating current, then into direct current, but at a set voltage. Also, the device of the tool is complicated by the presence of electronics, which makes it possible to control the welding process much more accurately.

The weight of the transformer for AC welding will depend on the brand. The minimum weight of such a tool can be 3 kg, but on the electrical market you can most often find devices weighing at least 10 kg.

Source: https://electrod.biz/oborudovanie/ustroystvo-svarochnogo-transformatora.html

What is a welding transformer

Welding transformer is a transformer that is widely used in the industrial sector and in everyday life for electric arc welding. Let's consider the design features of welding transformers, the principle of their operation and the types of this equipment.

Design features of the welding transformer

This unit is equipped with the following elements and assemblies:

magnetic core (core); Types of magnetic cores
primary winding made permanently using insulated wires;
a moving coil of the secondary winding, sometimes made of bare wires, to increase the intensity of heat dissipation;
an adjusting screw with a tape-type thread located vertically;
a nut for moving the screw, fixed to the output coil;
handle that controls the screw;
clamping devices designed for fastening contacts;
casing with gaps to ensure heat dissipation.

Welding transformer

The current strength parameters do not depend on the core design. But this unit is necessary to excite the magnetic flux and is completed from a package of plates made of transformer steel.

Manufacturing the core in the form of a single element is impractical due to the large number of losses in the magnetic field due to the formation of eddy currents, which reduce induction.

In order for the unit to operate quietly, it is important to tightly tighten the package of plates, eliminating vibration between them during operation of the transformer.

Different devices may differ in design based on the purpose and performance characteristics for which the transformer is designed.

What is the operating principle based on?

The unit operates as follows:

an electric current is supplied to the input coil, a magnetic field and an electromotive force are created, which is closed on the core;
as a result, its own magnetic flux and electric current are induced on the secondary winding;
the difference in the number of turns of the windings changes the current parameters, allowing one to achieve characteristics that ensure metal melting.

For welding work, a step-down type transformer is used, in which the number of turns on the input coil (primary winding) exceeds the output coil (secondary winding).

Transformer operating principle

The strength of the output electric current can be adjusted due to the movable design of the device - by increasing or decreasing the gap between the input and output coils. When moving the coil apart, the current decreases; approaching it causes an increase in the indicated characteristic. Adjustment is performed by rotating the handle.

The current value is selected based on the thickness and grade of the metal being welded and the location of the weld. The thicker the metal sheets being welded, the greater the current required to be generated at the output coil of the device.

The relationship between the current value and the diameter of the electrode and the thickness of the metal being welded

Idle mode

The unit can operate in two modes:

load;
idle move.

During the welding process, a welding arc is created that connects the output winding with the metal being welded through an electrode. A powerful welding electric current melts the metal being welded and creates a permanent connection. After the welding is completed, the secondary circuit opens and the transformer goes into idle mode.

Electromotive forces of dual origin arise in the input coil:

due to the creation of a magnetic field during operation of the device;
through dispersion - some of them are separated from the EMF on the core and form an no-load electric current.

The unit is designed in such a way that the no-load voltage does not pose a danger to the health of the person performing work using the transformer.

The idle voltage value is limited to 48 V, in some cases a value of up to 70 V is allowed. For safety purposes, a limiting device is installed that reduces the voltage when the specified value is exceeded, operating in automatic mode.

Additional protection is provided by grounding the device.

Features of the circuit and modifications of the device

In addition to standard devices, additional elements can be used in the welding transformer to improve the design of the unit. The scheme can be performed using:

several output coils;
capacitors;
pulse stabilizers;
thyristor converters.

The circuit can be supplemented with resistors that regulate the current strength if changing the distance between the coils does not allow achieving the required characteristics. These elements may be required if thin metal is to be welded, or the power of the equipment is excessively high.

Features of calculating transformers for welding

The reduction in current characteristics is ensured by calculating the number of turns on the primary and secondary windings. The output voltage parameters are reduced relative to the input by 10 to 100 times.

To ensure the required performance, the number of turns on the windings must be carefully calculated. The error is allowed within 3%.

Each device is characterized by its own transformation ratio, defined as the quotient of the current at the input and output. Taking into account the calculated data, equipment is created with characteristics depending on the expected operating modes and parameters of welding joints.

The calculation is carried out taking into account the following characteristics and nuances:

operational indicators - type of connected electrical network, adjustment range, actual power, duration of continuous operation;
the diameter of the electrode for which the device is designed;
operating conditions;
efficiency of the unit.

Some of the above characteristics are interconnected.

Types of welding transformers

This equipment is produced in various types, based on operating conditions and purpose. The devices may differ in the following characteristics:

weight and overall dimensions - from compact models carried on a shoulder strap to industrial units moved on wheels or lifting mechanisms;
voltage at idle – in the range from 48 to 70 V;
current strength ranging from 50 to 400 A. In large-scale production, models with a value of this characteristic up to 1000 A can be used;
number of phases of the electrical network - models with one and three phases;
supply of electric current - continuously or pulsed;
The diameter of the electrodes for which the device is designed is from 2 to 6 mm.

Modern industry produces many types of welding transformers. A household consumer can select a product based on the characteristics of the intended use and taking into account the manufacturer’s pricing policy.

Prices for household models of welding transformers range from 4 to 20 thousand rubles, depending on the characteristics and manufacturer. The choice of the consumer depends on his financial capabilities and the purpose of the device.

Welding transformers are equipment that is indispensable in everyday life and in industry. Using these units, you can obtain a reliable and permanent connection, without much effort or difficulty. Affordability allows a household user to purchase a device for use at home, and understanding the device and operating principle is not particularly difficult.

How to choose a welding transformer

When choosing equipment, it is necessary to take into account the tasks and, based on this, purchase a model. The following classes of devices are produced:

household - for minor work at home. Involves operation for up to 10 minutes, after which a break is required. The welding current does not exceed 200 A;
professional – used when performing structural repairs and is designed for long-term operation. Welding current indicators – from 200 to 300 A;
industrial - used in production. They assume the possibility of continuous operation throughout the day with minor pauses. Manufactured with welding currents from 250 to 500 A.

In addition to the class and current value, when choosing a device, you should take into account the rated voltage for which it is designed. Household networks assume a voltage of 220 V, with the possibility of deviation in one direction or another up to 15 percent.

Another important factor is cost. Everyone must choose based on price, depending on the previously listed criteria and the manufacturer's policies.

How to make a welding transformer with your own hands

Source: https://OFaze.ru/elektrooborudovanie/svarochnyj-transformator

Transformer in a welding machine: calculation and current in the primary and secondary windings

The equipment is divided into several types according to the complexity of the design, as well as the ability to produce the required voltage.

Welding transformer design and characteristics

To create an arc that heats and melts the edges of the workpiece, it is necessary to change the characteristics of the electricity supplied from the network. The welding transformer converts the incoming electricity as follows:

reduces tension;
the current increases.

The following nodes take part in the conversion of electricity:

Welding transformer device

magnetic circuit;
the first winding, assembled from an insulated cable;
moving second winding. It is made of wire without insulation, this is necessary to increase thermal output;
screw pair;
steering wheel for controlling the screw pair;
terminal blocks for welded cables.

Welding units include additional components that are designed to improve their operation.

Trigger device

The starting device includes a magnetic circuit, two windings and terminals. Switches change the voltage and the total number of windings connected to the rectifier. A regulator assembled on the basis of semiconductors (thyristors) is installed in the primary circuit. The second winding, connected to the rectifier bridge, provides two levels of variable voltage.

Transformer trigger device

To operate the starting device, a voltage of 220 V is required. The current ranges from 0 to 120 A, and the voltage reaches 70. In the case of self-manufacturing of the device, a core transformer is taken as a basis, 230 turns are wound on its first winding, 32 on the second. Control panel semiconductors are mounted above the inductor. Forced ventilation is used to cool the entire system.

Magnetic circuit design

The key parts of the magnetic circuit are plates or sheets made of electromagnetic steel. Structural parts include fasteners, housing, etc. Magnetic cores of welding transformers are divided into rod and armored. In rod-type devices, all segments of the magnetic circuit have the same cross-section. In armor-type magnetic cores, only the middle rod on which the windings are installed has a full cross-section.

Types of transformer magnetic cores

The cross-sections of the remaining sections of the magnetic circuit are almost two times smaller. The magnetic flux is closed along them. In sections of the magnetic circuit having a T-shape, each has its own cross-section.

Moreover, its size is three times smaller than the rod itself. For each section, a third part of the flow is closed. The plates included in the packages are coated with a special compound called oxide insulation.

Operating principle of a welding transformer Welding equipment operates according to the following algorithm:

Power is supplied to the first winding. It generates a magnetic flux that closes on the core.
The power is then sent to the second winding.
The magnetic core, which is assembled from ferromagnets, generates a constant magnetic field. The inducing flow produces an emf.
The difference in the number of turns allows the current to fluctuate with the parameters required for welding. The same indicators are taken into account when calculating welding equipment.

There is a relationship between the number of turns on the second coil and the output voltage. That is, to increase the current, the number of turns must be increased. But since the welding transformer is a step-down type, the number of turns on the second winding will be lower than on the first.

The design and principle of operation of the welding transformer provides adjustment of the current value. This is achieved by reducing or increasing the space between the coils. To achieve this, welding equipment contains moving components.

The distance between the windings changes the resistance and this makes it possible to select exactly the current needed for welding.

Homemade device options

It is not necessary to buy a welder; you can assemble the design of a welding transformer with your own hands. To do this, use one of the following methods:

They use an old LATR (autotransformer). The most important thing about LATR is its powerful toroidal core. Two copies of such magnetic cores are taken and a winding is wound on each ring. One will act as a primary, the other as a secondary. The most suitable autotransformer model for such processing is LATR 1M, the original winding of which can withstand current up to 10 amperes.
A magnetic circuit from an old electric motor is used. What can be taken from an engine to make a welder is its stator. It only needs to be freed from the old winding by removing it from the grooves and removed from the housing by breaking or cutting the latter. The core plates should then be fastened with pins and a new winding wound over it. Those engine magnetic cores that have a large diameter and small thickness are better suited for such operations.
Transformers from old color TVs such as TS-310 or TS-270 are converted into welding transformers. These network converters are convenient because they are large in size and have an easily disassembled U-shaped core.

Anyone who knows which welding transformer is best to choose among the models on the market, or has experience in making such a device, share your skills in the comments!