Transformer no-load mode
One of the most used electrical devices is the transformer. This equipment is used to change the magnitude of electrical voltage. Let's consider the features of the transformer no-load mode, taking into account the rules for determining characteristics for various types of devices.
The transformer consists of primary and secondary windings located on the core. When voltage is applied to the input coil, a magnetic field is formed, inducing a current in the output winding. The difference in characteristics is achieved due to the different number of turns in the input and output coils.
Transformer operating principle
What is idle mode
The idle mode is understood as the state of the device in which, when an alternating current is supplied to the input coil, the output coil is in an open state. This situation is typical for a unit connected to the mains, provided that the load to the output circuit has not yet been turned on.
Short circuit mode
How is the idle test performed?
When conducting an idle test, it becomes possible to determine the following characteristics of the unit:
- transformation ratio;
- power loss in steel;
- parameters of the magnetizing branch in the equivalent circuit.
For the experiment, a rated load is applied to the device.
When conducting an idle test and calculating characteristics based on this technique, it is necessary to take into account the type of device.
In this state, the transformer has zero useful power due to the absence of electric current at the output coil. The applied load is converted into heat loss on the input coil I02×r1 and magnetic core loss Pm. Due to the insignificance of heat losses at the input, they are not taken into account in most cases. Therefore, the total value of no-load losses is determined by the magnetic component.
The following are the features of calculating characteristics for various types of transformers.
For single phase transformer
The no-load test for a single-phase transformer is carried out with the connection:
- voltmeters on the primary and secondary coils;
- wattmeter on the primary winding;
- ammeter at the input.
The devices are connected according to the following scheme:
To determine the no-load current Iо, use an ammeter reading. It is compared with the rated current value using the following formula, resulting in a percentage:
Iо% = I0×100/I10.
To determine the transformation ratio k, determine the value of the rated voltage U1н according to the readings of the voltmeter V1 connected to the input. Then, using the voltmeter V2 at the output, the value of the rated voltage U2O is taken.
The coefficient is calculated using the formula:
K = w1/w2 = U1н/ U2О.
The amount of loss is the sum of the electrical and magnetic components:
P0 = I02×r1 + I02×r0.
But, if we neglect electrical losses, the first part of the sum can be excluded from the formula. However, an insignificant amount of electrical losses is typical only for low-power equipment. Therefore, when calculating the characteristics of powerful units, this part of the formula should be taken into account.
No-load losses for transformers with a power of 30-2500 kVA
For three-phase transformer
Three-phase units are tested according to a similar scheme. But the voltage is supplied separately for each phase, with the appropriate installation of voltmeters. You will need 6 units of them. You can conduct an experiment with one device, connecting it to the required points one by one.
When the rated voltage of the winding electric current is more than 6 kV, 380 V is supplied for testing. The high-voltage mode for conducting the experiment will not allow achieving the necessary accuracy for determining the indicators. In addition to accuracy, the low-voltage mode ensures safety.
The following scheme applies:
The operation of the device in idle mode is determined by its magnetic system. If we are talking about a type of device similar to a single-phase transformer or an armored rod system, the closure of the third harmonic component for each phase will occur separately, with a value increasing to 20 percent of the active magnetic flux.
Also read: Stray currents
As a result, an additional EMF arises with a fairly high rate - up to 60 percent of the main one. There is a danger of damage to the insulating layer of the coating with the possibility of failure of the device.
It is preferable to use a three-rod system, when one of the components will not pass through the core, with a circuit through air or another medium (for example, oil), with low magnetic permeability. In such a situation, the development of a large additional EMF, leading to serious distortions, will not occur.
For welding transformer
For welding transformers, idling is one of the modes of their constant use in operation. During welding in operating mode, the second winding is short-circuited between the electrode and the metal of the part. As a result, the edges melt and a permanent connection is formed.
After finishing work, the electrical circuit is broken and the unit goes into idle mode. If the secondary circuit is open, the voltage in it corresponds to the EMF value. This component of the power flow is separated from the main one and is closed through the air.
To avoid danger to humans when the machine is idling, the voltage value should not exceed 46 V. Considering that in some models the value of these characteristics exceeds the specified value, reaching 70 V, the welding unit is equipped with a built-in performance limiter for idle mode.
The blocking is activated within a time not exceeding 1 second from the moment the operating mode is interrupted. An additional protective measure is a grounding device for the welding unit housing.
Measures to reduce no-load current
The current when the transformer is in idle mode occurs due to the design features of the core. A ferromagnetic material exposed to an alternating current electric field is characterized by the induction of eddy inductive Foucault currents, which cause heating of the element.
To reduce eddy currents, the core is not made as a single piece, but is assembled from a package of thin plates. The plates are insulated from each other. An additional measure is to change the properties of the material itself, which makes it possible to increase the threshold of magnetic saturation.
Also read: Types of switchgears (RU)
To prevent a break in the magnetic flux with the appearance of a stray field, the plates are carefully adjusted during the recruitment process. Individual elements are ground to obtain a smooth, perfectly fitting surface.
Losses are also reduced due to more complete filling of the magnetic circuit window. This allows us to ensure optimal weight and dimensions of the unit.
Idling of a transformer is a mode in which important characteristics can be calculated. This is carried out for equipment in operation and at the design stage.
Source: https://ofaze.ru/teoriya/holostoj-hod-transformatora
Classification of welding arc power sources
Electric arc welding requires electricity of certain parameters: high power (amperage), low voltage (voltage). Under the influence of current, a powerful electric discharge is formed between the end of the electrode and the metal being welded, and a large amount of heat is released. Various converters are used as power sources for the welding arc.
Over the history of manual electric welding, devices have been created to ignite the arc that generate alternating and direct current. First there were transformers, after the advent of semiconductors, rectifiers were created. Generators convert energy from burning liquid or dry fuel into electric current. Inverters are new generation sources; their arc power capabilities are much wider than those of transformers.
When choosing a welding machine, it is advisable to take into account the advantages and disadvantages of the devices.
Requirements for welding arc power sources
Any power source for arc welding is selected based on its performance properties:
- The electrode should ignite upon contact with a metal workpiece; the contacts close the electrical circuit.
- When the additive melts, a short circuit is possible drop by drop. The welding machine should not fail in such a situation; the welding arc should be maintained stably.
- Before the arc flashes, a short-term short circuit lasting a fraction of a second occurs between the part and the electrode. The dynamic characteristics of the power source depend on the speed of restoration of the original voltage.
- From the idle mode, the welding equipment should quickly switch to working speed, that is, the voltage from 60–80 volts should drop to the required 18–20 V.
The requirements for all sources used to power the welding arc are the same. The conclusion suggests itself that the efficiency of welding equipment depends on the ability to maintain a stable arc, starting from the moment of ignition. The last point is that regulators and welding machines are designed for a wide range of operating current; it should be convenient to set the required current parameters.
Classification
It is generally accepted to gradate power supplies according to several criteria, determined by the electromechanical properties of electric current sources. Beginner welders just need to know the basic classification criteria:
To power the welding arc, there are two ways to obtain operating current:
- conversion of energy from the power network (single-phase and three-phase welders are distinguished);
- generating electricity operating parameters from another type of energy.
Grouping by type of generated current:
- variable;
- combined, which can be switched from constant to variable and vice versa;
- permanent.
Method of converting electricity: by changing voltage and amperage, by rectification - alternating current is converted into direct current.
Mobility of sources, arc power can be stationary (connection to main power grids) and autonomous (use of portable generators or batteries).
A method for adjusting arc operating parameters (voltage, amperage). In transformers, the number of turns involved changes: the position of the shunt, the mobility of the coil, and the sectioning of the secondary winding.
The gradation of power sources according to the external characteristics of the welding arc current is an assessment of the dependence of the average voltage at the contacts (electrode holder and terminal fixed on the metal) on amperage. The parameters of the current-voltage characteristics of equipment are of two types:
- A falling current-voltage characteristic is characterized by a high open-circuit voltage, up to 2.5 times higher than the operating voltage.
- Rigid is characterized by stable voltage at the terminals during the welding process. The short circuit amperage exceeds the rated welding amperage by 2 or 3 times.
The current-voltage characteristic of the source is determined experimentally. When the power is connected, the voltage at the terminals is measured.
Selecting a Power Source for Arc Welding
Of course, in addition to power characteristics, welding equipment is selected based on mobility, size, and weight. Speaking about the advantages and disadvantages of power sources, it is worth starting with the very first type of welders.
Transformer
Equipment with a secondary winding converts the voltage; due to inductive fields, the voltage from 80 volts can be lowered to 20. This is the simplest and most cumbersome type of welding machine. But it is very reliable, depends little on environmental conditions, and is not afraid of humidity or dust.
You can build a transformer yourself; the required voltage is obtained by a certain number of turns of the secondary winding. The efficiency of the equipment is quite high, the cost is low.
When the amount of work is small, welders with experience prefer to purchase transformers for the garage or home.
Source: https://svarkaprosto.ru/oborudovanie/istochniki-pitaniya-svarochnoj-dugi
Which welding inverter operating at reduced voltage should I choose?
An inverter welding machine is a direct current source for powering an electric arc. A conventional inverter power source for welding reduces dependence on the stability of the electrical network. It is able to withstand a voltage drop from 220 to 180-190V instead of 220. However, if the voltage drops even lower, such a device stops working normally or turns off. Welding inverters with reduced voltage are able to continue working even at the lowest network parameters.
Principle of operation
Inverter welding machine: what does it mean? A welding inverter is a converter of alternating current 220 volts to direct current 70-120 volts . An outdated welding rectifier does the same thing. The quality of the weld made using a transformer-rectifier strongly depends on the stability of the characteristics in the electrical network. The operation of the device itself can greatly influence the stability of the network parameters; when the arc is ignited, voltage surges begin.
What is inverter welding? The welding inverter also outputs 70-90 volts, but the conversion is carried out as follows.
- alternating current 220 volts 50 hertz is rectified and supplied to the input of the high-frequency generator;
- the generator creates a high-frequency (20-50 kilohertz) signal;
- it is fed to a transformer, which reduces the voltage to 70-90 volts;
- the current is rectified by the second rectifier and direct current is supplied to the electrode and the workpiece;
- the electric arc is ignited, the edges of the workpiece are melted, the electrode also melts, forming a cloud of protective gases and replenishing the weld pool;
- after cooling of the seam material, a permanent connection of high strength and durability is formed.
Now it becomes clear what inverter means: it is a converter with double inversion (from the Latin inversio, turning over, rearranging) voltage from alternating to direct and back.
Converting current at high frequencies has made it possible to reduce the weight and dimensions of the transformer many times.
Controlling the process at each stage using electronic circuits made it possible to ensure high stability of the output voltage, its independence from fluctuations in the supply network (within certain limits) and eliminated the negative impact of the inverter itself on jumps in the parameters of this network. In addition, welding inverters provide high stability of the arc, facilitate its ignition and prevent the electrode from sticking.
Welding rectifier device. The low-frequency transformer accounts for the bulky dimensions and heavy weight of the device.
These are the main differences between an inverter and welding rectifiers. Semi-automatic welding machines are also built on the basis of an inverter current source , supplying welding wire to the working area instead of a rod electrode.
If the parameters of the electrical network are significantly lower than 180-190 volts, then a conventional inverter can no longer compensate for such a voltage drop. Often in remote areas it drops to 150 volts.
In this case, inverters that can operate at reduced voltage come to the rescue . in their design there are two blocks designed to correct the situation:
- stabilizer with an extended range; it maintains the specified output voltage, despite fluctuations at the input;
- power factor corrector: an electronic circuit that adapts the operation of the entire device to changing power supply conditions.
These blocks do not perform miracles and do not violate the law of conservation of energy. If the input is below 135 volts, the welding machine will not work .
In addition, only the thinnest electrodes or wire can be used.
The corrector will try to keep the power delivered to the arc at the same level.
Advantages and disadvantages
The main advantages of such devices are as follows:
- the ability to reduce the supply voltage to 135 volts;
- ensuring stable arc power during large amplitude throws;
- compensation of losses when connecting through long extension cords.
There are also disadvantages:
- at reduced voltage you have to work on thinner electrodes or wire;
- the thickness of the workpieces to be welded is also limited;
- the cost of such a device is a quarter higher than a regular one (with equal power and general functionality).
If we compare the main advantages and disadvantages inherent in low-voltage inverter welding machines, the scope of their application becomes obvious. This:
- remote areas with low quality power supply;
- the need to operate from a household electric generator;
- connection via extension cords from 50 meters.
The devices will allow you to make seams of good quality even in such difficult conditions.
Ensuring efficiency
The instability of power network parameters is caused by the uneven distribution of electricity consumers between phases . In old-style networks there is no possibility of automatic phase-to-phase load balancing.
The second reason is severe wear and tear of switching and distribution network equipment, poor insulation condition, and insufficient cable cross-section.
All together these factors lead to the fact that, with a standard value of 220 volts, what is actually measured fluctuates between 140 and 270.
And this situation is typical and familiar for most rural areas, remote from regional centers and major highways.
To cope with network voltage instability and ensure efficient operation of the welding machine, use the following techniques:
- connection through a powerful voltage stabilizer, the power reserve must be at least 40% of the rated value for the inverter;
- use of an inverter-type welding machine with a KKM power correction function;
- inclusion in the circuit of an oscillator that generates high-frequency pulses and facilitates ignition and maintenance of the electric arc;
- selection of welding materials and welding modes to achieve high quality welds.
A powerful stabilizer is bulky and heavy, its price is approximately 1-2 thousand rubles per kilowatt of power. If the stabilizing unit is built into the welding machine itself, this can significantly reduce costs .
The power coefficient correction function also allows you to improve arc stability and seam quality, avoid electrode sticking and burn-through, and also consume slightly less electricity.
Recommended for low power conditions
Conventional models of welding inverters operate reliably in the voltage range from 190 to 240 volts. For markets in developing countries and special operating conditions, leading equipment manufacturers offer specially modified inverters that can operate at lower input voltages. Which inverter is better? When choosing a device, you need to pay attention to the following parameters and features:
- sufficient input voltage range for the area of use;
- Wide range of operating current settings;
- stability of open circuit voltage;
- “hot start” and “anti-stick” options;
- operating temperature range suitable for the climate zone;
- possibility of long-term continuous operation.
A number of models meet these conditions.
Fubag IR 200
The first unit is presented by a well-known German company with factories in China. The new product works stably with electrodes with a diameter of 1.6-5 mm when the voltage drops to 150 volts. Operating current range: 5-200 amperes. The device is equipped with a hot start and arc stabilization option. Retains performance from -10 to +40°C.
Svarog ARC -160
The simplest and most reliable low-power model of a well-known brand is compact and provides a stable arc with input fluctuations from 160 to 245 volts. The output current adjustment range is 20-160.
The device is equipped with a hot start and is capable of working with both conventional fusible electrodes and infusible tungsten electrodes. The disadvantages include the short duration of continuous operation: 40% of the total time.
Interskol ISA 160
The third model also has low power, the current varies from 20 to 160 amperes. During testing, it showed stable operation at a minimum supply voltage of 155 volts.
The device has a hot start, anti-sticking and forced arc mode, as well as a stable open circuit voltage. Can work without interruption thanks to an efficient cooling system.
Aurora PRO Inter 200
This new product stands out for the capabilities of its stabilizer and PFC unit. The test confirmed the ability to cook effectively even from 140 volts. In this case, the operating current develops from 20 to 200 amperes. Supports work with a 100-meter extension cord if the wire cross-section is 2.5 mm2 or more. Can work continuously up to 60% of the total time.
All of the listed models are compact and modest in weight, not exceeding 8 kg . Of course, when working at the lower limit of the supply voltage, you should not rely on the maximum welding current and 5 mm electrodes.
But 1.6 and 2 mm will cook stably, without sticking and annoying burns of thin workpieces and small parts. During prolonged operation, wear and tear on the parts and components of the device's power supply will increase.
It is also important to consider the reputation of the manufacturer . Little-known companies that have recently appeared on the market often offer their products at a low price compared to well-known brands.
At the same time, they promise miracles that contradict the law of conservation of energy, for example, operation at an input voltage of 90 volts. This can only mean one thing: a clear example of false advertising.
In this case, the input voltage will be close to the output voltage, and no matter how much it is converted, it will not be possible to maintain the required current parameters.
Conclusion
Inverters with reduced supply voltage are specially designed for areas with poor power supply conditions. They allow you to weld high-quality seams, but are limited in the thickness of the workpieces to be joined and the welding materials used.
Source: https://svarka.guru/oborudovanie/vidy-apparatov/invertor-rabotayushhiy-pri-ponizhennom-napryazhenii.html
What is the no-load mode of a welding transformer? — Metals, equipment, instructions
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.
Reverse step method of welding long seams
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.
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.
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://spb-metalloobrabotka.com/chto-takoe-rezhim-holostogo-hoda-svarochnogo-transformatora/
Minimum open circuit (and arc) voltage. What is the open circuit voltage of a welding machine
What is What is the open circuit voltage of a welding machine
Thank you for participating! Yes, I want to make either a single-phase with a rectifier (power supply from 380V - from 2 phases), or a 3-phase with a Larionov bridge. More precisely, both have already been wound and tested, but the results are still far from necessary. The fact is that I have a 3-phase network, limited to 6a circuit breakers, so I need to come up with something and build it. So the idea arose to reduce Uxx as much as possible in order to reduce the primary current. I also have a branded transformer that cooks well during breaks, but still, with a continuous seam, it knocks out the plugs, and cooking, constantly waiting for it to turn off, is annoying! In general, now I managed to get some results using single-phase. The arc burns steadily, the electrode melts, but there is no normal penetration or “biting” into the base metal. Uxx was 18.6V from the winding on top of the primary, 21.6V on the winding at a distance from the primary. A voltage booster of 105V was used. So, ANO-21 (2mm) burn, even UONI (which have been lying around for several years), which some welders have recognized as difficult to ignite. And now the main problem is that for some reason a low current flows when the arc burns (when I measured it, I saw 5-10A). It is possible that the arc was held too long when measuring. Short-circuit current 85a. In this regard, let me ask, is it possible to remove current from the transformer, for example, 80A at Uxx=18V? This is the only problem that prevents the implementation of the plan. I think it is necessary to calculate the transformer accordingly, in the role of which I now have a huge torus (external diameter 420 mm, internal diameter - 290 mm, cross-section ~ 78 cm2). It is unknown where it worked before, it seems that it was driven by a powerful electric motor. Powered by 380v. No-load current 1A. The primary is wound with insulated wire in one place of the torus. Previously, he cooked during recess at Uxx=50V.
websvarka.ru
Welding machine - types, device, characteristics, choice
To understand the question of how to choose the right welding machine that could be used in a house or country house, you need to consider all their types and find the best option.
The question is raised by almost all owners of dachas and private houses, because there is always work for a welder on the site. But inviting a master and paying him money for a small amount of work is expensive.
Therefore, it is worth purchasing a welding machine and learning how to perform simple welding operations that do not require exorbitant qualifications.
Types of welding machines
The name electric welding speaks for itself, that is, an electric welding machine is required to connect two metal elements. Manufacturers today offer units operating at 220 or 380 volts. Some models output direct current, others alternating current.
Transformers
Until recently, this was practically the only device with which welding was carried out. It only produces alternating current, and the polarity of the unit constantly changes during the welding process, which is very inconvenient.
This is expressed by the fact that the welding electric arc jumps all the time. Therefore, it is difficult to control; a huge number of sparks are produced during welding.
Hence the low quality of the weld, so only professionals with extensive experience could work with such welding machines.
They were used for welding only ferrous metals. The design of the transformer is simple - these are two step-down transformers with the ability to adjust the output current. True, the range of settings is small, the adjustment is not the most subtle. But this unit rarely broke down, and its repair was not difficult.
The big disadvantage of welding transformers is their heavy weight. Even the lowest-power device weighs at least 50 kg. What can we say about industrial designs that weighed at least 100 kg.
Another negative point is the voltage drop in the supply electrical network, especially when the electrode is ignited. Everyone knows that power surges negatively affect modern household appliances packed with electronics.
Therefore, today welding transformers are a rarity in private homes and country houses. And even if someone has them, they are practically not used and are kept by the owners just in case.
Rectifiers
In principle, this is the same welding transformer, in the design of which a rectifying unit is installed. Rectifiers are often called DC welding transformers. The output of the rectifiers is direct current, which simplifies the welding process. The electric welding arc is stable, but experience is still required. Like the transformer, the rectifier is simple in design; in principle, there is nothing to break here.
Among the disadvantages we can highlight:
- Heavy weight;
- Power is lost on the rectifying unit;
- Voltage drop during ignition and during operation;
- The voltage jumps not only for the owner of the unit, but also for the neighbors.
- The price is higher than that of a transformer.
Inverters
As soon as these welding devices appeared in stores, it was impossible to approach them. Their price was too high. But over time, the element base has changed, and accordingly the cost of the equipment has decreased, and with it the weight of the unit. A modern inverter-type home welding machine produces a current of 160-180 amperes, which makes it possible to weld with electrodes up to 4 mm in diameter. The weight of the device is 3 kg, this is the minimum.
The advantages of this type of welding machines include:
- Stable arc that is easy to control.
- Ease of use: the electrode does not stick, the seam is smooth and tight.
- The device does not sag the voltage in the network; it does not jump during operation of the unit.
- Wide range of welding mode settings. Inverters can weld metal products of different thicknesses. The main thing is to correctly set one or another mode on the device.
Attention! There is one condition that will affect the safety of operation of inverters. They can be plugged into a 220-volt outlet that has a grounding terminal. Since the protection class of welding inverters is IP21, they can be grounded through the power supply.
If you are faced with the question of which welding machine to choose, then you don’t have to think twice and choose an inverter. Of course, with it you will not immediately become a high-quality welder, but you will do many small welding operations at your summer cottage with your own hands.
Semi-automatic welding machines
Since we are talking about welding machines for home and garden use, units of this type are not included in this category. Most often they are used in the field of small businesses, and more specifically, in car repair shops.
Their design is based on one of the welding devices described above, plus a block with which the welding wire is fed automatically. The operating technology of these units is based on welding in a shielding gas zone, which allows the welding of thin parts and products made of non-ferrous metals.
These are ideal welding units with which you can weld thin metal sheets up to 0.8 mm thick. In this case, the seam turns out smooth and beautiful, the sheets do not lead or warp. The only drawback is that this type of welding device cannot weld thick parts. To do this, you will have to purchase a machine with electric arc welding.
The types of welding machines have been reviewed, now you can proceed to the selection to determine the best country or home welding device.
How to choose a welding machine for electric welding
The choice is based on several key parameters.
- Supply voltage. It is clear that this is 220 or 380 volts. This characteristic is important, because all the types of welding equipment presented above, except inverters, respond to the quality of the voltage in the supply network. If the voltage rises sharply, a protective unit is triggered, which turns off the device. At a low voltage value, all welding parameters sharply decrease, which leads to poor quality of the weld. And only inverters can safely operate in the range of 180-250 volts without changing their parameters. As for welding devices operating from a three-phase network, they are practically not used at dachas. Therefore, if we talk about which welding machine is best for the home, then in terms of voltage it is an inverter.
- Open circuit voltage. This is the voltage of the welding machine when it is plugged in, but there is no load on it. Why is it necessary to know this parameter? The thing is that the ease of igniting the electrode depends on it. And the higher this value, the simpler the ignition process, plus the stability of the arc increases. This indicator in modern welding machines varies from 45 to 95 volts. Experienced welders know that open circuit voltage influences the choice of electrode type. If you choose a low-voltage device, it is recommended to purchase rutile-coated electrodes for it. For electrodes with a basic coating, it is better to choose a unit with a high open circuit voltage.
- Output current. This selection criterion will depend on how long the device will operate. That is, periodically or more or less constantly. For most household work, a current of 160-180 amps is suitable. At this current, if you use an inverter, you can cook with electrodes up to 4 mm in diameter. If there is a need to weld thick metal parts, you will have to purchase a device that produces an output current of 190-250 amperes.
- Diameter of electrodes. Basically, this dimensional indicator affects the thickness of the products being welded. The thicker the metal, the larger the electrode diameter required. This relationship is shown in the table below.
| 2,5 | 2 |
| 2,5-3 | 3 |
| 3,2-4 | 4-5 |
| 4-5 | 6-12 |
| 5 | 13 |
And a few general recommendations that determine a good welding machine for home and garden at 220 volts. Much will depend on what tasks you intend to solve on the site. If you plan to weld parts from ferrous metal, then all this can be done using a cheap transformer.
If you plan to weld non-ferrous metals, stainless steel or thin steel structures, then it is better to use a semi-automatic machine. The inverter performs well when welding low-alloy or structural steels.
Although it should be noted that inverter-type equipment, in addition to non-ferrous metal and stainless steel, welds any steel structures.
https://www.youtube.com/watch?v=ZlOj3ebCsbw
At home, the size of the unit matters. Therefore, small and lightweight inverters are the best option for this. Low voltage in the network, which is present in almost all suburban villages, is the reason why the choice is given to inverters. These devices operate at a voltage of 180 volts, some models even at 160 V.
If you are a novice welder, then again it is recommended to opt for inverters. Simplicity of welding is the main criterion for the operation of the device: the electrode does not stick, ignition of the arc is easy, and when the electrode approaches the metal being welded at high power, the inverter immediately turns off. That is, in all respects, this is currently the ideal welding unit for a beginner.
Source: https://katlavan.ru/chto-takoe/chto-takoe-napryazhenie-holostogo-hoda-svarochnogo-apparata.html
What is a welding inverter: principle of operation, diagrams
Modern equipment for electric welding offers many modern solutions for productive and productive work, including a new generation of welding machines - inverters. What is it and how does a welding inverter work?
What is a welding inverter
A modern type inverter is a relatively small unit in a plastic case with a total weight of 5-10 kg (depending on the type and type of model).
Most models have a durable textile strap that allows the welder to hold the unit on himself during work and carry it with him when moving around the site.
On the front part of the case there is a control board for the welding inverter - voltage regulators and other parameters, making it possible to flexibly adjust the power during operation.
Modern welding machines are classified into household, semi-professional and professional, which differ in power consumption, range of settings, performance and other characteristics. Models from Russian and foreign manufacturers are popular with buyers on the market. The ranking of the most popular ones includes KEDR MMA-160, Resanta SAI-160, ASEA-160D, TORUS-165, FUBAG IN 163, Rivcen Arc 160 and other models.
How does a welding inverter work?
The inverter has a different operating principle and performance characteristics compared to transformer power supplies. This device and the operating principle of the inverter welding machine allows the use of smaller transformers than network transformers. Modern inverters for welding are equipped with a control panel that allows you to control current conversion processes.
The principle of operation of a welding inverter can be described in detail according to the stages of current energy conversion:
- Rectification of alternating mains current 220 V frequency 50 Hz;
- Conversion of direct current to alternating current with a frequency of up to 100 kHz;
- Reducing the high-frequency current voltage to 70-90 V;
- Reduced voltage rectification with the ability to adjust the current in the electric arc.
We recommend! reliability of inverter equipment
We invite you to watch the video and consolidate your knowledge of the design and operating principle of a welding inverter
Power consumption of inverters
An important indicator of the operation of a type of equipment is the power consumption of the welding inverter. It depends on the category of equipment. For example, household inverters are designed to operate from a single-phase 220 V AC network. Semi-professional and professional devices usually consume energy from a three-phase AC network to 380 V.
It should be remembered that in a household electrical network, the maximum current load should not exceed 160 A, and all accessories, including power circuit breakers, plugs and sockets are not designed for readings higher than this figure.
When connecting a device of higher power, it may cause circuit breakers to trip, burn out the output contacts on the plug, or burn out the electrical wiring.
Open circuit voltage of the inverter device
The open circuit voltage of a welding inverter is the second important indicator of the operation of a device of this type.
Open circuit voltage is the voltage between the positive and negative output contacts in the absence of an arc, which occurs during the conversion of the supply current on two series converters.
The standard idle speed indicator should be in the range of 40-90V, which is the key to safe operation and ensures easy ignition of the inverter arc.
Duration of switching on the welding inverter
Another important classifying indicator of the operation of inverter welding machines is its on-time (ON), that is, the maximum time of continuous operation of the device.
The fact is that during prolonged operation at high voltage, and also depending on the ambient temperature, the unit can overheat and turn off after different periods of time. The duration of switching on is indicated by manufacturers as a percentage.
For example, 30% duty cycle means the ability of the equipment to operate continuously at maximum current for 3 minutes out of 10. Reducing the frequency of the current allows you to extend the duty cycle. Different manufacturers indicate different PV, depending on the accepted standards for working with the device.
We recommend! Operating principle of a welding transformer
What are the differences from welding machines of previous generations?
Previously, various types of units were used for welding, with the help of which an output current of the required frequency was obtained to excite the arc. Various types of transformers, generators and other equipment had limitations in operation, largely due to their large external characteristics.
Most of the previous generation of machines worked only in conjunction with bulky transformers, which converted the mains alternating current into high currents on the secondary winding, making it possible to excite the welding arc. The main disadvantage of transformers was their large dimensions and weight.
The principle of operation of the inverter (increasing the output frequency of the current) made it possible to reduce the size of the installation, as well as gain greater flexibility in the settings of the device’s operation.
Advantages and main characteristics of inverter devices
The advantages that make the inverter welding current source the most popular type of welding machines include:
- high efficiency - up to 95% with relatively low electricity consumption;
- high duty cycle – up to 80%;
- protection against voltage surges;
- additional increase in power when the arc breaks (so-called arc afterburner);
- small dimensions, compactness, allowing you to conveniently carry and store the unit;
- relatively high level of operational safety, good electrical insulation;
- the best welding result is a neat, high-quality seam;
- ability to work with difficultly compatible metals and alloys;
- possibility of using any types of electrodes;
- the ability to regulate basic parameters during inverter operation.
Main disadvantages:
- higher price compared to other types of welding machines;
- expensive repairs.
Separately, mention should be made of one more feature of this type of welding machine. The inverter device is very sensitive to moisture, dust and other small particles. If dust, especially metal, gets inside, the device may malfunction.
The same goes for moisture. Although manufacturers equip modern inverters with protection from moisture and dust, it is still worth following the rules and precautions when working with them: do not work with the device in a humid environment, near a working grinder, etc.
Low temperatures are another “fad” of all inverters. In cold weather, the device may not turn on due to a tripped overload sensor. At low temperatures, condensation can also form, which can damage internal electrical circuits and damage the device. Therefore, during regular use of the inverter, it is necessary to regularly “blow” it out of dust, protect it from moisture and not operate at low temperatures.
Source: https://svarkagid.ru/instrumenty-i-oborudovanie/printsip-raboty-invertornogo-svarochnogo-apparata.html
Open circuit voltage
A transformer, like any electromagnetic device, has several stable modes in which it can (and should) operate indefinitely.
Transformer operating modes
There are five characteristic operating modes of the transformer:
- Work mode;
- Nominal mode;
- Optimal mode;
- Idle mode;
- Short circuit mode;
Work mode
The mode is characterized by the following features:
- The voltage of the primary winding is close to or equal to the rated value \(\dot{u}_1 ≈ \dot{u}_{1nom}\);
- The primary winding current is less than its rated value or equal to it \(\dot{i}_1 ≤ \dot{i}_1nom\).
Most transformers are used in operating mode. For example, power transformers operate with winding voltages and currents different from the rated ones. This is due to the variable nature of their workload.
Measuring, pulse, welding, separating, rectifying, booster and other transformers are also usually operated in operating mode simply because the voltage of the network to which they are connected differs from the nominal one.
Nominal operating mode
Characteristic features of the regime:
- The voltage of the primary winding is equal to the rated voltage \(\dot{u}_1 = \dot{u}_{1nom}\);
- The primary winding current is equal to the rated current \(\dot{i}_1 = \dot{i}_{1nom}\).
The nominal operating mode is a special case of the operating mode. All transformers can operate in this mode, but as a rule, with larger losses compared to the operating mode and, as a result, with lower efficiency (efficiency factor). Because of this, it is avoided when operating a transformer.
Optimal operating mode
The mode is characterized by the condition:
\begin{equation} k_{ng} = \sqrt{P_{xx}\over P_{kz}} \end{equation}
Where \(P_{xx}\) - no-load losses; \(P_{short circuit}\) - short circuit losses;
\(k_{ng}\) - load factor of the transformer, determined by the formula:
\begin{equation} k_{ng} = {I_2\over I_{2nom}} \end{equation}
Where \(P_2\) is the load current of the secondary winding;
\(P_{2nom}\) - rated current of the secondary winding.
In optimal operating mode, the transformer operates with maximum efficiency, so expression (1) essentially represents the condition for maximum efficiency [2, p. 308] (See “Transformers. Optimal operating mode”).
Idle mode
Characteristic features of the regime:
- The secondary winding of the transformer is open or a load with a resistance much greater than the rated load resistance of the transformer winding (1) is connected to it;
- A voltage is applied to the primary winding \(\dot{u}_{1хх} = \dot{u}_{1nom}\);
- Secondary winding current \(\dot{i}_2 ≈ 0\) (for a three-phase transformer - \(\dot{i}_{2ph} ≈ \dot{i}_{2l} ≈ 0\).
Figure 1 shows a diagram of the no-load experiment of single-phase, and Figure 2 - three-phase two-winding transformers.
Figure 1 - Diagram of the no-load test of a single-phase two-winding transformer
Figure 2 - Diagram of the no-load test of a three-phase two-winding transformer
Essentially, in no-load mode, the transformer is a coil on a magnetic circuit to which a voltage source is connected. The no-load mode is operational for voltage transformers. In addition, this mode serves to determine the current \(i_х\), power \(ΔQ_хх\) no-load and a number of other parameters [2, p. 291][3, p. 207] (see “Transformer no-load experience”).
- Note:
- The resistance of the rated load of the winding is understood as the value \(R_{Nnom}\), equal to the ratio of the rated voltage of the winding \(U_{nom}\) to its rated winding current \(I_{nom}\)
Short circuit mode
The short circuit mode is characterized by:
- The secondary winding is short-circuited or a load with a resistance much less than the internal resistance of the transformer is connected to it;
- Such a voltage value \(\dot{u}_1\) is applied to the primary winding that the current of the primary winding is equal to its rated current \(\dot{i}_1 = \dot{i}_{1nom}\)
- The voltage of the secondary winding is \(\dot{u}_2 = 0\) (for a three-phase transformer - \(\dot{u}_{2ph} = \dot{u}_{2л} = 0\).
The short circuit experiment diagram is shown in Figure 3 for single-phase, and in Figure 4 for three-phase two-winding transformers.
Figure 3 — Scheme of short-circuit experiment of a single-phase two-winding transformer
Figure 4 — Scheme of short-circuit experiment of a three-phase two-winding transformer
Short circuit mode is an operating mode for current transformers and welding transformers, while at the same time it is an emergency mode for other transformers. It is also used to determine the voltage \(u_к\), short circuit power \(ΔP_кз\) and other parameters of the transformer [2, p. 294][3, p. 209] (see “Transformer short circuit experience”).
List of sources used
- Bessonov, L.A. Theoretical foundations of electrical engineering: textbook / L.A. Bessonov - Moscow: Higher School, 1996 - 623 p.
- Woldek, A.I. Electrical machines: a textbook for university students / A.I. Woldek - St. Petersburg: Energy, 1978 - 832 p.
- Kasatkin A.S. Electrical engineering: textbook for universities / A.S. Kasatkin, M.V. Nemtsov - Moscow: Energoatomizdat, 1995 - 240 p.
Source: https://stroitel12.ru/naprjazhenie-holostogo-hoda/
A unit with a masculine character. Choosing a welding machine
Welding is used to quickly and securely fasten metal parts. If you plan to do welding work yourself, take the choice of machine seriously.
The range of welding machines is very wide: the E-Katalog catalog of descriptions and prices presents over 1000 models from domestic and foreign manufacturers. We will help you quickly navigate the abundance of options and choose a high-quality and reliable welding machine.
Device type
First of all, decide what type of device you need. Welding machines can be divided into 4 categories.
- Inverters. Inverter devices are compact and relatively lightweight. They produce stable current and are distinguished by high quality welding. The disadvantage is the high price.
- Transformers. If you need a unit to perform simple tasks (including household ones), the best choice would be to buy a welding transformer. These are the cheapest and simplest in design devices used for working with ferrous metals.
- Gas semi-automatic devices. They have a wider scope of application in comparison with transformer devices, as they allow the use of shielding gas during the welding process. The role of the electrode is played by the wire, which is automatically fed to the welding site.
- Semi-automatic inverters. Universal devices that combine the best qualities of gas semi-automatic machines (use of wire for welding) and inverter units (compactness, stable current). Semi-automatic inverters are very convenient to use, but, unfortunately, they are not cheap.
Having decided on the type of unit, proceed to selecting the appropriate model. We recommend using the E-Katalog website: with its help you can compare prices for equipment in online stores and the characteristics of different devices. What parameters are we talking about?
Input voltage
Single-phase devices can be connected to any outlet with a voltage of 220 V. The disadvantage of such models is their low power compared to three-phase units operating on a voltage of 380 V.
Since networks with this voltage are most often found in industrial workshops and other specialized premises, three-phase welding machines are used there.
E-Katalog also presents universal devices that provide the ability to connect to both single-phase and three-phase networks.
Welding machines (with the exception of inverter models) are sensitive to voltage changes. When the voltage drops, their power decreases; when the voltage increases, the unit may shut down in an emergency. Do not forget that any welding machine creates a large load on the electrical network, so use it only if you are confident in the quality of the wiring.
Open circuit voltage
The open circuit voltage ranges from 40–70 V. It shows what the output voltage of the device is without load. The larger it is, the faster the arc is ignited and the more stable it burns. You should pay attention to the no-load voltage of the welding unit when purchasing electrodes: some of them require low voltage, others need high voltage.
Maximum welding current
In simple units for home use, the maximum current can range from 20 A to 200 A. In professional models (most often three-phase) the current sometimes reaches 500 A.
What affects the maximum current value? The higher it is, the wider the scope of application of a particular unit. Powerful welding machines allow you to use thicker electrodes and generally cope with more difficult tasks. The thicker the elements being welded, the more current is required to connect them.
Switching frequency
The technical characteristics of welding machines also indicate the frequency of switching on. This parameter is measured as a percentage, and it is this parameter that allows one to judge the “endurance” of the unit.
The average operating cycle of a welding machine is 10 minutes. A device with a 30% switching frequency must be given a 7-minute break after every 3 minutes of operation. Devices for home use have a switching frequency of up to 40%, professional devices - 60% and higher.
Source: http://www.diy.ru/post/8337/
What is the open circuit voltage of a welding inverter?
You can test the welding inverter to see what it is capable of. We take the most affordable TIG welding inverter. I will give an example of a device in the photo there IN 256T/ IN 316T.
If you look at the table, it shows where the idle speed is located in the form of an indication. On such devices, the idle speed is programmed by a computer. When you select the desired mode, the idle current is automatically set. It can be checked with a regular voltmeter at the ends of the power wires in the on state. That is, on the holder and the crocodile. The voltage drop should not deviate by more than five volts when igniting the arc and welding.
For example, if you ate a Chinese state employee, you will not find information about idle speed at all. Plus the Amperes are too high. In fact, some won’t even handle Uoni 13/55 electrodes. And why all? This electrode requires an idle current of 70 volts at 80 amps. And such welding machines are designed in such a way that as the current increases, the voltage also increases.
In other words, at the highest current they will give you 90 volts. The voltage even before the secondary winding is controlled by a unit that converts the high voltage into the primary winding. Then, under the influence of electromagnetic force, it is transmitted to the secondary winding. The tension removed from her passes on. If the voltage at the input of the primary winding is low, then the output will be low.
Let's consider the primitive VD-306M U3. At low currents of 70-190 A, the voltage is 95 volts plus or minus 3 volts. At high currents of 135-325 A, the idle current is 65 volts plus or minus 3 volts. Moreover, it is stable in all current ranges. No matter how you twist the crank and change the amps to your heart's content, the idle speed will not decrease.
What am I getting at if the welding inverter does not weld well at low currents, the reason is in the control unit described above. As some say, install an additional choke or a ballast at the output. We turn the current up to full and adjust it at the ballast. The extra amperes will be taken over and the idle speed will remain unchanged.
Just for fun, check your welding machine. Throw the probes from the voltmeter onto the power cables and try to cook. See how the voltage drops. I myself personally cooked on a home network with an Interskol 250A inverter using 3mm UONI 13/45 electrodes with reverse polarity. As soon as I didn’t twist the amps properly and couldn’t ignite them, but the MP-3s burned, be healthy from the first touch.
When purchasing equipment, read in the passport how much idle current the device produces and at what currents. If this is not professional equipment, you will not be able to adjust the idle speed in any way. If not the method described above. You are unlikely to find such information on the unit body itself. Manufacturers usually hide it with big names and current strength.
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Answer:
Among the characteristics of welding inverters there are several important indicators. This is the supply voltage (220 or 380 Volts), the range of output current (from 10 to 600 Amperes), available functions, weight and dimensions of the device, as well as no-load voltage.
This characteristic shows us at what voltage the current reaches the electrode after it has gone through all the stages of conversion after the power supply.
Let us recall that current flows from the electrical network through the power cable to the first converter, from there it comes out constant and goes to the filter, and then to the second converter. As a result, we again get alternating current with a frequency of not 50 Hz, but 20-50 kHz.
This is followed by a decrease in input voltage with a simultaneous increase in current. As a result, we get an output voltage of 55-90 Volts and a force that can be adjusted within the range specified for each specific model.
This output voltage is the open circuit voltage. Two points depend on it: • The safety of the tool for the owner;
• Easy to ignite the welding arc.
The higher the open circuit voltage, the easier it will be to ignite the inverter's welding arc. It would seem that it would be worthwhile then to buy inverter devices with a high no-load voltage. But high voltage is quite dangerous for a person in case of contact, so it is not always made high.
If you still want to light the arc easily, then you should choose a welding inverter with a high voltage, but with an additional installed protection function that automatically reduces the voltage to a level safe for humans if there is a risk to the user, and then returns the level back.
If you have not yet chosen a welding inverter, then among household models, pay attention to Aurora welding machines and Blueweld inverters; for semi-professional models, we can recommend Foxweld welding machines and Svarog MMA equipment; for “professionals,” Kemppi welding machines and EWM MMA inverters are good. This equipment is available on our website in the catalog and can be purchased with delivery to any corner of Russia.
When coming to a store or looking at online portals, the buyer first of all looks at the price tag of the equipment presented, naturally looking for an option that would be optimal in terms of cost and quality ratio.
At the same time, price is not always an objective selection criterion. It is in the lowest price category that there is a huge layer of low-quality goods. In this article we will talk about technologies that are used to deceive buyers.
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Let's start with the simplest:
Overestimation of current characteristics
Often the numbers indicated on devices, in instructions or on equipment boxes have nothing to do with reality. It happens that the promised and actual values of the welding current differ by 20 or even 50%. For example, instead of the declared 200A, the device produces only 125.
When choosing a welding machine, the buyer looks at the upper limit of the welding current and compares the price with competitors based on their technical characteristics. As you understand, the cost of 120 and 200A devices differs significantly in favor of the first, and you are offered to pay for it as for a much more powerful device.
A professional never buys a welding machine with the current characteristics that he needs, i.e. If a welding specialist needs a 180A current source, then in the store he will opt for a 200 - 250A inverter. This choice, on the one hand, protects the buyer from underestimating the characteristics, on the other hand, allows you to have a reserve of power.
The manufacturer, knowing about this feature of the choice, periodically overestimates the current characteristics. As a result, the power reserve that the buyer expects to receive turns out to be zero, but the allegedly “200A” device costs a little more than the 180A analogue.
Another trick of marketers is to assign a name to a device with a digital code, which hints at the welding current, but has nothing to do with it. Let's take, for example, the imaginary device “Oak 250” (I hope there is no such thing), or even “Oak 250A” - the name seems to hint to us that the device should have a current of 250 A, while in the instructions for the inverter it is indicated 160A, but who reads these pieces of paper? So, less attention to the inscriptions on the case - more time studying the devices.
When making leapfrogs with characteristics, sellers rely on the buyer’s superficial knowledge. The average welding enthusiast will not be able to check the characteristics of the tool he plans to purchase.
Unfortunately, our people trust advertising or “digital displays” more, which often have nothing to do with real current. Here is clear proof: in one of our videos dedicated to comparing welding machines, we tested the ELAND inverter:
When connecting the device to a static load stand, it turned out that the readings of the ammeter on our device and the ELAND digital display differ by 50A (!). Many manufacturers install on their equipment not measuring instruments, but indicators that show values depending on the position of the adjustment knob. Those. the numbers on the display are not ammeter readings - they are just numbers.
Lipatov Timur Vladimirovich father
Additional functions
The reason for deception may be additional functions of the device. Antistick, Hot Start, Arc Force VRD voltage reduction function - they have become a gentleman's set, which is featured on almost all modern inverters. Sellers fear that the absence of any of these functions may alienate the buyer, and therefore write that the inverter is equipped with a full range of options, regardless of whether they are present on the device or not.
In turn, many buyers do not really understand what, for example, Hot Start is, or what is hidden behind the abbreviation VRD. Our little educational program on the links. Click - don't hesitate:
The most common type of deception, as you understand, is the absence of declared functions on the inverter.
Their presence, in addition to Antistik and VRD, can only be checked in a laboratory. Anti-sticking is checked by prolonged contact of the electrode and the part being welded. If this function is present, the electrode should not become red-hot: after a short heating period, the device, with the Anti-Stick function, should reset the welding current to a minimum and keep the electrode suitable for further work.
The presence of VRD is checked with a voltmeter connected to the device bayonets. The no-load voltage value when VRD is turned on should not exceed parameters that are safe for the welder: 12-18-24 Volts, depending on the values declared by the manufacturer. The presence of VRD is checked with a voltmeter connected to the device mounts.
Source: http://firmmy.ru/naprjazhenie-holostogo-hoda-svarochnogo-invertora
