What is VRD on a welding machine

How to choose an inverter welding machine? — Alpha Ars-welding, fasteners, tools

Before answering the question about choosing a welding inverter, you need to understand what is the fundamental difference between the huge number of welding inverters presented on the Russian market

MOSFET or IGBT
First of all, this is the technology on which they are produced - MOSFET or IGBT . We will not go into details of these technologies, but will highlight the main differences. MOSFET is a technology that was invented more than 50 years ago, IGBT is a modern technology that has a number of differences.

A welding inverter built on IGBT technology contains a much smaller number of transistors compared to MOSFET technology. It follows from this that fewer IGBT require fewer radiators for cooling, in addition, all IGBT are built on one board, which gives us a gain in weight and dimensions.

Often from the same manufacturer you can see welding inverters that are the same in terms of welding current, but differ in weight, dimensions and price, it’s all about the transistors used. Thermal protection of IGBT transistors operates at a higher temperature, and this directly affects the duty cycle (on duration).

IGBT and MOSFET remains controversial ; some service technicians claim that it is easier to repair an IGBT inverter, since it has one board and fewer parts, others are of the opinion that it is easier and cheaper to repair MOSFET - inverters due to the free layout of parts.

During the warranty period, some manufacturers do not even engage in diagnostics, replacement of boards, etc., but simply change the device because it is cheaper, for example, during warranty treatment, Lincoln Electric inverters from the Arcweld and there are never any problems with replacement.

So, if the weight is not 5.5 kg, but for example 4 kg, then this is IGBT inverter.

If you trust technologies that have been proven over the years more, then the choice is MOSFET - an inverter. If your budget is limited, then the choice will fall on IGBT inverter, although this technology is new, the cost of these devices is usually lower.

Operating voltage of welding inverter

The next thing you should pay attention to is the operating voltage range of the welding inverter. The standard range lies within 220V±15%, but there are models that are capable of producing high-quality welding even at 90V, but the cost of such devices is significantly higher, for example, the Svarog 160PFC device, which operates from 90V, is 80% more expensive than a similar 160A device.

You can choose a model that is in the golden mean and works well at 160V, i.e. We do not overpay for the operation of the device from 90V (you must agree that 90V is too low), but at the same time we are sure that in our dacha, where the voltage drop is often significant, 160V will be quite useful. For example, a very successful model of the Master 162 welding inverter operates from 160V.

 

Inverter price. 

How much should a reliable welding inverter cost? Like any product, the cheapest welding inverter contains a number of dangers - non-compliance with the declared welding characteristics, low quality components, poor build quality, low load duration, i.e. with the specified maximum current of 160A, we think that we will be able to weld with an electrode up to 4mm.

, but looking at the device’s passport, the load/on duration indicator may turn out to be 20%, which means that we can cook at a current of 160A for 2 minutes out of 10, and the device will cool down for the remaining 8 minutes. It is worth giving preference to proven welding inverters under brands such as Svarog, Foxweld , etc.

Devices under these brands are manufactured in the best factories in China, which export their products to the USA and Europe. 

Additional functions of the welding inverter

In some models of welding inverters, an additional feature of the device can be the argon arc welding function, i.e. You can use a welding inverter for TIG welding of stainless steel by purchasing a valve torch for argon arc welding, an argon cylinder and a gas regulator for the cylinder. In this case, the arc ignition will not occur in a non-contact manner, as in professional models, but in a contact manner - by striking a tungsten electrode.

But a person who buys a welding inverter for his home is unlikely to plan to weld stainless steel efficiently and beautifully, and is he even capable of doing this? TIG welding requires a special skill, and while many amateurs can weld with an electrode after several burnt electrodes, this option will not work with TIG welding - this is a jeweler’s work.

  Another function of welding inverters can be the VRD function - the function of reducing the open circuit voltage before igniting the arc. It lowers the open circuit voltage to 12V and below. But this function is necessary when welding in wells, tunnels, tanks and other confined conditions. When the source is idle, the full open circuit voltage of the welding machine usually reaches 70V.

At the moment of replacing the electrode, the welder touches one phase with his hand, and the other phase is in close proximity to him, or under his feet, as a result, the likelihood of an accident increases significantly. Therefore, this function is necessary to improve electrical safety.

 

What you shouldn’t buy into is the sellers’ stories that our device contains special functions such as “anti-sticking”, “arc force” and “hot start”, all these processes occurring on the arc are built into the welding inverter by default and their advertising is comparable with the slogan “our locks not only close, but also open.” 

Accessories for welding inverter

When choosing a welding inverter, you should definitely pay attention to the quality of the components - electrode holder, grounding clamp, welding cable and bayonet plugs.

Cheap devices most often contain a “disposable” electrode holder and a grounding clamp - the electrode holder falls apart, the grounding clamp burns after several uses, and in the future there are additional costs for these components.

The welding cable should not be too thin and overheat; it must correspond to the maximum welding current for which the machine is designed. Pay attention to the quality of components!  

Pleasant trifles

A nice addition to the welding inverter, in addition to its reliability and the necessary welding parameters, can be a digital indication, which helps to visually control the current values; such devices are 1000-1500 rubles more expensive than their analogues. Another nice addition can be a case for storing a welding inverter; you must agree, it’s much better when you have welding cables, a machine, a shield and a pack of electrodes in a convenient case, and not scattered around the garage.  

Storing the device

Well, when you bought a welding inverter, burned your first electrode and made sure that the money was not wasted, read the recommendations in the instructions for storing and maintaining your assistant.

The inverter must be stored in a dry room, do not turn on the device after a sharp temperature change - it is not recommended to turn on the device in a warm room after being in the cold, periodically blow the device from dust, it is advisable not to operate the device at maximum modes, avoid dropping the device or getting moisture inside. Taking good care of the device will allow you to operate it for a long time and without failure.  

Go to inverter selection

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Source: https://www.alfa-ars.ru/press-tsentr/poleznye-stati/kak-vybrat-svarochnyj-apparat-invertor

Practice welding deception. How not to make a mistake when choosing a device. Part 1

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.

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.

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:

Hot Start

VRD

Antistick 

Arc Force

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: https://Evrotek.Spb.ru/info/stati/i_welding/49029/

What is the vrd function in a welding machine?

What should you pay attention to when buying an MMA welding machine?

Maximum electrode diameter

Essentially the same characteristic of the operating current range. Sometimes, due to illiteracy or malicious intent, the diameter of the electrode is indicated, which will not be able to cook with the stated maximum current. Sometimes it’s the other way around: the maximum diameter of the electrode is indicated, which clearly does not reach the value of the declared welding current.

The latter option is occasionally a glimpse into the conscience of deceptive suppliers. They indicate the short-circuit current as the maximum current. But the maximum working diameter of the electrode is still indicated honestly.

Welding current type: direct (DC) or alternating (AC)

Cooking with constant (or direct, in English - DC) current is simpler: it is easier to hold the arc. Therefore, 99.9% of modern MMA inverter machines produce constant welding current.

But among transformers, previously the majority were AC devices.

Alternating current (in English - AC) is used for welding non-ferrous metals. But not with MMA devices, but with TIG devices. Therefore, an MMA welding inverter that produces alternating current is a rarity.

No load voltage

After turning on the device, until the arc is ignited, the voltage at the tip of the electrode is significantly higher than during operation. And the higher it is, the easier it is to ignite the arc. But standards prohibit open-circuit voltage levels on devices delivering direct current above 100V.

To further reduce risks, the so-called VRD blocks. A device equipped with a VRD has only a few volts at the tip of the electrode before the arc starts. And only when you touch the metal, the no-load voltage is restored to the level necessary to ignite the arc.

All electrodes always indicate the polarity of the connection, the type of welding current (direct or alternating) and the minimum level of open circuit voltage required for ignition. For the vast majority of widely used electrodes, it does not exceed 60V.

The open circuit voltage, as well as the welding current, depends on the input voltage level. The lower the voltage in the power supply, the lower the open circuit voltage. Therefore, as the supply voltage decreases, ignition of the electrode becomes more and more difficult.

Duty cycle, also known as PV (on period), also known as PN (payload)

PV is indicated by two numbers. The first is current strength. The second is the percentage of time. For example, “130A-50%” means that this device with a current of 130A can cook half the time. And the same amount of time will remain idle, waiting for cooling to operating temperature.

If measurements are carried out at the maximum current of the device, the first digit is omitted, leaving only the percentage indicator.

For example, if a device with a rating of 160A has the entry “30%” opposite “PV”, this means that with a current of 160 amperes it can operate 30% of the time, and 70% will cool down.

That's right. It only remains to add that the domestic GOST R IEC 60974-1-2004 does not establish a single mandatory method for measuring the PN indicator for MMA devices.

“The standard does not apply to limited-duty manual arc welding power supplies that are designed primarily for use by non-professionals.”

The European methodology, set out in the EN60974-1 standard, suggests measuring on a load stand at an ambient temperature of 40C only until the first shutdown due to overheating. The result obtained is referred to a 10-minute period. It turns out that the thermal protection worked after 3 minutes, the cycle of the device at this current is 30%.

Source: https://master-kleit.ru/origami/funkcija-vrd-v-svarochnom-apparate-chto-jeto/

Welding machine Wester

The Wester brand belongs to the Russian group of companies "Impulse". The company's products are associated in Russia with the concepts of reliability, quality, and style. The Wester brand produces household appliances, water supply devices, pumps, shut-off and control valves and many other products. Sales of welding equipment for industrial and civil purposes under the name Wester occupy a leading position, combining quality and affordable prices.

Typical design of a transformer converter

Transformer for welding is a device with the help of which single-phase or three-phase alternating voltage is converted into low-voltage, high-current electricity. The magnitude of the conversion depends on the difference in turns on the secondary and primary windings, the steel core, which combines the turns using magnetic induction. The design of the transformer itself is impossible without three components:

• magnetic steel core;
• primary winding consisting of hundreds of turns;
• secondary winding made of a thick cable or bus with several dozen turns.

Needless to say, this design is bulky and heavy with an efficiency of only 60%.

Inverter converter

Another thing is the inverter, the efficiency of which reaches 95%. With the invention of avalanche controlled transistors and thyristors, it became possible to abandon the traditional transformer and control the characteristics of the device using electronic systems.

Transformers in such systems are used in control circuits, converting small currents, which affected the size of the device as a whole; in addition, such a system was able to adjust the initial parameters by adjusting the control. A fundamentally new design is called an inverter welding converter.

How does an inverter work?

In an inverter welding machine, electricity is converted from an industrial voltage and frequency network. The output voltage can be smoothly adjusted, the polarity of the final voltage can be switched, welding on constant and alternating voltage is possible.

Rice. Block diagram of the operation of a welding inverter.

A distinctive feature of the inverter is the multi-stage conversion of mains voltage.

At the first stage, the sinusoidal voltage is converted into a constant pulsating current, the peaks of which are smoothed out by a special phase reactor.

On the second, the pulsating voltage goes directly to the inverter’s control circuit, where it is converted again into an alternating voltage with several frequency harmonics. The possibility of feedback for adjusting the various output characteristics of the device depends on the magnitude of the harmonics.

The final stage is the formation of a control voltage on the electrodes of avalanche thyristors, which, together with a transformer, convert the mains voltage into a welding load of a set value.
Depending on the power of the semiconductor converters, the output power of the welding arc on the electrode depends, which can be from 80 to 500A.

Wester MMA VRD 160, 180, 200A

Rice. Wester MMA VRD 200. Inverter. Manual welding. Max. welding current: 200 A. Electrode diameter: 1.60-5 mm. Functions: protection against electric shock VRD, Anti-stick, Hot start, Afterburner, Weight 6.4 kg. Mon -7.

They differ only in the maximum welding current.

Respectively 160, 180 and 200A. These are professional models with a high LO (Load duration index) - 7. This means that each of the devices will work for 7 minutes out of 10 at maximum power.

This time is enough to pass several meter-long seams on a steel sheet or metal structure.

Welding type: manual (MMA). The diameter of the welding electrode for the Wester MMA VRD 160 model is 4 mm; for the others, it is 5 mm.

The welding current is adjusted on the front panel with a potentiometer knob, the digital value of the stabilized welding current is displayed on the front panel of the digital indicator with an accuracy of up to 1 ampere.

VRD mode reduces the open circuit voltage. With this function, you can carry out work even in a damp room without fear of getting shocked by electricity. To enable this function, simply press the button located next to the power regulator potentiometer. The LED indication will light up and indicate whether the function is active or not.

Hold Start mode makes it easier to ignite the arc at the start of work by increasing the voltage at start-up.

The Anti Stick function stops and turns off the device when the electrode gets stuck.

Arc Force function. Maintains arc burning when the electrode is removed from the surface being welded.

The inverters are protected from overheating by the function of shutting off the load supply to the welding electrode; after cooling, the device will start again.

For ease of carrying there is a wide, durable plastic handle. There are rings for attaching a shoulder strap (the strap is not included).

The inverter kit includes an electrode holder and a ground holder.

Technical characteristics of Wester mma-vrd 160, 180, 200:

• Welding current A, respectively: 10 - 160, 10 - 180, 10 - 200;
• Power consumption: 7400 W, 8500 W, 8800 W;
• Electrode diameter 4 -5- 5 mm;
• Warranty: 36 months.
• Estimated price for a Wester inverter: 10,000 rubles.

Welding machine WESTER MINI 200 – 220T

Rice. Inverter Wester Mini 220 T. For manual arc welding (MMA) with max. current 220 A. Electrodes: 1.60-5 mm. Built-in functions: Anti-stick, Hot start, Weight 5 kg. Mon -6.

The Wester Mini 200 and Wester Mini 220 T are used for manual electrode welding of ferrous and non-ferrous metals.

The external and internal appearance are completely similar, the value of the maximum welding current differs. For stable operation of the inverter, fluctuations in the mains voltage are not a problem; they operate stably even at a voltage of 150 V.

This makes the devices indispensable in the garage or places remote from stable sources of electricity.

The welders are very compact and reliable, their weight is only 5 kg.

The circuit, made on the basis of modern asvt avalanche thyristors, allows increasing the efficiency of the device to 95%.

Characteristic PN (Load Duration Indicator) - 6. This means that out of 10 minutes of continuous welding at maximum current, you can continuously weld for 6 minutes.

The welding current is regulated by the regulator knob on the front panel. The available liquid crystal display allows you to control the set welding current. Two LED indicators on the front panel indicate network connection and overload.

Built-in thermal protection automatically interrupts the welding current when overheated.

Cold start function Hot-star - sharply increases the amount of current when starting work, the arc lights up faster.

The Anti Stick function will protect the inverter from overload when the electrode is stuck; thanks to the built-in function, the load supply is automatically stopped when the electrode is stuck.

Thanks to the shoulder strap, the device is very convenient to carry and work with it suspended on the shoulder.

Together with the equipment block there is an electrode holder and an “earth” clamp with a cable.

Technical characteristics of the Wester Mini 200 and 220 T:

• Output maximum current: 200-220A;
• Electrodes used: diameter 1.6 - 5 mm;
• Warranty: 36 months.

Reviews for the Wester welding machine:

I don't have much work to do, mostly around the house and in the garage. Although the work is not difficult, there is constant work. I bought this device on sale at the beginning of summer, I work for six months, almost every day for about 30-40 minutes. No jambs came out. I'm happy with the device. To make it clear in terms of the scope of work: I made two horizontal bars and a swing at the dacha. I welded the frame of the barbecue area and the sheathing for the fence. Grill and barbecue out of 5;

A good device: compact, lightweight. I carry it on my shoulders all day and don’t get tired. It is unpretentious to input voltage and surges, keeps the arc smooth. When purchasing, I did not believe in the possibility of working with 5 mm electrodes. but it really lights and holds the arc well with this electrode. Moreover, there is a 5 year warranty.

For small jobs for the home and garden, this is it. (I took it out of the closet, quickly set it up, worked, and installed it again). Compact, lightweight. The arc is stable, the seam is normal, the electrodes do not stick, the adjustment is up to 200A, everything is as written - it’s real.

DIY inverter repair

If the inverter begins to have problems, such as sticking of the electrode, spontaneous change or interruption of the welding current supply, then the problem is in the electronic filling of the device.

The electronics are made quite reliably, so before blaming the circuit, you need to understand the reasons that lead to such malfunctions.

Due to the fact that the inverter has a rather complex feedback system, therefore an incorrect choice of the diameter of the electrode to the current load leads to a constant supply of a shortage pulse to the control unit and the output unit, forcing the electronics to add a mode, but the regulator is at a low level, the device is in constant load regulation mode. Constant operation of the unit causes overheating of electronic parts and their failure. The approximate value of the current characteristics depending on the diameter of the electrode is given in the table below.

Rice. Table of correspondence of welding current to the diameter of the electrodes used.

Poor quality equipment can also lead to such malfunctions. For example, if a “ground” tin clamp is used, at a current of 150A, the “ground” - clamp contact may heat up, this gives an incorrect value on the control pulse, the control circuit begins to increase the current value on the electrode, which leads to unstable operation.

In addition, unreliable contact in the bayonets (welding cable connection terminals in the device body) can result. Periodic changes in contact resistance also lead to an incorrect understanding of the signal and, accordingly, a command to turn off or adjust the currents on the electrode.

Rice. Bayonet terminals for connecting cables and ground clamps. For high-quality operation of the inverter circuit, these structural elements must provide a reliable connection, preventing changes in resistance in the contact area.

You can buy a Wester welding machine and the necessary related equipment at a specialized dealership. You can also purchase various accessories there: a mask with a chameleon stack, mittens, and workwear.

It is better to entrust the repair of Wester inverters, especially its electronic components, to specialists, or if you still decide to look inside, we recommend watching a video clip that describes in detail how to find and replace faulty parts.

Source: http://themechanic.ru/svarochnyj-apparat-wester/

How to choose an inverter welding machine for home and workshop

Welding is one of the main technological processes of modern production. It is difficult to imagine a construction or industrial sector that would not use welding technologies. In some industries, the share of welding work reaches 65-70% of the total production time .

Now there are many different types of welding equipment on the market, for different types of tasks, operating from both alternating and direct current, having different ratings, both for use at home (in the country, in the garage), and for professional purposes when working with various materials. And they all may have different reviews. To choose the best inverters for manual welding, you should know exactly their types. Please note that these are not just household appliances, but rather complex and varied equipment.

Main types of welding equipment in Ukraine:

MMA - Manual Metal Arc - manual arc welding with artificial (coated) electrodes.

MIG / MAG - Metal Inert / Active Gas - arc welding with a consumable metal electrode (wire) in an inert / active shielding gas with automatic feed of filler wire.

TIG - Tungsten Inert Gas - manual argon arc welding with a non-consumable electrode in an inert shielding gas.

The most popular are MMA devices. Which are used in almost every household because they are affordable and easy to manage. These are truly the best universal welding inverters.

Thanks to the implementation of modern technologies, the welding process is 90% automated. Therefore, even a novice welder with the 2nd or 3rd electrode will be able to understand the process of welding parts.

Therefore, this type of device is widely used among users.

What criteria should you use to choose a device?

It is important to identify several factors that you should pay attention to when choosing a welding inverter

1. Welding machine class (household and professional);
2. Rated welding current;
3. Direct or alternating current;
4. The diameter of the electrode/wire that an inverter-type welding machine can operate;
5. Duty cycle;
6. Filling of the welding machine;
7. Design/ergonomics;
8. Weight;
9. Equipment.

Household or professional

To buy a good welding inverter, this issue should be taken into account first. Because when you buy a household device and use it for professional purposes, it may not meet your requirements. For example, the recommended maximum time of continuous operation under load, the quality and depth of the weld, as well as failure of the device due to heavy loads during operation.

Or vice versa, if you need a device for your home or garden, then professional equipment will be an unnecessary overpayment for you. After all, the cost of household models is an order of magnitude less. Therefore, by answering this question, you will be half a step towards the right choice.

There are more than 100 brands of MMA welding equipment on the Ukrainian market. Different price segments, power, capabilities.

For more than 10 years, the Dnipro-M brand has been creating new lines of welding machines based on user requirements. In 2017 and 2018, Dnipro-M welding equipment was awarded the national prize “Welding equipment No. 1 in Ukraine” .

During development, innovative technologies are used aimed at automation and safety of working with the tool.

New features and systems are constantly being added to make inverters even more reliable, convenient and functional.

The brand’s line of welding machines includes 2 main lines:

• devices for working with a hand electrode (SAB and MMA);
• semi-automatic - MIG / MMA for working with both electrode and welding wire.

The SAB line stands for “Household Welding Machine”, this already indicates that it was created specifically for housework or occasional professional tasks.

This series is the most popular in Ukraine. Over the past 2 years, more than 200,000 users have chosen the SAB line, which 100% satisfies all the needs of home instrument use. Depending on the tasks, devices in this line are also suitable for professional use.

The MMA line is professional semi-automatic welding machines with more power than SAB. This series is designed for intensive daily work at high current, which ensures high efficiency. Users of the MMA series of the Dnipro-M brand are several thousand enterprises in Ukraine, which highly evaluate the devices in terms of professional parameters.

The design of this line:

1. three boards. Thanks to this, the number of diodes in a small case has been increased - 8 pcs. This improves the smoothness of the welding arc and the quality of the seam.
2. increased network filter of 1880 uF, which allows you to work with the device from 140 V without loss of power.
3. The three-board design also made it possible to improve the cooling system. Therefore, the welder can perform each task at high current without stopping.

And the most important difference of this line is the American IGBT transistors FairChild and MOSFET technology - Toshiba. High-performance transistors from global manufacturers with a power of +30%.

Pairwise switching of transistors guarantees reliability, increases the service life of the device, and increases the operating time of the tool.

Job Opportunities

The SAB series devices, in turn, are divided according to the possibility of using welding electrodes with a diameter of 4 mm or 5 mm. Recommended SAB load times:

— at maximum current up to 3 hours without interruption;

- on medium current up to 8 hours without a break;

SAB-250/255/258 series - works with 1.6-4 mm electrodes.

Works with all types of electrodes: steel, stainless steel, cast iron

They weld up to 10mm/cut metal up to 8mm.

Non-stop operation (duty cycle): 40 electrodes d4 mm at a temperature of 25 ° C

SAB-260 series - work in a wide range - 1.6-5 mm.

Works with all types of electrodes: steel, stainless steel, cast iron

They weld up to 12 mm/cut metal up to 10 mm.

Non-stop operation (duty cycle): 40 electrodes d5 mm at 25 °C

MMA series - operate in the welding current range for an electrode of 1.6-5 mm.

Work with all types of electrodes: steel, stainless steel, cast iron.

Recommended load time:

— at maximum current up to 10 hours without interruption;

— on medium current up to 15 hours without a break;

— work without stopping (work cycle) 100 electrodes d5 mm at a temperature of 25 ° C.

I would also like to note the automation of work with welding machines of the brand. Most brands declare, but do not implement, features that make the welding process easier and better. This can be easily checked on the first burned electrode.

Automation functions of the welding process in Dnipro-M machines

HotStart - hot start - ensures reliable arc ignition. At the moment of arson, the device automatically increases the current strength for a split second in addition to that set by the welder, thanks to this the electrode instantly heats up and easily lights the arc;

ArcForce ( arc force ), if during the welding process the welding arc breaks and goes out for some reason, the arc force function automatically gives an additional current pulse, which allows the welder to work without accidentally breaking the arc;

AntiStick - easy distribution of stuck electrodes without damaging the coating.

Sometimes the electrode sticks to the metal and a short circuit occurs. It is almost impossible to separate the electrode from the workpiece at the moment. The AntiStick function is activated in the event of such a short circuit and resets the current value to a minimum. Such an electrode is easy to separate from the workpiece, after which the current automatically returns to the set values ​​and you can continue working with the same electrode

Read also: Everything you need to know about welding electrodes

VRD - when the open circuit voltage is applied, the machine is turned on, but welding is not performed. This function reduces the voltage to values ​​that are safe for humans 12 - 17 V. A collision with the electrode does not entail any risk for the welder to restore the semi-automatic welding process. The function is in demand in extreme conditions or in high humidity environments, mines, heat and water supply systems.

TermoControl - protection against overheating of the device.

Another quality standard for Dnipro-M welding machines is protection from dust, dirt, and condensation. This is ensured by high-quality coating of the boards on both sides with technical protective varnish. Therefore, when working in dusty rooms or high humidity, you don’t have to worry about a short circuit occurring.

Ergonomics and convenience

Along with the technical characteristics of the device, its ergonomics, convenience and reliability of operation are also important.

For example, the presence of a digital display helps to accurately set and adjust the required welding current values ​​and allows you to monitor the process. This is especially true when the welder works in poorly lit rooms or in the evening.

Devices marked “D” are equipped with a special display.

258D / 258DPB / 258PW / 260DB / 260DPB / 250DPFC / 250D MOS

Second recommendation: pay attention to the package and the network cable!

Dnipro-M welding machines are equipped with elongated rubberized power cables 2.5 m/3 m (model SAB-250N/255 - 2 m each). Also, the network cable is 2 m. This allows the welder to provide a working area of ​​up to 5 m when connected from the network, increasing his maneuverability.

If it is important for you that the device is equipped with a case for easy transportation and convenient storage, pay attention to the models:

Source: https://dnipro-m.ua/news/svarochnye-apparaty-invertory-sab-mma/

Welding machine - what is it, device, main types and their characteristics

Welding, as a type of joining metal elements, became widespread more than a century ago. It is used in many areas, creating various products, from microcircuits to giant structures. In any case, a welding machine comes to the rescue, which today is produced in an assortment.

What is a welding machine?

The product is an electrical device with which a durable and reliable connection of metal elements is made. An inverter or other type of welding machine is used in various fields, ranging from microelectronics to construction. Among the advantages are the reliability and speed of joining materials with minimal time and effort.

Welding machine design

Until recently, the unit was very simple in terms of operation, but modern models have been supplemented with electronics, which has increased functionality. The internal filling of the welding source is determined by the operating principle of the device. The power unit responsible for changing the current consists of the following parts:

1. Network rectifier . Takes up a lot of space on the main equipment board. Avoiding overheating is possible thanks to the presence of a diode bridge mounted on a cooling radiator.
2. Noise filter . Used to suppress electromagnetic interference affecting the electrical network. Consists of a choke placed on a magnetic coil.
3. Inverter . It is constructed from transistors, some of which are mounted on a radiator for cooling. To protect them from dangerous voltage surges, damping chains are installed.
4. Output rectifier . Made from powerful diodes. To avoid overheating of the device, high-speed diodes are mounted on a radiator.
5. Starting circuit . Consists of power unit components. Power from the main rectifier is supplied to the stabilizer, and then to the control circuit through series-connected resistors. The rectified current is used to operate the cooling fan and light indicators on the instrument panel. An additional component of this unit is a soft start relay. With its help, inrush currents are limited when the welding machine is turned on.

The control unit consists of a PWM controller that coordinates the operation of all transistors. It looks like a microcircuit that controls the device. In addition, it controls the input voltage and welding current parameters.

In the event of a malfunction, protection is triggered and, as a result, the device is blocked. The control unit is used in the process of manually adjusting the current strength; this is done by rotating the resistor knob.

On those models that are designed for several types of welding, there is a mode switch.

Types of welding machines

Currently, not a single construction project or large workshop can be completed without the use of a device for connecting different metal elements. Modern welding apparatus is divided into the following main types:

• transformers;
• rectifiers;
• inverters.

In addition, the division occurs into the following subtypes:

• semi-automatic;
• generators;
• other devices for industrial use.

Transformers

This is a device that converts the alternating voltage of the input network into direct voltage for electric welding. The current strength in it is regulated by changing the inductive reactance of the circuit or using phase regulation. Such a welding machine for home and other places has the following advantages:

• relatively high efficiency up to 90%;
• ease of operation;
• reliability and low cost.

The disadvantages include:

• low arc stability;
• the need for special electrodes;
• input voltage fluctuations;
• ban on welding stainless steel and non-ferrous metals;
• heavy weight of the product.

Rectifiers

This is the next generation of units after transformers. Their power part consists of a transformer, a rectified block and a smoothing choke. This welding technique has the following advantages:

• use of direct current;
• high-quality seam;
• creating less splashing;
• Possibility of welding stainless steel.

Among the disadvantages of rectifiers are:

• relatively heavy weight;
• loss of some power;
• a strong “sag” of voltage in the network during its operation.

Semi-automatic

The device is a unit for welding in a shielded gas environment with mechanized wire feed. By design, a semi-automatic welding machine is divided into: double-body or single-body. It is used in the gas sector. The advantages include:

• ease of welding thin metal;
• high-quality seam;
• a large number of settings and adjustments;
• high performance.

Among the disadvantages, the following points are highlighted:

• high cost of equipment;
• a three-phase network is required for connection;
• ban on working on the street.

Inverters

It is a device in which direct current is converted into alternating current. The welding inverter has the following advantages:

• light weight and size;
• high voltage frequency;
• Efficiency 95%;
• ideal power factor;
• there is no need for frequent cooling;
• smooth adjustment of modes;
• wide range of currents;
• Can be used for large voltage drops.

The inverter welding current source IIST and other models has the following disadvantages:

• high price;
• increased requirements for storage conditions.

Generators

This is a device that combines a welding machine and a full-fledged generator. classification is made according to the type of fuel consumed. In addition to its main purpose, a welding machine for home and garden can be used to supply electricity to a room. The advantages include:

• more stable arc burning;
• high quality welding;
• possibility of using different electrodes;
• less sensitivity to voltage changes.

Among the disadvantages are:

• presence of parts requiring operator supervision;
• the importance of periodic repairs;
• low efficiency;
• high cost.

Tig welding machines

Complex equipment with a large number of settings. This welding is a process performed by an electric arc in an argon atmosphere. The inert gas protects the treated surface from exposure to oxygen. The home welding inverter has the following advantages:

• minimum number of defects in seams;
• reduction of metal deformation;
• elimination of metal splashing;
• no slag;
• ability to work with different metals.

Among the disadvantages are:

• high cost of equipment;
• low productivity;
• need for complex settings.

How to choose a welding machine?

To make a confident purchase, it is important to weigh all the pros and cons, only in this case the process will only bring pleasure. Before choosing a welding machine, you need to answer the following questions:

1. From what network will welding be carried out? In production, the process will occur at 380 W, and at home at 220 W. In order to avoid problems with equipment, it is recommended to purchase a welding machine in which the electronics are controlled by power supply networks; this will prevent the device from working until it receives normal power.
2. What metal will be joined? To weld cast iron or non-ferrous metal, you need to take a DC machine. For a thinner one, choose a semi-automatic machine. For material thicker than 1 mm, a cheap welding machine with normal characteristics will do.
3. How thick will the weld be? The power of the unit will depend on the desired penetration depth. The thickness of welding with direct current is 20% greater than with alternating current.
4. How long will the welding take? For long-term operation, it is better to choose a device with a high duty cycle; this is the only way to protect the device from peak loads and ultimately increase its service life.
5. What weight of welding machine is needed? The greater the mass, the better the performance. If movement and simple work are expected, it is recommended to choose the IIST welding inverter. According to many, it is ideal for such work.

Welding machine power

This indicator indicates how much current the device is capable of delivering and what thickness of metal it can work with. The passport that comes with the device contains information about the maximum power consumption, as well as peak loads and other important indicators. A welding device for household use produces up to 250 A, and a professional welding device from 300 A. This must be taken into account when choosing a unit for use.

welding machines

With a large selection on the market and lack of experience with these devices, it is very difficult to choose the right option. Professionals prefer only proven models that have proven themselves over time. The current leaderboard looks like this: The best inverters for manual arc welding:

• FUBAG IR 200;
• Wester MMA-VRD 200;
• welding machine Resanta SAI-220;
• Eurolux IWM-190.

The best semi-automatic welding inverters:

• BLUEWELD Starmig 210 Dual Synergic;
• Aurora OVERMAN 180.

The best universal inverter-type welding machines:

• Aurora INTER TIG 200 AC/DC Pulse;
• Torus 200c Super;
• Svarog TECH ARC 205 B Z203;
• Quattro Elementi MultiPro 2100;
• Fast and Furious-161;
• Cedar MIG-160GDM;
• BLUEWELD Prestige 186 PRO.

Rules for using the welding machine

Some people decide to hire a specialist to carry out the work, although in fact there is nothing difficult in working with such equipment. A semi-automatic welding machine or other modification requires compliance with certain rules before and during work. Before starting work:

• wear protective clothing and face protection;
• remove unnecessary items from the workplace;
• check the serviceability of the welding part of the apparatus;
• include the ventilation system.

During welding:

• lay the part stably;
• the flame can only be viewed through protection;
• electrode cinders are thrown into a special box;
• during short breaks, the electrode holder is hung on a stand;
• If there is carbon deposits on the electrode, clean it by first turning off the transformer.

Source: https://womanadvice.ru/svarochnyy-apparat-chto-eto-takoe-ustroystvo-osnovnye-vidy-i-ih-harakteristika

MMA welding inverter: design features and functions

Repair and construction work often requires special equipment for joining metal elements, products and parts - professional or household MMA welding inverters. Such devices replaced bulky and heavy transformers, which, moreover, were not stable.

MMA welding method

Before considering the method itself, you should learn about MMA electrodes, that these are special melting metal rods coated with special compounds for connecting different grades of steel.

The main stages of this type of welding, such as MMA, what it is, the nuances and features are described by the technology for performing the work, which is as follows.

The current supplied to the electrode forms an arc with a high temperature between the surface of the products to be welded and the metal of the rod. When the rod and the surface of the product are heated, a melting area is formed. In the volume of metal brought to a liquid state, a special zone is created - a weld pool, into which the melting metal of the electrode enters in the form of individual particles covered with slag.

In the melting zone, the incoming metal and product material are mixed, and the lighter molten slag is pushed onto the surface of the formed weld. The maximum recess at which the metal of the welded element is melted is called the “penetration depth”.

The dimensions of the weld pool depend on the work mode. In manual MMA arc welding, the share of the metal of the product in its formation reaches 35%.

When the electrode coating melts in the weld pool, a special gas regime is formed. Gases released during MMA welding displace air and form a protective environment that prevents direct contact of the melt with the external environment. This layer contains mainly vapors of molten steel or other metals and alloying substances.

Advantages of inverter-type devices

Electric arc welding, performed using coated MMA electrodes, is effective for joining elements made of alloy steel grades with a thickness of 20-50 mm. Products less than 1.5 mm thick are completely melted before the bath is formed, which makes it impossible to join them.

Advantages of MMA welding:

• connection in any plane;
• small size and weight of equipment;
• lack of cylinders;
• economical process.

Experts call the disadvantages of the method:

• low welding speed;
• the need for regular removal of slag formed on the surface of the elements being joined.

Welding inverters for MMA welding have the following advantages:

• reliable connection on direct and alternating current;
• suitable for working with stainless steel, cast iron, aluminum and its alloys;
• equipped with various electronic overload protection circuits and arc control functions.

Despite the rather high cost, in recent years the technology has become increasingly available for domestic use, and not just in industrial enterprises.

Technologies and types

To perform various production tasks, different types of inverter devices are used, differing in functionality:

• for electric manual arc welding (MMA);
• for argon welding with non-consumable electrodes;
• for semi-automatic welding in gas protective atmospheres (MIG/MAG);
• semi-automatic for MIG/MAG and MMA modes;
• universal, through which MMA welding and other welding methods are performed;
• devices for air plasma cutting of metals.

According to technical parameters and level of performance, inverters are divided into:

1. Household models, characterized by low cost and simple equipment.
2. Semi-professional, equally suitable for home and small workshops.
3. Professional, manufactured for continuous use for production purposes.

Characteristics and descriptions

An MMA welding machine is a type of inverter that supplies direct or alternating current to a consumable electrode . The main characteristics that an inverter must have are:

1. Electrode size (maximum).

This parameter is also characterized by the operating current range.

AC (variable) or DC (constant). In the latter case, the welding process is simpler, because most machines supply direct current. A variable is needed to connect elements made of non-ferrous metals.

1. No-load voltage.

When the inverter is turned on before an arc forms at the end of the electrode, the voltage is significantly higher than during welding. The higher this voltage, the easier it is to ignite the arc. However, the standards for “no-load voltage” of devices are limited to 100 V.

1. On period (OP) and payload (PN).

PV is indicated by two numbers, the first of which is the current strength, the second is the percentage of time. For example, the decoding “130A-50%” means that with a current of 130 A the machine can weld only half the time and must stand for the same amount of time waiting for cooling to operating temperature.

Most inverters using IGBT transistors are assigned insulation class H, indicating a maximum heating temperature of 180°C. Devices of a lower class (F) have a heating limit of up to 155°C, and a higher class (C) - more than 180°C.

The parameter indicates the design option of the device regarding exposure to solids (first digit) and liquids (second). Inverters are produced mainly with a level of protection corresponding to classes IP21-23.

1. Heat resistance of insulation.

The ability to operate welding inverters is subject to certain restrictions related to cooling and heating from the external environment. Most devices operate in the temperature range 0-40°C.

How to choose an inverter

When choosing a welding machine, knowing what MMA welding is and how it is performed, future owners most often focus only on the cost of the device.

On the domestic market there are the following main categories of tea-makers:

• cheap Chinese;
• more expensive ones from European manufacturers.

The main characteristic of any inverter is its power. The principle of operation of the device is based on the formation of high-frequency pulses coming from transistors under significant voltage - the so-called “power switches”. These elements are needed to increase the current strength when it decreases in the supply network. To protect against burnout of power switches, protection must be provided in the inverter.

In budget models, the presence of protective circuits is not provided, which is why in the event of a sharp voltage surge, the inverter may fail. Therefore, when choosing a device, you should take into account factors such as the stability of the power supply at the place where the welder is used.

An equally important parameter is the power consumed by the device . It is especially necessary to take this indicator into account if the device is intended to be used at maximum welding current. In this case, the power of the electrical network must exceed the predicted load by a margin, taking into account other consumers.

Before purchasing a welder, it is important to determine the permissible duration of its non-stop operation, which is indicated in the technical passport. This parameter indicates the operating time of the device at maximum current.

The most important characteristics when choosing a device

When selecting an inverter, you should also pay attention to other important parameters and characteristics:

1. Availability of additional options that make working with the device comfortable and convenient. These include the “Hot Start” function, which ensures rapid formation of a welding arc; “Anti-sticking” - when the electrode sticks to the surface being processed, the supply of welding current to it automatically stops; “Arc force” is a function necessary for the formation of welding seams located in a vertical plane.
2. Suitability of the device for repair. Welders are equipment with a complex structure; their maintenance and repair require special knowledge and spare parts . Therefore, if there are no service centers of specific manufacturers in your place of residence, then it is better to focus on models of other brands.
3. Guarantee. Most manufacturers provide a product warranty of up to 2 years; Chinese “no names” and little-known factories either have no return period and free repair period at all, or it is limited to 2-3 months.
4. Upgradeable to improve functionality. This option is important only in cases where the device is intended to be used not only for ferrous metals, but also for non-ferrous metals, the high-quality connection of which is possible only in a protective gas environment with a non-consumable electrode (TIG method). In this case, you should choose devices with the possibility of additional connection of cylinders and devices for supplying inert gas.

Source: https://svarka.guru/oborudovanie/vidy-apparatov/invertor-mma.html

Inverter welding: what is it, equipment features and technology

Inverter welding is a popular method of welding different types of metals, with which you can obtain high-quality and durable seams. It is often used by professional and novice welders who have already appreciated its high quality.

During this process, inverters are used, which have long replaced rectifiers and transformers on the market. This equipment has many advantages: it has high power, productivity, and the ability to work in different weather conditions.

Welding inverter device

Before starting the process, it is worth knowing what an inverter welding machine is. Previously, this device had a fairly simple operating scheme. But recently the device has been improved and received a lot of additional functions that could make it modified. Engineers were able to add electronics to it, which increased its functionality.

To understand what a welding inverter is and how it works, it is worth considering its operating principle:

• the device can operate from an alternating current network with a voltage of 220 or 380 volts and a current frequency of 50 Hz. An ordinary household inverter device just needs to be plugged into a household outlet;
• The welding current entering the inverter passes through the diode bridge. In this area it smooths out and becomes permanent;
• the resulting electrical energy passes through a block of transistors, and a high switching frequency is observed. The result is alternating current again, but it has a high frequency - 20-50 kHz;
• in the subsequent period, the current voltage is converted; at the output of the inverter it decreases to 70-90 volts. And if we follow the principles of Ohm's law, then a decrease in voltage causes an increase in current. At the output (at the end of the electrode) a current strength of 100-200 amperes will be observed. This is precisely the current strength of the welding process.

Features and rules for choosing an inverter

So what is a welding inverter? This is a unique device that allows you to perform high-quality welding of different types of metal. The multifunctional device is capable of working with different types of electrodes that can support direct and alternating current.

But what does an inverter welding machine mean for production? This is unique equipment that could greatly facilitate the welding process of large metal structures.

Important! The devices are highly mobile; they can be easily moved and rearranged to the required height. If you need to carry out welding work above ground level, then these devices will be an excellent option.

What does an inverter welding machine mean? Help you find out the important features that need to be taken into account when choosing it: 

1. Network power supply . There are single-phase devices on sale that operate from a standard 220V outlet. They are great for home use. Three-phase equipment is professional; it has high power.
2. The magnitude of the welding current . In accordance with this indicator, the thickness of the electrodes for soldering metal elements is selected. Its range for different inverter models can be from 5A to 350A. Electrodes with a thickness from 1.6 to 5 mm can be used for them. For domestic conditions, devices with a current value of 200A are excellent, on which an electrode with a thickness of 3 mm can be used.
3. Load duration . This parameter means the operating time of the device from one cycle until the device is turned off. In the documentation it is indicated as “PN”, but in practice it is capable of pulling up to 60%. For example, if the passport indicates 10 minutes, then the device can withstand 6 minutes, this time is quite enough for industrial and domestic use.
4. Availability of additional functions . For example, in some models the Arc-Force function may be provided; it stabilizes the welding arc, namely, in the event of an accidental interruption, the machine causes an increase in the current strength to restrain it. The TIG function enables argon welding, HOT-START facilitates contact ignition of the arc.

Rules for preparing for work

We almost already understand what a welding inverter is and how it works. Now you can start using it in practice, but first you need to prepare for the welding process. To do this, you must follow the following recommendations:

1. Protection. It includes all the important features that must be used for safety purposes. You need to wear gloves made of thick fabric on your hands; they can protect the skin from sparks. Glasses and a mask are used for the face. A robe made of material that can withstand fire is suitable for the entire body.
2. Preparation of the workplace. Cooking should be done on a durable iron table; it should not be covered with varnishes or paints. The welder must stand on a wooden base when welding.
3. Preparation of the necessary consumables, namely electrodes. They should be selected depending on the thickness and type of metal.
4. Cleaning metal from dirt and various coatings.

Inverter welding technology

What inverter welding is can be understood by considering its technology.

The whole process is carried out in stages:

• At the initial stage, the arc is ignited. This can be done in several ways - by scratching, tapping or touching;
• then we begin to melt the metal, a weld pool should form;
• the electrode can be carried out at a right angle of 900 or obliquely at an angle of 30-600;
• When carrying out the welding process, it is imperative to hold the welding arc. During this process, it is necessary to maintain a uniform distance between the metal and the electrode. The most suitable level should be 2-3 mm.

It is worth noting! Some inverter models have an automatic arc hold function. If you cannot do this manually, then it is advisable to use this option.

If you look at the detailed instructions, you can understand what inverter welding means. This is a unique process that allows you to join different metal workpieces. Convenient welding machines provide maximum convenience when working in difficult production conditions, which often require welding at heights.

Interesting video

Source: https://osvarka.com/vidy-i-sposoby-svarki/invertornaya-svarka

What is the duty cycle of a welding inverter

The appearance of welding inverters on the electrified tool market has produced a kind of technological revolution.

Thanks to them, the operation of joining metals by using the properties of an electric arc has become available not only to professional welders, but also to any home craftsman.

Today we will tell you about what the operating principle of the inverter is based on and what you should pay attention to when purchasing this tool.

High frequency is the key to solving the problem

The first who managed to put into practice the effect of heating metals by an electric discharge arc and transferring its molecules with it was the Russian electrical engineer Nikolai Bernandos. This was in 1882. Its installation used a non-consumable carbon electrode, and the joining of metals occurred when an intermediary, a molten metal rod, was introduced into the arc combustion zone.

In fact, it was the prototype of modern TIG welding. Six years later, engineer Nikolai Slavyanov created an installation in which the electrode, which provoked the occurrence of an electric arc, simultaneously played the role of a molten filler rod. This is how MMA (consumable electrode welding) arose.

What these electrical installations have in common is the nature of the occurrence of the electric arc. It ignites as a result of breakdown of the gaseous medium - the gap between two conductors. To bring it under control, engineers needed a device with electrical inertia, since the avalanche-like increase in current could destroy everything in its path.

This is an alternating current transformer consisting of two windings placed on a metal core. The magnetic flux in it has a force directly proportional to the current that generated it, but is directed opposite to it.

The transformer also solves another problem - it reduces the voltage relative to the input, due to which the current increases, which is the root cause of breakdown of the medium and the occurrence of an electric arc.

The higher it is, the stronger its heating and the greater the number of metal molecules it can transfer.

In order for a transformer to operate in short circuit mode, its windings must effectively resist the current that destroys them. To do this, the cross-section of the wire is made very large, and the core is as massive as possible.

Electrical engineers discovered the effect that the physical effect of electron flow on a conductor is stronger, the lower its oscillation frequency. For example, if a current of 50 Hz and 50 amperes is passed through a copper wire with a cross-section of 1 mm2, it will melt. But if, with the same number of amperes, its frequency is 20-30 kHz, then it will remain cold.

The main disadvantage of high-frequency currents is the inability to transmit electricity over long distances. Therefore, the frequency of industrial current is 50 (in some countries 60) Hz. This is the optimal value that allows you to obtain a satisfactory level of losses and not make the electrical installations too massive.

Welding machines, the transformer windings of which are supplied with an industrial frequency current of 50 Hz, have a large mass and dimensions due to the fact that they must operate in short circuit mode and not be destroyed.

They cause excessive overloads in the electrical network, which significantly complicates their use in everyday life. The opportunity to bring to life the idea of ​​​​using high-frequency vibrations in welding operations appeared only at the end of the 20th century, when sources of high-frequency continuous vibrations were designed based on semiconductor devices.

Welding inverters

The circuit, when the current of an industrial frequency of 50 Hz is converted into a high-frequency one, is called inverter from the English word inversion - transformation, change. The operating principle of any type of inverter is as follows:

1. AC power frequency 50 Hz is rectified. To do this, it is first fed to a step-down AC transformer. And then to the so-called diode bridge, consisting of four elements with one-way conductivity. Its output produces a pulsating voltage, which is smoothed by a capacitor. This is the first stage of inversion.
2. DC voltage is used to power a semiconductor generator of continuous oscillations, which are an endless sequence of rectangular pulses of different polarities. It is commonly called a quasi-sinusoid due to its similarity to the voltage diagram of an alternating current generator. This is the second stage of inversion - obtaining high frequency alternating current.

The design of a welding inverter differs significantly from electrical installations built on this principle. For example, from a frequency converter used to control the rotation speed of asynchronous electric motors.

First of all, the oscillation frequency in it increases to tens of kilohertz (for frequency generators it is no higher than 60 Hz). This makes it possible to make a transformer that operates in short-circuit mode compact.  

In this case, the value of the output voltage by the transformer decreases, and does not increase, as in the same frequency converter.

220 volts are supplied to the input of the device, and from 40 to 80 volts are removed from the connectors for connecting wires.

This is done not only in order to obtain a welding current of more than 50 amperes, which is the main condition for the occurrence of an electric arc, but also in order to protect the welder from electric shock.

The principle of operation of the welding inverter is also different in that it produces double inversion - to ignite the arc and transfer metal, it uses direct current obtained by rectifying high-frequency oscillations.

This complicates the circuit and makes the device more expensive, but designers go to such lengths for the reason that they created the device for mass and non-professional use.

The household use of such a device is also facilitated by the fact that welding with an inverter does not cause a network overload (when using industrial equipment of 50 Hz, the voltage drop is noticeable by the weakening of the glow of incandescent lamps). And this happens for the reason that the high-frequency pulse generator plays the role of galvanic isolation.

Selecting a welding inverter

Knowing how the equipment of an inverter welding machine works, you can make the right choice when purchasing it. You need to pay attention to the following parameters:

• Power consumption. This value affects how long the welder can operate under load without critically heating the circuit elements. For the average consumer, it may not be very clear, so the technical specifications also indicate the duration of switching on at maximum current (MC) as a percentage. For example, if the duty cycle is 60%, then the duty cycle consists of six minutes of operation under load and four minutes of idling to cool down. Amateur models with a power of up to 2 kW have a duty cycle of 30%. And for professional devices (from 4 kW and above) the PV is always above 50%.
• Operating current range. It is usually made in the range from 16 to 220 amperes. For domestic use, 110-120 amperes are sufficient. Two hundred and twenty are required for welding shaped metal products of large cross-section and mass.
• Idling. Voltage at the output contacts of the inverter without load. For a welder, the open circuit voltage of a welding inverter is a factor that influences the ease of igniting the arc. The larger it is, the simpler it is. However, a large XX causes the seam to become porous and clogged with slag, which weakens it. For work with pure metal, it is enough that XX is equal to 40 volts. For rough welding of rusty pipes and profiles, 70-80 volts are needed.
• Options. Hotstart - an increase in welding current at the moment the electrode touches the surface. It helps when working with rusty metal or low voltage at the inverter input. Arcforce – arc forcing, which prevents it from going out during operation if, for example, a thick layer of oxides is encountered. Antistick – resets the welding current to zero when the electrode sticks. Allows you to easily tear it off the seam without shedding the flux layer. Saves consumables. They will help novice welders quickly master the basics of the profession and protect them from inevitable defects in their work.

A welding inverter is necessary for every home craftsman. It gives real freedom of action when repairing and installing metal structures.

Source: https://steelfactoryrus.com/chto-takoe-rabochiy-tsikl-svarochnogo-invertora/

What is MMA, TIG, MIG/MAG - description of technologies

It is sometimes difficult for a non-specialist to understand the terms and definitions used in welding. The complexity is additionally caused by the fact that there are no strictly regulated and classified methods and techniques. However, manufacturers of welding equipment and materials adhere to generally accepted English abbreviations, which will be discussed in this article.

MMA (RDS)

MMA (Manual Metal Arc) - manual arc welding with piece (coated) electrodes using an inverter or transformer. The technical literature of Soviet times used the designation RDS.

The welding process occurs due to the melting of a metal rod - an electrode, coated with a special coating, which have their own classification. Its main purpose is to protect the weld pool from air, preventing oxidation of the metal.

The molten rod forms a weld and the used coating remains as slag.

Covered electrode welding

RDS is possible on both direct and alternating current. With direct current, there are two options for connecting the ground clamp and the electrode holder, so there is welding with direct and reverse polarity. Alternating current does not have this feature - how to connect the electrode in this case does not matter. The given reliability rating of welding inverters will help you choose a machine that will last for many years.

Since the MMA method is the most popular due to its simplicity and relatively inexpensive equipment used, you should definitely familiarize yourself with the question of how to learn how to weld with electric welding yourself.

TIG(WIG) or RADS

TIG (Tungsten Inert Gas) – technology of arc welding in an inert gas environment with a non-consumable electrode. Tungsten is a very refractory metal with a melting point of about 3500 C, so it is the basis for the production of this kind of electrodes. Sometimes you can find other variations of this method:

• WIG (Wolfram Inert Gas) – the name is derived from the German spelling;
• GTA (Gas Tungsten Arc) – this abbreviation omits the chemical reaction of the shielding gas.

The choice of materials is carried out according to the color marking of tungsten electrodes, indicating the types of metals being welded, as well as welding modes.

Because the electrode is non-consumable, the argon welding process occurs according to a different scenario:

• an electric arc is excited between the end of the electrode and the metal being welded;
• the welding seam is filled by supplying a special filler material - a rod - into the welding zone;
• the weld pool is protected by a gas cloud.

TIG welding process

Protective inert gas, i.e. a gas whose molecules do not chemically interact with the base and filler materials during the welding process; in this case, argon is used. That is why the name “manual argon-arc welding” or RADS was assigned to it.

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It is worth noting that this name is not entirely correct, because Other gases, such as nitrogen, helium, and gas mixtures, can be used as a shielding gas.

Argon can be used when welding consumable electrodes - the MIG method, which will be discussed below.

In the technical characteristics of welding equipment, in addition to the TIG designation, it is always supplemented by a mention of the type of welding current DC (Direct Current) - direct current or AC / DC (Alternating Current / Direct Current) - alternating / direct current. In this case it is very important. For example, welding aluminum with argon is carried out using alternating current.

MIG/MAG

MIG/MAG (Metal Inert/Active Gas) is a method of arc welding in a protective atmosphere of inert/active gas using a consumable electrode in the form of steel or other wire, depending on the type of metal being joined.

Schematic representation of the mig/mag method

MIG or MAG welding usually means semi-automatic welding. The main objective of this method was the idea of ​​​​creating an “endless electrode”, thereby achieving significant welding productivity. Indeed, with the RDS method, you often have to change the electrode as it is used up, which in some cases is extremely inconvenient. As with TIG welding, shielding gases are used here.

The inert agent is usually argon and its mixtures, which is suitable, for example, for semi-automatic welding of aluminum and its alloys. The active gas, i.e., interacting with the metal being welded in the process, is usually carbon dioxide (carbon dioxide). You may hear from a welder the phrase “semi-automatic welding in a carbon dioxide environment,” meaning the MAG method.

This method is the most common due to its increased productivity compared to MMA, and gives a better result in the quality of the weld. The rating of household semi-automatic machines based on reviews of experienced welders will help you decide on the choice of a welding machine.

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We hope that this article will help you understand the classification of basic welding methods, and will also be useful when choosing equipment and materials with English abbreviations.

Source: https://svarkagid.ru/tehnologii/metodi-svarki-mma-tig-mig-mag.html