Welding inverter Resanta SAI-250 – characteristics and features

The most popular type of welding equipment are inverters for manual arc welding. They are chosen mainly by amateurs for work in the country, students, beginners who want to gain experience; home craftsmen to earn extra money and solve their own problems. Inverters are ideal for on-site repairs of low complexity. It is for such purposes that manufacturers produce dozens of inexpensive models, among which it is easy to choose the most acceptable option.

The Resanta brand was no exception and introduced its household level welding machines to the consumer market. The manufacturer's catalog presents a fairly wide range of budget inverters of the SAI series. Among the models there are also individual modifications that are distinguished by technical characteristics, equipment and dimensions.

• Technical characteristics of the inverter Resanta SAI-250 (Resanta 250A)
• Welding machine Resanta SAI 250PROF
• Welding inverter Resanta SAI 250PN
• Inverter welding machine Resanta SAI 250K

Characteristics

The technical characteristics of the Resant SIA 250 show that this device reaches the professional level. Although it cannot operate at maximum current all the time, no other household appliance can cook with six in domestic conditions.

Device parameters:

• Mains voltage, V: 140…242
• Eg. idle, V: 80
• Eg. under load, V: 29…30
• Max current consumption, A: 35
• Power consumption, kW: 7.7
• Welding current, A: 10…250
• PV at maximum current, %: 70
• Protection class: IP21
• Operating temperature, ºC: -10…40
• Weight, kg: 5.2

The device is also equipped with anti-stick and “hot start” capabilities. If the electrode is caught and the arc does not break out, the current automatically decreases and the electrode can be removed without difficulty. Hot start, on the contrary, increases the current automatically to facilitate arc ignition. Both functions are implemented by high-speed electronics that control the device.

Operation of the device

The machine is cooled by a built-in fan and this introduces some subtleties that welders accustomed to working with older arc welding machines may not have encountered.

Protect the device from moisture and metal filings and shavings! Stay as far away from them as possible.

Inside the case there is a board with electronics, almost the same as in computers or other electronic equipment. High-power parts (key transistors of the converter and rectifier diodes, chokes), through which large currents flow, are adjacent to small parts on this board.

These small parts belong to the rather complex electronic circuits that control the operation of the converter. The voltage on them is only about a few volts, but damage to them will instantly lead to failure of the power circuits of the device. As a result, the device will either “quietly die” or stop working with a bang.

Since the fan constantly drives air through the device, the following objects, which are not uncommon at construction sites, in workshops and during repairs, can easily fly into it:

• scale particles;
• metal dust;
• metal shavings;
• sparks from a grinder;
• drops of water or solution.

Once on the board, metal shavings or moisture will cause a short circuit in the converter control circuits. Even a short (on the order of a millisecond!) malfunction of the powerful transistor switches of the converter bridge will lead to the so-called through current, which will instantly damage expensive IGBT transistors.

At the same time, it should be clear to the welder that it is also impossible to close the machine from blowing air, it will quickly overheat and the protection will turn it off. (This will be indicated by a warning light.) In this regard, consumers often have a question: is it possible in this case to lengthen the standard welding wires?

Of course it is possible, but at the same time it is necessary to maintain their resistance no less than it was in the factory kit, so as not to lose welding power. Only a proportional increase in its cross-sectional area can maintain equal resistance to a conductor when it is lengthened. And it is related to the diameter of copper using the square root.

Simply put, if you want to double the length of the welding wires, then their copper diameter should be one and a half times larger (1.41 times). In this case, the weight of the cable and its price will be four times more expensive.

When operating at maximum current, operate for no more than 5 minutes, and then give the device another 5 minutes to cool down. Use grounding when working.

Try to work at normal mains voltage! Do not be fooled by low voltages “from 140 Volts”. At reduced voltage, the device operates in difficult conditions, delivers significantly reduced power and runs the risk of failure.

The question often arises: is it possible to connect the device to an electric generator if, due to operating conditions, the power grid is unavailable? It is possible, but it is necessary that the power of the generator be one and a half times greater than the power consumption of the welding machine. For Resanta 250 this is 12 kW .

Video:

Reviews and price of inverter

In the Resanta SAI 250 PROF (price 19,000 rubles), during normal operation, malfunctions should not occur for a very long time.

Competent welders praise him very much. Negative reviews, as their careful study shows, are left by consumers who quite flagrantly violated the operating conditions.

Video: review of Resanta SAI-250 PROF.

Diagram of the welding machine RESANTA SAI-250 PROF - Download.

Resanta 250 PN , the price of which, by the way, is 4-5 times lower than Western European analogues (average cost 12,500 rubles), requires a new attitude towards the welding machine. This is no longer the mortar-stained, rusty iron box at a construction site; it has delicate things inside.

Video: review of Resanta SAI 250PN.

PS If you operate the device according to the instructions, it will serve for many years, and the faults will be minor and easily fixed.

This is interesting: Schematic diagram of a welding inverter: let’s look into the details

Technical characteristics of the inverter Resanta SAI-250 (Resanta 250A)

The model is one of the most expensive among the SAI line. It is positioned on the market as equipment intended for household use. Indeed, the functionality makes it possible to perform mid-level tasks. This is an excellent choice for home use or as a training tool for on-the-job training.

The maximum available welding current is 250A. In order to prepare the Resanta SAI 250 inverter welding machine, it is enough to connect it to a single-phase network. The weight of the equipment is light. Therefore, you can attach a strap to the case and carry it around.

Among the functionality of the device, it is important to note the cooling system and preliminary temperature control. If the welding overheats, the automation will notify the user. The metal body is quite durable, and all the parts fit well. The equipment is minimal: the device comes with instructions and two power cables. The rest of the equipment will have to be purchased additionally.

Specifications:

Among the features of the model, it is worth emphasizing the ability to quickly connect cables, convenient adjustment of operating parameters, and ease of use. Main advantages of the inverter:

• works well from a household network. Does not require connection via an additional transformer;
• an inverter system assembled on transistors, in combination with other technical features, ensured the small size of the welding machine;
• plus light weight, which makes it possible to use the equipment during field work;
• complete safety in operation;
• an effective forced ventilation system allows you to work longer hours without interruption and complete complex tasks;
• the model has functions that facilitate the work of the welder: anti-sticking and hot start;
• the durable metal case protects the components well from possible damage;
• has the ability to convert high-frequency current and a large range of operating adjustments;
• allows the use of electrodes for both direct and alternating current;
• The device does not require special knowledge from the welder. Even beginners can operate it.

In what configuration is it sold?

There are 4 models in the equipment line. 250A in the name means the current adjustment range is 10 - 250. In addition to the basic model, there are 3 more:

• 250K - has a compact size;
• 250PN - safe at low input voltage;
• 250PROF - suitable for complex work performed by a master.

Along with the device itself, the kit includes:

• Cable with electrode holder.
• Ground wire.
• Technical certificate.
• Package.

The kit includes the welding machine itself, a cable with an electric holder, and a cable with a grounding terminal.
Some models are equipped with a stylish storage case.

What is remarkable about the inverter of this model

The welding machine of this model is very convenient to use for domestic purposes, since its design ensures reliable operation even with significant voltage drops (140–240 V). With minimum permissible voltage values, such an inverter allows you to effectively perform manual arc welding.

Technical characteristics of the Resanta line of welding machines

When working with this device, it is allowed to use electrodes whose diameter can reach up to 6 mm. The upper limit of the current, which can be adjusted over a wide range, for this inverter model reaches 250 A. The protection systems provided in this welding machine allow it to withstand significant loads for a long time. It should be noted that not all inverters offered on the modern market have such characteristics.

The no-load voltage of this model is 80 V. The presence of IGBT series transistors in the design of this device provides it with exceptional durability even under conditions of active operation under high loads. This model of welding inverter has a protection level of IP21.

The cost of such a device is approximately 12,000 rubles

Its compactness and high mobility greatly facilitate the use of such an inverter. In order to quickly and without serious labor costs transport such a device around the work site, a convenient handle is provided. The inverter of this model is also distinguished by the simplicity and accuracy of setting all its parameters. What is important is that the set parameters retain their values ​​even in cases where voltage surges occur in the electrical network.

The main technical characteristics of this inverter model have the following meanings.

• At maximum current (250A), the load duration is at least 70%.
• The maximum value of current consumption is 35A.
• The device can be operated in a temperature range from –10 to +400.
• The operating welding current can be adjusted in the range of 10–250A.
• The welding arc formed using such a device has a voltage of 30V.

If it is not possible to use a centralized electrical network, then the device can be connected to a gasoline generator with a power of at least 5 kW. When choosing electrodes for welding using such a machine, you should take into account the fact that the value of the welding current decreases along with a decrease in the input voltage.

» data-lazy-type=»iframe» src=»data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7″>

Types and features of welding machines Resanta 250

Like many other manufacturers, the creator of the Resanta 250 inverter offers professional and amateur users several types of devices with which you can perform all the tasks assigned to the master. Let's take a closer look at the types of devices from this line.

Under the Resanta brand, 4 lines of welding inverters are produced, which differ slightly in design, but significantly in performance characteristics. For example, you can buy units with a maximum current from 190 to 250 Amperes in a case. The following series are distinguished:

• SAI-250K;
• SAI-250;
• SAI-250PN;
• SAI-250PROF.

At the same time, the series of 250 A devices includes 3 models: Resanta SAI-250, Resanta 250PN, SAI-250K. The latest modification is also Resanta Prof, as it is equipped with an improved arc ignition system without touching and additional protection of the inverter itself from overloads.

The devices have a convenient carrying handle and eyelets for pulling the strap over the shoulder. To prevent accidental violation of current settings, protective glass is provided on the front panel.

Where is it used?

Convenient size and handles allow you to carry out work at home and on the road. Applicable for:

• eliminating breakdowns in household equipment;
• welding work in a car repair shop;
• installation of fences and gates;
• repair of garden greenhouses and summer cottage equipment;
• installation of gutters;
• service repairs in specialized centers, etc.

Resanta SAI-250 is used for welding work in an auto repair shop.

Resanta 250 devices are powered by a 220 Volt network and a generator.

Their scope of application is limited by the current output and the size of the electrodes.

Review of Resanta with SAI index - 250k and SAI - 250 pn

Inverter manufacturers are constantly searching and adapting products to any consumer request. The differences between the presented converters with different indices have a slight difference: Resanta SAI - 250k has a compact body, with a maximum electric arc current of 250A. And it is designed to work with electrodes from 2 to 6 mm in diameter. Resanta SAI - 250 pn is designed for unstable mains power supply, that is, it can operate at an unstable voltage from 140 to 250 Volts. This is especially true in garages or at remote sites. And with a small-sized and lightweight body it is much easier to do installation work. The converters are universal in their application and have all the functions inherent in Resanta inverters.

Read also: How to make a tool case yourself

The body has a compact rectangular shape measuring 130×260×190 mm and is made of galvanized sheet 0.4 mm in size. This design is multifunctional:

• has additional heat dissipation;
• the iron has stiffening ribs, the body is very durable and can be easily removed to inspect internal parts;
• electrical safety according to class IP 21 (the inside of the device is sufficiently protected from falling from 2 meters, not protected from slanting rain).

Connectors for connecting power cables are located on the front panel. Also on the front panel there is a voltage and arc stiffness regulator. The digital indicator will easily help you set the required welding current. To perform work with forward and reverse current, it is enough to change the terminals on the panel. The panel also has temperature sensors that warn of overload shutdowns with a special indicator.

Reliable operation and safety of the Resanta SAI-250K inverter converter is ensured by a special protective system. Temperature sensors detect the approach of dangerous overheating in advance and warn the user by turning on the emergency indicator.

Safety precautions when working with a welding inverter

To extend the service life of the SAI-250 model inverter, professionals recommend keeping it for 2-3 hours at a positive temperature before using it. Condensation will not form in the device, which can cause emergency situations. In addition, you must be very careful to ensure that the welding cables and connection wires do not damage the insulating layer. This is contrary to safety requirements and may also cause device failure.

The SAI-250 inverter, the scope of which is very wide, cannot be turned on in rooms where parts are processed using methods that involve the formation of metal dust or small chips. Such metallic particles in the air can get inside this device and damage it. This inverter (as well as others) cannot be used outdoors during rainfall or in rooms where the air humidity level is high.

Follow standard safety requirements when working with Resanta SAI-250

Even if you are a very good and experienced specialist, before using such a device it is better to once again familiarize yourself with the safety requirements that must be observed when working on electrical installations for industrial and domestic use. There are several simple rules that should be strictly followed when working with such equipment.

• The place where welding work is carried out must be well ventilated, it is necessary to ensure a flow of fresh air.
• Strictly follow fire safety requirements.
• When working, be sure to use a welding mask, special clothing, thick gloves and a hat. These safety features will ensure that your eyes and skin are protected from burns.

The internal structure of the welder

The storage requirements for such equipment must be strictly observed. To do this, it is necessary to use rooms that should not contain alkali vapors, acids, or large amounts of dust. The conditions in which the welding inverter of this model is stored must meet the following requirements:

• ambient air humidity level – no more than 80%;
• ambient temperature – from –10 to +50 degrees Celsius.

This is interesting: Collet for a hand router: types, purpose and application features

Useful and necessary functions:

PFC (Power Factor Correction)

One of the important parameters of the welding transformer is the power factor correction function PFC (Power Factor Correction). With its help, voltage stabilization on the inverter increases and the load on the electrical network is reduced to 30%, a stabilized voltage is maintained, which ranges from 60 to 200 Volts on the transformer, and reduces the load to the pulse generator and output transformer. This allows for 15% more power output with the same grid load. PFC is mandatory for devices with the “prof” index. First of all, when purchasing a welding inverter Resanta Sai 250 for the first time, in addition to the price and reviews, you need to decide on the operating conditions and frequency of its use.

Arc Force function

Another parameter, the Arc Force function, allows you to adjust the rigidity of the arc when working with thin-sheet steel sheet profiles.

A welding transformer equipped with this function allows you to comfortably work with low voltages and low currents - this is very important for welding thin sheet metals or even sheet metal. Without this function, to perform such work efficiently, experience and daily practice are required. The electrode sticks at low currents, and inaccurate contact with the metal can lead to burnout.

It is to eliminate such cases that the inverter contains “Arc Force”. On the Resanta Sai 250 Prof welding machine, this function is set manually using the arc stiffness adjustment knob. On the Resanta Sai 250 pn welding machine, which does not have the abbreviation “prof” on it, the adjustment is performed automatically when the welding mode value is set

Load duration indicator

When choosing an inverter for work, less experienced users pay attention only to the maximum welding currents; on the one hand, this is correct, because the higher the welding current, the greater the functionality of the device, for example, you can cut a corner or profile with a high-power arc. And many do not pay attention to such a concept as load duration (LOD), or as it is also called - the duty cycle. This indicator is key in determining the duration of use of the device.

The coefficient is described using percentages, in proportions (10 minutes - 100%, 5 minutes - 50%). That is, at 100%, the converter operates for 10 minutes out of 10 possible at the maximum declared current without turning off the overheating protection. Accordingly, if only 5 minutes, it will be 50% of the working hours. In the line of inverter welding machines Resanta Sai 250 and other modifications, the coefficient reaches 70% - this is one of the best PN indicators among existing household inverters.

Hot-star - hot start (Hot-star)

With this function, the electrode is ignited at the beginning of welding with increased voltage and automatically decreases when the arc is ignited.

Anti-stick - anti-sticking (Anti-stick)

This function automatically reduces the short circuit current when the electrode gets stuck, which can then be easily torn off with a slight movement of the holder.

Safety Compliance

Resanta inverters are used by both masters and novice welders. For safe and high-quality work, it is important to follow the safety precautions for operating the device:

• Before welding begins in the room, it is necessary to open windows and doors so that the work area is ventilated.
• Wear protective clothing to protect against thermal burns.
• It is prohibited to weld without a special mask.
• The device cannot be used in conditions of high humidity and low temperatures.
• Do not carry out work with high dust generation close to the inverter. Its particles can harm the device.
• Do not connect the device to a professional high-voltage network.
• Do not start welding if damage to wiring or cables is detected.

Before using Resanta SAI-250, you need to wear special clothing to protect against thermal burns.
For the safety of the master and the device, it is important to follow the “Rules for the technical operation of consumer electrical installations” and the “Safety rules for the operation of consumer electrical installations.”

Preparation for use

You can turn on the device only after a long stay in the heat. This will prevent condensation from forming on the parts. Operating procedure:

• Connect the grounding cable and the wire with the electrode holder to the connectors on the front of the case in accordance with the polarity.
• Move the power switch lever to the “OFF” position.
• Plug the power cord into a power outlet.
• Set the power regulator to the minimum value.
• Switch the lever to the “ON” position.
• Set the required operating current value using the regulator.

After completing the work, turn off the device in the reverse order:

• Turn the switch to the “OFF” position.
• Disconnect the device from the power supply.
• Disconnect welding cables.

The device can only be turned on when it is warm.

Device capabilities

The device has found wide application in household and minor professional repairs. Technical capabilities:

• capable of operating at low input voltage - from 100 V;
• provides a high operating time at maximum power - 7 out of 10 minutes;
• prevents sticking of electrodes;
• maintains a stable arc due to the afterburner function;
• precise control over the current level is ensured by the presence of an electronic display;
• provides effective cooling of equipment due to ventilation holes in the housing;
• equipped with a built-in cooling system for internal components.

These indicators allow the welder not to be interrupted for a long time and create neat, even seams. SAI 250 PROF is distinguished by high quality of work and increased electrical safety.

The device is capable of operating at low input voltage.

Advantages and disadvantages

Benefits include:

• ease of transportation due to its compact size;
• low power consumption;
• controlled arc force;
• hot start function;
• wide range of voltage consumption;
• power supply from 220 V;
• warranty period - 2 years;
• ease of use.

Among the shortcomings, buyers indicate:

• short cables;
• high cost of the inverter and its components;
• lack of ability to connect to a 380 V network.

The advantages include low energy consumption.

What can cause damage

If you follow the instructions and rules for operating the device, there will be no malfunctions for several years. To avoid repairs for a long time, you need to know what actions and circumstances can damage the device:

• The welding current is incorrectly adjusted. The indicator must correspond to the values ​​stated on the packaging with the electrodes.
• Using non-factory welding cables or power cords.
• Connecting the inverter via an extension cable of more than 40 m.
• Connection to faulty sockets, intermittent networks.
• Operating at high power for longer than the permitted period.
• Using the device in low temperature conditions.
• If dust, debris, sediment, or sand gets inside the device.
• Mechanical damage, device falling.

Spontaneous shutdown

In some cases, repairs can be carried out independently if the device begins to turn off spontaneously. Most models of welding machines are equipped with a protective circuit (automatic) that is triggered in a critical situation, accompanied by a deviation from normal operation. One of the options for such protection involves blocking the operation of the device when the ventilation module is turned off.

After spontaneous shutdown of the welding machine, first of all, you should check the state of the protection and try to return this element to working condition.

If the protective unit is triggered again, it is necessary to proceed to troubleshooting using one of the methods described above related to short circuits or malfunctions of individual parts.

In this situation, first of all, you should make sure that the cooling unit of the unit is working normally and that overheating of the internal spaces is excluded.

In the absence of internal protection, a circuit breaker can be installed in the electrical panel. To maintain normal functioning of the welding unit, its settings must correspond to the selected modes.

Thus, some models of such devices (welding inverter, in particular), in accordance with the instructions, must work according to a schedule that requires a break of 3-4 minutes after 7-8 minutes of continuous welding.

Operating principle of welding machines Resanta 250

Even a beginner can work with such a device with his own hands, but only if he follows some recommendations. The device works as follows:

1. You plug the unit into a socket specially prepared for it. The installation diagram and recommendations on this matter are in the instructions. In a nutshell, let's say that it should be separate from the panel and connected to its own circuit breaker, equipped with a third grounding wire. In this case, the wiring must be designed for a maximum current of 40 Amps. It is important to know that a regular household outlet will not work, because it can withstand a maximum current of 25 A.
2. The device charges the input filter and the soft start circuit turns off, at the same time the fan starts.
3. The user selects the desired current ranging from 10 to 250 A.
4. The electrode is installed in the holder, the mass is connected to the parts being welded. The welding area must be cleaned and sharpened if necessary.
5. The master begins work by choosing the optimal location of the holder with the electrode to the plane of the parts, in accordance with the thickness of the parts and the diameter of the electrode.

Checking the chip

If visible damage has been eliminated, but the equipment remains inoperative, it is necessary to check the radioelements and microcircuits for damage. It is better to entrust this work to professionals. If for some reason you have to independently inspect the microcircuit, it is important to observe caution and safety precautions. Verification steps:

• Visual inspection of parts in order to detect visible damage: swelling, scorching, disconnected contacts.
• Checking the diode bridge to detect a short circuit, breakdown or break. You can do this yourself with a multimeter set to the “diode ringing” mode.
• The next step is to check the serviceability of the 4n90c key transistor. This element is responsible for increasing the frequency of the DC current and sending it to the pulse transformer.
• If there is a malfunction in the operation of the power unit, you will need to remove the transistors for testing. These steps are also performed to check the driver.
• Irregularities in the operation of the control board are detected by connecting an oscilloscope. If a yellow signal lights up on the device, it means that voltage measurements are required at the control panel connectors. If the readings deviate, the board will need to be removed.
• On the soldered board you need to find the UC3845B (UC3842) PWM controller chip in order to measure its operating modes. If faulty resistors are detected, they should be replaced. After power is restored to all elements of the microcircuit, a control measurement of the input voltage is carried out.
• After confirming the operation of the PWM controller, the control board is returned to its place and re-checked with an oscilloscope. If the yellow diode does not light up, you can test run the inverter.

If the Resanta SAI-250 does not work, you need to check its radio elements and microcircuits.

How does the Resanta welding inverter work?

Any inverter is an AC to DC converter. Power parts of the process:

• transistor rectifier,
• inverter unit;
• a step-down transformer;
• output rectifier.

Resanta SAI-250 is a welding inverter designed for manual arc welding.
The incoming 220 V current passes through these stages, where it is rectified and acquires a power of 400 V. It is then converted into a modulated high-frequency voltage. A step-down transformer optimizes this current to operating current. The process is regulated by a PWM controller chip, which controls the operation of the transistors, setting the rhythm.

Smooth start of the device is ensured by a powerful resistor.

Recommendations for working with devices

• If you decide to buy a Resanta 250 Prof inverter welding machine, then keep in mind that it consumes a lot of energy at the maximum level. Accordingly, it is necessary to take into account the power reserve in the network.
• It is not recommended to use this welding machine for purposes other than welding. For example, as a high-current source for experiments, since under long-term loads the power component can quickly fail, since they are designed for pulsed operation.
• Select the correct current value and electrode diameter. For example, to weld 2-3 mm steel, it is enough to have 2-3 mm electrodes. 3-4 mm can handle the rest.

Device malfunctions

When buying a Resanta 250 device, someday you will encounter problems with its operation, and accordingly, repairs will be required. For example, the most common, judging by the reviews, is a disconnection in the connectors. They are clamped with a screw, but the wire is not crimped with anything. Also, one of the problems that craftsmen often encounter is the failure of power transistors.

Construction of welding machines Resanta 250

The Resanta 250A welding machine is a professional model that is capable of much. This is a professional device, but designed to be powered from a single-phase network capable of withstanding currents up to 35 A. Given the high amperage, this model is more suitable for workshops than for home use, since high currents can cause the network to fail.

The circuit of such a device is an inverter assembled using special power transistors with frequency control. The process of regulating the output current occurs through pulse width modulation. Accordingly, its device can be divided into functional blocks:

• low current input rectifier;
• soft start circuit;
• filter and pre-charging capacity to stabilize the arc;
• logical part with PWM, feedback and overload protection logic;
• power unit with transformer;
• rectifier and choke.

It is equipped with standard connectors for MMA welding. You can also cook in TIG mode using a special sleeve with a hose, a torch and an adapter for connecting to the power supply.

Malfunctions of inverter devices

Before repairing an inverter welding machine with your own hands, it is advisable to familiarize yourself with the principle of operation, as well as its electronic circuit. Knowing them will allow you to quickly identify the causes of breakdowns and try to eliminate them in a timely manner.

Electrical diagram

The use of an intermediate high-frequency signal makes it possible to obtain a compact pulse device that has the ability to effectively regulate the output current.

Failures of all welding inverters can be divided into the following types:

• malfunctions associated with errors in choosing the welding mode;
• operational failures caused by failure of the electronic (converter) module or other parts of the device.

The method for identifying inverter malfunctions associated with disturbances in the operation of the circuit involves sequential execution of operations carried out according to the principle “from simple damage to more complex damage.” The nature and cause of breakdowns, as well as repair methods, can be found in more detail in the summary table.

It also provides data on the main welding parameters, ensuring trouble-free (without turning off the inverter) operation of the device.

Features of operation

Maintenance and repair of inverter-type welding machines differs in a number of features related to the complexity of the circuitry of these electronic units. Repairing them will require certain knowledge, as well as the ability to handle measuring instruments such as a digital multimeter, oscilloscope and the like.

In the process of repairing an electronic circuit, a visual inspection of the circuit boards is first carried out in order to identify burnt or “suspicious” elements within individual functional modules.

If during the inspection no violations can be detected, the troubleshooting continues by identifying violations in the operation of the electronic circuit (checking voltage levels and the presence of a signal at its control points).

To do this, you will need an oscilloscope and a multimeter, which you should start working with only if you have complete confidence in your abilities. If you have any doubts about your qualifications, the only right decision is to take (take) the device to a specialized workshop.

Specialists in the repair of complex pulse devices will quickly find and eliminate the malfunction, and at the same time carry out maintenance of this unit.

Inverter welding machine SAI-250K (compact)

Description

Features and Benefits

• The inverter welding machine SAI-250K (compact) operates from a household electrical network and does not require a special connection method.
• The inverter system uses a relatively small transformer complete with IGBT transistors and ensures a small size and light weight of the device, which allows it to be easily moved to the location required by the operator. There is a special convenient shoulder strap for this purpose.
• The device is equipped with warning elements against dangerous overheating, which makes its operation safe and reliable.
• The unit has the functions “anti-sticking” (ANTI STICK) and “hot start” (HOT START), and the duration of its activation is 70%.
• A high-quality, durable housing protects the components of the welding machine from damage and at the same time ensures reliable cooling of the working transformer.
• The ability to convert high-frequency current (hence the small parameters of the transformer) and a wide range of regulation of the welding current power are the advantages of this device.
• It is possible to use AC or DC electrodes.
• The device does not require special training to connect and use it. It is enough for the user to have initial knowledge and practice.

general description

The Resanta SAI-250K device is a portable inverter-type device for manual welding, capable of providing full-fledged welding work at the household (and not only) level. The unit is simply connected to a household power supply with a voltage of 220+/-10% V and is designed to work with coated welding electrodes and a metal core diameter of up to 6 mm inclusive.

Welded joints of metal elements are quite common both in production and in domestic conditions. Welding transforms different iron elements into a single, strong, non-demountable structure, the strength of which is incomparable to anything else. As a rule, this connection method is used to obtain the most reliable connection where it is impossible or impossible to use a threaded connection. Manual welding is quite widespread both in everyday life and in production (any construction, installation, repair work, etc.). And if previously, to carry out such work, bulky and heavy units were required, then with the advent of inverter devices, these shortcomings were eliminated.

The described Resanta SAI-250K unit is one of the most convenient and compact tools for performing work of this kind. He can do almost any welding operation. Light weight and dimensions, a comfortable and durable shoulder strap allow the welder to easily move the device to the location required for work.

The system includes working cables (power with electrode holder and grounding cable). The length of each working cable SAI-250K is 2 meters. The system also has a power cable (170 cm) with a plug. If necessary, you can use an extension cord of the appropriate cross-section.

A special welding helmet and other personal protective equipment must be purchased separately.

To make the welder’s work easier (especially for beginners), the designers of Resanta SAI welding machines have created such a useful function as a “hot start” (HOT START). At the moment the electrode is sufficiently close to the elements being welded, the system automatically creates an increased operating current pulse, which contributes to the rapid formation of an electric arc. At the same time, the welding process is greatly facilitated.

The “anti-stick” function (ANTI STICK), also characteristic of all Resanta SAI devices, in turn is designed to facilitate the work of the welder, eliminating the phenomenon of electrode sticking during the arc burning period. In this situation, the device automatically reduces the welding current, facilitating easy tearing of the electrode. Immediately after this, the system restores operating parameters.

The main part of Resanta welding machines is made on the basis of high-tech IGBT transistors. As a result, it was possible to achieve a significant increase in the service life of the system, as well as significantly reduce its dimensions and weight. The transistor board is typically located in a vertical plane, which prevents the accumulation of dust and, as a result, unnecessary overheating.

Another characteristic feature of the system is the on-time (ON). This is a value that characterizes the ability of the device to operate continuously over a certain period of time. The basis was a 10-minute time interval. For the SAI-250K device, this parameter is 70% at maximum load. This means that welding can be carried out continuously for 7 minutes out of 10 and 3 minutes - a break at idle.

The welding machine of this model has a fairly significant open circuit voltage (80 V). This facilitates easy and quick ignition of the electric arc, which allows you to work with non-ferrous metals.

The creators of the welding machine also took care of its safe use. The main danger for devices of this kind is overheating, which can cause breakdown of the unit and other undesirable consequences. Resanta SAI-250K has a special warning system, which turns on (before dangerous overheating) an emergency indicator light. When the indicator lights up, it indicates the need to pause welding work. A 5-minute break is enough to restore the unit’s functionality. There is no need to disconnect it from the power supply.

Design and functionality

The housing of the Resanta SAI-250K welding machine has a compact rectangular shape, dimensions 130×260×190 mm and is made of high-quality sheet metal with a protective coating. The flat base of the case allows it to be placed stably on any surface, even with a slight slope. There are specially made slots on the sides of the housing through which ambient air can easily circulate, cooling the main transformer. The electrical safety of the housing meets the criteria of class IP 21 (protection against the ingress of foreign objects, but work should be done in a fairly dry atmosphere).

The switch and power cable are located on the rear panel of the case, and the control panel is located on the front panel. It is very simple, understandable and will allow even a beginner to understand it. Here the designers placed a rotary regulator for operating current from 10 to 250 A, a network indicator and an indicator warning of the approach of emergency overheating. On the same panel there are terminals for connecting the power cable with the electrode holder and the cable that ensures the closure of the electrical circuit for the welding process. At the top of the case there are fastenings for a shoulder strap.

All components of the welding machine are located inside the housing, ensuring its safe functionality within the limits of technical capabilities. The main element in this matter is a conversion transformer with special equipment that converts alternating current with a frequency of 50 Hz (power grid) into direct current, followed by its reverse conversion into alternating current, but with a much higher frequency (more than 20 kHz). Thus, it is possible to increase the current to 250 A at a voltage of 80 V. These transformations make it possible to achieve significant quality of the weld, which is especially important for the final result. The transformer has a finned light alloy surface that promotes intense heat transfer and efficient cooling of the element. This is also facilitated by two built-in fans.

Reliable operation and safety of the Resanta SAI-250K welding machine is ensured by a special protective system. Temperature sensors detect the approach of dangerous overheating in advance and warn the user by turning on the emergency indicator.

The principle of welding is that between the edges to be joined and the electrode close to them, with the help of a working current, an electric arc lights up, heating them to the melting temperature. The molten electrode firmly welds the joined edges together, forming a weld seam. The hot start and anti-stick functions are provided by automatic adjustment of the operating current. The initial approach of the electrode to the edges provides an increased impulse for rapid ignition of the arc. Then the current drops sharply, preventing the electrode from sticking. The special coating of the electrode consists of a special flux and prevents direct contact of the melt with oxygen and nitrogen impurities contained in the surrounding air. The quality of the weld directly affects the strength of the joint, so it must be checked. To do this, you should beat off the slag deposit with a hammer and make sure that the seam is uniform and intact.

Preparation for work and safety measures

The Resanta SAI-250K inverter welding machine is not complicated. Almost any adult can prepare it for work and operate it. Initially, you should take into account and ensure some safety points in order to prevent electric shock and other unpleasant consequences. The device is grounded through the power cord, so you should make sure that the socket has the appropriate equipment. After the working cables have been connected to the required terminals, you can plug the power cable into the outlet (the “mains” toggle switch should be off and the operating current regulator should be in the lowest position). Now you can turn on the device and set the required operating current. After completing welding work, turn off the device in the reverse order.

If welding work is carried out indoors rather than outdoors, care must be taken to ensure that it is well ventilated and that there are no flammable materials or gases in it. When starting work, the user must use protective equipment (gloves, headgear, special clothing and a special mask to protect the eyes and face). In addition, it is necessary to strictly adhere to fire safety rules and requirements for the safe operation of equipment of this kind.

The manufacturer of the welding inverter Resanta SAI-250K provides a guarantee for its impeccable operation for 24 months from the date of its official sale.