Instructions: Welding machine Resanta SAI 250 PROF [65/31]

The Resanta line of welding machines has been supplemented by the new model SAI 250, designed by a Latvian company and manufactured by a Chinese manufacturer. This one is one of the most powerful

inverters using a household power supply with a voltage of 220 V are positioned as having industrial purposes.

Like all inverters, it has an advantage over conventional transformer welding machines, since it is easier to use and has some features that make it easier to use.

Technical parameters of the Resanta Sai 250 inverter

The wide declared range of values ​​satisfies the requirements of domestic and industrial applications.

• Weight
  - 5.0 kg. This is quite small and makes it easy to transport the inverter and use it as a portable one. The body has fastenings for a shoulder strap, so welding can be carried out without leaving the device on a dirty or wet floor.
• Current consumption
  is up to 35 A. The maximum value cannot withstand most household networks, so it can be used in industrial premises - workshops, laboratories or workshops equipped with suitable electrical equipment and wiring.
• Welding current adjustment
  - from 10 to 250 A. Load duration at peak welding current - 40% (you can cook continuously for 4 minutes, after which you need to let it cool for 6 minutes). A continuous welding cycle can be organized at a current of about 160 A, which is absolutely sufficient for all household purposes when using 3 mm electrodes.
• The open circuit voltage
  of 80 V drops to 29 V during welding. Low values ​​increase electrical safety during operation.
• The protection of the device
  prevents objects longer than 80 mm and a diameter of more than 12 mm from getting into the body (protection from fingers), as well as from water drops falling from above (from the onset of rain). Protection corresponds to international protection class IP 21.
• Maximum power consumption
  is from 7.7 to 9.1 kW. This is caused by periodic design changes made by the manufacturer and the presence of devices from previous batches in warehouses. The inverters currently produced have a power of 8.0 kW.

Reviews of the use of Resanta Sai 250 and its price

A separate parameter is the price, which is $260-300, which differs little from the cost of the closest household inverter in the series. This is obviously caused by slightly lower demand than for devices with more modest parameters - the welding current for domestic purposes is excessive, and the disadvantages discussed below are not entirely suitable for industrial welding.

Minuses

The most noticeable disadvantages of Resant SAI 250 are related to the quality of its production and some technological shortcomings.

Chinese production does not necessarily mean a large proportion of defects, but it does not allow us to provide reliable statistics - in one batch, 9 out of 10 devices will work out the warranty period without complaints, and in another - only half.

Many breakdowns are associated with improper or careless operation, because inverters are often chosen by amateurs precisely because of their ease of use. Failure of an electronic component is the most unpleasant in terms of complexity and high cost of repair. Sometimes it’s easier to buy a new welding machine and throw away the broken one or sell it to a service center for spare parts.

Repairing the cooling system and crimping electrical connections to reduce overheating is much easier to perform, so such malfunctions are among the simplest.

Welding at maximum current is not very convenient due to the low load duration. This problem is partly solved in modifications in which it is a maximum of 70%. The possibilities of working with a lower welding current at home are not always acceptable for industrial conditions in which welding work can be carried out throughout the working day.

Therefore, this inverter can be successfully used only by small construction teams involved in the construction of private houses, dachas, cottages, garages, but will fail prematurely during the construction of multi-story buildings or intensive factory welding.

pros

Resanta Sai 250 – affordable and easy to use.

Professional inverters from well-known European companies cost users 4-5 times more. Any breakdown that occurs due to the user’s fault or after the expiration of the warranty period means a repair cost comparable to purchasing a new Chinese inverter. Household work at home or in the country occurs from time to time, so it makes no sense to buy an expensive device.

For professional construction of small buildings

and
performing repairs
on the Resant SAI 250 is quite enough. Uninterrupted operation can be ensured by purchasing two devices. Their cost will be significantly lower than that of a German or Italian brand, but work will not need to be interrupted if one of the inverters fails.

Working with thick 6mm electrodes, which can be used at maximum welding current, allows you to effectively cut metal sheets

, if no other suitable tools are available.

The device has the functions of preventing electrode sticking and hot start, which facilitates the occurrence of an arc. During operation, its afterburner is also implemented, ensuring stability. These functions acquire particular importance when working at maximum welding current, when you need to get the maximum result in the minimum permissible work cycle.

• use a voltage stabilizer when working with very unstable network parameters (if the voltage is below 140 or above 240 V). Although the use of stabilizers together with welding machines is not recommended, with frequent power surges they are necessary to prevent device failure;
• Do not place the inverter directly on the floor, since the forced cooling system has the unpleasant ability to pollute the inside of the device with dust. Use a few bricks as a stand, which are always at hand at a construction site, and do not turn on the grinder next to working equipment;
• after bringing the welding inverter from a cold room to a warm one, wait 2-3 hours before starting welding, otherwise a sharp bang when turned on and a trip to the workshop will be inevitable due to the formation of moisture and a short circuit.

Summing up

We conclude that this inverter has advantages comparable to its cost.

Being very inexpensive, the device copes with the stated tasks and can be used not only by amateurs, but also by specialists involved in welding work. It is designed to perform heavy, but not very long tasks - welding all day long is not for it.

Almost ideally, Resanta SAI 250 is suitable for private construction teams engaged in welding as an integral part of their main activity.

Similar materials.

The Resanta SAI 250 inverter represents a welding machine that is assembled in China using Latvian designs. Its purpose is limited to household use. This is an electric arc welding unit designed to operate at high power in repeated short-term intervals. Positive reviews and a reasonable price make it one of the best purchases for welding at home.

The welding inverter Resanta SAI-250 is available in two modifications: PROF and NP. The price for the first is about 19 thousand rubles, the second on average costs about 12.5 thousand rubles.

The inverter-type welding machine Resanta SAI-250 is an AC-to-DC converter. This device implies the ability to control the current strength for welding, which is possible thanks to wide-pulse modulation of the high-frequency voltage received.

The welding inverter Resanta SAI 250 PROF is made in a metal case with power connectors on the front panel. Wires for welding, a welding current regulator and devices for monitoring the network and possible overheating of the unit are connected to these connectors.

The inverter device includes a ventilation system that removes heated air from the unit body. This avoids overheating of the welding machine during operation.

The inverter has a system that automatically turns off the device when the power wires are shorted. A sensor on the device body notifies that this has happened.

Ease of use and efficiency of Resanta SAI 250 is possible thanks to two more functions:

1. Hot start
   allows you to ignite the arc in one moment, since the increase in current for welding occurs automatically;
2. The anti-stick system
   automatically reduces the current if the electrode sticks to the metal. As soon as the electrode is released, the current returns to its previous value.

In many characteristics, this inverter welding machine is close to professional. For example, this is the only unit for domestic use that allows welding with a sixth electrode.

Features of operation

The scheme for preparing the Resanta SAI 250 welding inverter for operation is not difficult. It is recommended that you always follow these steps, as this will significantly extend the life of your equipment.

1. Wires with a connector for the electrode and grounding are connected to the power connectors in compliance with the polarity necessary for welding;
2. The current regulator is set to a minimum, after which the device is connected to the electrical network and only then put into operation;

1. After completing the welding work, the current regulator is again moved to the minimum level zone. Then the inverter turns off and is disconnected from the electrical network;
2. Lastly, the holder and ground wires are disconnected.

Important features of working with this inverter are contained in its built-in fan. Earlier units for arc welding do not have such features.

The device must be kept away from moisture and metal shavings!

The internal contents of Resanta are a board with electronics, in which large and powerful parts are mixed with smaller ones. It is the small parts that control the operation of the converter, and if they are damaged, the device will simply stop working.

The ventilation is designed in such a way that air flows are forced through the body of the device, thereby cooling it. The air currents are strong enough to draw metal shavings or other objects located in the immediate vicinity of the Resanta into the body. In this case, it makes no sense to close the ventilation holes - the device will simply overheat and the protection will work, which will turn it off.

A possible solution is to extend the standard wires of the unit yourself. Note that to maintain resistance, you will need to increase the diameter of the wires. For example, when doubling the length, you need to take wires 1.4 times wider. Such a cable will cost 4 times more than the original one.

Resanta SAI 250 can operate at reduced voltage, but this is fraught with the rapid failure of the device. The device can also be powered by an electric generator. The required power is 12 kW.

Reasons for failure of inverters

One of the main components of the converter is the power section. The power part consists of several parts, which includes power transistors, which are controlled by a reference oscillator with a frequency of several tens of kilohertz. That is, the control unit closes and opens the transistors with pulses of a certain frequency, and this in turn controls the amount of current passing through the transistors to the output transformer. It is on this effect that the adjustment of the inverter modes is based.

This method is called pulse width modulation (PWM). Voltage dips or surges, uncertain movement of the electrode are an important factor in stabilizing the work because In this case, the control unit has to sharply reduce or reset the welding current to maintain the arc current within the specified mode. Therefore, the reference transistors may overheat and fail.

Therefore it is important! make sure that the power source is sufficient to operate the device.

It is very important to use quality equipment. For example, if used

a clothespin type clamp with tin contacts, then very poor contact is formed with the “ground” of the product since the contact area is small, this can also happen due to poor cleaning of the connection surface with the “ground” because of this feedback sends a signal to the control transistors , which add current to the arc, for which it is necessary to increase the power of the device itself. And so - as it is taken from the primary circuit, hence the increased load on all systems, including the primary winding of the step-down transformer.

A “crocodile” can be considered good, which has completely copper jaws with the obligatory braided connection of 2 contacts. It is needed to remove current from two parts of the metal being welded. The same situation with electrode holders

Another problem is when there is weak contact in the bayonet connections. The connection of the welding wire with connection sockets has a unique

Known fasteners. As can be seen from the figure, to connect the terminal, simply insert the bayonet pin into the terminal block and turn it until it stops. And if this is not done, a weak contact results, and if there is a weak contact, current will pass through the resulting air gap and heat the connector. It is very important that all power connection terminals should be made of brass, but not aluminum or metal, such as steel.

Bayonet connectors are available in different types: 10-25 and 31-51, respectively 100-250A and 300-500 A. It is very important to use the correct cross-section of wires, the larger the cross-section of the wire, the better. Before each use of the device, it is necessary to check the tightness and fastening of the wires in the bushings of all connections.

When used correctly, the device has a good power reserve. All components and the Resanta Sai 250 welding machine can be purchased at any dealership. Another way to place an order is on available Internet resources.

Attention Bearing Buyers

Dear customers, send your questions and requests for the purchase of bearings and components by email or call now: +7 [email protected] Delivery of bearings in the Russian Federation and abroad. Bearing catalog on the website

themechanic.ru

Trouble-shooting

The safety margin of the Resanta unit is quite large. In its class, this device is, without any hesitation, the best. If the operating procedures are followed, the unit can operate properly for years, but like any technical device it requires repair and troubleshooting.

Repair of the Resanta 250 welding inverter is recommended to be carried out in specialized centers that are authorized to work with Resanta equipment. Note that various devices of the company are in great demand in Russia, which does not create problems when finding certified workshops for the repair and maintenance of these products.

It is important to note that some problems of Resanta that arose during operation can be solved on your own:

• If overheating is frequently indicated, it is necessary to open the unit housing and clean it of dust and dirt;
• If the welding machine does not reach the maximum possible power, then it is necessary to dry the electrode;
• Another reason for the lack of power is the low voltage in the supply network.

Do you need a welding machine, but you have no experience in this field and are confused by the variety of models and brands? I will share my experience and tell you about one of the good options that has proven itself in work - the Resanta SAI 250. You will learn all the features of this model, and as a bonus, I will tell you how to properly prepare the device for work.

Application of manual electric welding

Electric welding as a method of connecting metal parts to each other is widely used in repairs and construction where welding of metal workpieces is necessary. Moreover, with the invention of inverter machines, welding has become much easier. First of all, the inverter differs from the welding transformer in its low weight, making it easy to move the device to hard-to-reach places. With the use of the latest circuit developments, electricity consumption has decreased to the level of household appliances: electric kettles or microwave ovens - this is very important when working at home. One of the popular household welding machines is the inverter welding resanta sai 250

Description of the device

The abbreviation SAI stands for “inverter welding machine,” that is, it converts alternating current into direct current. The equipment allows for manual arc welding using coated electrodes. This is one of the most powerful welding inverters operating from a single-phase 220 Volt network.

Equipment parameters

The main characteristics are:

If you carry out work at home, then the maximum current is limited to such an indicator so as not to overload the wiring of the apartment or house. If this is not done, then at best the plugs or circuit breakers will be knocked out, and at worst the wiring will catch fire due to overheating.

Let's look at the main features of the Resanta 250 welding inverter:

• Loading duration - 70%
  . This means that at maximum current you can work 70% of the time, that is, out of 10 minutes, 3 are allocated for rest and cooling of the device. When the current is set to 160 A and below, you can work without interruptions until all the work is completed;
• Anti-stick system
  . Eliminates sticking of the electrode to the metal when starting welding or when working with a short arc. The system provides an automatic reduction in current when the electrode is torn off, after which the voltage is restored to the desired level;
• Hot start -
  this function ensures a strong and even seam even at the very beginning of welding. At the moment of arc ignition, the current increases briefly and then decreases to the required value;
• Arc force is
  a special function that prevents burning of thin metal;

• Overheat protection system
  . If the system heats up above permissible limits, the unit will automatically turn off. An indicator on the front panel will light up so you can see what is causing the stoppage.

The design includes a fan that cools the inside of the case. Air is taken in through the front grille, so covering the device during operation is prohibited.

With dimensions of 25x13x40 cm, the design is convenient to carry, transport and store. It easily fits in the trunk of a car or on a shelf in the garage.

The price for the set ranges from 7 to 8 thousand rubles, which is a reasonable cost for equipment of this class.

Features of operation

I’ll tell you about the design features of the Resanta SAI 250 welding machine and analyze the process of preparing it for work:

The Resanta SAI 250 single-phase inverter welding machine was developed in Latvia and assembled in China.

It is intended for electric arc welding in domestic conditions, and the developers tried to include in the device operation at high power in intermittent mode. The Resanta SAI 250 welding machine has good reviews, and the price of 10,000 rubles, with its good capabilities, makes it a good purchase.

The device operates according to modern principles of energy conversion, and its efficiency reaches 95-98% (versus a maximum of 70% for a conventional welding transformer). At the same time, the device is very light in weight, only 5.2 kg, and can be worn on a shoulder strap while working.

The input mains voltage is rectified and powers a powerful pulse converter operating at a high frequency of the order of tens of kilohertz. Thanks to this, the output transformer, which can be placed in the palm of your hand, converts all the power with almost no heat. The voltage is then rectified and applied to the output terminals of the welding circuit. So, the device cooks with direct current.

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:

The Resanta SAI-250 inverter machine is designed for welding using the MMA method - manual arc using coated stick electrodes. Its layout and design were developed by Latvian engineers, and it is produced by a Chinese manufacturer. This inverter is one of the most powerful among those operating from a single-phase 220 V network and is classified as an industrial device.

Block diagram of the inverter

Welding with the Resanta Sai 250 inverter welding machine is carried out with direct current, which is converted from a household alternating voltage network of 220 V. Let's take a closer look at how the inverter circuit works.

The purpose of welding transformers is to form a metal melt in the arc burning zone under the electrode, usually the edges of the metal parts being connected. The very first machines - welding transformers - have low efficiency, are heavy and quickly overheat under load. Inverters operate on a different principle, which has made it possible to increase the number of characteristics and make them smooth and convenient.

Principle of operation

The operating principle of the inverter is multi-stage conversion of alternating mains voltage. The first stage consists of converting alternating current into direct current, but having a pulsating component; the pulsation peaks are smoothed out by a special reactor. After the smoothing reactor, the rectified current goes directly into the inverter circuit, where at the first stage it is converted back into alternating current, but with several high-frequency harmonics. It is at this stage, through the feedback block, that the possibility of adjusting various output characteristics of the arc at the output opens up.

[content-egg module=GdeSlon template=list limit=3 offset=3]

At the final stage, high-frequency alternating current is converted into direct welding current using avalanche thyristors and a transformer. Due to the development of technology of structural elements, in particular power thyristors, the weight of the inverter can be reduced to several kilograms, and the power consumption is 2-5 kW with an arc power of 250 A.