Overview of the welding machine brand Resanta SAI 250, its types, pros and cons

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The most common type of welding equipment is manual arc welding. Such a device is often bought by all amateurs, as students of technical professions, and craftsmen.

The advantage of such a device is that it can be easily carried, so it can be easily used for portable repairs.

Of course, factory owners know that this type of device is popular, so try to adapt to the client by releasing budget lines that will be available to students and amateurs.

The variety of such devices is huge, with different configurations and sizes, so everyone can buy a device for themselves. The Resanta brand also produces this type of device.

When you go to the brand’s website or look through the product catalog, you will find the SAI line there, which is considered inexpensive, of course there are not many items there, but from the quantity that the manufacturer offers you can easily buy the right one.

In principle, it cannot be said that the SAI line has big differences from other similar devices, but still some modifications are present. There are different sizes, features and configurations.

In our article we want to talk about the Resanta SAI-250 device and its other subtypes.

• Subtypes SAI 250 Welding Resanta SAI250
• Welding RESANTA SAI-250 PROF
• Welding RESANTA SAI 250PN
• Welding Resanta SAI 250 K

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.

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

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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.

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.

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.

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.

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Specifications

This device has the following characteristics:

Before using any such power unit, you should carefully study the instructions, which are also included in the case with the unit. It will also describe all the technical characteristics and capabilities of the device:

• The welding current control limit is from 10 to 250 A.
• The load duration or PN is 70%, this indicates that with a welding current of 160 Amps you can work without stopping. If the current is maximum, then there should be a break in the operating interval, amounting to approximately 20-25%.
• Permissible voltage deviation in the network. For these devices it can change down to -30, and up to +10%. In voltage readings this will be from 154 to 242 V.
• Also, when purchasing, you can pay attention to such parameters as cable length, device dimensions and even weight. But this does not affect the operation of the device.
• The diameter of the electrode used can range from 1.6 to 6 mm.
• The output voltage of the unit in idle mode is 80 V, under load during welding - 29 V.

Inverter welding machine Resanta SAI-250K

The welding machine Resanta SAI-250K is designed for manual electric arc welding with direct current with a coated electrode. This device can be used in both the household and industrial segments.

Specifications

Principle of operation

It consists of converting alternating mains voltage with a frequency of 50 Hz into a direct voltage of 400 V, which is converted into high-frequency modulated voltage and rectified. Pulse width modulation is used to regulate the welding current.

Device SAI-250K

The product is made in a metal case, on the plastic front panel of which there is:

• Regulator of welding current value. Using the welding current regulator, you can set the desired current depending on the thickness of the welding electrode.
• Power connectors for connecting welding cables.
• The “network” indicator lights up when the device is turned on.
• The “overheating” indicator lights up for a few seconds when the AIS is turned on and when the device overheats and turns off after it has cooled to operating temperature.
• Power switch (installed on the rear panel).

Hot start (HOT START)

To ensure better ignition of the arc at the beginning of welding, the inverter automatically increases the welding current. This will greatly facilitate the start of the welding process. Thanks to this function, the device can be used not only by experienced welders, but also by beginners. This function is installed on all Resanta welding machines.

Anti-stick (ANTI STICK)

When starting welding, the arc must be ignited. This often leads to the electrode sticking to the product. In this case, the inverter itself automatically reduces the welding current, and the electrode easily comes off. Subsequently, after the stuck electrode comes off, the inverter resumes the set welding parameters. All SAI series welding machines are equipped with this function.

IGBT

Without exception, all Resanta inverters are made using IGBT transistors. The effect is that due to them the service life of the device increases by 7 times. In addition, weight and dimensions are reduced. With IGBT, the board is located vertically, dust does not settle on it.

PV (on duration)

The meaning of the “PV” parameter is as follows: this is the time during a 10-minute interval that the device is capable of operating at the specified current. This means that for 70% of a 10-minute interval (that is, 7 minutes), the device can continuously cook without breaking the arc at the specified current, and for the remaining 3 minutes it must “rest” at idle, and the device cannot be turned off from the network, so that forced cooling (fan) works.

Open circuit voltage

The higher the open circuit voltage, the easier it is to strike the arc. With this inverter it is 80 V, the arc ignites easily, and it is possible to cook non-ferrous metals.

The holder and ground cable are 2 meters long, the power cord length is 1.7 m, the length of the welding machine is 30 cm. A total of 4 meters of working space. For more convenient work, a regular extension cord of the required cross-section is sufficient.

Equipment

Documentation

Passport for welding machine Resanta SAI-250K

Certificate of conformity for Resanta welding machines

Dear buyer!

The manufacturer sets the official service life for inverter welding machines to 5 years, subject to compliance with operating rules. The Resanta Trading House expresses its deep gratitude to you for your choice. Our company has done everything possible to ensure that this product satisfies your needs, and the quality corresponds to the best world standards.

Advantages and disadvantages

The features of devices from this series include, first of all, high quality and stability of operation at any input voltage. This model is also equipped with the following features that were not implemented in others or worked slightly differently:

• Anti-stick function – Anti-stick. That is, when working on short arcs in conventional devices, the electrode often sticks. In this model, the current will sharply decrease, and after the arc is restored, it will increase again. During operation, the master will not notice anything, but the device will do its job.
• It also has a hot start function. Ensures high quality welding immediately after work begins. To ensure this level from the first seconds, manufacturers have introduced some features into the operating principle. In particular, after ignition of the arc, the current increases and then decreases slightly.
• Arc forced function, that is, with such a device you will never burn through thin metal.

In addition to the built-in functions, it is also equipped with a large number of protections that will prevent its premature failure; the manufacturer made sure that it stably ignites the arc and welds the seam.

In addition, the device is relatively lightweight, which makes it possible to use it in hard-to-reach places, for example, while sitting astride some metal structure.

The disadvantages include the fact that the device is quite expensive, because it can withstand high currents and has a lot of protection against overheating of the power part, overvoltage in the network, overload in the current part, etc.

Its cost is explained by numerous advantages, which is why it is chosen by professionals for regular work. As practice shows, they easily cope with their tasks during the working day.

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.

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.