Comparison Kentavr SV-255NM vs Kentavr SV-250NM

Power consumption of the welding machine, expressed in kilovolt-amperes.

kVA is a unit of power used in welding machines along with the more traditional kilowatts. The physical meaning of both units is the same — current multiplied by voltage; however, they denote different parameters. So, in kilowatts, only a part of the total power consumption is recorded — active power (goes to do work and to losses due to heating of individual parts); according to this indicator it is convenient to calculate the practical capabilities of the device. And kilovolt-amperes denote the total energy consumption — it also takes into account reactive power (it goes to losses in coils and capacitors during the operation of alternating current circuits). This data is useful for calculating the total load on the network or other power source.

The apparent power input in kVA will always be greater than the power in kW. However, some manufacturers go to the trick and indicate full power not at full, but at partial (for example, half) load. This gives the impression of efficiency, but is incorrect from a technical point of view. As for the ratio of energy consumption, the active power in kW is often 20-30% lower than the apparent power in kVA. So, in terms of kilovolt-amperes, it is quite possible to evaluate the performance of the unit.

As for specific values, in the most modest models they do not exceed 3 kVA. An indicator up to 5 kVA is considered low, up to 7 kVA — average, and in the most powerful units, the power consumption can reach 10 kVA or even more.

The highest current that the welding machine is capable of delivering through the electrodes during operation. In general, the higher this indicator, the thicker the electrodes the device can use and the greater the thickness of the parts with which it can work. Of course, it does not always make sense to chase high currents — they are more likely to damage thin parts. However, if you have to deal with large-scale work and a large thickness of the materials to be welded, you simply cannot do without a device with the appropriate characteristics. Optimum welding currents depending on materials, type of work (see "Type of welding"), type of electrodes, etc. can be specified in special tables. As for specific values, in the most “weak” models, the maximum current does not even reach 100 A, in the most powerful ones it can exceed 225 A and even 250 A.

— Hot start. A function that facilitates arc ignition: when the electrode touches the welding spot, the welding current increases for a short time, and when the machine enters the mode, it returns to standard parameters.

— Forcing the arc (Arc Force). Devices with this function are able to increase the welding current with a critical reduction in the distance between the electrode and the parts to be welded. This increases the rate of melting of the electrode and the depth of the weld pool, which helps to avoid sticking.

— Protection against sticking (Anti-Stick). In this case, a protective measure is implied in case sticking of the electrode still could not be avoided: the automation of the welding machine significantly reduces the welding current (or even turns it off), which makes it easy to disconnect the electrode, and in addition — to avoid unnecessary energy consumption and overheating devices.

— Decreased voltage x. X. (VRD). This function is used to significantly reduce the open circuit voltage of the machine. When the VRD is turned on, the open electrodes receive not a standard voltage of several tens or even hundreds of volts, but only 9-12 V. At the same time, the operating parameters are restored automatically — when the electrode touches the workpiece and a high current occurs; and when the arc is e...xtinguished, the voltage again drops to the minimum values. This format of work provides two main advantages. Firstly, it provides additional safety: in particular, closing contacts with a hand or other part of the body does not lead to a serious electric shock, and the risk of such an injury in high humidity is also reduced. Secondly, lower voltage helps to save energy.

— Pulse welding. Usually, this refers to gas-shielded arc welding (MIG / MAG or TIG), carried out in the so-called pulsed mode. With this format of operation, the main welding current, which is relatively low, is supplemented by high-power pulses (7-10 times higher than the background current), which follow at a frequency of several tens per second. There are also various modifications of the pulse mode, with more complex current control; however, the basic principle remains the same. Anyway, the advantages of pulsed welding are the uniformity of both the arc itself and the resulting seam, as well as an improvement in the overall quality of the joint: pulses help to mix the metal in the weld pool and eliminate pores, oxides and other defects. The disadvantage of this function is traditional — an increase in the cost of welding machines.

— 2/4-stroke mode. Possibility to choose the control mode of the device — two-stroke or four-stroke. This allows you to further adjust the control to the specifics of the situation. Recall that in push-pull mode, the device works while the button is pressed, and turns off when it is released; this is especially useful for short seams and other similar tasks when welding does not need to be switched on for a long time. In turn, with a four-stroke control format, the first press-release turns on welding, the second turns it off. This method is indispensable for long-term work, when it would be tiring to keep the button pressed all the time.

— Synergetic management. A function mainly used when operating in the pulse mode described above. Synergic control can also be called "intelligent": it is carried out using built-in electronic microcontrollers that control most of the settings and automatically change them if necessary. In fact, it looks like this: it is enough for the welder to set a number of inputs (type and thickness of the material, composition of the shielding gas, wire thickness, etc.), and based on this, the machine will automatically select the optimal operating parameters (output voltage, pulse configuration, feed rate wire, etc.). Moreover, if one of the inputs changes in the course of work, the other parameters of the work change accordingly.
Synergic control greatly simplifies the operation of the device and at the same time improves its quality, reducing the likelihood of burns and other serious errors. This is especially convenient for inexperienced welders who are not accustomed to dealing with fully manual parameter settings; however, even professionals appreciate the ease and speed of adjustment that is characteristic of synergic models. The main disadvantage of this feature is that it has a significant impact on the cost.

— Digital display. The presence of its own display in the design of the welding machine. This is, usually, the simplest segment screen, designed to display 2 – 3 digits and some special characters. However, even such screens are more informative than light and other similar signals: they can display a wide variety of data (input and operating voltage, time until shutdown "to rest", error codes, etc.). And the advantages over dial indicators are in small size and versatility — the display can display different types of information. As a result, this function can greatly simplify the work with the welding machine.

— Connector for the remote control. Connector for connecting a remote control to the device. Depending on the model, we can talk about both traditional hand controls and foot pedals. Anyway, such an accessory provides additional convenience in some situations — in particular, it allows you to turn the power on and off, and even change individual operation parameters, without approaching the device every time. However most often welding machines are supplied without a remote control — however, this gives certain advantages: you can choose such an accessory at your discretion (the main thing is to make sure it is compatible).

— Liquid cooling. Presence of a liquid cooling system in the configuration of the welding machine. Such cooling is more efficient than air cooling, it intensively removes heat from the hardware of the apparatus, the burner and allows you to achieve a very high duty cycle (see above) — up to 100%, and at currents of 200 A or more. Its disadvantages are complexity, high cost, bulkiness and significant weight. In light of the latter, liquid cooling units are often made separately from the welding machines themselves and can be connected / disconnected depending on what is more important at the moment — efficient cooling or portability. Also note that for many models, the manufacturer recommends using specialized coolants, and they are most often not included in the delivery set.

— Built-in compressor. Compressor for air supply built directly into the machine. This feature is found only in models operating in PLASMA mode. Recall that this mode involves cutting metal using a powerful jet of highly heated and ionized air; To create the desired pressure, a compressor is needed. It can also be external; however, the built-in compressor allows you not only to always have all the necessary equipment with you, but also to reduce the overall dimensions of this equipment. In addition, with such equipment, you do not need to worry about the compatibility of the device and the air supply system. The disadvantages of models with built-in compressors include the increased cost, as well as the dimensions and weight of the entire body.

— Starting the car engine. The ability to use the device to start the car engine, namely to power the starter. In other words, models with this function are also able to work in the launcher mode. Such an opportunity will be useful if the regular car battery is dead, out of order or missing, but there is a power source (mains or generator) nearby from which you can power the welding machine. Note that most often in this case it means the launch of cars with 12-volt on-board networks — cars, light trucks and buses; however, technically, nothing prevents to provide compatibility with heavy equipment (trucks, buses) operating on 24 volts. These details should be specified separately.

— Transport wheels. The presence in the design of the welding machine of special wheels that facilitate transportation. The weight of some modern models can reach several tens of kilograms, and it is difficult even for several people to carry such a device manually. The presence of wheels makes it possible to manage by the forces of one person, even with a significant weight of the unit.