Comparison Interskol ISA-170 vs Vihr IS-200

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 voltage supplied by the welding machine to the electrodes. As the name suggests, it is measured without load — i.e. when the electrodes are disconnected and no current flows between them. This is due to the fact that at a high current strength characteristic of electric welding, the actual voltage on the electrodes drops sharply, and this does not make it possible to adequately assess the characteristics of the welding machine.

Depending on the characteristics of the machine (see "Type") and the type of work (see "Type of welding"), different open circuit voltages are used. For example, for welding transformers, this parameter is about 45 – 55 V (although there are higher voltage models), for inverters it can reach 90 V, and for semi-automatic MIG / MAG welding, voltages above 40 V are usually not required. Also, the optimal values \u200b\u200bdepend on type of electrodes used. You can find more detailed information in special sources; here we note that the higher the open-circuit voltage, the easier it is usually to strike the arc and the more stable the discharge itself.

Also note that for devices with the VRD function (see "Advanced"), this parameter indicates the standard voltage, without reduction through VRD.

The smallest current that the device is able to supply through the electrodes during operation. For different materials, different thicknesses of the parts to be welded and different types of welding itself, the optimal welding current will be different; there are special tables that allow you to determine this value. The general rule is that a high current is far from always useful: it gives a rougher seam; when working with thin materials, it is possible to melt through the junction instead of connecting the parts, not to mention excessive energy consumption. Therefore, if you have to work with parts of small thickness (2-3 mm), before choosing a welding machine, it makes sense to make sure that it is capable of delivering the desired current without “busting”.

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.

The duty cycle allowed for the welding machine.

Almost all modern welding machines require breaks in operation — for cooling and general "recovery". The frequency of inclusion indicates what percentage of the time of the total work cycle can be used directly for work. In this case, 10 minutes is usually taken as a standard cycle. Thus, for example, a device with a duty cycle of 30% will be able to work continuously for less than 3 minutes, after which it will need at least 7 minutes of interruption. However, for some models, a cycle of 5 minutes is used; these nuances should be clarified according to the instructions.

In general, high frequency is required mainly for high-volume professional work; with a relatively simple application, this parameter does not play a decisive role, especially since you have to take breaks during work. As for specific values, the mentioned 30% is a very limited figure, typical mainly for entry-level devices. A value of 30 – 50% is also low; in the range of 50 – 70% is the majority of modern devices, and the most "hardy" models provide a frequency of more than 70%.

The largest diameter of the electrode that can be installed in the welding machine. Depending on the thickness of the parts, the material from which they are made, the type of welding (see above), etc. the optimal electrode diameter will be different; there are special tables that allow you to determine this value. Large diameter may be required for thick materials. Accordingly, before purchasing, you should make sure that the selected model will be able to work with all the necessary electrode diameters.

In modern welding machines, an electrode diameter of 1 mm or less is considered very small, 2 mm — small, 3 mm and 4 mm — medium, and powerful performant models use electrodes of 5 mm or more.

The insulation class determines the degree of resistance of the insulating materials used in a particular device to heat. To date, welding machines use materials mainly of the following classes:

B — have a resistance limit of 130 °C;
F — 155 °C;
H — 180 °C.

Note that the vast majority of modern welding machines have electronic overheating protection, which turns off the device long before reaching the insulation resistance limit. Therefore, this parameter will be relevant only in an emergency, when the built-in protection fails. Nevertheless, it fully allows you to assess the safety of using the device — the higher the insulation class, the more likely it is to notice dangerous overheating in time (for example, by a characteristic smell) and turn off the device before damage occurs.