Minimum input voltage
The minimum actual input voltage at which the welding machine remains operational.
Such information is useful primarily for working in unstable networks, where the voltage tends to “sag” a lot, as well as from autonomous power sources (for example, generators), which can also produce voltage below the nominal one.
Power consumption
The maximum power consumed by the welding machine during operation, expressed in kilowatts (kW), that is, thousands of watts. In addition, the designation in kilovolt-amperes (kVA) can be used, see below for it.
The higher the power consumption, the more powerful the current the device is capable of delivering and the better it is suitable for working with thick parts. For different materials of different thicknesses, there are recommendations for current strength, they can be clarified in specialized sources. Knowing these recommendations and the open circuit voltage (see below) for the selected type of welding, it is possible to calculate the minimum required power of the welding machine using special formulas. It is also worth considering that high power creates corresponding loads on the wiring and may require connection directly to the shield.
As for the difference between watts and volt-amperes, the physical meaning of both units is the same — current times voltage. However, they represent different parameters. In volt-amperes, the total power consumption is indicated — both active (going to do work and heat individual parts) and reactive (going to losses in coils and capacitors). This value is more convenient to use to calculate the load on the power grid. In watts, only active power is recorded; according to these numbers, it is convenient to calculate the practical capabilities of the welding machine.
Min. welding current
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”.
Max. welding current
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.Protection class (IP)
The protection class to which the housing of the welding machine corresponds.
This parameter is traditionally denoted by the IP standard with two digits. It characterizes how well the case protects the hardware from foreign objects and dust (first digit), as well as from moisture (second digit). It is worth noting that in welding machines the degree of such protection is usually small — this is due to the fact that the case must be made ventilated. Here are the levels of protection against solid objects / dust that are relevant for modern models:
1 — protection against objects larger than 50 mm (comparable to the size of a human fist or elbow);
2 — from objects larger than 12.5 mm (we can talk about protection from fingers);
3 — from objects larger than 2.5 mm (the probability of accidental hit by most standard tools is excluded);
As for protection against moisture, it can be generally zero — that is, such a device can only be used in dry conditions. However, there are more advanced options:
1 — protection against drops of water falling vertically, with a strictly horizontal position of the device (the minimum degree of protection, in fact — from accidental ingress of a small amount of moisture);
2 — from vertical drops of water when the device deviates from the horizontal up to 15 ° (slightly higher than the minimum);
3 — from splashes falling at an angle of up to 60 ° to the vertical (we can talk about protect...ion from rain);
4 — from splashes falling from any direction (possibility of use in rain with strong winds);
Sometimes, instead of one of the numbers, the letter X is put — for example, IP2X. This means that the protection class for the corresponding type of exposure is not defined. In such a case, it is best to assume that there is no protection at all — this will provide maximum security and avoid unpleasant surprises.
Insulation class
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.
