Power consumption
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.
Duty cycle
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%.
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.
