Reactive and apparent power
The reactive and apparent power, is also measured in watts. The reactive power describes the power that is important for the transmission of the active power to the end consumer. In order for electricity to flow through a grid at all, generators, motors or transformers build up a magnetic field with the help of reactive power. When electric current flows through the line, as much of it as possible should of course reach the end consumer. The power that ultimately reaches the user is the active power.
The active power and the reactive power are finally combined to form the apparent power. It thus describes the overall performance.
If a consumer has inductive and capacitive components in addition to the ohmic resistance, then a time shift occurs between current and voltage, also called phase shift. This is the case with resistance welding, due to the welding transformer used. In addition to the active power, there is, therefore, also reactive power that is not converted into heat.
Instead, the reactive power is shifted back and forth with the frequency of the AC voltage. The reactive power is not consumed, so it is not calculated as electricity consumption. It must still be provided by the electricity supplier. With DC voltage, the apparent power is equal to the active power P. An often used, and not entirely serious comparison to explain reactive, active and apparent power is the filled beer glass. The level of beer corresponds to the active power, the height of the foam corresponds to the reactive power and the total height of beer and foam represents the apparent power.
In this sense: Cheers.