In AC or three-phase networks, the occurrence of reactive power is unavoidable. Reactive currents are caused by inductive as well as capacitive loads, but also by network elements such as cables and transformers. Inductive loads arise, for example, from devices that generate an electromagnetic field. These include motors, lighting systems with ballasts or transformers. Capacitive loads, on the other hand, are generated mainly by capacitors or also in the case of medium- and high-voltage lines in the form of underground or submarine cables. In certain cases it is necessary to reduce or compensate reactive current. This is because reactive currents put a strain on both the power grid and the equipment operated with it, and increase power loss. For this reason, the use of reactive current compensation makes sense and is economically efficient.

There are three different types of power factor correction: static, dynamic and the hybrid solution. Which solution is ultimately suitable always depends on the requirements and must be planned on a project-specific basis.

Static power factor correction consists of a capacitor or reactor bank that can be switched in steps. This solution is sufficient for networks or plants with relatively constant reactive power consumption.

For dynamic power factor correction, frequency converters are used that can continuously compensate for rapidly changing reactive current loads.

In some projects, a combination of static and dynamic compensation is useful, then it is called a hybrid solution.