The FRE Series capacitor banks with detuned filters have been designed for power compensation purposes in networks with fluctuating load levels, a high content of harmonics and where there is a risk of resonance. Power variations are relatively quick (in milliseconds) so that the switching operations can be carried out by thyristors, which are connected to a voltage control plate; the capacitor is connected and disconnected with a zero voltage difference. This system avoids transients in the connection and disconnection of steps, with an immediate response to load fluctuations.
The most common application is with individual loads or in installations where a quick compensation response is needed (for ex., welding units, motors for lifting units, lifts, etc.) and where there is a high content of harmonics in the network.