Short-term mains interruptions are bridged by QUINT BUFFER, a maintenance-free capacitor-based buffer module with SFB technology (selective fuse breaking technology). Systems can therefore also run in unstable networks or, in the event of longer failures, are correctly shut down after all relevant process data is saved. The buffer module also acts as a power storage device for peak loads and for tripping fuses. For function monitoring, an active switching output and a control lamp are used. With the integrated diode, loads can be divided into buffered and unbuffered loads. The buffer time is thus extended and the buffered loads are protected against errors in the internal network.