The SITOP PSE200U selectivity module distributes the load current across several 24 V branches and reliably monitors them for overload and short circuits. It allows short-term current peaks, such as those caused by high inrush currents, while branches experiencing prolonged overload are switched off. This is ensured even on high-resistance lines and in the case of creeping short circuits. Here, circuit breakers may not trigger or may do so too late, even if the power supply could provide the necessary tripping current. The intact branches are continuously supplied with 24 V by the SITOP extension module without interruption or feedback, thereby potentially preventing a complete failure of the system.