The AC/DC-sensitive RCCBs DFS 2 B and DFS 4 B by Doepke are the ideal protection when using consumers with operating frequencies up to the kilohertz range or multi-phase operated or frequency-controlled electronic devices such as cranes, pumps, fans or concrete vibrators: Cranes, pumps, fans, compressors or concrete vibrators. They make a particularly important contribution to electrical safety on construction sites.