Automatic reclosing devices (ARDs) or remote actuators are generally used to increase system availability. Usually flange-mounted to the side of the corresponding circuit-breaker devices, they are able to switch these devices back on or switch them off remotely. One or more relays report the status. According to device standards, ARDs must be able to lock if a system fault is detected. In this case, remote switching is not possible and manual intervention is necessary. Series DFA devices are only designed for operation on Doepke residual current circuit-breakers DFS 2 or DFS 4. To optimise costs, the remote actuators are adjusted to the devices’ rated currents up to 63 A or 125 A, respectively. Depending on the design, the DFA devices are operated with different supply voltages, are fitted with relays to report the switching or locked status and either do not carry out any switch-on attempts or perform one or three attempts. Furthermore, some DFA designs are able to connect an interface to the Dupline bus system, which can transmit control commands and status messages across long distances. The DFA devices are mounted to the RCCBs on the left. Devices of this design can be operated on residual current circuit-breakers from series DFS 2 and DFS 4 with a rated current of up to 63 A. This variant is supplied power from a voltage source of either 24 V AC or DC.