The protection functions also support different types of networks, such as, isolated neutral networks, resonant-earthed networks and partially earthed networks. The application area also covers medium-sized three phase asynchronous motors as well as protection and control of shunt capacitor banks used for reactive power compensation. In addition to protection, measurement, control, condition monitoring and general functions, the REF 541 feeder terminals are provided with a large amount of PLC functions, which allow for several automation and sequence logic functions, needed for substation automation, to be integrated into one unit.