The control of the primary distribution system is designed on a hierarchical system with control having to be passed from a lower level to a higher level. The lowest level is at the primary distribution unit and the highest is at the SCADA system.
Safety and operational interlocking take place at device level, thus a failure of the SCADA system does not compromise the system integrity.
Closed transition transfer from the A supply to the B supply and vice versa can only be carried out by using the generators, this transfer can be carried out either manually or automatically.