Automatic earth fault isolation and restoration of supply in cable distribution networks

The author discusses the use of faulted section indicators (FSI) to reduce revenue losses after a cable fault on 11 kV carbon distribution networks. Following the detection of earth fault current, FSI transmit their location back along the 11/13 kV cable, using, time slotted, high frequency mains borne signals, to a receiver located in the primary substation. This receiver logs in the fault location data and interfaces with a telecontrol/SCADA system to enable onward transmission of the data to the central control room. The control engineer is thus able to give the precise location of the faulted section of cable together with instructions as to which switching operations must be performed to enable an engineer to go directly to the relevant secondary substations and re-configure the network with the minimum delay