The purpose of the transmission system is to transmit electricity, at a higher voltage, from sources of generation to Bulk Supply Points or Major Substations. The electricity is then stepped down to lower voltages to supply distribution networks, which in turn supply customers.
The transmission network consists of 66 kV lines on steel lattice towers, wooden poles, concrete poles and underground cables. The transmission lines form a ring system and one radial feeder supplying southern areas of the island. The system load is predominantly to the central part of the island between St. Louis and Wooton and towards the North.
The 66 kV lines interconnect power plants and major 66/22 kV substations. The 22 kV outgoing lines from these substations either supply the rural regions or are used for 'sub-transmission' feeding 22/6.6 kV substations.
Modern techniques are now being deployed to assess the status of power system equipment so as to identify those that demonstrate failure signs from the start. The conditions of several assets such as transformers, overhead lines, cables, switchgear, and other transmission and distribution network equipment will be monitored to forecast and prevent, as far as possible, their eventual failure. Partial Discharge, tan delta or Infra-red
techniques will be used as preventative maintenance tools. Some
pieces of equipment have already been received.