LV & 11kV Networks
The LV Sure system comprises a source breaker, the Intelligent Fuse Unit (IFU); plus a number of mechanical isolating switches, or Intelligent Link Units (ILUs) installed at strategic positions along the LV circuit.
Isolation of the faulted section and restoration of supply to un-faulted sections of the circuit is fully automated and does not require communication between the devices which comprise the LV Sure system.
When a fault occurs on the LV network the IFU disconnects supply to the entire circuit. The ILUs along the route, sense no voltage and automatically open, in effect sectioning the circuit. Both the IFU and the ILU incorporate sensing circuitry which tests for the presence of a fault on the electrical section downstream of each Unit. The IFU would commence the restoration process by testing downstream and if healthy would restore supply to the first section. Each ILU in turn would initially sense it has an incoming voltage, then test downstream and again, if healthy, restore supply. This would continue until the faulted section was reached when testing would inhibit the ILU from closure. Circuits with an alternative supply from a remote end could complete the restoration process until all sections had supply restored except the faulted section.