System switching apparatus e.g. for optical repeater in high voltage transmission line

摘要

The apparatus includes a voltage feed unit (1A,1B) which is monitored by voltage (5) and current (7) comparators. Correct operation drives a logic state (8). A second logic state (B2) is generated from a detector which monitors the switching state. The logic states are monitored (15) in a further switch control logic circuit (16). An alarm (B4) monitors the correct operation of the logic. The control logic (B3) drives relays (181,182) which ensure correct connection of the power supply to the optical repeater (23).