摘要 |
A branching unit for an optical transmission system, an optical transmission system and a method of operation of said branching unit ( 30 ) is disclosed having a first branch ( 38 ) and a second branch ( 40 ), each connected to a main branch ( 42 ). First directional current flow means ( 54 ) and second directional current flow means ( 58 ) are operable to allow electrical current to flow substantially in one direction only along the first branch ( 38 ) and the second branch ( 40 ) respectively such that electrical current flow from the first branch to the second branch and from the second branch to the first branch is substantially prevented and a simultaneous conduction of current between the first branch and the main branch and between the second branch and the main branch is prevented.
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