Optical fibre pilot differential relaying for a 138 kV Eletrosul short transmission line

The author discusses and details the design alternatives on optical fibre pilot differential relaying applicable to the Anastacio-Aquidauana transmission line (Mato Grosso State-Brazil). In its first part, this paper analyses the technical advantages and disadvantages of each alternative, the protection and teleprotection schemes proposed, including their relevant economical aspects and comparisons to conventional relaying/teleprotection. The second part weights up the optical fibre pilot differential relaying and the conveniences of sharing the optical link with other functions (voice/data). The third part presents the basic requirements of the protective relays, instrument transformers and optical fibre pair that one should point out in a bidding specification. In addition, the mechanical and economical pros & cons of using the shield cable of the transmission lines as the `carrier´ of the optical pair are resumed