This guide provides general guidelines toward the preparations of a functional specification of transmission fixed-series capacitor (FSC) banks using overvoltage protection based on three technologies: ??metal oxide varistors ??metal oxide varistors with a forced-triggered bypass gaps ??thyristor valve bypass The commercial aspects of the specification for a particular project are outside the scope of this guide. This guide does not apply comprehensively to thyristor-controlled series capacitors. A more complete reference is IEEE Std 1534?-2002.1 The standard for fixed-series capacitors is IEEE Std 824?-2004. 1 Information on references can be found in Clause 2. Purpose This guide presents technical clauses that may be used as the basis of a functional FSC specification. The annexes of this guide include related explanatory information. The annexes are cross referenced to the main part of the document.