This document provides general guidelines toward the preparation of a functional specification of transmission static var compensators (SVCs) using conventional thyristor technology. Many clauses will be useful for compensator systems using gate turn-off (GTO) thyristor technology [static compensator (STATCOM)] or other semiconductor devices, or SVCs associated with high-voltage dc (HVDC) converter stations, or industrial and distribution applications. General terms and conditions forming the commercial part of a specification for a particular project are outside the scope of this document.