This standard gives guidance on writing the technical specification for the procurement of turbine-driven generators and their auxiliaries for use in electricity generating stations (power stations). This Guide for procurement is not applicable to equipment for use in the nuclear reactor plant area of nuclear power stations. Other possible applications of such equipment have not been considered in the preparation of this Guide. The generators may be air, hydrogen, or liquid-cooled. The excitation system may be of the static or rotating rectifier type fed by a static or rotating power supply. The equipment covered by this Guide is defined by its function rather than design type. Therefore, the guidance to the specification is stated in performance terms rather than being specified by a detailed description of the equipment to be supplied. This Guide indicates to potential purchasers how their specification should be prepared so that: - the equipment type and capacity interfaces correctly with other elements of the systems; - predicted performance is achieved; - ancillary equipment is properly sized; - reliability, availability and safety requirements are achieved; - proper consideration is given to the evaluation process and the quality measures to be applied. This Guide does not determine the type of specification (e.g. detailed, performance, functional) or the extent of supply for any given contract which is normally decided on the basis of the purchaser’s project strategy. It does not cover: - any commercial, contractual or legal issues which are normally in separate parts of an enquiry; - any allocation of responsibilities which are determined by the contract. This Guide does not prescribe the arrangement of the documents in the enquiry. NOTE: As a comprehensive European environmental policy is still under preparation, this Guide does not address the environmental implications of the equipment.