Gharahbeiglu - Moshanir- Iran
Helbig - Siemens- Germany
Saemi - Moshanir- Iran

The aim of this article is to introduce and recommend an improved method of planning and evaluating high voltage substations. To scrutinise different kinds of switchgear solutions with the objective to achieve sustained business profitability, it is recommended to use: 1. Functional Specifications instead of the common detailed technical specifications of the substation, and a 2. Life Cycle Cost LW calculation model instead of the common Procurement Cost comparison. The article emphasises the economic benefits that can be derived by the use of the Functional Specification and Life Cycle Cost approach. In contrast to the conventional way of describing the planned substation by a single line diagram and the associated detailed descriptions of the technical requirements on the different components, this method is based on a systematic description of the substation in terms of its availability, which is a function of its reliability and outage time.

High voltage substations, life cycle costs, availability, gas-insulated switchgear, air-insulated switchgear, functional specification, H-scheme