Life cycle cost model for circuit breakers in electricity transmission utilities

Circuit breakers are one of the important equipments used by electricity transmission utilities. With the various options of interrupting media and energy storage there are many different types of circuit breakers available to purchase in the market. In general, the equipment acquisition process used by industry does not take into consideration the assets whole of life cycle such as operational requirements, maintenance needs, operating conditions and risk consequences. Maintenance and risk need to be considered prior to making any procurement decision. This paper presents a Life Cycle approach to assist decision-making when purchasing outdoor dead or live tank circuit breakers in electricity transmission utilities. Whole of life cycle phases are considered during the model construction using AS IEC 60300.3.3 - 2005 (Australian Standard "Dependability Management, Part 3.3: Application Guide - Life Cycle Costing"). The model has three main phases; acquisition, maintenance and disposal with detailed subheadings for each of the phase. During model construction, the relevant object structures are identified as contributing factors and then the cost is estimated over 40 years to enable NPV (net present value) analysis to comparedifferent equipment types, models and manufacturers on a total life cycle basis. In this paper the routine maintenance, dominant failures, potential refurbishment activities and likely risks are identified and captured in the model for informed, long term asset investment decision.