To develop a set of profiles for a family of Alliant Energy´s oil circuit breakers

Electric utility companies use several kinds of maintenance practices such as preventive, corrective and predictive, or condition based, to ensure reliability and availability of their transmission and distribution systems to serve customer needs, while at the same time, maintaining employee safety. Condition-based maintenance techniques are the new standards being applied to a variety of substation equipment including transformers, load tap changers, and circuit breakers. This paper concentrates on one element of an oil circuit breaker predictive maintenance program at the Alliant Energy Corporation. Circuit breakers are devices that protect personnel and equipment from injury or damage during high fault current conditions such as lightning strikes, ice storms, etc. Oil samples are taken from circuit breakers, and gas and particle content, along with fluid quality, are determined through analysis. These figures are indicators of the conditions of contacts, interrupters and other load path components internal to the circuit breaker. Although several studies have been undertaken on interpreting results from the gas analysis, this work goes beyond that by applying the use of statistical concepts to analyze the data and identify commonalities based on manufacturer, breaker model and nominal voltage. Various parameters are being considered in an effort to identify their significance, including ratios of individual heating gases to acetylene and the impact of operations under normal and fault conditions. An emphasis will be laid on profiling a family of circuit breakers, and then developing an optimum maintenance schedule for them by analyzing the condition indicators.