Affordable Cable System Reliability and Life Extension Strategy
Today, there is increased pressure for electric distribution cooperatives to maintain system reliability without increasing membership costs. This challenge is further compounded by the need to maximize existing legacy infrastructure. While membership reliability is a key consideration, a static economy, a commitment to a lower carbon footprint and the need for rate stability are also key factors that translate into increased operating costs. Many consider age to be the silent killer of America's critical infrastructure. The large fleets of equipment deployed by electric utilities and limited real-time monitoring makes it nearly impossible to know the duty each specific piece of equipment has experienced, thus age alone is used as the main determinant of remaining life. The economic and staffing requirements to replace these aged fleets based solely on in-service life is untenable. The need to find a lean approach to better address this challenge has lead to new technologies that provide detailed information about the equipment's true health or condition to allow the right measure of asset rehabilitation, replacement or extended deployment using actual condition assessment. There are millions of miles underground power distribution systems in service today that are operating beyond the original accounting defined depreciation life and failing at an ever increasing rate. Until recently, management of these underground assets was particularly challenging because once put into service, their concealment prevents visible inspection. A new cable life extension process is revolutionizing the industry by providing a means to field assess, rehabilitate and then certify cable systems to like new status. The proven assessment technology has certified more than 90,000 underground cable systems around the world and has shown that over 75% of aged assets still perform as well or better today as they did when they were first installed, decades ago. The Federal Energy Regulatory Commission's ("FERC") decision to allow capitalization of this new cable life extension technology is prompting many utilities and electric cooperatives coast to coast to reduce cable replacement budgets and make a positive impact on membership costs. These forward looking utilities have experienced extended capital reach, lowered operating and maintenance (O&M) expenditures, efficient resource utilization, minimal property intrusion and a dramatic real-time improvement in cable system reliability.
Diagnóstico e Monitoramento de Cabos Isolados através da Análise de Descargas Parciais: O Estado da Arte
This paper presents a broad and detailed literature review on the use of partial discharges measurement and analysis for the diagnosis and condition monitoring of medium and high voltage cable insulation. All the methods for detection of partial discharges activity have been discussed, along with the appropriate sensors to be employed in every one of them, highlighting the advantages, limitations and applications. It is also presented a discussion on the methods and parameters for the measured data processing and how they influence the distinction among signals actually related to partial discharges and external noises. Finally, in order to illustrate the use of such techniques, case studies reported in the literature have been selected, where monitoring methodologies based on the partial discharges level control have been adopted to derive maintenance strategies for the company. Resumo: Este trabalho apresenta uma ampla e minuciosa revisão bibliográfica sobre a avaliação de descargas parciais para o diagnóstico e monitoramento do estado da isolação de cabos de média e alta tensão. Todos os possíveis métodos de detecção da atividade de descargas parciais, com os respectivos sensores adequados para cada situação, são discutidos de forma a explicitar suas vantagens, limitações e aplicações. É apresentada também uma avaliação dos métodos e parâmetros utilizados no tratamento dos dados de medição e discutido como os mesmos influenciam na distinção entre os sinais associados a descargas parciais e ruídos externos do sistema. Por fim, de forma ilustrar a aplicação das técnicas discutidas, são apresentados relatos de casos encontrados na literatura nos quais foram empregadas metodologias de monitoramento baseadas no controle dos níveis de descargas parciais em cabos isolados e adotadas estratégias de manutenção baseadas nesse princípio.
The power of negativity : selected writings on the dialectic in Hegel and Marx
Part 1 The Philosophic Moment of Marxist-Humanism Part 2 Studies in Hegalian and Marxian Dialectics, 1956-63 Part 3 Theory and Practice at a Turning Point, 1964-71 Part 4 After Philosophy and Revolution: Hegel's Absolutes and Marx's Humanism, 1972-81 Part 5 The Changed World and the Need for Philosophic New Beginnings, 1982-87