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.
Uma Discussão sobre a Análise de Descargas Parciais para o Prognóstico de Falhas de Cabos Isolados e Gerenciamento de Ativos
Resumo—Este trabalho apresenta uma criteriosa revisão bibliográfica e uma discussão sobre a avaliação do estado da isolação de cabos isolados de média e alta tensão baseada na análise de descargas parciais, além da formulação de planos de manutenção e de gerenciamento de ativos baseados neste mesmo fenômeno. São apresentados os possíveis métodos de detecção de descarga parciais e os sensores adequados para cada aplicação, além de métodos para a estimativa do tempo de vida restante de cabos isolados empregando-se o valor da descarga aparente medido. Por fim, são mostrados diferentes métodos e sistemas que aplicam as descargas parciais como um parâmetro de auxilio no planejamento da atividade de manutenção preditiva e gerenciamento de ativos.
Overproduction of a truncated poly (vinyl alcohol) dehydrogenase in recombinant Pichia pastoris by low-temperature induction strategy and related mechanism analysis
Based on the N-terminal sequencing of poly (vinyl alcohol) dehydrogenase (PVADH), a 1,644-bp gene encoding a truncated PVADH (tPVADH) was amplified using the synthetic gene (GenBank accession No. JQ235753) as a template, and was further transformed into Pichia pastoris GS115 with the vector pPIC9K. The maximal tPVADH activity reached 546 U/mL in shake flask. The influence of methanol concentration and induction temperature on tPVADH production was further investigated in 3-L bioreactor. When the methanol concentration and induction temperature were controlled at 15 g/L and 22 °C, respectively, the maximal tPVADH activity reached 8,464 U/mL, which was nearly 10 times that of mature PVADH expressed under the same condition and was the highest level ever reported. The reason responsible for the significant improvement of tPVADH production at low induction temperature was explored in terms of cell viability, extracellular proteases activity, and alcohol oxidase activity.