Insulating paper ageing and furfural formation

Abstract

Abstrad: Transformer condition monitoring is carried out regularly to establish state of the health of transformer. Based on results corrective actions are taken to preserve and prolong the lifetime ofthe unit. All insulation materials used in construction of transformer are, made from organic compounds and therefore, decomposes and deteriorates at high temperature. Insulating oil in service will oxidise and eventually reach to a step, which is not kit for the purpose. In such case maintenance guide recoinmend to change the oil. Insulating paper in service is similarly subjected to heat and also damaged by the oil oxidation products. The same maintenance regime is not applicable to the paper and reaction of paper degradation is not reversible, therefore life of transformer is life ofthe paper. In practice, it is impossible to have an accurate condition asessment without opening the transformer and have paper sample. In the other hand this is impossible practice and condition of the paper is assessed indirectly. It is established earlier that furfurals are by-products of paper ageing and can be used as indication of paper ageing. However, to relate furfuraldehyde, also named furfural (ZFAL), content of a unit to age and extend of paper deterioration more research and laboratory studies are required. This paper describes laboratory studies of paper ageing and relating by-product of paper ageing to state of the insulating paper. Oil and paper are aged at different temperature, ZFAL, gases and moisture of aged samples are measured. A model for paper ageing is established.

Caracterização de bauxita ativada antes e depois da saturação com óleo mineral isolante

“…Estes depósitos dificultam o processo de convecção do óleo e a troca térmica do sistema espira/óleo, resultando em superaquecimento, diminuindo, assim, a eficiência do sistema de isolamento óleo/papel e, conseqüentemente, a vida útil do equipamento. [3][4][5][6] A regeneração do óleo mineral isolante é definida como um processo que elimina, por métodos químicos e/ou por adsorção, contaminantes ácidos e coloidais e produtos de deterioração do óleo, de forma a se obter um produto com características similares às do óleo novo. A regeneração do óleo mineral isolante com bauxita (embora não se trate de um mineral, mas sim de um minério, esse é um termo mais usual que "bauxito"), 7 como meio adsorvente, recupera as características físico-químicas originais do óleo removendo seus produtos de oxidação.…”

Lifetime Monitoring and Estimation Strategy for Large Power Transformer

“…The method is mainly based on thermal aging model, electrical aging model and electro-thermal aging model, as (2), (3) and (4) [25].…”

“…It happened seldom that the decrease of insulation's electrical property causes the termination life of a transformer. So the aging degree of solid insulating materials in oil-paper insulating power transformers is mainly determined by the mechanical strength, but not the electrical strength [3]. Cellulose is the main component of solid insulating materials and its mechanical strength mostly comes from the bonds in and between cellulose molecules.…”

A Holistic Framework for Supporting Maintenance and Asset Management Life Cycle Decisions for Power Systems

“…Typical furan compounds that emerge from such polymerisations include 2-furaldehyde (2-FAL), 2-acetylfuran (2-ACF), 2-furfuryl alcohol (2-FOL), 5-methyl-2-furaldehyde (5-MEF) and 5-hydroxymethyl-2-furadehyde (5-HMF). Extensive information with regards to measurement and classifications of furanic compounds are available in an earlier study by Pahlavanpour and Martins [78]. Furan tests are often recommended for ageing PTs (typically those more than 25 years old) or if signs of overheating are observed.…”