Studies of the condition of insulation in aged power transformers. 2. Fundamental electrical and chemical considerations

For pt.1 see ibid. vol.2, p.1116-19 (July 1991). The authors address the question of remanent life in the insulation of aged power transformers. After reviewing the current techniques available for studying the condition of such insulation, new techniques are proposed based on sensitive analytical instrumentation recently developed for the scientific study of the chemical and physical structure of degraded synthetic polymers. An outline is given of a major research project being undertaken at the University of Queensland, with active participation by supply authorities and electrical manufacturers. The project´s research methodology is described, and some preliminary results are given to indicate early progress. The use of size exclusion chromotography appears to be very promising in identifying important components in insulation paper, by characterizing their molecular weights and molecular weight distributions. Preliminary results are given of electrical and chemical tests on insulation taken from an old 25 MVA 11/132 kV transformer