No abstract

When electrical discharges occur in sulphur hexafluoride gas (SF 6 ) lower fluorides are produced within the discharge, and they in turn react readily with impurities, insulators and the electrodes. The final stable compounds formed include sulphur oxyfluorides and sulphur oxides. The aim of the present work was to optimize an analytical method for determining the decomposition products, and finding the dependence of the reaction route followed on the reaction conditions (input energy, contaminants present in the system). By performing model experiments and using various GC/MS techniques, several decomposition products were identified and correlations found between the abundances of the individual components and the decomposition conditions.

Furans are amongst the decomposition products which are generated by the degradation of cellulose in paper. Paper insulation is used in capacitors, cables and transformers. These furans dissolve in the impregnating mineral oil, and a method, involving liquid/liquid extraction, solid phase extraction and high performance liquid chromatography, has been developed to determine the concentration of 2-furfural the most stable compound in oil. The degradation of paper is being examined in order to find correlation between the change in dielectric and mechanical properties and the increase in concentration of 2-furfural in the oil.

When electrical discharges occur in sulphur hexafluoride gas (SF 6 ) lower fluorides are produced within the discharge, and they in turn react readily with impurities, insulators and the electrodes. The final stable compounds formed include sulphur oxyfluorides and sulphur oxides. The aim of the present work was to optimize an analytical method for determining the decomposition products, and finding the dependence of the reaction route followed on the reaction conditions (input energy, contaminants present in the system). By performing model experiments and using various GC/MS techniques, several decomposition products were identified and correlations found between the abundances of the individual components and the decomposition conditions.

In thermally stimulated exoelectron emission (TSEE) dosimetry the irradiation is generally executed in air while the read out is in methane. Under these conditions adsorption/desorption effects appear which influence the exoemission. BeO:Li and BeO:TiO 2 ceramics were compared from this point of view. The effect of adsorption/desorption was studied in such a way that in the cycles of irradiation/read-out the cooling down was executed successively in a methane atmosphere or in air. The TSEE curves of the BeO:TiO 2 ceramic were more influenced by the cooling atmosphere than those of the BeO:Li ceramic. In order to explain this result the thermal desorption spectra of these materials was taken.