Study of Factors Determinant of Siliceous Electrical Porcelain Resistance to Structural Degradation

The subject of this study was investigation of the factors that have a decisive influence on the resistance of siliceous porcelain to degradation processes. There was tested material C 110 type, which is widely used for the production of low-voltage (LV) elements such as insulators and bushings. On the basis of mechanical-acoustic and microscopic research of small-sized samples, which were subjected to compression, there were distinguished successive stages of degradation of the material structure. In the authors’ opinion, they have a reference to the ageing process, taking place during many years of work under operating conditions. Thus, it was possible to assess the structural factors that determine the durability and reliability of LV electroinsulating elements. The results were related to electrical aluminous porcelains.

CHARACTERIZATION OF ELECTRICAL PORCELAIN INSULATORS FROM LOCAL CLAYS

In this thesis, the characterization of electrical porcelain insulators based on local clays has been investigated. Test samples were made by varying the quantities of feldspar and silica required to form a mouldable plastic body with each clay sample. The clay samples were bisque fired which is to 900°C and glazed before it was fired to 1250°C after air-drying. An electrical property such as dielectric strength (breakdown voltage) was determined for each test sample that survived the high temperature. The composition for optimum properties from Ekwulobia and Iva Valley clays each is at composition 3 of 60% clay, 25% feldspar and 15% silica; while for Nawfija clay, the composition for optimum properties was 50% clay, 30% feldspar and 20% silica. Porcelain insulators containing 50-70% clay, 20-30% feldspar and 10-20% silica were found to have requisite properties that make them suitable for domestic production of porcelains insulators from the clay samples studied.