Optimization of process parameters for producing hardened-glass insulating parts for high-voltage insulators

Abstract

The optimization of process parameters and hardening equipment for glass insulator parts that have nonuniform thickness and complex configurations is described. Technical solutions that improved the quality and reliability of insulators are considered.Hardened glass insulators are currently the most common linear insulators for all voltage classes both for direct and alternating current in most countries. Therefore, optimizing the process parameters and equipment for producing insulators is a topical problem in the context of improving the quality and reliability of insulators.The processes of batch preparation, glass melting, glass melt feeding, and molding hardened insulation glass particles are similar to the processes in the production of molding glass articles but have stricter requirements on glass melt quality. The heterogeneity of glass registered by the centrifuge method should not be higher than 1.8°C. Heating molded insulator parts, which have different thickness and complex configurations, to the temperature of hardening and cooling is rather difficult with respect to maintaining the geometrical shapes of articles and preventing excessive temperatures and stress gradients in hardening.For the purpose of developing effective technical solutions to ensure high-quality hardening and reliable service of insulating parts made of low-alkali glass S-14, we determined the dependence of the rate and quality of heating insulator parts on temperature, wavelength of radiant flows from the heaters, and convection flows in the furnace. Furthermore, we investigated the dependence of hardening quality on the cooling conditions and rejection efficiency and the dependence of reliability of insulating parts on thermal control parameters and relaxation of residual stresses in the production of parts.The hardening parameters for flat glass are sufficiently well studied. We investigated the rate and quality of heating up to the hardening temperature of molded glass articles of varying thickness and complex configurations using samples of sizes 120´35´13 mm with a thermocouple inserted in the inner layer and insulator parts. Molded samples and insulators parts were placed on special supports at a distance of 100 m inside a continuous electric furnace for heating them to the hardening temperature. The variable parameters in the furnace were the transport grid velocity, the volt-ampere characteristics at the upper and lower heaters across the zones, and the heater spiral section, in order to vary the radiant energy wavelength and efficiency.The temperature curves inside the furnace were recorded using a thermocouple, and the zones were monitored by potentiometers. The glass surface temperature at the entrance and at the exit from the furnace was monitored by an ITS Izolyator thermometer. The spectral characteristics of glass were analyzed at the Kiev Branch of the VIASM JSC. The deformation of the samples was measured with a IZV-1 instrument and that of the insulator parts was measured with a height gage. The time of articles...