A Study on the Reliability of Polyester Insulators Blended with Borax
Tracking is the main factor which limits the safe working electric stress of insulation in power system applications. Polymer samples have been tested in laboratory conditions according to ASTM D2303 on accelerated inclined plane tracking test. In this paper, a model based on improved Weibull statistics is proposed for estimating the breakdown time of polymeric insulating materials with borax. The confidence intervals of the Weibull shape parameter and the Weibull scale parameter are determined for the borax concentration values using the Weibull 7++ program.
Experimental and numerical investigation of alumina trihydrate effect for improvement of polymer flashover voltage strength
Abstract Flashover voltage is considered one of the important factors affect the Power system reliability. Environmental conditions and filling of insulators are parameters should be considered in flashover voltage evaluation. In this work, laboratory studies are carried out on insulator with Alumina Trihydrate [ATH] filling at different concentration and different weather conditions to investigate the flashover voltage. The evaluation of flashover voltage is carried out at three conditions dry, wet and salt wet condition. In each test, four different lengths with different filling concentration are considered. Several curve fitting methods are used to obtain an equation of flashover voltage. The obtained equation first is only function of filling at different insulator lengths with approximately zero errors. Although the accuracy of this method, it gives flashover voltage only at discrete lengths. Thus, for continuous length validation the flashover is fitted again to be a function of both length and filling.
Entzündlichkeit und Flammhemmung bei organischen Hochpolymeren und ihre Beziehungen zur chemischen Struktur
Entzundlichkeit und Flammstabilitat sind mehr relative als absolute Begriffe. Die Grundlagen dieser Eigenschaften werden an Hand von Stabilitatsdiagrammen und Verbrennungsmechanismen dargestellt. Die Verbrennung von Polymeren fangt mit der Pyrolyse an. Es besteht eine deutliche Korrelation zwischen dem Oxygen Index als Masstab fur die Entzundlichkeit einerseits und dem Pyrolyse-Ruckstand eines Polymers anderseits. Eine andere Korrelation besteht zwischen dem Oxygen Index und der spezifischen Verbrennungswarme. Aus diesen Zusammenhangen konnen interessante Folgerungen fur die erwunschten Polymer-Strukturen und fur die moglichen flammhemmenden Additive gezogen werden. Es wird eine Klassifikation von flammhemmenden Additiven gegeben. Zum Schlus wird die Entwicklung von flammfesten Polymeren beschrieben.