Analyse der elektrischen Durchschlagmechanismen in syntaktischen Schäumen

  • Analysis of electrical breakdown mechanisms in syntactic foams

Tröger, Karl Alexander; Schnettler, Armin (Thesis advisor)

Aachen : Mainz (2009)
Dissertation / PhD Thesis

In: Aachener Beiträge zur Hochspannungstechnik 11
Page(s)/Article-Nr.: 147 S. : graph. Darst.

Zugl.: Aachen, Techn. Hochsch., Diss., 2009

Abstract

Functionality, a long lifetime and a high reliability are still key requirements for the development of high voltage apparatus and equipment. In addition to these properties, also a light and compact design is becoming more and more important. This trend can especially be observed in the case of mobile or moving systems. An optimization in respect to volume and weight can often not be achieved by modifying the general assembly and the circuitry. This measure normally leads to a constraint of its functionality. A popular alternative to reduce the size and the weight of equipment is therefore to apply a lighter and more efficient insulation system. A promising possibility for the fulfillment of this task is the utilization of syntactic foam as insulating material. Syntactic foam is produced by mixing hollow and gas-filled spheres with a diameter of less than 200 µm into a suitable polymer. By changing production parameters like the volume ratio and the diameter of the hollow spheres, the mechanical properties of the material (specific gravity, mechanical strength etc.) can be modified and adjusted to the requirements of the application. The influence of a parameter modification on the electrical properties of syntactic foam is by contrast not known. The electrical properties of syntactic foam on the basis of epoxy resin and glass hollow spheres as well as the effect of different production parameters on its electrical behavior are determined in this work. The effect of different production parameters on the electrical behavior is also tested with focus on the determination of the short-time electrical strength and the partial discharge behavior of the foam. High AC- and DC- overloads lead to an electrically inflicted damage of the foam structure which precedes breakdown. The processes that electrically inflict damage on the material are documented in further experiments. Their detection and analysis is achieved with the help of scalar electron microscope pictures. On the basis of the presented research results, a heuristic model of the electrically triggered breakdown mechanisms is developed, concluding with a plausibility check of the made assumptions.

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