Ausschaltvermögen von Mittelspannungs-Lasttrennschaltern bei Verwendung atmosphärischer Lösch- und Isoliergase

  • Interruption Capability of Medium Voltage Load Break Switches Utilizing Atmospheric Quenching and Insulation Gases

Bendig, Marvin; Schnettler, Armin (Thesis advisor); Niayesh, Kaveh (Thesis advisor)

1. Auflage. - Aachen : Verlagshaus Mainz GmbH (2020)
Book, Dissertation / PhD Thesis

In: Aachener Beiträge zur Hochspannungstechnik
Page(s)/Article-Nr.: 1 Online-Ressource (X, 130 Seiten) : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2020

Abstract

Medium voltage load break switches are essential components in today’s energy systems. As a part of secondary medium voltage switchgear they are responsible for interrupting load currents and ensuring a safe insulation distance in the off-state. In the course of the ongoing medium voltage grid expansion, mainly gas insulated switchgear filled with sulfur hexafluoride (SF6) is installed. The use of SF6 permits a compact and reliable switchgear design. In contrast, SF6, with a global warming potential of 23.500 CO2 mass equivalents, is the most potent greenhouse gas known. A substitution of SF6 while keeping the size and reliability of the switchgear is desirable. In the process of subtituting SF6 in medium voltage switchgear the load break switch is the critical component, as the gas serves as insulating and quenching medium. Possible substitutes have a lower dielectric strength as well as a lower arc quenching capability. Hence, a fundamental redesign of the load break switch is necessary. The objective of this thesis is the identification and quantification of the main influencing parameters on the switching capability of a medium voltage load break switch filled with an alternative insulating gas. In a parametric study the thermal interruption capability and the dielectric recovery are determined for different design parameters of a model load break switch. A sufficient arc cooling is essential for a sufficient interruption performance and can be ensured by a convective cooling by axial arc blowing as well as by the “Hartgas“-effect, resulting from polymer ablation close to the arc. Both mechanisms can be influenced by the design of the load break switch. From the experimental results of the study a catalog of design criteria is derived. These criteria are used to develop a demonstrator of an environmentally friendly medium voltage load break switch. At the end of the thesis, the demonstrator’s interruption capability is successfully tested according to standards.

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