ISBN 9783843956727

978-3-8439-5672-7, Reihe Energietechnik

Timo Meyer
Post-arc current measurement method for vacuum interrupter

130 Seiten, Dissertation Technische Universität Braunschweig (2025), Softcover, A5

Zusammenfassung / Abstract

The vacuum circuit breaker is an alternative to the green house sulphur hexafluoride circuit breaker used in high-voltage networks. In order to replace the sulphur hexafluoride device completely, new vacuum interrupter designs are being investigated. An objective evaluation criterion is needed to assess their successful interruption.

One such criterion is the post-arc current. It provides insight into the residual plasma remaining in the interruption gap after contact separation. If this residual plasma does not dissipate quickly enough or if the rising transient recovery voltage is too high, a restrike or reignition may occur. By measuring the post-arc current, a threshold can be defined above which the interruption gap is likely to fail. A switching operation is deemed successful only if neither restrikes nor reignitions takes place. However, experiments by different researchers have not been comparable, due to disturbances introduced by their test circuits.

This thesis develops a methodology that separates the post-arc current from measurement-circuit-induced interference. That makes analyses more precise and renders the results comparable and traceable for the first time. The results reveal a measurement-error-corrected correlation between the observed post-arc current, short-circuit currents, and complex vacuum-arc behaviour. These findings offer new insights into future applications of vacuum circuit breakers in high-voltage systems. Short-circuit currents up to 15 kARMS were investigated at a standard contact gap of 10 mm.

The proposed methodology successfully isolates the post-arc current from disturbances, greatly enhancing the analysis of current behaviour and paving the way for future measurements at higher voltage levels or in DC systems. In doing so, it opens deeper insights into the dynamics of the after-current and its practical applications.