Die Idee dahinter ... : Aspekte zur Gestaltung lernreicher Lehre

Der Band umfasst zahlreiche Beispiele von Lehrenden, die ihre Veranstaltungen in mehreren Aspekten ‚lernreich(er)’ gestaltet haben. Die Konzepte wurden alle im Rahmen des Vertiefungsmoduls des Programms „Professionelle Lehrkompetenz für die Hochschule“ des Netzwerks "hochschuldidaktik nrw" an der Universität Siegen entwickelt oder weiterentwickelt. Die elf Beiträge umfassen ein breites Spektrum an Veranstaltungsformaten und Fächern: Natur- und Ingenieurwissenschaften sind ebenso vertreten wie Architektur, Pädagogik, Soziale Arbeit und Literaturwissenschaft. Bei den Veranstaltungen handelt es sich um Praktika, Seminare, Übungen usw., oft mit Projektcharakter bzw. -elementen, häufig auch mit wechselnden Lernorten, semester-begleitend oder kompakt

Impact of the Initial Transient Interruption Voltage (ITIV) on the Design and Operation of Hybrid Current-Injection DC Circuit Breakers

In hybrid DC circuit breakers with current-injection, the arc in the mechanical switch is extinguished with a current pulse. After the arc extinction, the voltage increase across the mechanical switch must be limited in order to avoid an arc reignition. The voltage across the MS is usually assumed to be equal to the voltage across the capacitor CCI in the current-injection circuit, which increases slowly due to slow charging of the capacitor by the fault current. However, in reality the voltage across capacitor CCI is usually not zero at the point in time of the arc extinction. This results in high transient voltages across the mechanical switch, the so called so-called initial transient interruption voltage (ITIV) after the arc extinguishes. However, a fast increasing ITIV can lead to a thermal reignition of the arc. Therefore, it is crucial for the design of a DC-CB to understand, which effects contribute to a high ITIV. In this paper, these causes and the influence of the ITIV are investigated. Furthermore, the beneficial influence of grading capacitors parallel to the MS is investigated. Finally, an optimization of a DC-CB including the ITIV and its results are presented for a typical implementation of a current-injection DC-CB

Optimization of Hybrid Current-Injection Circuit Breakers Including Mechanical Switch Limitations

Circuit breakers with current injection enable fast interruption of fault currents in DC grids. Independent of the topology, a high number of semiconductors and capacitors is required. The minimum required number of semiconductors and capacitors depend mainly on the system voltage and the maximum fault current. However, also the MS characteristics have considerable influence on the required number of semiconductors and capacitors. Therefore, in this paper the influence of the MS characteristics on the arc extinction and the influence of the arc voltage on the DC-CB design is presented. In addition, optimization procedures for current injection circuit breaker are presented, which include the MS characteristics and four different possibilities to include the arc voltage. Finally, three DC-CB topologies are compared in terms of number of semiconductors and capacitors

Hybrid Circuit Breaker for HVDC Grids with Controllable Pulse Current Shape for Fast Fault Clearing

This poster presents two new hybrid Circuit Breaker (hCB) with current injection circuit to extinguish the arc in the MCB after opening. Compared to other hCBs, this hCBs uses a current injection circuit, which is able to adapt the pulse current and so ensures a low current slope at the arc extinction to prohibit a reignition. Additionally, it is shown that with the increased controllability the volume of the passive components can be decreased compared to existing solutions

Comparison of Energy Dissipation Concepts for DC Circuit Breakers

In DC grids, DC circuit breakers (CB) are used to interrupt currents in case of a fault and to dissipate the remaining energy in the line. Independent of the actually DC CB concept, different energy dissipation concepts can be used, which also influence the performance of the DC CB. In this paper, the energy dissipation with different circuit arrangements, where the energy is dissipated in a single loop, in two loops or in two coupled loops, are discussed and compared. Additionally, the effect of different voltage waveforms across the DC CB and the distribution of the current limiting inductance on the input and the output side of the DC CB are investigated