15.05.2020

TU Ilmenau researches new circuit breakers for the energy transition

Haus mit PhotovoltaikanlageiStockphoto/filmfoto

In a major joint project, Technische Universität Ilmenau is developing mechanical circuit breakers for electrical devices and systems that operate on the basis of direct current. Up to now, the power grid in Germany has been largely based on alternating current, but in the course of the energy transition, more and more devices are using direct current: photovoltaic systems on house roofs, electric cars or even charging stations for mobile phones. New types of circuit breakers are now needed to protect them, because the switches commonly used to date used the properties of alternating voltage. The research project "FASS Fast and selective Switching" is being funded by the Federal Ministry for Economic Affairs and Energy at the TU Ilmenau with 1.3 million euros for three years.

You put the plug into the socket and want to turn on the vacuum cleaner, but clack! suddenly the lights in the whole apartment go out: The fuse or circuit breaker has blown. Every day across Germany, circuit breakers protect electrical devices and save lives in the process. But the energy transition brings new challenges for energy technology. The German government has set itself the goal of significantly increasing the share of electricity generated from renewable energy sources while at the same time reducing energy losses during transport and consumption. Both the systems for generating renewable energies, such as photovoltaic systems, and many consumer devices such as PCs, televisions or LED lighting are already based on direct current. Therefore, the switch from conventional alternating current to direct current networks is the order of the day for households as well as for industry. However, the different properties of AC and DC require new technologies to protect electrical systems and equipment. New types of circuit breakers are needed to switch them off in just a few microseconds or milliseconds.

Grafik Stromkreis mit GleichstromschutzschalterTU Ilmenau / Matthias Streck

The biggest challenge in developing a DC circuit breaker is to safely and quickly shut down the circuit in any conceivable fault condition, such as a short circuit. After the fault has been detected, switching contacts open inside the circuit breaker and an arc occurs. In order to interrupt the current flow and prevent a fire, this arc must be extinguished immediately. However, while with alternating current the arc extinguishes itself at the latest at the moment when the current changes direction this happens hundreds of times per second with direct current which flows continuously in a certain direction as required additional measures must be taken to ensure that the arc is artificially extinguished, so to speak. How this is done is now being researched in the Electrical Apparatus and Switchgear Group at the TU Ilmenau under the scientific direction of Prof. Frank Berger. His idea: "We drive the arc into an extinguishing device with the help of a strong magnetic field, which increases the power requirement of the arc and thus also its resistance." This is no easy task, because in order to switch off the circuit quickly enough, the arc must be driven into the quenching device as early as possible, as soon as the contacts open, in just a few microseconds and this must also function absolutely reliably in every single fault case.

TU Ilmenau
The FASS project team around project leader Prof. Berger

The basic experimental research required to be able to develop innovative circuit breakers is now being carried out in the Electrical Apparatus and Switchgear Group at the TU Ilmenau under the scientific direction of Prof. Berger. Accompanied by the groups for Materials for Electrical Engineering and Electronics and Probability Theory and Mathematical Statistics, the university offers expertise not only in switchgear technology, but also in changes in materials caused by switching processes and in data analysis. The task of the Ilmenau scientists is clear: they now have three years of hard basic research ahead of them to investigate the behaviour of electric arcs as a function of a strong magnetic field the basis for a functioning model circuit breaker in the age of the energy transition.

The FASS project is coordinated by E-T-A Elektrotechnische Apparate GmbH from Altdorf near Nuremberg, the world market leader in equipment circuit breakers. The Physikalisch-Technische Bundesanstalt in Braunschweig is contributing its expertise in measurement technology. The three research partners are supported by the Competence Center for Electrical Contacts Ilmenau (KEKI) in addition to E-T-A GmbH, the companies SIEMENS, Doduco and Heraeus.

 

Contact:
Prof. Frank Berger
Head of Electrical Devices and Systems
+49 3677 69-2837
frank.berger@tu-ilmenau.de