The Fast and Selective Switching (FASS) project, carried out by the Physikalisch‑Technische Bundesanstalt (PTB) in Braunschweig and Berlin from 1 January 2020 to 30 June 2023, aimed to advance measurement technology for direct‑current (DC) networks that are increasingly used in low‑ and medium‑voltage distribution and islanded systems. The project was funded by the German Federal Ministry of Education and Research under grant 03EI6005E and supported by the industry consortium comprising Siemens AG, Doduco GmbH, Heraeus Holding GmbH, and Rockwell Automation Switzerland GmbH. Its goal was to provide reliable, efficient, and economical energy supply by developing selective protection devices and measurement equipment that can handle the unique challenges of DC systems, such as high fault currents and voltage spikes.
Technically, the project produced a suite of mobile calibration setups for transient high currents and voltage spikes. The surge‑current calibration system was designed to generate controlled, high‑amplitude pulses that mimic fault conditions, enabling the characterization of contact devices and protective relays. A separate mobile voltage‑spike calibration unit was built to produce rapid voltage transients, allowing accurate testing of voltage‑sensing components. Both systems include reference voltage dividers and current‑measurement devices that provide traceable, high‑accuracy data. The measurement devices were procured, calibrated, and characterized, with performance metrics such as bandwidth, accuracy, and repeatability documented in the project reports.
A key scientific outcome was the development of intelligent, magnet‑field‑controlled mechanical switches for DC systems. By actively steering the magnetic field during contact closure, the switching time was significantly reduced compared to conventional devices, improving the selectivity of fault isolation. The project also investigated material selection for contacts in power‑electronics‑based DC networks, identifying alloys that balance conductivity, wear resistance, and thermal stability. The combined DC and impulse energy of fault events was calculated using the measured current and voltage waveforms, providing a basis for designing protective devices that can withstand realistic fault conditions.
The project’s results are organized into work packages (AP 1–AP 5). AP 2 focused on defining technical boundaries, building the mobile calibration setups, procuring and characterizing measurement equipment, and determining fault energy. AP 3 and AP 5 addressed further device development and standardization support. The final report includes a plan for exploitation, outlining how the developed measurement systems and switching devices can be integrated into industry standards and commercial products.
Overall, the FASS project delivered advanced, mobile calibration equipment for transient DC phenomena, a new class of fast, selective DC switches, and comprehensive data on fault energy and contact performance. These contributions support the development of robust DC distribution networks and help drive the standardization of protection schemes for future renewable‑energy and power‑electronics‑based systems.