A bidirectional, ultra-fast DC-breaker, such as the breaker technology offered by SCiBreak, can with great benefits be used also in AC-systems. Especially in 16.7 Hz railway applications, the ability to dramatically reduce the total fault clearance time brings a unique and valuable tool to the grid owners.
The requirements on and possibilities enabled by a fast-acting fault detection system will be investigated in the form of a EUREKA-project called LimBreak-Rail.
The project will be carried out as a collaboration together with the innovative Finnish SME Arcteq, which develops detection systems for both 50 Hz and 16.7 Hz applications. A fault detection system will, as a part of the project, be demonstrated and tested in the grid of the Swedish national railway operator, Trafikverket.
During last week, SCiBreak AB tested a DC circuit breaker module prototype at the KEMA laboratories of DNV GL, as a task within the EU-project PROMOTioN. A fault current of 10.8 kA was delivered by short circuit generators and was interrupted against a transient voltage exceeding 40 kV.
These tests verify the function of the developed technology and constitute a major milestone for SCiBreak. The fault current was interrupted, and the corresponding energy of 0.6 MJ was dissipated in surge arresters included in the module. An artificial zero-crossing was created in the vacuum interrupter by an oscillating current excited by a power electronic converter. An ultra-fast Thomson coil actuator created the necessary contact separation in less than 3.5 milliseconds after the trip order was received by the DCCB module.
The photo below shows the tested module surrounded by engineers from KEMA Laboratories and SCiBreak.
SCiBreak got some good news for Christmas, a significant milestone was reached. For the first time, a 10 kA current was interrupted against a recovery voltage of 40 kV with SCiBreak’s technology. After ramping up the ratings of the prototype during the whole year of 2017, we thus reached our initial target.
The current was successfully commutated to the energy absorption branch within 3 ms after the trip order was given to the circuit breaker. This was achieved thanks to the ultra-fast main interrupter which is operated with our Thomson-coil actuator.
In the picture below, the measured resonant current reaches the same value as the fault line current at 800 us. At that moment, the arc is extinguished and the voltage across the breaker increases to a voltage level of nearly 40 kV.
These current and voltage levels correspond to the test that will be performed at the KEMA laboratory next june. To be continued!
SCiBreak has been accepted as a partner in the PROMOTioN project, which is part of the EU-financed Horizon 2020 program. The project seeks to develop meshed HVDC offshore grids on the basis of cost-effective and reliable technological innovation. It gathers more than 30 partners among manufacturers, TSOs, consultants and academia and has a budget of more than 50 MEUR.
SCiBreak will contribute in several ways to the project.
SciBreak is moving into new facilities in Kallhäll north of Stockholm. The new facilities comprise 100 m2 in the ground floor for test setup and workshop and 100 m2 office is available on the upper floor.
SCiBreak will,together with the Swedish TSO Svenska Kraftnät and the Belgian university KU Leuven, carry out a development project — HIBREAK — to develop and verify a high-speed DC circuit breaker module for 40 kV, 10 kA with operation time below 5 ms. The project runs during 2017-2018 and includes testing for Proof Of Concept for validation of SCiBreak’s DC circuit breaker technology.
The project will be funded by Innoenergy, the Swedish Energy Agency and Svenska Kraftnät.