Throughput Capacity of Metal-Oxide Surge Arresters Used as Part of DC Vacuum Circuit Breakers
The article presents the results from numerical simulation and experimental investigation of the throughput capacity of Type 0PN-TP-3.0/4-UKhL 3 metal-oxide surge arresters (MOSA) used as part of a high-speed automatic DC vacuum circuit breaker for the maximal voltage equal to 4.1 kV. The vacuum circuit breaker operation principle isbased on forced lymaking the disconnected current to pass through zero by means of arranging opposite discharge of a pre-charged capacitor. A numerical model is proposed, whichhas been implemented in the Matlab 6.5 software package using the Sim Power Systems library. The applicability of the model has been experimentally confirmed in disconnecting a current by a vacuum circuit breaker through simulating a short-circuit fault current with different current growth rates. The investig a tions were carrie doutata heavy-current high-voltage test bench realizing an oscillatory circuit involving a capacitor bank for the maximal voltage of up to 6 kV and the total energy storage capacity of up to 1.8 MJ. The numerical model satisfactorily describes the processes in disconnecting acurrentina DC vacuum circuit breaker with forcedly making the current to cross zero. The model also make sit possible to estimate the amount of energy dissipated in the MOSA unit in disconnecting a short-circuit fault current. Byusing the proposed model itis also possible to estimate the number of parallel-connected MOSAs in disconnecting emergency currents in traction DC power supply networks with an inductance ranging from 5 to 15 mH.