Analysis of 3 kV DC Contact Line High-Speed Circuit Breaker Unit Protection Scheme Limitations

Abstract

The High-Speed Circuit Breaker (HSCB) is a de-facto electro-mechanical contact line protection device employed in the 3 kV DC traction power supply system. The breakers installed at the terminal ends of the contact line make a unit protection scheme configuration. While the HSCBs seem to trip under fault conditions, there is an unknown source that keeps on supplying residual current into the faults. This necessitates some explanation of the source of energy of the continual flow of residual energy. This paper makes an analysis of the limitations in the HSCB unit protection scheme using MATLAB simulation and how the scheme can be optimized with digital protection devices augmented with a peer-to-peer transfer trip as an end-to-end protection solution.